The relationship of lean limb volume to performance in the handgrip and standing long jump tests in boys and girls, aged 11.6–13.2 years

Twenty-three girls and 19 boys performed the handgrip and standing long jump (SLJ) tests. Their total forearm and leg volumes were calculated from circumference and length measurements and the lean volumes (bone + muscle) were calculated by making allowance for skinfold thickness. Although the boys were older than the girls (12.8 and 12.4 years), there was no significant difference in their heights or body masses. The absolute performances of the boys were superior to those of the girls in both tests (handgrip 234 and 205 N and SLJ 1.53 and 1.34 m), but when jumping performance was expressed as distance x body mass, there was no significant difference. In both tests, performance in terms of unit lean limb volume showed no significant gender difference. When performance was related to lean limb volume, both boys and girls showed a linear relationship in the two tests, with no significant difference between them. This absence of a gender difference contrasts with the results of a previous study on young adults and comparison shows that the relationships between lean limb volume and performance in the two tests for both boys and girls lie just below those of the young, adult females. The difference between the girls and the young adult females was just significant in the handgrip (p less than 0.05), but not significant in the SLJ (p greater than 0.25), whereas the differences between the boys and young adult males were significant (p less than 0.01) in both tests. Thus it would appear that a gender difference in the performance of skeletal muscle develops during adolescence and possible contributory factors are discussed.     

Modification of the standing long jump test enhances ability to predict anaerobic performance

The purpose of this study was to investigate whether modifying the standing long jump test would enhance its ability to be a better predictor of anaerobic performance compared to other common anaerobic power tests. Three modified box long jump (MBLJ) tests were performed using 1, 2, or 3 boxes. Subjects consisted of 38 healthy males (age, 21.7 +/- 1.7 years) who performed all the testing procedures. All 3 variations of the MBLJ test showed significant correlations (p < 0.05) with the vertical jump (VJ); standing long jump (SLJ); 50-, 100-, 200-, 400-m runs; long jump; triple jump; and shot put ability (r = 0.362-0.891). All 3 variations of the MBLJ test also showed significant correlations with isokinetic peak torque knee extension and flexion, Wingate mean power (W), and Wingate mean power per kilogram (W/kg) (r = 0.357-0.504). Generally, correlations of the 3 MBLJ tests were stronger than correlations between VJ and SLJ ability to the same measure of power. Generally, the 3-box MBLJ tests showed stronger correlations with measures of power than the 1- and 2-box MBLJ tests. Multiple linear regression models indicated that the 3-box MBLJ test is a major predictor of the track and field performances compared to the other tests of anaerobic power. Along with other independent variables, the 3-box MBLJ test explained 55%, 44%, 51%, 61%, 52%, and 72% of the variance of 50-, 100-, 200-, and 400-m runs; long jump; and triple jump performance, respectively. In conclusion, due to the significant correlations between the MBLJ tests, especially the 3-box version, and other measures of power, these tests are appropriate for testing lower body power.     

Sex dimorphism in the thyroid gland. IV. Cytologic aspects of sex dimorphism in the rat thyroid gland

This study was designed to explain whether the sex-dependent differences in the structure of the thyroid gland of adult male and female rats depend on quantitative or qualitative changes in the thyroid follicular cells. Absolute thyroid gland weight was similar in male and female rats, but its relative weight was markedly higher in females however. Volume fractions of epithelium and stroma were higher and that of colloid lower in male than in female rats and the epithelium/colloid ratio was higher in the males. Also absolute the volumes (in mm3) of epithelium and stroma were higher in the males; the thyroid gland of females contained more colloid. The average volume of a thyroid follicular cell, estimated by stereology, was higher in males than in females, although the thyroid gland contained similar numbers of follicular cells in both sexes. Also, thyroid glands from both male and female rats contained a similar DNA quantity. Results of the present study show that the sex dimorphism in the rat thyroid depends upon a difference in the mean volume of thyroid follicular cells, with males having larger cells than females. However, in both sexes the thyroid gland contains a similar quantity of these cells.     

