Argon laser punctal therapy versus thermal cautery for the treatment of aqueous deficiency dry eye syndrome

1. Pregnant Wistar rats were treated orally with a single dose of 100 microg 3,3',4,4'-tetrachlorobiphenyl (PCB 77)/kg b.w. or 10 microg 3,3',4,4',5 pentachlorobiphenyl (PCB 126)/kg b.w. on day 15 of pregnancy. The control rats received peanut oil at the same day. Developmental landmarks were assessed in all offspring rats and reproductive effects of PCB 77 and PCB 126 on male offspring were studied on postnatal day 65 (at puberty) and on postnatal day 140 (at adulthood). 2. The ano-genital distance as well as the ratio ano-genital distance to body length was reduced in male pups of the PCB 126 group and the age at vaginal opening was significantly delayed in the female pups. 3. Testis, brain weights and daily sperm production were permanently increased and seminal vesicle weights were decreased in male offspring of the PCB 77 group. In male rats of PCB 126 group, the brain weights were permanently increased and ventral prostate weights permanently reduced. In both PCB groups, however, serum testosterone concentration was reduced only at adulthood. Additionally, the male rats of the PCB 126 group showed alterations in sexual behavior. In these rats the number of mounts with intromissions was significantly increased. 4. The results of this study show that PCB 126 elicits some TCDD-like reproductive effects after in utero exposure, while the reproductive effects of in utero exposure to PCB 77 on male offspring may be attributed to the neonatal hypothyroidism induced by the substance during early fetal development. Further studies using multiple doses and providing thyroid hormone data will be necessary to support this hypothesis.     

90-day feeding and one-generation reproduction study in Crl:CD BR rats with 17 beta-estradiol

Over the past several years, there has been increasing concern that chemicals and pesticides found in the environment may mimic endogenous estrogens, potentially producing adverse effects in wildlife and human populations. Because estrogenicity is one of the primary concerns, a 90-day/one-generation reproduction study with 17 beta-estradiol was designed to set dose levels for future multigenerational reproduction and combined chronic toxicity/oncogenicity studies. The purpose of these studies is to evaluate the significance of a range of responses as well as to provide benchmark data for a risk assessment for chemicals with estrogen-like activities. This 90-day/one-generation reproduction study was conducted in male and female Crl:CD BR rats using dietary concentrations of 0, 0.05, 2.5, 10, and 50 ppm 17 beta-estradiol. Endpoints were chosen in order to evaluate both subchronic and reproductive toxicity. In addition, several mechanistic/biochemical endpoints were evaluated for their usefulness in follow-up studies. In the P1 generation, dietary administration of 2.5, 10, and 50 ppm 17 beta-estradiol produced dose-dependent decreases in body weight, body weight gain, food consumption, and food efficiency. At 10 and 50 ppm 17 beta-estradiol, minimal to mild nonregenerative anemia, lymphopenia, decreased serum cholesterol (50 ppm only), and altered splenic lymphocyte subtypes were also observed in the P1 generation. Additionally, at these concentrations, there were changes in the weights of several organs. Evidence of ovarian malfunction, characterized by reduced numbers of corpora lutea and large antral follicles, was observed at 2.5 ppm 17 beta-estradiol and above. Other pathologic changes in males and females fed 10 and 50 ppm 17 beta-estradiol included centrilobular hepatocellular hypertrophy; diffuse hyperplasia of the pituitary gland; feminization of the male mammary glands; mammary gland hyperplasia in females; increased number of cystic follicles in the ovary; hypertrophy of the endometrium and endometrial glands in the uterus; degeneration of seminiferous epithelium; and atrophy of the testes and the accessory sex glands. In the reproduction portion of this study, rats fed 10 or 50 ppm 17 beta-estradiol did not produce litters. While there was no evidence that the 50 ppm treated rats mated, 33.3% of the rats fed 10 ppm mated but did not produce litters. No effects on mating and fertility indices were observed in rats fed 0.05 and 2.5 ppm 17 beta-estradiol. Pup weights at birth were statistically decreased relative to control in the groups fed 0.05 and 2.5 ppm 17 beta-estradiol. Weights of the rats in the 0.05 ppm group recovered by postnatal day 4 and remained similar to control throughout the remainder of the study. The mean gestation length of the 0.05 ppm group was slightly, albeit not statistically significantly, shorter (0.5 days) than that of the control group, which may have contributed to the decrease in birth weight of the 0.05 ppm group. In contrast, the weights of the F1 generation rats fed 2.5 ppm 17 beta-estradiol remained decreased relative to the control group throughout the study. Parental administration of 17 beta-estradiol did not alter anogenital distance in male or female pups. The onset of sexual maturation, as measured by day of preputial separation in males and day of vaginal opening in females, was delayed in male rats fed 2.5 ppm (by 8.2 days) and was hastened in female rats fed 0.05 and 2.5 ppm (by 1.6 and 8.8 days, respectively). The age at vaginal opening ranged from 26 to 37, 26 to 35, and 21 to 25 days for rats fed 0, 0.05, and 2.5 ppm 17 beta-estradiol, respectively. Hence, the range of age at vaginal opening was similar between the control and 0.05 ppm group. The organ weight and pathologic alterations observed in the adult F1 generation rats were similar to those observed in the P1 generation rats. (ABSTRACT TRUNCATED)     

