Are young female gymnasts malnourished?

Summary Competitive rhythmic sportive gymnastics have been accused of promoting an unphysiologic weight reduction which may progress to manifest anorexia nervosa. In this study, eight young female gymnasts who represented Norway in the European Championships in Rhythmic Sportive Gymnastics 1982 were examined for evidence of malnutrition. Ten girls, matched for age and height, served as controls. The examination included registration of anthropometric data (height, weight, and body-mass index), motor and sensory neurography and biopsies of the vastus lateralis muscle with exact measurements of muscle fibre areas on sections stained for myofibrillar ATPase activity.The mean body weight of the gymnasts did not differ from that of the control group or of a large series of age matched Norwegian females. This finding excludes the possibility of general malnutrition among the examined gymnasts. Muscle fibres of both types 1 and 2 were found to be smaller in the gymnasts than in the controls, with values of 3,404 m² vs 3,811 m² for type-1 fibres and 2,985 m² vs 3,942 m² for type-2 fibres respectively. Although contradictory to most previous reports, this finding suggests that the reduction in fibre size among the gymnasts might be an effect of physical training. There were some differences in neurographic parameters between the groups, but the mean values were all within normal ranges. The motor nerve conduction velocity in the proximal segments of the median and ulnar nerves was significantly slower in the gymnasts and, as a possible consequence of smaller muscle fibres, the motor responses were generally less in this group.     

Effects of septal lesions on shock thresholds in weanling male and female rats

Twenty-four-day old weanling male and female rats were either lesioned in the septal area, gonadectomized, lesioned and gonadectomized, or untreated. Tests for reactivity to electric shock were conducted at 26 and at 40 days of age. Neither males nor females showed any effect of the lesions are measured by flinch and jump thresholds to electric shock immediately following surgery; both male and female lesioned groups showed a significant lowering of thresholds when tested at 40 days of age. The effects of septal lesions on response to electric shock were dissociated from the effects on hyperemotionality measured over the same period of time after the lesions, and appeared to have their effect independent of the sex or hormonal condition of the animals.     

Anosmia and play fighting behavior in prepubescent male and female rats

Prepubescent male and female rats were paired after intranasal treatment with isotonic zinc sulfate or saline solutions to determine the influence of peripheral anosmia upon play fighting behavior. In Experiment 1, male isolate residents pinned intruders significantly more often than intruders pinned residents but anosmia treatment had no influence on pinning behavior. In Experiment 2, males and females differed significantly in all major categories of play fighting but anosmia treatment had no influence on play fighting of either males or females. In Experiment 3, male groups matched for play fighting behavior prior to intranasal zinc or saline treatment were paired with like-treated males. All males in all pairings engaged in play behavior but anosmic males played less than controls. Evidently, intranasal zinc treatment depresses play behavior only when both members of a pair are anosmic. Play behavior is more markedly affected by resident-intruder status and by gender than by peripheral anosmia.     

Stimuli from pups of adrenalectomized and malnourished female rats

The present study was designed to examine the effects of maternal adrenalectomy on pup cues. In Experiment 1, pituitary-adrenal activity of test mothers was differentially affected by cues from handled and shocked pups of adrenalectomized (ADX) and control (CON) mothers. The results suggest that the cues provided by pups of ADX mothers are less arousing to lactating females than are cues from pups of CON mothers. In Experiment 2, ultrasonic vocalizations in response to handling and shock were measured in pups of CON, ADX and malnourished (MAL) mothers. For all types of pups, shocking evoked more signaling than did handling on postnatal Days 8, 9 and 11. Pups of CON mothers showed a peak of vocalizations on Day 4. Pups of ADX and MAL mothers vocalized as frequently as did pups of CON mothers, but did not reach their peak of signaling until Day 11. This experiment demonstrates a retardation in the development of ultrasonic signaling in pups of ADX mothers. This effect appears to be due to the pup malnutrition that maternal adrenalectomy produces because pups of MAL mothers show a similar retardation.     

Acquisition of DRL-20 behavior in male and female, Roman high- and low-avoidance rats

Female RLA rats were more efficient than male RLA, male and female RHA rats (in that order), in the acquisition of DRL-20 operant conditioning behavior. It was concluded that RHA rats were less capable of inhibiting nonrelevant activity in that test.     

Preventing and alleviating hypothermia-induced amnesia in weanling and young adult rats

Reminder (Experiment 1) and familiarization (Experiment 2) treatments were found to have similar effects on the 24-hr retention performance of 24- to 26- and 90- to 100-day-old rats that either did or did not undergo an amnesic treatment (hypothermia) immediately after training. Similar degrees of retrograde amnesia and normal forgetting were evident in both trained age groups that were not subjected to familiarization or reminder treatments. These results suggest that memory processes in weanling and adult rats are similar in susceptibility to disruption by an established amnesic treatment (hypothermia) and in the ease of prevention of and recovery from amnesia by recognized preventive (familiarization) and alleviation (reminder) measures. The similarity of the effects of these preventive and alleviation treatments on normal forgetting and induced amnesia suggests that experimentally induced amnesia may be a fruitful approach to studying the ontogeny of memory processes and, more specifically, to studying factors that influence infantile amnesia.     