Physiological and anthropometric characteristics of Australian junior national, state, and novice volleyball players

The purpose of this study was to investigate the physiological and anthropometric characteristics of junior volleyball players competing at the elite, semi-elite, and novice levels and to establish performance standards for these athletes. One hundred and fifty-three junior national (N = 14 males; N = 20 females), state (N = 16 males; N = 42 females), and novice (N = 27 males; N = 34 females) volleyball players participated in this study. Subjects underwent measurements of standard anthropometry (body mass, height, standing reach height, and sum of 7 skinfolds), lower-body muscular power (vertical jump and spike jump), upper-body muscular power (overhead medicine ball throw), speed (5-m and 10-m sprint), agility (T-test), and estimated maximal aerobic power (multistage fitness test) during the competitive phase of the season, after obtaining a degree of match fitness. Significant differences (p < 0.05) were detected among junior national, state, and novice volleyball players for height, standing reach height, skinfold thickness, lower-body muscular power, agility, and estimated maximal aerobic power, with the physiological and anthropometric characteristics of players typically improving with increases in playing level. Male players were taller, heavier, leaner, and had greater standing reach height, speed, agility, muscular power, and estimated maximal aerobic power than female players. These findings provide normative data and performance standards for junior volleyball players competing at the elite, semi-elite, and novice levels. Given the improvements in lower-body muscular power, agility, and estimated maximal aerobic power with increased playing level, and given the importance of these qualities to competitive performances, conditioning coaches should train these qualities to improve the playing performances of junior volleyball players.     

A sex difference in the effect of CCK-8 on food and water intake in obese (ob/ob) and lean (+/+) mice

Male and female ob/ob and +/+ mice were tested with CCK-8 (1, 2, 4 and 8 micrograms/kg) administered 15 min prior to 30-min access to solid food after 17.5 hr food deprivation and 15 min prior to 30-min access to water after 17.5 hr water deprivation. The threshold dose for suppressing 30-min food intake was 2 micrograms/kg for all mice. Larger doses of CCK-8 inhibited food intake in male obese and lean mice in a linear fashion. The dose-response relationship for female mice, however, was not linear: lean females failed to suppress food intake following 4 or 8 micrograms/kg and obese females did not suppress food intake at 4 micrograms/kg. There was also a sex difference in the effect on water intake. No dose of CCK-8 changed water intake in lean males and only the 8 micrograms/kg dose decreased water intake in obese males. In contrast CCK-8 (1, 4 and 8 micrograms/kg) increased water intake in obese females, CCK-8 (1 and 8 micrograms/kg) increased water intake in lean females and no dose of CCK-8 decreased water intake in females. These data demonstrate significant sex differences in the effect of CCK-8 on food and water intake in mice.     

Vascular volumes and hematology in male and female runners and cyclists

To examine the hypothesis that foot-strike hemolysis alters vascular volumes and selected hematological properties is trained athletes, we have measured total blood volume (TBV), red cell volume (RCV) and plasma volume (PV) in cyclists (n = 21) and runners (n = 17) and compared them to those of untrained controls (n = 20). TBV (ml x kg(-1)) was calculated as the sum of RCV (ml x kg(-1)) and PV (ml x kg(-1)) obtained using 51Cr and 125I-labelled albumin, respectively. Hematological assessment was carried out using a Coulter counter. Peak aerobic power (VO2peak) was measured during progressive exercise to fatigue using both cycle and treadmill ergometry. RCV was 15% higher (P < 0.05) in male cyclists [35.4 (1.0), mean (SE); n = 12] and runners [35.3 (0.98); n = 9] compared to the controls [30.7 (0.92); n = 12]. Similar differences existed between the female cyclists [28.2 (2.1); n = 9] and runners [28.4 (1.0); n = 8] compared to the untrained controls [24.9 (1.4); n = 8]. For the male athletes, PV was between 19% (cyclists) and 28% (runners) higher (P < 0.05) in the trained athletes compared to the untrained controls. The differences in PV between the female groups were not significant. Although the males had a higher (P < 0.05) TBV, RCV and PV than the females, no differences between cyclists and runners were found for either gender. Mean cell volume was not different between the athletic groups. VO2peak (ml x kg(-1) x min(-1)) was higher (P < 0.05) in both male [68.4 (1.5)] and female [54.8 (2.1)] runners when compared to the untrained males [47.1 (1.0)] and females [40.5 (2.1)]. Although differences existed between the genders in VO2peak for both cyclists and runners, no differences were found between the athletic groups within a gender. Since the vascular volumes were not different between cyclists and runners for either the males or females, foot-strike hemolysis would not appear to have an effect on that parameter. The significant correlations (P < 0.05) found between VO2peak and RCV (r = 0.64 and 0.64) and TBV (r = 0.82 and 0.63) for the males and females, respectively, suggests a role for the vascular system in realizing a high aerobic power.     