Effects of 2-ethylhexanoic acid on reproduction and postnatal development in Wistar rats

Reproductive toxicity of 2-ethylhexanoic acid (2-EHA) was studied in Wistar rats. The animals (24 animals per sex per group) were given 2-EHA as a sodium salt in drinking water at daily doses of 100, 300, or 600 mg/kg. Control animals received plain water. Male rats were exposed to 2-EHA for 10 weeks and females for 2 weeks prior to mating, both sexes during the mating period and females during the entire gestation and lactation period. 2-EHA caused a slight but dose-dependent decrease in fertility; time to mating increased at 300 and 600 mg/kg and even total infertility ensued. 2-EHA slightly decreased sperm quality in males. The spermatozoa were significantly less motile at 100 and 600 mg/kg and abnormal sperm occurred more frequently at the two highest dose levels. The average litter size was reduced by 16% in the dose group receiving 600 mg/kg. The birth weights of the pups were unaffected but the body weight gain was transiently slower during lactation at 600 mg/kg. Several pups appeared abnormal (kinky tail, lethargic, slightly paralyzed legs) and the physical development assessed by several landmarks (opening of eyes, eruption of teeth, hair growth) and reflexes (grip reflex, cliff avoidance) was delayed at 300 and 600 mg/kg. In another experiment, a single dose of 600 mg/kg 2-EHA was given to pregnant females by gavage on Gestational Day 4, 5, 6, or 7 and the number of implantations were counted on Gestational Day 10. Administration on Day 6 decreased the number of implantations and caused resorptions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Scopolamine's effect on passive avoidance behavior in immature rats

Male albion rats ranging in age from 15-30 days were injected with either scopolamine hydorbromide or saline, prior to training and retention testing on a black-white passive avoidance (PA) task. Pretraining administration of a 1.0-mg/kg dose of scopolamine significantly increased the median number of trails to criterion for 18-, 21-, and 30-day-old rat pups when compared with their saline controls. Fifteen-day-olds showed drug-related PA deficits when a 2.0-mg/kg dose was given. Retention data reflect characteristic age-dependent memory loss over the 1-week acquistionretention period with no apparent state-dependent effects. The data suggest the presence of cholinergic inhibitory mediation of PA responding in preweanling and postweanling pups.     

In utero and lactational exposure to 2,3,7,8-tetrachlorodibenzo-rho-dioxin: effects on development of the male and female reproductive system of the mouse

To evaluate effects of in utero and lactational 2,3,7,8-tetrachlorodibenzo-rho-dioxin (TCDD) exposure on male and female reproductive system development of the mouse, the offspring of pregnant ICR mice administered 0, 15, 30, or 60 microg TCDD/kg on Gestation Day (GD) 14 were examined at the postweanling, pubertal, young adult, and adult stages of development. Dam and offspring body weights and prenatal and postnatal mortality were unaffected by TCDD exposure. The most sensitive endpoints in male offspring were decreased ventral prostate, coagulating gland, and thymus weights, accelerated eye opening, and hydronephrosis. Decreases in pituitary gland weight and epididymal sperm numbers were also found in TCDD-exposed male offspring. Testis, epididymis, and dorsolateral prostate weights, anogenital distance, latencies to testis descent and to preputial separation, and serum testosterone concentrations were unaffected. At the highest maternal TCDD dose uterus weights were decreased in female offspring evaluated during estrus and diestrus. No morphologic changes in the external genitalia of female offspring were found, nor were there alterations in ovary or pituitary gland weights. Cross-species comparisons showed that the mouse was not as sensitive to TCDD-induced developmental reproductive toxicity as the rat and hamster. Many endpoints affected by TCDD in rat and hamster offspring were either not affected or were less sensitive in mouse offspring. Endpoints of androgenic status were not affected in the mouse, decreases in accessory sex organ weights were restricted to fewer organs in the mouse, and decreases in daily sperm production were not found in the mouse. The only developmental reproductive endpoint observed in all three species was a reduction in epididymal sperm numbers.     

