Female regulation and choice in the copulatory behavior of montane voles (Microtus montanus).

To study female choice of mating partners in montane voles, a male was tethered at each end of an elongate chamber, and an estrous female was allowed to move betweeen the 2 males and a neutral area. In Exp I, using 16 females and 32 males, females with a choice of 2 gonadally intact males copulated preferentially with 1 of them. Preferred males were more effective than nonpreferred males at gaining intromission and had more thrusts per intromission. In Exp II, with 10 females, 10 castrated males, and 10 sham-operated males, females spent more time with and mated preferentially with intact rather than castrated males. It is therefore suggested that the opportunity to copulate is reinforcing for female voles and that they display distinct preferences, correlated with copulatory stimulation, for some partners. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Testosterone and persistence of social investigation in laboratory rats.

In 5 experiments 92 mature male and 44 mature female Long-Evans rats were individually exposed in their home cages to sexually immature conspecifics. A prominent sex difference was observed in duration of social investigation prior to a criterion of neglect. When pups were 5 days of age, no sex difference was observed, but when pups were 8 days of age and older, mature males consistently investigated them for significantly longer intervals than did mature females. Furthermore, intact males investigated prepuberal conspecifics for significantly longer intervals than did castrated males, castrated females, or intact females; none of the latter 3 groups differed significantly from each other. Following testosterone treatment, castrated males investigated unfamiliar, prepuberal conspecifics for a significantly longer duration than did untreated castrated control Ss. Combined results support the conclusion that gonadal testosterone effects a greater perseveration of social investigation in males. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hormonal influences on sexual dimorphism in rate of extinction of a conditioned taste aversion in rats

The hormonal influences on the slow extinction rate of a conditioned taste aversion shown by male rats and the fast extinction rate shown by female rats were investigated. When males were castrated, they extinguished as quickly as females. When castrated males were given testosterone propionate replacement, they had a slow extinction rate. Castration had no effect on the extinction rate of females. But when testosterone propionate was administered to castrated or intact females, they had a slow, malelike extinction rate. Thus, sexual dimorphism in the extinction rate of a conditioned taste aversion seems to be due to the activational effects of testosterone.     

Patient noncompliance in the managed care setting. The case of medical therapy for glaucoma

After treatment with TCDD, the activities of cytosolic AhR-associated c-Src kinase, microsomal protein kinase C (nPKC epsilon), microsomal c-Src kinase, nuclear p44/42 MAPK, c-Jun N terminus kinase, and the amount of microsomal pan-Ras protein were different in males and females. TCDD did not decrease body or adipose tissue weights in transgenic src-deficient male mice as compared to their wild-type littermates, and the activity of AhR-associated c-Src kinase was not increased by TCDD in src-deficient male mice. Similar results were obtained when TCDD was given to male guinea pigs treated with the Src-kinase inhibitor, geldanamycin. Treatment with estradiol protected male guinea pigs from TCDD-induced wasting. TCDD induced similar changes in protein tyrosine kinase activity in adipose tissues of castrated male and intact female guinea pigs. The gender-specific mechanisms of TCDD-induced toxicity appear to involve c-Src kinase, nPKC epsilon, and pan-Ras, as well as overlap in the cytosolic signal transduction pathways of TCDD and sex steroids.     

Interactions of contact, odor cues, and androgens in strange-male-induced early pregnancy disruptions in mice (Mus musculus).

Novel males can disrupt early pregnancy in female house mice (Mus musculus). In Experiment 1, exposure to novel males disrupted pregnancy, but exposure to male urine did not. In Experiment 2, urine from male or female mice or rats painted on females' noses did not influence pregnancy. In Experiment 3, the conjunction of urine painted on female's noses and vulval stimulation did not affect pregnancy more than water with similar stimulation. In Experiment 4, males housed above females were separated from them by a wire mesh grid; intact males disrupted pregnancy, but castrated ones did not. In Experiment 5, such housing of castrated males or ovariectomized females produced a strong disruption of pregnancy if the stimulus animal was given testosterone but not if it was given oil injections. In Experiment 6, transfers of odorous emissions failed to disrupt pregnancy. Contact and androgen activity are necessary for strange males to disrupt pregnancy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of castration on grooming in goats