Restoration of sexual performance in old rhesus macaques paired with a preferred female partner

Experiments were undertaken to determine whether the decline in the ejaculation frequency of old male rhesus macaques is due to a decrease in physical capacity. In the first experiment, the capacity of old males to ejaculate in a series of biweekly tests was investigated. Six old (18–23 years) and six young (8– 12 years) male rhesus macaques were given 10-min tests of sexual behavior with nine different females chosen at random. The old males were also given 10-min tests with a preferred female, 1339. When the old males were tested with nine different females, their sexual performance (e.g., frequency of ejaculation) was significantly less than that of the young males, but their performance was comparable to that of young males in nine tests with female 1339. In a second experiment, the capacity of old males to show repeated ejaculations over a 3-hr period was tested. The same old and young males were given a 3-hr test with female 1339. The sexual performances (number of ejaculatory series completed and behavior displayed within each ejaculatory series) of the old males did not differ significantly from those of the young. Also, no significant differences in behavior were observed between young and old males during the first 10 min of the 3-hr tests. Our data show that the decline in the sexual performance of old rhesus males is not due to a decreased capacity to perform sexually or to physical debilitation.     

Alveoli increase in number but not size from birth to adulthood in rhesus monkeys

Postnatal developmental stages of lung parenchyma in rhesus monkeys is about one-third that of humans. Alveoli in humans are reported to be formed up to 8 yr of age. We used design-based stereological methods to estimate the number of alveoli (N(alv)) in male and female rhesus monkeys over the first 7 yr of life. Twenty-six rhesus monkeys (13 males ranging in age from 4 to 1,920 days and lung volumes from 41.7 to 602 cm(3), 13 females ranging in age from 22 to 2,675 days and lung volumes from 43.5 to 380 cm(3)) were necropsied and lungs fixed, isotropically oriented, fractionated, sampled, embedded, and sectioned for alveolar counting. Parenchymal, alveolar, alveolar duct core air, and interalveolar septal tissue volumes increased rapidly during the first 2 yr with slowed growth from 2 to 7 yr. The rate of change was greater in males than females. N(alv) also showed consistent growth throughout the study, with increases in N(alv) best predicted by increases in lung volume. However, mean alveolar volume showed little relationship with age, lung volume, or body weight but was larger in females and showed a greater size distribution than in males. Alveoli increase in number but not volume throughout postnatal development in rhesus monkeys.     

Influence of season and body condition on plasma volume levels of white‐tailed deer,Odocoileus virginianus

Abstract

Changes in the circulating plasma volume were monitored for twelve consecutive months in five white‐tailed deer (Odocoileus virginianus) maintained outdoors in a 2.4‐ha enclosure in northern New York stale. The mean annual relative plasma volume of the two male white‐tailed deer (43.6 ± 1.0 ml/kg) was not significantly different from that of three females (45.7 ± 0.7 ml/kg). Mean annual absolute plasma volume, however, was significantly higher in males (2588 ± 90.7 ml) than in females (2092 ± 79.1 ml), mainly because of the greater body weights of males in late summer and early fall. Both sexes had a marked seasonality in the level of relative and absolute plasma volume regulation. Relative plasma volumes were lowest in February‐March and highest in May‐June and again in October, while absolute plasma volumes were lowest in late winter to early spring, when body weights in the annual cycle were lowest, and volumes were highest in mid‐fall, at the annual peak of body condition. Males had a greater excursion about their annual mean relative plasma volumes (‐16 to 13%) and absolute plasma volumes (‐23 to 32%) than did females (respectively, ‐11 to 9% and ‐13 to 19%). Variations in the level of plasma volume regulated are related to the annual cycle of environmental conditions and changes in body and physiological condition of white‐tailed deer.     