Endocrine mechanisms underlying reproductive toxicity in the developing rat chronically exposed to dietary lead

A dose-response study was conducted in a rat model to examine the effects of lifetime lead exposure on the development of the reproductive system and the endocrine mechanisms underlying these effects. Time-impregnated female Sprague-Dawley rats (n = 10-15/group) were exposed to lead acetate in the drinking water at levels of 0.05%, 0. 15%, or 0.45% (w/v) initiated on gestational day 5. At birth, litters were culled to four male and four female pups. Exposure of dams to lead was continued until weaning, following which, the pups continued to be exposed to lead acetate in drinking water until sacrifice. One male and one female pup from each litter were sacrificed at age 21, 35, 55, and 85 d. A significant dose-responsive decrease in birth weight and crown-to-rump length was observed in all lead-exposed litters. However, no marked effects were observed on anogenital distance/crown-to-rump length ratios. Lead exposure resulted in a delay in sexual maturity as measured by prostate weight in male pups and time of vaginal opening in female pups, which increased with lead dose. These disruptions in reproductive physiology were accompanied by a significant decrease in neonatal sex steroid levels and suppression of the plasma concentrations of testosterone (male) and estradiol (female) during puberty. In male pups, this was accompanied by a significant decrease in plasma luteinizing hormone (LH), elevated pituitary LH content, and a decrease in plasma testosterone/LH ratios at the highest dose. In female pups, although no effects were observed on plasma LH concentration, a similar significant elevation in pituitary LH content was observed during early puberty. Postpuberty, plasma LH and sex steroid concentrations were unaffected at any dose in spite of continued lead exposure. No significant effects were observed on epididymal sperm count in male pups at 85 d of age. In female pups, estrus cycling was only significantly disrupted at the highest lead dose. These data suggest that the reproductive axis is particularly sensitive to lead during specific developmental periods, resulting in delayed sexual maturation produced by suppression by sex steroid biosynthesis. The mechanisms underlying this appear to involve lead actions on both LH release and gonadal function. At low, environmentally relevant blood lead concentrations, adaptation to the continuous presence of the metal ion occurs and surprisingly little effect is observed on adult reproductive endocrinology and physiology.     

Effects of DDT on reproduction in multiple generations of beagle dogs

The effects of chronic oral exposure to 1, 5, and 10 mg of technical DDT/kg/day on: 1) age at puberty, length of gestation, fertility, success of pregnancy, litter size, and lactational ability of dams; 2) viability, survival to weaning, sex distribution and growth of pups; and 3) morbidity, mortality, organ/body weight ratios, gross and histologic abnormalities in all animals were studied through three generations of Beagle dogs. There were a total of 135 adult female and 63 adult male dogs in the project which produced 650 pups. There were no statistically significant differences among control and DDT-treated dogs in any of the reproductive variables, with the exception of age at puberty of the females. DDT-treated females had their first estrous cycles 2 to 3 months earlier (P less than .001) than the control dogs. Selected DDT-treated females, held for a second breeding period, had normal anestrous periods between their first and second estrous cycles. There was no effect of DDT on survival, growth, and sex distribution of pups, nor was there any influence on morbidity, mortality, gross or histologic findings in any of the dogs. All organ/body weight ratios were normal, with the possible exception of an increase in liver/body weight ratio in some DDT-treated animals.     

