Role of the infraorbital nerve in retrieving behavior in lactating rats.

Studied the acute effect of perioral anesthesia on retrieval of pups in primiparous Wistar rats. Injecting lidocaine into the mystacial pads of Ss rendered the snout insensitive to touch and abolished Ss' ability to retrieve. In Exp I, injecting the drug into masseter muscles or ip did not render the snout anaptic or abolish retrieval, indicating that the effect of intramystacial lidocaine treatment could not be attributed to systemic toxicity or to the drug's spreading from mystacial pads to affect masseter muscles. In Exp II, cutting the infraorbital nerves produced temporary retrieval impairment that was indistinguishable from that produced by intramystacial lidocaine. The deficit was not due to postoperative debilitation. Infraorbital section did not interfere with the ability to locate and consume a piece of cheese. Cutting the facial nerves abolished vibrissal movement but did not disrupt retrieval. In Exp III, the possibility was tested that infraorbital deafferentation has a profound effect on retrieval because anaptic dams, in their initial attempts at picking up pups, elicit distress vocalizations from offspring. Ss injected with lidocaine in the mystacial pads failed to retrieve pups that had been anesthetized to abolish distress vocalizations. Thus, pup-produced vocalizations are not responsible for the retrieval impairment exhibited by anaptic mothers. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of neonatal capsaicin and infraorbital nerve section on whisker-related patterns in the rat trigeminal nucleus

In the present study, we investigated the effect of neonatally administered capsaicin on whisker-related pattern formation in the rat trigeminal complex. Both normal whisker-related patterns of barrelettes and the modified patterns seen after neonatal section of the infraorbital nerve were assessed. Capsaicin caused no change in the pattern or size of cytochrome oxidase (CO) barrelettes in the principal trigeminal nucleus (Vp) or trigeminal nucleus interpolaris (Vi) or caudalis (Vc). Injections of horseradish peroxidase (HRP) or wheatgerm agglutinin conjugated to HRP (WGA-HRP) into the posteroorbital (PO) whisker follicle in vehicle-treated animals showed that WGA labelled a larger number of trigeminal ganglion cells than HRP (203 +/- 23; cf. 158 +/- 19), with an increased labelling of small-diameter neurons (HRP: 25.9 +/- 7.7 microm; WGA: 23.2 +/- 7.2 pm). Capsaicin caused a loss of smaller diameter cells but had no effect on the location, cross-sectional area, or rostrocaudal extent of the transganglionically labelled HRP terminations in Vp, Vi, Vc, and cervical dorsal horn. WGA-HRP labelling revealed similar, but less dense, central terminal areas as HRP and an additional area of superficial terminals in the caudal medulla; these were also unaffected by capsaicin treatment. After infraorbital nerve section, CO patches and transganglionically labelled afferent terminations, corresponding to innervated nonmystacial whiskers, were approximately doubled in size. Capsaicin had no effect on the increased size of these spared whisker patches or their afferent terminal areas. These results suggest that barrelette formation is not dependent on unmyelinated afferents and that the changes in response properties seen after capsaicin, such as increased receptive fields, reflect functional changes rather than anatomical expansion of afferent terminal areas.     

Self-administration of ethanol and saccharin in newborn rats: Effects on suckling plasticity.

Responsiveness to a surrogate nipple providing water, saccharin, 5% ethanol, or 10% ethanol was tested in newborn rats naive to suckling (3–5 hr old) on Postnatal Day (P) 0 and in older neonates with regular suckling experience on P1 or P2. At all ages, pups demonstrated greater nipple attachment for saccharin or 5% ethanol than for water. Intake of saccharin and 5% ethanol was high in newborns, far exceeding that of water. At P1 and P2, pups exhibited a preference for saccharin, but not for 5% ethanol. Preexposure to a nipple providing ethanol or saccharin (but not a nipple alone or fluids alone) increased subsequent responsiveness toward an empty surrogate nipple (no fluid), both 1 hr and 24 hr after preexposure. Although, during preexposure, pups responded most positively to the nipple providing saccharin, the longest time spent on an empty nipple was observed in pups preexposed to 10% ethanol. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of electroacupuncture and transcutaneous electrical nerve stimulation on survival of musculocutaneous flap in rats

The effects of electroacupuncture (EA) and transcutaneous electrical nerve stimulation (TENS) were investigated in the musculocutaneous flap in a rat model by measuring the surviving area and blood flow in the flap. Rats were divided into the control group, and groups treated with EA and TENS. Experimental results of this study show that flap survival area did not increase by EA but increased significantly by TENS treatment, and that blood flow in the periphery was significantly larger than that at the base.     