Growth and moulting in nematodes: Changes in the dimensions and morphology of Rotylenchulus reniformis from start to finish of moulting

At a temperature of 24°C, freshly hatched second stage larvae (L₂) of Rotylenchulus reniformis take 2 weeks to complete moulting and become either adult males or immature females. Measurements of different nematode stages were made using a computer-interfaced digitizer (CID). This proved to be more rapid and reproducible than conventional techniques.Moulting and development were followed in individual living specimens viewed under Nomarski optics and oil immersion. The mean loss in body volume of these specimens from L₂ to immature female is about 17% compared with about 19% for the mean loss in body volume from L₂ to male. The mean volumes for a total of 70 randomly selected living specimens measured are 95·6 pi for L₂s, 72·9 pl for immature females and 74·2 pl for males. Mean losses in body volume during moulting calculated from these randomly selected stages were slightly higher than those observed for individuals, being about 24% for the immature female and about 22% for the male.     

Standard anthropometric, body composition, and strength variables as predictors of jumping performance in elite junior athletes

The aim of the study was to investigate whether variables routinely assessed while testing athletes can also predict movement performance. The relation between jumping performance and standard strength, anthropometric, and body composition variables was examined in elite junior basketball players. The 33 males were tested for maximal vertical jump, as well as for maximal isometric voluntary force and rate of force development of hip and knee extensors. Standard anthropometric and body composition measures (body height, lean body mass, as well as the percentage of fat and muscle tissue) were also taken. Except for maximal isometric forces (0.38 and 0.52 N.kg(-1) for hip and knee extensors, respectively), all correlation coefficients between the selected variables and jump height were insignificant. As a consequence, the corresponding multiple correlation coefficient, R = 0.71, also suggested a moderate predictability of jumping performance by the standard strength tests and anthropometric and body composition variables. The results obtained dispute the use of the examined tests in sport performance assessment, and also question applying the tests for other purposes such as evaluation of training procedures or selection of young athletes. Therefore, the results are in line with the concept that a reliable performance assessment in homogeneous groups of athletes requires predominantly movement-specific testing.     

Leptin in a lean population of Filipino adolescents

To clarify the role of leptin as a signal of energy status in humans, this study investigated the relationship of leptin to measures of body composition, maturity, and lifestyle factors in a lean sample of 293 male and 303 female Filipino adolescents (age 14-16 years). Participants were selected from the Cebu Longitudinal Health and Nutrition Survey, a representative birth cohort study begun in 1983. Using IOTF criteria, the prevalence of overweight (2.2%) and obesity (0.3%) were extremely low, and leptin levels were among the lowest reported in any healthy population (mean: 0.78 and 3.57 ng/dl in males and females). As expected, adiposity was the strongest predictor of leptin, with triceps skinfold explaining 40.2 and 30.6% of leptin variance in males and females. In females, subscapular skinfold was a significant predictor of leptin independent of triceps, while no anthropometric measure predicted leptin independent of triceps in males. There were few relationships between lifestyle factors and leptin independent of adiposity. In males, leptin levels varied little across most of the triceps distribution, suggesting that the leptin-adipose regulatory system is sensitive to very small changes in leptin in lean populations, at least among males. These findings add to the small but growing list of studies documenting differences in leptin biology among chronically lean populations.     

Stem cell activation in adults can reverse detrimental changes in body composition to reduce fat and increase lean mass in both sexes