An experimental model of pleural cancer. Value of orthotopic implantation of human tumor tissue in nude mice

In a comparison article we report that maternal PO exposure to 2.5 mg/kg all-trans retinoic acid (RA) daily for 3 consecutive days over gestational days (GD) 11-13 produces a 10% reduction in weight of cerebellum at 4 weeks of age, not accompanied by other malformations. Here we report the results of a preliminary behavioral analysis of offspring exposed gestationally to RA as above. Exposed dams were allowed to deliver normally, and litters were culled to eight pups (4 +/- 1 of each sex) at birth. Both male and female offspring were tested prior to weaning on GD 21. Thereafter females were killed on postnatal day (PND) 28 for verification of RA effects on regional brain weight, and all subsequent behavioral testing was conducted on males. Preweaning tests were restricted to negative geotaxis (PND 8-9) and open field activity (PND 22). Postweaning tests included open field activity (PND 43), auditory startle response (three times, on PNDs 22, 43, and 84), 2-week activity in residential running wheels (PNDs 62-76), complex maze performance for 5 consecutive days (PND 83-87), emergence latency (PND 106), and assessment of the behavioral response to an amphetamine challenge (PND 107). Males were then killed on PND 108 for verification of RA effects on regional brain weights. In this study, RA reduced weight of cerebellum but not striatum. Cerebellar weight was 92% of control values in PND 28 females, and this weight difference had diminished to 95% of control weight by PND 108 in males. There were no treatment effects on negative geotaxis, activity in a small open field, auditory startle amplitude, or latency to enter an illuminated alley from a dark chamber. Maze learning occurred at levels equal to or slightly better than controls. Running wheel activity was enhanced by RA exposure, whereas activity in response to an amphetamine challenge was reduced by such exposure. We conclude that RA doses low enough to produce mild weight reductions in cerebellum, without attendant malformations, can alter behavior. The precise nature of these alterations remains to be elucidated, but the findings reported here suggest that effects may be more pronounced on activity than on learning.     

Confirmation study, using nitrobenzene, of the Combined Repeat Dose and Reproductive/Developmental Toxicity Test protocol proposed by the Organization for Economic Cooperation and Development (OECD)

A confirmatory familiarization study of the Combined Repeat Dose and Reproductive/Developmental Toxicity Screening (ReproTox) test protocol proposed by the Organization for Economic Cooperation and Development (OECD) was performed using nitrobenzene, a testicular toxicant. The agent was given daily by gavage to groups of 10 male and 10 female Sprague-Dawley rats at doses of 100, 60, 20 and 0 mg/kg body weight. Some of the high dose animals exhibited neurological signs, and two males and 9 females died. Hemolytic anemia due to methemoglobin formation was evident in treated males. Histopathologically, treated males showed atrophy of seminiferous tubules of the testis, reactive changes secondary to hemolytic anemia in the hematopoietic organs, and hepatocellular swelling. Cerebral gliosis was observed in middle and high dose males. Male fertility was not affected. The body weights of pups from treated dams were lowered, and their postnatal loss was increased. Most of the known toxicological properties of this chemical was demonstrated in the present study, with the exception of reduced fertility. Therefore, the ReproTox protocol was concluded as being useful as a screening test of existing high production volume chemicals. It should be noted that while the reproductive toxicity test alone is insensitive for detection of male fertility disturbances associated with testicular toxicity, the latter easily be distinguished on morphological grounds.     

The anatomy of a consultation: a teaching method

Two dosages of Smokeless Tobacco (ST) extract were given to gravid Sprague-Dawley rats by oral gavage on gestational days (GD) 6-20. The low dosage contained ST extract equivalent to 1.33 mg/kg nicotine (STD-1), and the high dosage contained ST extract equivalent to 4.0 mg/kg nicotine (STD-2). Dams were dosed three times daily at 8 a.m., 11 a.m., and 2 p.m., thus providing total daily nicotine equivalent dosages of 4 mg/kg/day and 12 mg/kg/day. Controls received equivalent amounts of distilled water by gavage. Dams were allowed to deliver and all experimental pups were fostered to control mothers. On postnatal day 1 (PND 1) litters were culled to 4 +/- 1 females and 4 +/- 1 males. Weights, physical landmark development, and behavioral performance of pups were monitored during pre- and post-weaning periods. Behavioral tests included: surface righting, negative geotaxis, swimming development, open-field activity, active avoidance in shuttle box, and Cincinnati swimming maze. Our results show that the STD-2 dose resulted in reduced maternal weight gain. Offspring weights were reduced in a dose-related manner, with the most consistent weight deficits seen in the STD-2 group until PND29. Consistent STD-1 weight deficits were seen up to PND 8. The incidence of deaths was increased in the STD-2 dosage group. No significant treatment-related differences were observed in development of physical landmarks. Male STD-2 pups righted faster than controls, and significant differences were noted in swimming development with the STD-1 group of pups performing less effectively than controls. Activity levels, assessed during both pre- and post-weaning periods were not affected. No treatment-related differences were seen in the active avoidance shuttle box or Cincinnati swimming maze tests, which assessed learning. Female brain weights were reduced in the STD-1 treatment group.     