Effects of gastric loads and food deprivation on subsequent food intake in suckling rats.

In 4 experiments, a total of 478 suckling Charles River rats were subjected to deprivation periods of 6-8 hrs. Intake following deprivation was greater in deprived than in nondeprived Ss but did not increase with increasing deprivation. Gastric loads of NaCl solutions depressed subsequent intake; 3% NaCl was more effective than .9% NaCl. Other gastric loads of varying osmotic and caloric values also depressed subsequent intake. In order of increasing effectiveness in depressing intake, the gastric loads were protein hydrolystate, heavy cream, water, milk, lactose, glucose, and corn oil. Effectiveness was unrelated to osmotic or caloric value of the load. Gastric fill and, possibly, some property of carbohydrate appeared to be important determinants of satiety in the S. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of neonatal RU486 on adult sexual, parental, and fearful behaviors in rats.

Exposure to gonadal hormones during perinatal life influences later behavior. The finding that sex differences exist in progestin receptor expression in the perinatal rat brain suggests differential sensitivity of male and female brains to progesterone (C. K. Wagner, A. N. Nakayama, & G. J. De Vries, 1998). Because these sex differences are in neural sites that influence sexually differentiated sexual, parental, and fearful behaviors in adults, this study examined the effects of administering the progestin receptor antagonist RU486 for the first 10 days after birth on these behaviors in adulthood. Neonatal RU486 significantly reduced sexual behavior in males but did not impair reproduction in females. Neonatal RU486 did not affect parental responses of virgin rats exposed to pups (sensitization) but reduced fear in the elevated plus-maze in both sexes. Treatment of pups with RU486 affected neither mother–litter interactions nor plasma testosterone levels in males during or after treatment. These results suggest that neonatal exposure to progesterone, in addition to androgens and estrogens, influences behavioral development in rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Protein utilization, growth and survival in essential-fatty-acid-deficient rats

The relationship between essential fatty acids (EFA) deficiency and the utilization of dietary protein, growth rate and survival of offspring was investigated in rats during development and reproduction. EFA deficiency was induced by feeding a 200 g casein/kg-based diet containing 70 g hydrogenated coconut oil (HCO)/kg as the only source of fat. The conversion efficiency of dietary protein was assessed as net protein utilization (NPU), using a 10 d comparative carcass technique. Consumption of the deficient diet during the 10 d assay period induced biochemical changes characteristic of mild EFA deficiency in humans (triene:tetraene 0.27 (SD 0.04) compared with 0.026 (SD 0.004) for non-deficient controls), but there were no significant changes in growth rate or protein utilization. These variables were also unchanged when the deficient diet was fed for an additional 7 d before the assay, although triene:tetraene increased to 0.8 (SD 0.02). Feeding the deficient diet for 63 d before assay produced severe EFA deficiency (triene:tetraene 1.4 (SD 0.3) v. 0.036 (SD 0.005) for controls), a fall in growth rate (25% during assay period), and NPU (31.5 (SD 0.63) v. 39.0 (SD 0.93) for controls). These severely-EFA-deficient animals had a 30% higher fasting-resting rate of energy metabolism than that of age-matched controls. However, there was no change in the rate of endogenous N loss. Voluntary energy consumption was increased in animals fed on deficient diets, either with 200 g protein/kg, or protein free. The reduced efficiency of protein utilization could be entirely accounted for by the restricted amount of energy available for growth and protein deposition. Consumption of an EFA-deficient diet during pregnancy and lactation resulted in high mortality (11% survival rate at weaning compared with 79% for controls) and retarded growth in the preweaning offspring. It is concluded that animals are particularly sensitive to EFA deficiency during reproduction and pre- and post-natal stages of development. However, after weaning only severe EFA deficiency retarded growth, primarily through changes in energy balance.     

Effects of unilateral hypothalamic manipulations on the sexual behaviors of rats.