In African antelope and North American cervids, breeding males during the rut engage in less oral self-grooming, and harbor a greater density of ticks, compared with conspecific females and non-breeding males. The purpose of this study was to experimentally test the proposition that down-regulation of self grooming in some male bovids occurs via the direct or indirect action of testosterone. Domestic dairy goats (Capra hircus) were used as a model. In Experiment 1, comparative observations conducted on twelve gonadally intact male goats (bucks), nine males castrated at 3 weeks of age (wethers), and twelve intact females (does) supported the prediction that the grooming rate of intact males would be depressed relative to wethers and does. Bucks oral groomed at one-third and one-fourth the rate of wethers and does, respectively, and they scratch groomed half as much as does. There was no significant difference between wethers and does in oral or scratch grooming rates. Experiment 2 involved castration of eleven bucks from Experiment 1, followed by 2 months of observation. Similar to the pattern of other testosterone-dependent behavioral changes after castration in adult males, there was a good deal of variation in the individual grooming response of males to castration, with increases in grooming taking 2 to 8 weeks to be manifested in ten of eleven goats. Overall, castrated males oral groomed about 3 x above their intact rates, supporting the prediction that castration removes testosterone-mediated suppression of grooming. This is the first example of alteration of grooming behavior in males by gonadal androgen, and the first demonstration of enhancement of any mammalian behavior by removal of gonadal androgen.     

Effects of gonadal steroid hormones on hypothalamic vasopressin mRNA level in male and female rats

Experiments were carried out in 10-11-week old gonadectomized male and female Sprague-Dawley rats. Dot-blot analysis and 3'-end digoxigenin-labeled 26 meroligonucleotide probe was used in detecting the mRNA level hypothalamic vasopressin (AVP). The basal hypothalamic AVP-mRNA level in the sham-operated intact males was 45% higher than that in the sham-operated intact females (P < 0.05). Plasma osmolality was also higher in the sham-operated intact males than in the sham-operated intact females (P < 0.05). The hypothalamic AVP-mRNA level in ovariectomized rats was 30% higher than that in sham-operated intact females (P < 0.05). Although the hypothalamic AVP mRNA level tended to be lower in castrated males than in sham-operated intact males, the difference was not statistically significant. The difference in plasma osmolality between gonadectomized males and females was statistically insignificant. In castrated males, hypothalamic AVP-mRNA level was decreased following sc injection of estradiol (P < 0.05), but testosterone, progesterone or a combination of estradiol and progesterone were without effect. In ovariectomized rats, sc injection of estradiol or a combination of estradiol and progesterone resulted in a decrease in hypothalamic AVP-mRNA level (P < 0.01), but progesterone or testosterone had no effect. The difference in plasma osmolality between gonadal steriod hormones-treated rats and vehicle-treated rats was not statistically significant. These findings indicate that gonadal steriod hormones can affect hypothalamic AVP-mRNA level in rats, through some central mechanism.     

Effects of sex hormones on protein and collagen content of the temporomandibular joint disc of the rat

PURPOSE: The effect of sex hormones on the protein and collagen content of the temporomandibular joint (TMJ) disc of adult male and female rats. MATERIALS AND METHODS: One hundred forty-four Wistar rats were assigned to 14 groups of 12 each. Two groups, one female and one male, served as a control and received no treatment, and two other groups (one female and one male) received a sham gonadectomy and placebo hormone. The remaining 10 groups (five males and five females) received either orchiectomy or ovariectomy, followed by administration of estrogen, progesterone, combined estrogen and progesterone, or testosterone. The total protein and collagen content of the TMJ disc were determined using the calorimetric hydroxyproline method. RESULTS: The collagen content of TMJ discs of control males was statistically greater than the collagen content of the control female rats. This difference disappeared after ovariectomy of females and orchiectomy of males. Also, there was a general trend for a decrease in collagen and protein content to be produced by estrogen, progesterone, and by estrogen combined with progesterone in castrated male and female rats, and by orchiectomy of male rats. There was also a trend toward an increase in collagen and protein content after ovariectomy in female rats and administration of testosterone to castrated male and female rats. However, the only statistically significant effect of the drugs tested was that of estrogen combined with progesterone in ovariectomized female rats (a lowering effect on the total protein) and of estrogen alone in orchiectomized male rats (a lowering effect on the collagen content). CONCLUSION: Steroid sex hormones have an effect on the collagen and protein content of the TMJ disc of the rat as indicated by the difference in the values between control males and females and by the disappearance of this difference on castration of both male and female animals. This was also manifested by the significant effect of estradiol on collagen content of castrated males, by the effect of estrogen combined with progesterone on the protein content of castrated females.     