Intravenous gestational cocaine in rats: effects on offspring development and weanling behavior

Pregnant rats were injected with cocaine (CN; 6 mg/kg) or an equal volume of saline (SAL), via the tail vein, on gestation days 8-20. A third group was untreated (UT). Maternal weight gain was not affected by dam treatment despite slight differences in food intake. Litter characteristics (e.g., litter size, pup weight) did not differ among groups. Indices of fetal mortality were not affected by the treatments. Developmental tests, initiated on postnatal day (PND) 2, indicated slight delays in the negative geotaxic response and eye opening in cocaine-exposed pups. Open-field and tail-flick tests were performed on PND 21. Pups were acutely injected with cocaine (10 mg/kg, IP), saline, or received no treatment before placement in a novel open field; morphine (1.5 mg/kg, SC) or saline was injected prior to the tail flick test. Pups from CN dams exhibited a significant decrease in spontaneous exploratory behavior compared to both controls, and a time-dependent increase in rearing compared to pups from UT dams. The acute cocaine injection prior to placement in the open field did not alter locomotion or rearing among dam treatment groups. However, the acute cocaine injection did increase stereotypy ratings for female pups from CN dams compared to similarly treated males, and females from SAL and UT dams. No differences were observed among groups in the tail-flick test. These data suggest that the IV route of administration provides a viable method of cocaine delivery in pregnant rats, and provides further evidence of the developmental and behavioral teratogenicity of prenatal cocaine exposure.     

Effects of cocaine on fetal and postnatal development in mice

The goal of the current investigation was to study the effect of in utero exposure of cocaine on fetal and postnatal development. 48 adult female NIH Swiss mice were used as experimental animal models. Each of the 24 mice were injected intraperitoneally with cocaine HCl at a daily dose level of 45 mg/kg (body weight). Each of the 24 control animals were daily injected with saline. One week after the treatment started, one male was introduced into each female cage. The day the vaginal plug was found was recorded as day one of pregnancy. Both cocaine treated and saline treated animals were subdivided into three subgroups each with 8 animals in each subgroup. Subgroup one was used to obtain midgestational (11 day) fetuses, subgroup two was used to obtain full term fetuses (18 day) and subgroup three was used to obtain pups. Individual fetal weights were taken and each fetus was examined for developmental anomalies. Midgestational fetuses exposed to cocaine had lower body weights than those of the controls. The full term fetuses, however, had similar weight in both experimental and control groups. The pups were weighed every 2 days from day 2 to day 16. The pups showed a slightly wider range of weights in the cocaine treated group as they matured to 16 days. All fetuses and pups revealed no soft tissue anomaly which, along with the weight data, supported our earlier findings.     

Ontogeny of noradrenergic effects on ultrasonic vocalizations in rat pups.

The ontogeny of noradrenergic effects and the interaction of opioid and noradrenergic systems on vocalizations in rat pups from Day 10 to Day 18 were evaluated. Day 10 pups given clonidine (0.05 or 0.5 mg/kg) ip showed a sustained high level of calling throughout a 25-min isolation period that was reversed with yohimbine (0.1 mg/kg). Day 15 pups showed identical profiles with a lower baseline rate. Day 17 pups' calls were differentially affected according to dose; Day 18 pups reduced vocalizing with clonidine. In addition, it was found that at all ages when clonidine increased calling during isolation, the pups vocalized in the nest as well. Naltrexone, an opioid antagonist, lost its effectiveness to increase vocalizations after Day 15 unless it was given subsequent to clonidine. These results suggest that pups' vocalizations are differentially affected by noradrenergic and opioid stimulation or inhibition with developmental changes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of initial breeding weight and management system using a high-producing sow genotype on resulting reproductive performance over three parities