Sexual behavior in aged, noncycling female rats

Sexual behavior of 19 month old, noncycling, female rats was evaluated for a period of 8 days. The sexual behavior of 11 aged females revealing constant vaginal cornification (CVC) for 30 days prior to, and during the observation period was variable. Eight of the CVC females showed consistently high lordosis quotients (LQ), whereas 3 showed no lordosis. A significant negative correlation was found between food intake and LQ over the 8 day period. In 8 other aged females, the vaginal smear was characterized by a mixture of both leucocytes and cornified cells, each day, for a period of 30 days prior to, and during the observation period. Lordosis behavior was absent in all females revealing this mixed type (MX) smear when they were tested. At random times after the test period, 3 CVC and 2 MX females showed a vaginal cycle. As the vaginal cycle was observed each female was again tested for sexual behavior. All 5 females were highly receptive when placed with the male during the evening of vaginal proestrus, but not at other times. It is concluded that despite disruptions of regular ovarian cyclicity, aged female rats are still capable of showing a lordosis response.     

Kindling-induced emotional behavior in male and female rats

Modeling fear in animals is a critical approach for identifying the neural mechanisms involved in human disorders such as generalized anxiety and panic. Amygdala kindling has proven useful in this regard because it produces dramatic increases in fearful behavior. The purpose of this experiment was to compare the behavioral effects of kindling in male and female rats. Compared with the sham-stimulated rats, the kindled male and female rats showed similar increases in fearful behavior, with some sex differences in fear-related open-field activity. They also showed decreased immobility in the forced-swim test and increased sucrose consumption. These results suggest that kindling-induced fear is generally similar in male and female rats and that kindling does not appear to induce depression-like behavior.     

Discriminated lever press avoidance conditioning in male and female rats

Discriminated lever press avoidance and step through passive avoidance conditioning were studied in male and female rats. In lever press avoidance female rats showed superior avoidance performance, less intertrial responding and shorter durations of leverholding than male rats. Castration of males tended to improve their avoidance performance, whereas ovariectomy had no effect. In passive avoidance more males than females showed an avoidance response. From these results it is concluded that aversive stimulation seems to elicit different behavior tendencies in male and female rats rendering males less prepared for active avoidance, but at the same time more prepared for passive avoidance conditioning. The data do not support the hypothesis that sex differences in activity underly the dimorphism in active and passive avoidance conditioning.     

Olfactory control of the sexual behavior of male and female mice

Bilateral removal of the olfactory bulbs virtually eliminates sexual behavior in male and female mice. In the studies reported here, mice were rendered anosmic by intranasal application of a zinc sulfate solution. Peripherally induced anosmia did not affect the sexual behavior of male mice. Peripherally induced anosmia attenuated the hormone induced display of sexual receptivity in female mice, but peripherally anosmic females were significantly more receptive than bulbectomized females. This finding suggests that (1) pheromonal factors may be involved in the full arousal of sexual receptiveness in female mice, but (2) that the effect of bulbectomy upon sexual receptivity in female mice cannot be attributed solely to the surgical production of anosmia. The general failure of peripherally induced anosmia to mimic the effects of olfactory bulb removal upon the display of sexual behavior in male and female mice suggests that the olfactory bulbs are importantly involved in the control of sexual behavior in some manner not related to sense of smell.     

Testosterone induced mounting behavior in adult female rats born in litters of different female to male ratios

Female rats can show mounting behavior towards isosexual or heterosexual conspecifics. The present experiments were designed to study whether the prenatal presence of male fetuses would affect display of this mounting behavior in adulthood. Therefore mounting behavior, after gonadectomy and during continuous treatment with testosterone propionate (TP) was studied in female rats which were born in litters without male siblings (“all female” litters) and in litters with a variable number of male siblings. Litter composition at birth did not affect display of adult mounting behavior during protracted tests (a total of 6 tests during 8 weeks of treatment with TP). The data indicate that TP induced mounting behavior in adulthood occurs independent of the prenatal presence of male fetuses. If mounting behavior in adulthood has to be “organized” by prenatally present androgen (the current way of thinking), then the present data indicate that female rat fetuses provide themselves with these hormones. It would then seem inappropriate to judge adult mounting behavior as a sign of “masculinization” of the rat brain.     