Detrimental changes in body composition are often associated with declining levels of testosterone. Here, we evaluated the notion that multipotent mesenchymal stem cells, that give rise to both fat and muscle tissue, can play a significant role to alter existing body composition in the adult. Transgenic mice with targeted androgen receptor (AR) overexpression in stem cells were employed. Wild-type littermate and AR-transgenic male and female mice were gonadectomized and left untreated for 2 months. After the hypogonadal period, mice were then treated with 5α-dihydrotestosterone (DHT) for 6 weeks. After orchidectomy (ORX), wild-type males have reduced lean mass and increased fat mass compared to shams. DHT treatment was beneficial to partially restore body composition. In wild-type females, ovariectomy (OVX) produced a similar change but there was no improvement with DHT. In targeted AR transgenic mice, DHT treatment increased lean and reduced fat mass to sham levels. In contrast to wild-type females, DHT treatment in female transgenic mice significantly ameliorated the increased fat and decreased lean mass changes that result after OVX. Our results show that DHT administration reduces fat mass and increases lean mass in wild-type males but not females, indicating that wild-type females are not as sensitive to androgen treatment. Because both male and female transgenic mice are more responsive than wild-type, results suggest that body composition remains linked to stem cell fate in the adult and that targeted androgen signaling in stem cells can play a significant role to reverse detrimental changes in body composition in both sexes.     

SEXUAL SELECTION IN AMERICAN TOADS: A TEST OF A GOOD-GENES HYPOTHESIS

Adaptive mate choice in species lacking male resource control and/or paternal care might be maintained by selection because preferred males sire genetically superior offspring. For such a process to occur, some male phenotypic trait(s) must both reliably indicate male genetic quality and influence the pattern of mate choice by females. In American toads, Bufo americanus, male body length has been documented to influence female mating patterns: females usually mate with males that are larger than average. However, the relationship between male size and male genetic quality is unknown. We conducted a controlled breeding experiment using 48 sires and 19 dams to determine if larger males sire offspring with superior larval performance characteristics (greater survival to metamorphosis, larger mass at metamorphosis, and earlier metamorphosis). We also aged each sire to test the hypothesis that older males are, on average, genetically superior to younger males. We crossed each female with three sires representing three body size categories (mean and 1 SD ± mean snout-ischium length). Hatchlings (500 from each cross) were reared to metamorphosis in seminatural ponds in the field. Metamorph weight (log transformed) and age at metamorphosis showed significant heritability and were genetically correlated with each other. Hence, sires differed in genetic quality. However, none of the three measures of offspring performance was correlated with sire body size or age. Thus, we obtained no support for the prediction that sire body size or age is related to genetic quality.     

Myocellular triacylglycerol breakdown in females but not in males during exercise

The resting content and use of myocellular triacylglycerol (MCTG) during 90 min of submaximal exercise [60% of peak oxygen uptake (VO(2 peak))] were studied in 21 eumenorrheic female and 21 male subjects at different training levels [untrained (UT), moderately trained (MT), and endurance trained (END)]. Males and females were matched according to their VO(2 peak) expressed relative to lean body mass, physical activity level, and training history. All subjects ingested the same controlled diet for 8 days, and all females were tested in the midfollicular phase of the menstrual cycle. Resting MCTG, measured with the muscle biopsy technique, averaged 48.4 +/- 4.2, 48.5 +/- 8.4, and 52.2 +/- 5.8 mmol/kg dry wt in UT, MT, and END females, respectively, and 34.1 +/- 4.9, 31.6 +/- 3.3, and 38.4 +/- 3.0 mmol/kg dry wt in UT, MT, and END males, respectively (P < 0.001, females vs. males in all groups). Exercise decreased MCTG content in the female subjects by an average of 25%, regardless of training status, whereas in the male groups MCTG content was unaffected by exercise. The arterial plasma insulin concentration was higher (P < 0.05) and the arterial plasma epinephrine concentration was lower (P < 0.05) in the females than in the males at rest and during exercise. MCTG use was correlated to the resting concentration of MCTG (P < 0.001). We conclude that resting content and use of MCTG during exercise are related to gender and furthermore are independent of training status.     