A study was conducted with sows of a high-producing genotype to evaluate their reproductive performance using three breeding weights over a three-parity period in two management systems. A total of 114 F1 gilts (Landrace x Yorkshire) were used in a split-plot, randomized, complete block experiment conducted as a 3 x 2 factorial arrangement of treatments in two replicates. Three gilt breeding weights of 120, 135, and 150 kg were achieved by feeding 1.8, 2.3, or 3.2 kg/d of a .73% lysine corn-soybean meal (C-SBM) diet, respectively, from 5 to 8 mo of age. Two locations, each with different management systems, were considered the main plot and consisted of 1) outside, concrete-floored gestation lots and indoor farrowing pens or 2) indoor gestation pens and farrowing crates. All sows were fed 1.8 (Parity 1) or 2.1 (Parity 2 and 3) kg/d of a .73% lysine C-SBM diet during the breeding and gestation periods, whereas a .82% lysine C-SBM diet with 5% added fat was available ad libitum during lactation. All sows lost weight during the first lactation; larger weight losses occurred as breeding weight increased (P < .01). During the second and third lactations the 135- and 150-kg sow breeding groups had less lactation weight change, whereas the 120-kg group lost more weight, resulting in a breeding weight x parity interaction (P < .01). The 120-kg breeding weight group consumed less feed (P < .05) for the three lactation periods than did the heavier weight groups. Initial breeding weight had no effect on number of pigs born (total, live) or pig and litter weights at birth. Pig mortality increased with increasing breeding weight (P < .01) and parity (P < .05), a response that was exacerbated when sows farrowed in pens vs crates. Postweaning breeding intervals and sow removal from the experiment were not significantly affected by initial breeding weight, but a numerically higher percentage of sows in the 120-kg group were anestrous or failed to conceive than the percentage of such sows in the heavier weight groups. These data suggest that an initial breeding weight of approximately 135 kg at 8 mo of age may be best when sows farrow in crates, whereas when sows farrow in pens a lower breeding weight may be more desirable.     

Luminescence and structure of the protonated forms of meso-tetraarylporphyrins in solution

A distillate of light alkylate naphtha (CAS number 64741-66-8; LAN distillate) was administered via inhalation, 6 h/d, 7 d/wk to 4 groups of Sprague-Dawley rats (10/sex/dose) at target concentrations of 0 (filtered air control), 5, 12.5, or 25 g/m3 with the highest dose exceeding 60% of the lower explosive limit of LAND. Exposure began 2 wk prior to mating and continued throughout gestation until postnatal d 4 for females or for 8 consecutive weeks for males. No apparent clinical signs indicative of systemic toxicity were observed in the F0 and F1 animals of either sex. Inhalation exposure to LAND up to and including the 25 g/m3 dose level had no effect on parental food consumption, body weights, absolute and relative organ weights, and reproductive indices. All groups had comparable delivery data and a fertility index > or 80%. Pups in all groups showed comparable birth weights, weight gain, a viability index (postnatal d 4) for all groups of > or = 97%, and no histopathological changes. In the dams, there were no significant differences in the mean numbers of corpora lutea, implantation sites, and resorptions recorded at necropsy. In the males, the only remarkable findings at necropsy were a small right epididymis and testis seen in one mid-dose male and an abscess on the right epididymis of a high-dose male. In both cases, the dams that had been bred to these males produced normal litters. There were no test material-related microscopic changes observed in the testes and epididymis of the F0 male rats or ovaries of the F0 female rats exposed to LAND. Under the conditions of this experiment, the no-observed-adverse-effect level (NOAEL) for LAND via inhalation in rats is established at greater than 24.7 g/m3 (analytical concentration).     

Protein kinase C isotypes theta, delta and eta in human lymphocytes: differential responses to signalling through the T-cell receptor and phorbol esters

CD-1 mice received daily subcutaneous injections of either cocaine (20 mg/kg or 40 mg/kg) or saline solution (0.9% NaCl) from postnatal days 2 to 15. Pups were tested on days 16-17 for learning and 24-h retention of a passive avoidance task, where entering a dark compartment was punished with a mild foot shock. Locomotor activity and general behaviour in an open field arena were assessed on day 21, following administration of either the muscarinic blocker scopolamine (0.8 mg/kg) or saline solution. In addition, immunostaining for the enzyme choline acetyltransferase (ChAT) was measured in different basal forebrain areas (medial septum, striatum, and nucleus basalis) on day 30. Cocaine treatment failed to affect either learning or retention capabilities. Nonetheless, neophobic behaviour during the learning session was enhanced in control nonpunished mice exposed to the 20-mg/kg dose. In the open field test, although baseline activity levels were unaffected by cocaine exposure, the 40-mg/kg cocaine-treated pups showed decreased sensitivity to the hyperkinetic effects of scopolamine. ChAT immunocytochemistry revealed a significant reduction of the number of ChAT-immunopositive neurons in the nucleus basalis but not in the other cholinergic basal forebrain regions.     