Four experiments that assessed the contributions of each side of the hypothalamus to the control of sexual behavior found the following: (1) Exposing the left, but not the right, ventromedial nucleus to estrogen neonatally defeminized sexual behavior in female rats. This asymmetry did not reverse as sexual differentiation progressed. (2) Unilateral cuts lateral to the medial preoptic area disrupted mounting in females that had mounted regularly before surgery, when given testosterone. The deficits were greater when the cuts were on the left side, but a third of the females with unilateral cuts showed severe deficits regardless of the side. (3) Comparable cuts did not impair masculine sexual behavior in gonadally intact males. In fact, left-side cuts seemed to accelerate copulation in males. (4) Unilateral lesions of the ventromedial nucleus disrupted lordosis in female rats in an essentially all-or-none fashion. This effect did not vary with side. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intrinsic programmes of growth and survival in developing vertebrate neurons

Neurons become dependent on a supply of target-derived neurotrophins for survival when their axons reach their targets in development. Because the distance axons have to grow varies from one population of neurons to another, the timing of dependence on neurotrophins likewise varies. Although it would be expected that the simplest way of getting the timing right would be for the target to provide a suitable signal to the arriving axons, detailed studies on developing cranial sensory neurons suggest that these neurons are programmed, before differentiation, to acquire dependence at the correct time independently of external signals. Neurons not only partly compensate for different target distances by extending axons more rapidly the further they have to grow, but possess an intrinsic clock that switches on dependence at the right time in accordance with the time it normally takes their axons to reach their targets. Here the experimental evidence for these intrinsic programmes of growth and survival is reviewed, the rationale that might have favoured their evolution is discussed, and parallels are drawn with other developing neuronal systems.     

Olfactory, thermal, and tactile controls of suckling in preauditory and previsual rats.

Determined exteroceptive control of nipple attachment in Sprague-Dawley rats and their litters by altering maternal sensory features. Preauditory and previsual pups, 2, 5, 8, and 11 days of age, were permitted to locate and attach to the nipples of their anesthetized mother after she had received one of the following treatments: (a) thermal--peripheral temperature was lowered to either 31 or 28°C; (b) tactile--the mother was shaved; (c) thermotactile--the mother was shaved and her skin temperature was lowered to 31°C; or (d) olfactory--all nipples were cleaned with methylene chloride and alcohol solvents. Only the olfactory treatment severely affected nipple attachment at all ages studied. Washing the nipples virtually eliminated suckling; painting them with a vacuum distillate of the nipple extract or of pup saliva reinstated suckling. The other manipulations either did not interfere with nipple attachment or did so at one age only. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of dopamine-depleting brain lesions on suckling and weaning in rats.

Rats given large dopamine (DA)-depleting brain lesions as adults exhibit severe impairments in ingestive behavior and sensorimotor function. In contrast to these well-known effects, the present 2 studies showed that virtually complete destruction of central dopaminergic neurons produced no such dysfunctions when it occurred in neonates (Sprague-Dawley). Ss continued to suckle and grow, albeit somewhat more slowly, and they could be weaned readily when they were 27 days old. Although most brain-damaged Ss did not survive weaning when they were 18 days old (controls exhibited no difficulty), this failure appeared to be the consequence of their reduced body weight and related inability to maintain body temperature in a relatively cool environment (22°C). Such premature weaning occurred more successfully when growth was stimulated by rearing brain-damaged pups in small litters or when ambient temperatures were raised to 31°C to minimize heat loss. Results demonstrate that the effects of near-total DA-depleting brain lesions are considerably less severe when they occur in infants than when they occur in adults, and, consequently, they reveal a capacity for neural plasticity during development that is no longer present at maturity. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some determinants of milk ingestion in suckling rats.

Eight experiments were conducted to examine several possible determinants and controls of milk intake in 10-day-old preweanling Sprague-Dawley rats. Results indicate that while the amount of milk the mother provides is a major determinant of milk consumption, pups will individually adjust their intake in response to certain treatments. Deprived pups ingested more milk than nondeprived littermate controls if given access to enough milk. Intragastric intubations of skimmed milk or distilled water reduced milk intake; heavy cream or isotonic saline did not. Injections of polyethylene glycol or formalin, which produced hypovolemia, increased milk consumption, and hypertonic saline decreased it. Results indicate that preweanling rats are behaviorally responsive to certain changes in body fluids and suggest that milk intake involves more than an invariant reflex. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Daily biorhythmicity influences homing behavior, psychopharmacological responsiveness, learning, and retention of suckling rats.