Effects of chronic systemic administration of 5-HT on food intake and body weight in rats

The effects of chronic peripheral administration of 5-HT on food intake and body weight was investigated. In normal male Wistar rats, normal female Wistars, obese Zucker males, ovariectomised Wistar females, or normal Wistar males free fed a cafeteria diet, suppression of the creeping weight gain typical of control animals is observed. In females, this effect is not dependent on the local hormonal environment, because intact and ovariectomised females showed similar responses to treatment. One sex difference is that the weight suppressive effect in males is accompanied by an anorectic effect, whereas this anorectic effect is absent in females. Thus, although reduced food intake may partially explain the suppression of weight gain in males, in females it must be due to other, perhaps metabolic, effects. It is possible that these metabolic effects may also occur in males, suggesting one possible explanation of why the effect was typically larger in males than females.     

Gender differences in ethanol preference and ingestion in rats. The role of the gonadal steroid environment

An ethanol oral self administration paradigm showed the existence of gender differences in alcohol preference in rats: whereas males and females initiated alcohol drinking at similar rates, females maintained their preference for ethanol over a longer duration. Neonatal estrogenization of females, which effectively confers a male phenotype on a genetically female brain, resulted in patterns of drinking that were similar to those displayed by intact male rats, indicating that gender differences in alcohol drinking patterns may be, at least partially, accounted for by sexual differentiation of the brain. To test whether gonadal steroids also exert activational effects on ethanol-seeking behavior, we also examined the effects of gonadectomy alone, or in combination with gonadal steroid replacement therapy. Castration did not significantly alter ethanol consumption in males, although treatment of castrated rats with dihydrotestosterone resulted in a significant inhibition of this parameter. As compared with the situation in intact female rats, ethanol ingestion was significantly reduced in ovariectomized female rats receiving estradiol (E2) and in ovariectomized female rats receiving combined E2 and progesterone replacement therapy. However, neither ovariectomy nor progesterone replacement in ovariectomized rats resulted in ethanol drinking patterns that were different compared to those observed in intact female controls. Thus, dihydrotestosterone and E2, respectively, appear to exert modulatory influences on the male and female rats' preference for ethanol, but further investigations are necessary to determine to what extent these effects result from activational actions on the brain.     

Hormonal modulation of genital reflexes in male and masculinized female dogs.

When testosterone propionate (TP) is administered to adult, neonatally castrated male dogs and to adult females with masculinized genitalia produced by prenatal and neonatal exposure to androgen, both types of animals are unsuccessful in their attempts to copulate with receptive females. In the present experiment, 6 neonatally castrated male and 10 genitally masculinized female beagles were tested before and after TP treatment for responses to manual stimulation of the genitalia. An additional experimental group consisted of 6 males castrated as adults, and there was a control group of 5 normal males. After a series of TP injections (5 mg/kg), neonatally castrated males, adult castrates, and genitally masculinized females exhibited complete and strong erectile and ejaculatory reflexes. Erect penis lengths of neonatally castrated males and masculinized females were significantly shorter than those of normal males or of males castrated as adults. It is suggested that the failure of males castrated at birth, and of genitally masculinized females, to insert and lock when mounting receptive females is due to incomplete penile development and not to incomplete "organization" of spinal reflex mechanisms. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Binding of low mobility group proteins with DNA examined in homologous and heterologous systems by gel retardation assay