Fertility impairment in granulocyte-macrophage colony-stimulating factor-deficient mice

Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been identified as a potentially important mediator of intercellular communication in the female reproductive tract, with principal target cells being the large populations of myeloid leukocytes in the cycling and pregnant uterus, the preimplantation embryo, and trophoblast cells of the developing placenta. To determine the physiological significance of this cytokine in reproduction, the fertility of genetically GM-CSF-deficient (GM-/-) mice was examined. Implantation rates were normal in GM-/- mice, and viable pups were produced. However, the mean litter sizes of GM-/- x GM-/- breeding pairs were 25% smaller at weaning than those of GM+/- x GM+/- pairs, due to fetal death late in gestation and early in postnatal life, with a disproportionate loss of male pups. On Day 17 of pregnancy, the mean number of resorbing and malformed fetuses was twice as high in pregnant GM-/- females (21%, vs. 11% in GM+/- females); the mean fetal weight and the mean fetal:placental ratio in surviving conceptuses were diminished by 7% and 6%, respectively; and the number of very small fetuses (< 500 mg) was 9-times as high (23% vs. 2.5%). Mortality during the first 3 wk of life was 4.5-times as high in pups born to GM-/- mothers (9%, vs. 2% in GM+/- females), and diminished size persisted in GM-/- pups, particularly males, into adulthood. The detrimental effect of maternal GM-CSF deficiency was less apparent when GM-/- females were mated with GM+/+ males; litter sizes at birth and at weaning were not significantly smaller than in GM+/- matings, and fetal weights and fetal:placental ratios were also comparable. When polymerase chain reaction was used to genotype embryonic tissue in heterozygote matings, GM-/- fetuses from GM-/- females were found to be smaller than their GM+/- littermates and smaller than GM-/- fetuses gestated in GM+/- females. The size and distribution of uterine granulocyte and macrophage populations were normal during the estrous cycle, during early pregnancy, and in midgestation. Analysis of placental structure revealed that the ratio of labyrinthine to spongiotrophoblast areas was reduced by approximately 28% in GM-/- placentae, and the proportion of vacuolated trophoblast "glycogen cells" in the spongiotrophoblast layer was diminished. Compromised placental function as a result of subtle developmental aberrations may therefore partially account for embryonic growth retardation in GM-CSF-deficient mice. Collectively, these studies show that fetal growth and viability are jeopardized in the absence of maternal GM-CSF. The detrimental effects are most clearly evident when the conceptus is also GM-CSF deficient, suggesting that GM-CSF of either maternal or fetal origin is required for optimal growth and survival of the fetus in mice.     

Study of the effects of beta-myrcene on rat fertility and general reproductive performance

beta-Myrcene (MYR) is a monoterpene found in the oils of a variety of aromatic plants including lemongrass, verbena, hop, bay, and others. MYR and essential oils containing this terpenoid compound are used in cosmetics, household products, and as flavoring food additives. This study was undertaken on investigate the effects of MYR on fertility and general reproductive performance in the rat. MYR (0, 100, 300 and 500 mg/kg) in peanut oil was given by gavage to male Wistar rats (15 per dose group) for 91 days prior to mating and during the mating period, as well as to females (45 per dose group) continuously for 21 days before mating, during mating and pregnancy, and throughout the period of lactation up to postnatal day 21. On day 21 of pregnancy one-third of the females of each group were submitted to cesarean section. Resorption, implantation, as well as dead and live fetuses were counted. All fetuses were examined for external malformations, weighed, and cleared and stained with Alizarin Red S for skeleton evaluation. The remaining dams were allowed to give birth to their offspring. The progeny was examined at birth and subsequently up to postnatal day 21. Mortality, weight gain and physical signs of postnatal development were evaluated. Except for an increase in liver and kidney weights, no other sign of toxicity was noted in male and female rats exposed to MYR. MYR did not affect the mating index (proportion of females impregnated by males) or the pregnancy index (ratio of pregnant to sperm-positive females). No sign of maternal toxicity and no increase in externally visible malformations were observed at any dose level. Only at the highest dose tested (500 mg/kg) did MYR induce an increase in the resorption rate and a higher frequency of fetal skeleton anomalies. No adverse effect of MYR on postnatal weight gain was noted but days of appearance of primary coat, incisor eruption and eye opening were slightly delayed in the exposed offspring. On the basis of the data presented in this paper the no-observed-adverse-effect level (NOAEL) for toxic effects on fertility and general reproductive performance can be set at 300 mg of beta-myrcene/kg body weight by the oral route.     