Punishment of food rewarded lever holding in male and female rats

Up to now, better retention of passive avoidance behavior by male rats has been observed only in situations involving the re-entry into a compartment as the punished response. The present study is aimed at investigating whether this sex difference can be generalized to situations in which this spatial factor is unimportant. Male and female rats were trained to hold down a lever continuously for ten seconds to obtain a food pellet. After extensive training on this program, two sessions were scheduled in which both a food pellet and a foot shock were contingent to lever holding. Extinction of punishment was studied in twenty-four sessions in which animals again only received a food pellet upon meeting the requirement for reinforcement. Although the effects of punishment extinguished very slowly, females showed faster extinction than males. They emitted more responses and received more reinforcers during the postshock stage. In addition, male rats showed more abortive responding, i.e., in males a higher percentage of responses was terminated before meeting the requirement for reinforcement. Several hypotheses accounting for sex differences in aversively motivated learning are discussed. The present data are taken as support for the fear motivation hypothesis.     

Delayed alternation in adolescent and adult male and female rats

The prefrontal cortex continues to develop throughout adolescence in several species, and our laboratory has demonstrated that during adolescence there is a decrease in neurons in the rat medial prefrontal cortex (mPFC). A PFC-dependent task, the delayed alternation task, was used in the present study to examine the function of the mPFC while it is still maturing in rats of both sexes. A deficit was found in adolescents when compared to adults during 15- and 60-s delays but not at other delays (5, 10, 30, and 90 s). Furthermore, adolescents committed more perseverative errors. No significant sex differences occurred at any delay for either age group; however, in the no delay training sessions, adolescent males reached criterion faster than females. These results indicate that performance on a mPFC-dependent task improves between adolescence and adulthood.     

Exercise and the development and persistence of dietary obesity in male and female rats

Adult male and female hooded rats were housed in sedentary conditions or were given free access to a running wheel. Exercising and sedentary rats received either a palatable, mixed, high energy diet with chow (experimental group) or only chow (control group). Exercise reduced the weight gain of the males but not of the females. All experimental groups preferentially selected the palatable foods. Both exercising and sedentary females and the sedentary males became obese compared to their controls, but the exercising males did not. The mixed diet was withdrawn after 10 weeks: thereafter the male and female sedentary experimental groups maintained the elevated body weight. The exercising experimental females showed significant weight loss. Analysis of x-ray photographs indicated that elevated body weight in the experimental rats probably reflected increased deposition of fat and not skeletal growth. The results show that the effect of exercise on the development of dietary obesity is different in males and females, and that sedentary male and female rats can both show persistent dietary obesity after withdrawal of the palatable foods.     

Histamine-elicited drinking in weanling and adult rats

A total of 260 male and female adult (60-70 days of age) and weanling (22-25 days of age) Sprague-Dawley derived rats were used in these experiments. Subcutaneous administration of histamine (HA) elicited drinking in a dose-dependent manner for both ages tested, although the threshold dose varied with age. A dose of 5.0 mg/kg HA elicited significant increases in water intake for adults, whereas for weanlings a dose of 20 mg/kg HA was necessary. Adult rats exhibited decreased latency to drink after all doses of HA tested, whereas for weanlings, decreased latency was evident only after doses of HA sufficient to elicit increases in water intake. Combined antagonism of H1 and H2 receptors for HA, using dexbrompheniramine and cimetidine, respectively, inhibited HA-elicited drinking in adults and weanlings. Further investigation of the ontogeny of histamine- and food-related drinking may provide a useful approach to examine the physiological mechanisms underlying fluid consumption in adult animals and as they are gradually elaborated during ontogeny.     

Sexual behavior of the naive male mouse as affected by the presence of a male and a female performing mating behavior.

Sexually naive male mice allowed to observe conspecifics engaged in copulation later exhibited a preference (p<0.01) for the odor of estrous females over that of diestrous females. They also mounted estrous females more frequently than diestrous females (p<0.001). Naive males observing noncopulating pairs or isolated females exhibited a preference (p<0.01) for the odor of diestrous females over that of estrous females but showed no difference in mounting behavior in the presence of estrous versus diestrous females.     

Sexual behavior of male and female septal lesioned rats

Gonadectomized male and female rats were given septal lesions (SL) or sham surgery at approximately 60 days of age. After 3 weeks lordosis behavior tests were initiated. Females were tested after daily injections of 2 μg estradiol benzoate (EB) for 3 days, while males were tested after EB only (2 μg×3 days), and after EB plus progesterone (Prog). The mean lordosis quotients (LQ) of septal lesioned female rats were significantly higher than those of sham operated controls. No increase in lordosis responding was seen in male rats with either EB alone or EB+Prog. Following an additional 3 week interval without steroid treatment masculine behavior tests began. All animals received a pretest and were tested again on Day 4, 7, 11 and 15 daily tesosterone propionate (150 μg/day) treatment. No alterations in masculine sexual behavior (relative to that of controls) were found in either male or female septal lesioned rats. It is concluded that the increased hormone sensitivity is specific for lordosis behavior, at least when the SL are given in adulthood.