In addition to age-related deficits in morphine antinociception in female rats, gender and gonadectomy differences have also been observed, with male rats displaying greater magnitudes of effects than females and castrated males. Since there are little data indicating how aging, gender, and gonadectomy interact in modulating morphine antinociception, the present study evaluated alterations in this response as functions of age (6, 12, 18, and 24 months), gender, and gonadal status (intact, gonadectomized) across a dose range (1-10 mg/kg) and time course (0.5-2 h) on the tail-flick test. The maximal percentage effect (MPE) of morphine (1 mg/kg) was significantly increased in castrated males (18 months), sham females (18 and 24 months), and ovariectomized females (18 months) relative to 6-month-old groups. Increases in the MPE of morphine (1 mg/kg) occurred in sham females (24 months) relative to corresponding sham males and ovariectomized females. The MPE of morphine (2.5 mg/kg) was significantly increased in sham males (18 months) and decreased in sham females (12 months). Decreases in the MPE of morphine (2.5 mg/kg) occurred in castrated males (18 and 24 months) as well as sham (18 months) and ovariectomized (18 and 24 months) females relative to sham males. Whereas the MPE of morphine (5 mg/kg) was unchanged by these variables, the MPE of morphine (10 mg/kg) was significantly decreased in sham females (18 and 24 months) relative to females aged 6 months, as well as males and ovariectomized females aged 24 months.(ABSTRACT TRUNCATED AT 250 WORDS)     

Odor preference and urine-marking scales in male and female rats: Effects of gonadectomy and sexual experience on responses to conspecific odors.

Investigation and urine-marking responses of 112 male and female Long-Evans rats toward conspecific urine odors were recorded in pair-wise comparison tests. Each of 16 S groups was given 15 preference tests, 1 for each of the possible pairs of 5 urine odors and a no-odor control (N). The urine sources were own group (G), intact male (M), castrated male (Mc), ovariectomized female (Fo), and estrous females (F). Results were scaled by using a technique based on L. L. Thurstone's (1927) law of comparative judgment. Intact males with sexual experience ordered their odor preferences N?     

Neonatal androstenedione and adult sexual behavior in golden hamsters.

Notes that male rats castrated and given androstenedione neonatally can show high levels of both masculine and feminine copulatory behavior in adulthood. In the present study, 24 intact female and 30 intact male hamsters castrated at birth were treated for their 1st 20 days with oil, free testosterone, or androstenedione. All neonatal androgen treatments mimicked the naturally occurring developmental process of the male in that all androgenized groups were capable of high levels of male behavior (males but not females showing ejaculation patterns) as well as moderate levels of lordotic receptivity. There were no significant differences in effect among neonatal androgen treatments. Results are discussed as they relate to species differences, sex differences, hamster "bisexuality," and posthormone copulatory performance. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A testosterone-mediated trade-off between parental and sexual effort in male Mongolian gerbils (Meriones unguiculatus).

Effects of testosterone (T) on parental behavior of male Mongolian gerbils (Meriones unguiculatus) were examined. After undergoing gonadectomy, castrated males were implanted with empty capsules or capsules containing T; sham-operated males were implanted with empty Silastic capsules. Subsequently, each male was paired with a pregnant female, and after delivery, families were observed 15 min/day for 20 days. Gonadectomized males without T spent more time in contact with, huddling over, and licking pups than did either sham-operated males or gonadectomized males with T When given a choice between nest sites and displaced pups, females and males with low T preferred pups, whereas intact males and castrated males with T preferred nest sites. The findings are consistent with E. D. Ketterson and V. Nolan's (1994) hypothesis implicating T in mediating trade-offs between parental and sexual effort. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Open-field and avoidance behavior after neostriatal lesions in male and female rats.

The behavioral effects of lesions of the anterodorsal or posteroventral parts of the caudate-putamen were studied in 2 experiments with a total of 115 male and 101 female adult albino Holtzman rats that were gonadectomized or left untreated prior to brain surgery. Anterodorsal (ADC) lesions consistently impaired acquisition of 1-way avoidance behavior and tended to interfere with the development of a 2-way avoidance response; comparable effects were observed in gonadectomized and intact Ss of both sexes. By contrast, ADC lesions increased activity in the open field only in intact females and increased rearing only in ovariectomized females. Posteroventral caudate (PVC) lesions caused transient aphagia and adipsia in both sexes but did not consistently affect open-field activity or the acquisition of 1-way avoidance responses by either sex. These lesions profoundly impaired acquisition of shuttle box avoidance responses by intact males. By contrast, castrated males and intact and ovariectomized females with PVC lesions avoided normally in the shuttle box. Results suggest that localization of behavioral functions within the striatum differs with the sex of the S, in part because of activational effects of gonadal hormones. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of ovarian secretions on female behavioral potentiality in the rat.