Effects of cocaine administration during early organogenesis on prenatal development and postnatal growth in mice

Cocaine use has been associated with adverse developmental effects in humans. However, clinical reports both confirm and deny an association between cocaine use and malformations. Similarly, differences in species and strain, as well as route and timing of cocaine administration, have added to the difficulties in determining the teratogenicity of cocaine in animal models. This study was undertaken to compare the effects of dose, route, and timing of cocaine administration in ICR mice during early organogenesis. A single intraperitoneal (ip) administration of cocaine ( > or = 60 mg/kg) on Day 9 of gestation (plug day = 1) produced maternal lethality. The predominant developmental effect of cocaine administration was an increase in the percentage of litters exhibiting an enlarged renal pelvis. Despite a high incidence of affected pups at these doses, the enlargement was not severe. These results, in agreement with previous reports, provide further evidence that the developing urogenital system is sensitive to cocaine administration. When cocaine was administered using a subcutaneous route, pup weights were greater and the incidence of enlarged renal pelvis was lower than when an ip route was used. To better mimic human binge cocaine abuse, the toxicity of a "split dose" was determined. A 60 mg/kg dose was administered using one administration of 60 mg/kg, two treatments of 30 mg/kg, or three administrations of 20 mg/kg with 1 hr separating the treatments. The incidence of enlarged renal pelvis was similar when cocaine was administered as one or two but was decreased when cocaine was administered as three treatments. Both the route and split-dose studies suggest that high-peak serum concentrations are required to perturb development. There were no differences in the incidence or severity of enlarged renal pelvis when cocaine was administered on Day 8, 9, or 10 or on all 3 days of gestation. This suggested that the increase in enlarged renal pelvis may not be a specific teratogenic effect of cocaine administration but may be a delay of normal development induced by cocaine exposure during this early period of organogenesis. To address this hypothesis, cocaine was administered on Day 9 using an ip route and the pups were allowed to be naturally born. In pups whose mothers received cocaine there was an increase in postnatal deaths and a trend toward a reduction in pup body weight/litter at Postnatal Day 21. However, when renal morphology was assessed on Postnatal Day 21 no abnormal kidneys were seen. This supports the hypothesis that enlarged renal pelvis produced by cocaine administration during early organogenesis represents a developmental delay and not a persistent teratogenic defect. These studies suggest that high peak cocaine concentrations are required to delay normal kidney morphogenesis in mice.     

Complementary oligonucleotides and the origin of the mammalian involucrin gene

Bombesin (BN) administration has been shown to suppress food intake across diverse species. Preliminary results have shown that BN elicits a satiety-like state from postnatal day (PD) 1, through unknown mechanism(s). We have recently shown that in adult rats, alpha-methyl histamine (alpha-MH), a selective H3 receptor agonist that inhibits the release and synthesis of histamine, blocks the feeding suppressant effects of BN. The objective of this study was to determine if such a mechanism was operation at birth or whether it developed over time. Thus effects of histamine H3 receptor agonists as well as BN-histamine interactions in the regulation of food intake were assessed during early development. On PD 1, 5, 10 and 15, groups of food deprived Sprague-Dawley rat pups (n = 8-12) were injected with BN alone (0 (saline), 0.006, 0.06 or 0.6 mg/kg, s.c.), H3 receptor agonists alone (alpha-MH or Imetit (3 or 5 mg/kg s.c.)) or the combination of BN and H3 receptor agonists, and their ingestive behavior was monitored. Results confirmed that pups were sensitive to feeding suppressant effects of BN starting from PD 1. Imetit or alpha-MH either failed to affect food intake or at certain time points enhanced food intake. Pretreatment with the H3 receptor agonists significantly attenuated the feeding suppressant effects of BN, suggesting that early in ontogeny, BN may suppress food ingestion possibly by facilitating histamine release at some relevant site(s).