Physical fitness of children aged 5 and 6 years

Maximal oxygen uptake (Vo2 max) of 85 healthy kindergarten children, 46 boys and 39 girls, aged 5 and 6 years, was determined by means of track running. Their physique, skinfold thickness, grip and back muscle strength, and performances of 25 m-run, 50 m-run, standing broad jump, and 5 min-endurance run were also measured. Skinfold thickness of girls was significantly larger than that of boys. Boys were significantly superior to girls in all the motor performances. The Vo2 max per unit of body weight was 49.46 ml/kg/min for boys and 46.30 ml/kg/min for girls, the sex difference being significant at the 0.001 level. The correlation coefficient between Vo2 max per kg body weight and 5 min-endurance run performance was 0.417 for boys and 0.049 for girls, while that between absolute Vo2 max and body weight was 0.899 for boys and 0.563 for girls. The regression equation of the absolute value of Vo2 max (liter/min) on body weight (kg) was: Y=0.051X-0.025 for boys and Y=0.024 + 0.408 for girls, the regression coefficient of boys being twice as large as that of girls. It appears that at ages 5-6 sex differences are exhibited ont only in muscle strength and agility but also in endurance run and aerobic work capacity.     

Take-off flight performance in the butterfly Pararge aegeria relative to sex and morphology: a quantitative genetic assessment

Adult fitness components may strongly depend on variation in locomotory performance such as flight; this variation can be sex specific. Fast take-off to intercept females and competing males is an essential behavioral component of the territorial perching behavior in male speckled wood butterflies (Pararge aegeria L.). Females on the other hand avoid frequent take-offs particularly under suboptimal temperatures, typically showing fewer but longer flights than males. We estimated the heritability of take-off acceleration performance under suboptimal body temperatures by a restricted maximum-likelihood model. We calculated genetic correlations between this performance and a selection of morphological traits: size (body mass), flight muscle investment (relative thorax mass), and wing shape (forewing aspect ratio). Our results show significant additive genetic variation for mean acceleration performance and a similar but nonsignificant trend (P= 0.08) for maximal acceleration performance during take-off in males (h(2)= 0.15). In females, heritability was not significantly different from zero for either of the acceleration performance measures. Morphological traits and take-off performance were genetically linked in a sex-specific way. In males, relative thorax mass and forewing aspect ratio were positively genetically correlated with acceleration performance. In females, there was a negative genetic correlation between acceleration performance and abdomen mass, but not with residual abdomen mass (i.e., regressed on total body mass). To fully understand the evolution of sexual differences in flight performances and morphology, several other flight performances will have to be included. This multifunctional nature of flight and its consequences for the evolutionary study of flight has not yet been fully appreciated in the literature.     

Voluntary activation failure is detectable in some myositis patients with persisting quadriceps femoris weakness: an observational study

This cross-sectional, observational study was undertaken to examine whether voluntary activation failure could contribute to the persisting weakness observed in some patients with treated idiopathic inflammatory myositis. In 20 patients with myositis of more than six months' duration (5 males, 15 females; mean [± 1 SD] age 53 [11] years) and 102 normal subjects (44 males, 58 females; mean age 32 [8] years), isometric maximum voluntary contractions (MVCs) of the dominant quadriceps femoris (QF) were quantified. Absolute MVC results of normal subjects and patients were then normalised with respect to lean body mass (force per units of lean body mass), giving a result in Newtons per kilogram. Based on mass-normalised force data of normal subjects, patients were arbitrarily stratified into "weak" and "not weak" subgroups. During further MVC attempts, the "twitch interpolation" technique was used to assess whether the QF voluntary activation of patients was complete. This technique relies on the fact that, because muscle activation is incomplete during submaximal voluntary contractions, electrical stimulation of the muscle can induce force increments superimposed on the submaximal voluntary force being generated. No between-gender differences were seen in the mass-normalised MVC results of healthy subjects, so the gender-combined results of 6.6 (1.5) N/kg were used for patient stratification. No between-gender difference was found for mass-normalised MVCs in patients: males 5.4 (3.2) and females 3.0 (1.7) N/kg (p > 0.05). Mass-normalised MVCs of male patients were as great as those of normal subjects (p > 0.05), but mass-normalised MVCs of female patients were significantly smaller than those of the normal subjects (p < 0.001). Only one of the six "not weak" patients exhibited interpolated twitches during electrical stimulation, but six of the 14 "weak" patients did, the biggest twitches being seen in the weakest patient. That interpolated twitches can be induced in some myositis patients with ongoing QF weakness during supposed MVCs clearly suggests that voluntary activation failure does contribute to QF weakness in those patients.     