385 Sprague-Dawley suckling rats were used to investigate the effects of 24-hr biorhythmicity on performance. Nest-seeking (homing) in 7-day-old Ss and its facilitation by dextro-amphetamine varied across time of day. Analysis of initial choice revealed that Ss' ability to detect and position themselves in the direction of the nest did not vary across time of day. Homing behavior was not an artifact of random activity level but was related to Ss' motor performance, which varied with a daily rhythm. Circadian rhythmic influences on acquisition and retention of an amphetamine-induced odor aversion were demonstrated by manipulating time of day of conditioning and subsequent retention testing. The time of day effect on conditioning was attributed, in part, to daily rhythmic changes in the effectiveness of the UCS. Retention was optimal in Ss tested at the time of day corresponding to that of their original training. Thus, time of day may serve as an important contextual stimulus for retention in immature as well as adult Ss. (101 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Methysergide-induced nipple attachment depends on suckling experience in juvenile rats.

These studies were designed to investigate the links between pharmacological and behavioral procedures that facilitate suckling in weanling rats by assessing the effects of methysergide on nipple attachment behavior following experiential manipulations known to either promote or attenuate suckling. In the first experiment, methysergide failed to stimulate suckling in 25-day-old rats separated from their dam on Day 20, although it facilitated suckling in rats kept with the dam until either Day 24 or Day 25. In the second experiment, methysergide did not facilitate suckling in 35-day-old rats separated on Day 25, although rats separated on Day 30 or 34 were induced to suckle. In the third experiment, rats were housed with preweanling litters until Day 35 and then separated, housed with 25-day-old litters, or housed with preweanling litters for another 10 days. Rats in a fourth group remained with their dams until Day 35 and were then separated for 10 days. When tested at Day 45, nipple attachment was facilitated by methysergide only in the three groups that had received extended suckling experience. These results demonstrate that serotonergic inhibitory mechanisms modulate nipple attachment only when suckling experience is recent or extensive. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nutritive and nonnutritive determinants of milk intake of suckling rats.

Determined the factors that enhanced milk intake during deprivation in albino rats 15, 20, and 25 days of age. Ss were subjected, for 8 hrs, to 1 of 6 regimens. Results show that intake at Day 15 was reduced by the opportunity to suckle, independent of receiving a milk load. This same trend was apparent, although not as strong, among Day 20 Ss. By Day 25, nonnutritive suckling during the privation period no longer attenuated milk intake, although preloads did, whether or not they were paired with nonnutritive suckling. Thus, suckling in Ss became increasingly freed from oral demands and more responsive to the nutritive consequences. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of space allocation and temperature on periparturient maternal behaviors, steroid concentrations, and piglet growth rates

Preparturient sows were randomly assigned to either a farrowing crate (n = 12) or farrowing pen (n = 12) across cool and hot seasons (with or without drip cooling) to study space allocation and temperature effects on periparturient maternal behaviors, steroid concentrations, and piglet growth rates. Concentrations of estradiol-17 beta (E2 beta), progesterone (P4), and cortisol were quantified in blood collected from surgically implanted vena cava cannulas. Sows were videotaped from 2 h before to 2 h after farrowing. Similar periparturient behaviors were displayed by all sows, regardless of farrowing environment. Sows in pens had lower (P < .05) prepartum P4 concentrations from d -6 to the day preceding farrowing and a reduced (P < .05) piglet birth interval compared with sows in crates (12.95 +/- 1.35 min vs 18.31 +/- 2.21 min, respectively). Additionally, compared with multiparous sows in crates, multiparous sows in pens weaned heavier piglets (P < .05). Estradiol-17 beta concentrations were lower (P < .01) throughout lactation during hot weather for sows with or without drip cooling, averaging 9.30 pg/mL and 8.57 pg/mL, respectively, compared with 18.65 pg/mL for sows during cool weather. This decrease in E2 beta concentration in sows during hot weather was correlated with an extended (P < .05) interval from weaning to first estrus for the sows in hot weather compared to sows during cool weather. Cortisol concentrations decreased progressively during lactation and were not associated with litter weight gains or the interval between weaning and first estrus.     