Measured receptivity in female Sprague-Dawley rats ovariectomized at 5 ages, in neonatally gonadectomized females and males implanted with ovaries, and in neonatally castrated males injected with estradiol benzoate (EB) or oil. Mean receptivity, darting, and lordosis scores were higher during the 1st 4-5 mating tests in females and males having ovaries prepubertally. In amounts greater than .01 mg., EB inhibited female behavior. Even after ovariectomy, body weight was lightest in males and females having ovaries for 60 days. Progesterone and EB decreased weight gain faster in Ss gonadectomized prepubertally. Results indicated that physiological amounts of ovarian hormones, while not necessary for development of female potentiality, permanently influence it by modifying rate of utilization of estrogen circulating during adulthood. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Control of cell growth. II. Requirement of thyroid hormones for the in vivo estrogen-dependent growth of rat pituitary tumor cells

A subclone of rat pituitary tumor cells, designated GH3/C14, was isolated from the parent population of GH3 pituitary cells and was estrogen-dependent for growth in vivo. GH3/C14 cells inoculated into host animals formed tumors in intact females, estrogen-treated ovariectomized females, and estrogen-treated males, but not in untreated intact or castrated males, or untreated ovariectomized females. Exogenous treatment with estrogens supported tumor formation in male animals. Radioimmunoassay of the average serum estradiol concentrations that support tumor growth in intact females, estradiol-treated intact females, and estradiol-treated intact males gave values of 41 +/- 4, 1,130 +/- 150, and 730 +/- 140 pg/ml, respectively. Tumor formation by GH3/C14 cells inoculated into male animals was not supported by either exogenous progesterone or hydrocortisone acetate. Further, these two steroid hormones had no significant effect on the estrogen-promoted growth in males or females. Exogenous testosterone treatment promoted tumor formation in males and ovariectomized females, but dihydrotestosterone was completely ineffective. Radioimmunoassay of the serum from tumor-bearing animals and the medium from the cells in culture showed that the cells produced growth hormone in vivo and in vitro but did not produce measurable amounts of luteinizing hormone or follicle-stimulating hormone. The groth of GH3/C14 cells in culture was examined in medium without added estrogen, and with estradiol added to the level of either the normal intact female rat or the estradiol-treated animals. No direct growth stimulation by estrogens could be detected in culture; the data suggested an indirect growth control mechanism.     

Effects of olfactory bulbectomy on social behavior of male guinea pigs ( Cavia porcellus ).

Studied the effects of olfactory bulbectomy on social behavior in 16 male guinea pigs. Both brief exposure pairing techniques and a group-living observation period were employed to test for disruption. During short-term testing sessions bulbectomized Ss courted females less than but mounted them as frequently as controls. While the groups did not differ in fighting behavior during short-term tests, controls scent-marked more frequently. Subsequently, Ss were observed as same-treatment pairs living continuously with females, and behavior was sampled over a 3-wk period. Under these conditions bulbectomized males, unlike controls, failed to form dominance orders, exhibited virtually no intermale aggressive activity, had markedly depressed sexual activity, and scent-marked rarely. It is concluded that olfactory bulbectomy profoundly alters the behavior of male domestic guinea pigs and that those alterations are most evident when experimental Ss are observed in a species-typical group-living environment. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of prenatal androgen and ovarian secretions on receptivity in female and male rats.

A total of 102 male and 146 female offspring of Sprague-Dawley rats injected daily from Day 16 through Day 20 of gestation with either 2 mg of testosterone propionate (TP) in .1 ml of sesame oil or oil alone were tested for sexual receptivity following injections of 3.3 μg of estradiol benzoate (EB) and .5 mg of progesterone (P) beginning at 40, 80, or 120 days of age. At each age, neonatally gonadectomized males and females from TP-injected litters exhibited less receptivity than corresponding oil-injected controls. Prenatally androgenized females were similar to neonatally castrated oil-injected males at all ages. Ovarian implants from birth to 35 days of age significantly increased receptivity in neonatally castrated males and androgenized females. Increasing the age at which testing was initiated systematically reduced receptivity in all groups. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)