Medial Preoptic/Anterior Hypothalamic Lesions Induce a Female-Typical Profile of Sexual Partner Preference in Male Ferrets

In T-maze tests given to gonadectomized ferrets treated daily with estradiol benzoate (EB), females consistently prefer to approach and interact sexually with a stud male whereas male subjects, on average, prefer an estrous female. In the present experiment this sexually allomorphic pattern of partner preference was changed in males given lesions of the medial preoptic area/anterior hypothalamus (mPOA/AH). Electrolytic lesions, which caused extensive bilateral damage to the mPOA/AH, including the sexually dimorphic male nucleus (MN) of the POA/AH, led males to shift their mean preference away from the estrous female to the stud male. Their postoperative profile of partner preference more closely resembled that of sham-operated females than that of sham-operated males or of males which sustained either partial or minimal bilateral damage to the mPOA/AH so as to spare the MN-POA/AH in one or both hemispheres. Males with extensive bilateral mPOA/AH lesions, like sham-operated females, showed an even stronger preference to approach the stud male during T-maze tests in which the subjects could smell, see, and hear the stimulus animals without physically interacting with them. After receiving testosterone propionate, male ferrets with either extensive or partial lesions of the mPOA/AH showed significant deficits in neck gripping and mounting performance in tests with either female or male stimulus animals which were sexually receptive after gonadectomy and EB treatment. The present results, coupled with those of a previous study using excitotoxic mPOA/AH lesions, suggest that the male-typical profile of preference for an estrous female depends on the functional integrity of sexually dimorphic mPOA/AH neurons and the reward engendered by coital interaction with such a female. When these neurons either are destroyed experimentally (as in male ferrets with extensive bilateral mPOA/AH lesions) or are absent (as in sham-operated females), subjects are attracted by distal (possibly chemosensory) incentive cues from a stud male.     

Vascular dilatatory responses to sodium nitroprusside (SNP) and alpha-adrenergic antagonism in female and male normal and diabetic rats.

Diabetes is associated with impaired vascular dilatatory responses that appear to be influenced by sex as well as diabetic state. Therefore, we hypothesized that vascular and sympathetic control function exhibit a greater deterioration following the induction of diabetes in female than in male rats. We conducted a comparative determination of the effect of sodium nitroprusside (SNP, a nitrous oxide donor) and that of an alpha1-adrenergic antagonist, prazosin, on selective vascular flows, mean arterial pressure (MAP), and heart rate (HR), in female and male normal and diabetic rats. Rats were made diabetic using streptozotocin (50 mg/kg, iv) and maintained for 5-6 weeks. Following anesthesia with urethane/alpha-chloralose, the femoral artery and vein were cannulated for recording and sampling. Flow probes were placed on the iliac, renal, and superior mesenteric arteries. SNP (1, 5, 10, and 20 microg/kg) infusions resulted in a dose-dependent decrease in MAP in normal and diabetic rats. The decrease in MAP in normal males was 37% less at the 20 microg/kg concentration of SNP when compared to normal females. The HR was not significantly changed in response to the hypotensive effect of SNP; however, reflex tachycardia was more prominent in diabetic males. The vascular conductance (flow/MAP) was increased by SNP in normal and diabetic rats in a dose-dependent fashion; however, the responsiveness was decreased in the iliac and superior mesenteric and increased in the renal arteries in diabetics when compared to normals. Diabetic males were 42% and 28% less responsive to SNP in the iliac and superior mesenteric arteries, respectively. On the other hand, diabetic females were 1.5-fold more responsive in the renal artery when compared to normals. Prazosin (4 mg/kg) decreased the MAP in normal and diabetic rats to a comparable degree. Prazosin increased the vascular conductance in all three vascular beds in normal and diabetic rats with the greater increase occurring in the iliac (118%) and superior mesenteric (110%) arteries. We concluded that diabetes is associated with an increased response to NO in the renal vessels and a decreased response in the iliac and superior mesenteric vessels in both females and males. alpha-Adrenergic tone was greatest in diabetic female and male rats. This study suggests that decreased vascular flow in diabetes is a result of a combination of decreased sensitivity to NO and increased adrenergic tone.