Effect of milk-borne epidermal growth factor on the hepatic microcirculation and Kupffer cell function in suckling rats

A Rehabilitation Information System was created in July 1993 in order to register war victims in need of physical rehabilitation all over Croatia. The system is currently operating and presented data covers the period from July 1991 to July 1995. Approximately 15,000 questionnaires had been completed and returned from medical institutions on in total 8589 disabled war victims in need of rehabilitation. People with severe disabilities comprised about 20% of all in need of rehabilitation. Those reported injured were 3.5 times more than those in need of physical rehabilitation. Most common types of injuries were fractures with a permanent disabling condition (3109 persons), peripheral nerve injuries (1213 persons) and amputations (956 persons). Traumatic brain injuries were registered for 594 and spinal cord injuries for 262 persons. Causes of injuries were explosive devices (such as mines, mortar shell shrapnel, etc.) in 37% of cases, bullets in 22%, accidents in 7%, other (such as fire, blast injuries, etc.) and unknown causes in 34%.     

Effects of reflection, restatement, probe, and nonverbal behaviors on client affect.

Examined the effects of counselor verbal behavior (reflections, probes, and restatements) and nonverbal behavior (presence or absence of nodding and smiling) on the verbal responses of 48 undergraduates. Each S participated in a half-hour counseling session which was divided into 4 time periods (baseline, counselor intervention, baseline, and counselor intervention). It was observed that probes resulted in more discussion of feelings than did either reflections or restatements. Nonverbal behavior did not affect discussion of feelings. Possible reasons for the effectiveness of the probe are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of prenatal stress on suckling calves

Pregnant Brahman cows (n = 42), bred to either Brahman or Tuli bulls, were randomly assigned to one of three treatments: 1) transported in a stock trailer for 24.2 km, unloaded at a second farm and penned for 1 h, and then returned to the original farm (TRANS); 2) i.v. injection of ACTH, 1 IU/kg BW (ACTH); or 3) walked through the handling facilities (SHAM). Treatments were initiated on d 60 and repeated at 80, 100, 120, and 140 d of gestation. The calves from these cows were subjected to tests to measure their capacity to react to stress. In Test 1, Tuli-sired calves were restrained at 10 and 150 d of age for 3.5 h. In Test 2, Brahman-sired calves were restrained for 3.5 h and given an injection of ACTH (.125 IU ACTH/kg of BW). In Test 3, Test-2 calves were restrained at 180 d of age and hot-iron branded. In Test 4, Test-1 calves were restrained at 180 d of age and given an injection of cortisol (6.7 ng/kg BW) to estimate cortisol clearance rate. During all tests, calves were restrained for 3.5 h, and heart rates were recorded and blood samples were taken at -15, 0, 15, 30, 45, 60, 90, 120, and 180 min. The 10- and 150-d-old TRANS calves maintained greater plasma cortisol in Test 1 (restraint) than the ACTH and SHAM calves (P < .01). The ACTH challenge (Test 2) increased plasma cortisol and ACTH, but cow treatment did not alter the response (P > .4). In response to branding (Test 3), the TRANS, ACTH, and SHAM calves' overall mean plasma cortisol was not affected by treatment (52, 51, and 43 +/- 3 ng/mL, respectively; P > .1), nor was the calves' overall heart rate (91, 94, and 86 +/- 3 beats/min, respectively; P > . 1). In Test 4, TRANS calves cleared plasma of cortisol at a slower rate than did the SHAM calves (P < .01), but not the ACTH calves (261, 374, and 473 +/- 50 mL/min, respectively; P > .1). The TRANS calves had an overall greater heart rate than did the ACTH or the SHAM calves (91, 79, and 77 +/- 2 beats/min, respectively; P < .001). Exposing cows to repeated transportation stress during gestation altered their calf's physiological response to stress, and these alterations could have a profound influence on the calfs ability to adapt to stress, thereby influencing its welfare. Further research should examine the growth, immune function, and reproductive function of prenatally stressed calves to determine whether these changes in plasma cortisol are beneficial or deleterious.