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1.
Exercise-associated hyponatremia (EAH) has mainly been investigated in runners and triathletes. In mountain bikers, EAH was studied in two multi-stage races, but not in a single stage race. The aim of this study was to investigate the prevalence of EAH in a single-stage mountain bike ultra-marathon. In the 'Swiss Bike Masters' over 120 km with a climb of ~ 5,000 m in altitude, we determined pre and post race body mass, hematocrit, plasma sodium concentration ([Na?]), and urinary specific gravity in 37 cyclists. Athletes recorded their fluid intake while racing. No athlete developed EAH. The cyclists drank on average (means ± SD) 0.7 ± 0.2 l/h. Fluid intake was significantly and negatively related to race time (r = -0.41, P < 0.05), but showed no association with post race plasma [Na?], the change in plasma [Na?], post race body mass, or the change in body mass. The athletes lost 1.4 kg body mass (P < 0.05), plasma [Na?] decreased by 0.7% (P < 0.05), plasma volume increased by 1.4% and urinary specific gravity increased by 0.4% (P < 0.05). The change in body mass was neither related to post race plasma [Na?] nor to the change in plasma [Na?]. The decrease in plasma [Na?] was not related to fluid intake. The change in plasma [Na?] was related to post race plasma [Na?] (r = 0.40, P < 0.01). Ad libitum fluid intake showed no case of EAH in a single-stage mountain bike ultra-marathon. In contrast to previous findings, the faster athletes drank more than the slower ones.  相似文献   

2.
In groups ofGorilla g. beringei, male aggression towards females regularly takes the form of male display. This paper examines male display towards females in two Karisoke study groups (Group 5 and Group BM) in 1989, a period when none of the females were new immigrants. Results are based on 259 hr of focal observations and 121 hr ofad libitum observations on male behaviors towards females. The goal is to see if the data are compatible with four non-mutually exclusive hypotheses to explain male displays towards females: (1) demonstration of male fighting abilities to influence female long term residence decision; (2) decrease potential competitive inequities between females; (3) provision to females of an occasion to confirm their subordinance to a male; and (4) short term influence on mating. First, male-female proximity was tested against proportion of male displays, to rule out the possibility that males display towards females simply because they happen to be close by. There was no association between proximity and male display. Dominant males were responsible for a higher proportion of displays than subordinate males. This is consistent with the idea that males display to demonstrate their fighting abilities, or their qualities as protector, since dominant males are the ones offering long term protection against infanticide and predators. Females that were in a position to transfer did not receive a higher proportion of male display, however. Long term resident dominant females received a higher proportion of displays from the dominant males, which is consistent with the idea that males attempt to decrease potential competitive inequities between females. There was an association between female appeasement reactions and male displays, which suggests that males display to create occasions for the females to confirm their subordinance to them. Estrous females did not receive a higher proportion of male displays, and there was no association between male display and copulation, suggesting that male displays are not a form of courtship aggression aimed at influencing mating in the short term.  相似文献   

3.
Gonadal function in trisomy 21   总被引:2,自引:0,他引:2  
Endocrinologic evaluation of 39 patients with trisomy 2 and associated hypogonadism demonstrated elevations of follicle-stimulating hormone and luteinizing hormone; consequently, it can be concluded that both germinal and Leydig cell function are affected. A negative correlation between testicular size and plasma follicle-stimulating hormone was documented. Plasma testosterone levels were found to be normal in male patients as were estradiol levels in female patients with trisomy 21. On the basis of these findings, the simplest and most practical diagnostic approach to evaluate germinal cell function appears to be a single plasma follicle-stimulating hormone determination supplemented by an accurate measurement of testicular volume in males.  相似文献   

4.
Immunoreactive (ir)-dynorphin levels were measured, and the species characterized by high performance liquid chromatography (HPLC), in the pituitary and hypothalamus of intact and castrate male rats. On HPLC, ir-dynorphin co-eluted with authentic dynorphin A 1-8, dynorphin A 1-17 and dynorphin 1-32 in the hypothalamus and intermediate lobe; in two different reversed phase (RP)-HPLC systems, anterior lobe ir-dynorphin co-eluted uniquely with dynorphin 32 (4K dynorphin). Anterior lobe levels of total ir-dynorphin were significantly lowered 7 days after castration, while HPLC profiles in all tissues remained unchanged. The change in anterior pituitary ir-dynorphin levels was reversed in a dose-related manner by dihydrotestosterone (15-500 micrograms/100 g b. wt/day); estradiol benzoate (3 micrograms/100 g/day) was without effect. The changes on castration and androgen administration suggest that gonadal steroids play a role in the regulation of dynorphin, as well as gonadotrophins and prolactin, within the anterior pituitary gland.  相似文献   

5.
2 siblings with Fanconi's anemia, 1 male and 1 female, aged 22 and 24 years, respectively, were evaluated at the Johns Hopkins Hospital because of short stature and hypogonadism. Plasma levels of somatomedin-C were normal in both patients, suggesting that the production of biologically active growth hormone was normal in these subjects. In addition, measurements of serum gonadotropins and plasma androgens in our patients, along with data accumulated from previous studies in the literature, show that abnormal sexual development in patients with Fanconi's anemia is due to hypergonadotropic hypogonadism.  相似文献   

6.
Gonadal function was assessed in eight men in remission of leukaemia who had completed treatment eight months to eight years previously. All four men treated for acute myeloid leukaemia had normal sperm counts and motility, compared with only one of the four with acute lymphatic or undifferentiated leukaemia. Hormonal studies indicated that the sterility resulted from gonadal failure rather than pituitary dysfunction after cranial irradiation. These findings are important in the counselling of patients with leukaemia.  相似文献   

7.
There is much evidence that gonadal steroids modulate brain and behavioral development. However their possible influence on age-related deteroriation of brain and behavior has received little attention. We now present evidence that neonatal castration reduces the decline in locomotion, motor coordination, and circadian activity rhythms that normally accompanies old age in male rats. Three behavioral tests (open field, Rota-Rod, and wheel running) were conducted with aged male rats (24 months). Those castrated in the first 24 hr of postnatal life were more active in the open field (P less than 0.001) than aged rats that were sham-operated neonatally. The sham-operated aged males showed a more marked deterioration of motor coordination in the Rota-Rod (P less than 0.01) and greater disorganization of circadian wheel-running (P less than 0.05) than the neonatal castrates or than young rats neonatally sham-operated.  相似文献   

8.
Male golden hamsters underfed for 11-16 weeks showed a 30% decrease in body weight accompanied by significant testicular regression. Pinealectomy did not prevent underfeeding-induced gonadal regression. Resumption of ad-libitum feeding restored body weights to near control levels and permitted testicular redevelopment in animals with previously regressed tests. These data indicate that chronic food restriction can affect the reproductive status of hamsters and that this effect does not depend on an intact pineal gland. Body weight changes may serve as a secondary proximate cue in addition to photoperiod for timing the hamster seasonal breeding cycle.  相似文献   

9.
This study examined the role of gonadal androgens during puberty on the development of environment-related social interaction (SI) in male rats. SI in an unfamiliar environment versus SI in a familiar environment was evaluated in young adult rats as a function of sex and gonadal status. Intact male rats at 60 days of age exhibited a differential response to the two environments, whereas SI in intact female rats at 60 days was equivalent in the two environments. Furthermore, male rats castrated as juveniles and tested for SI at 60 days displayed a pattern of environment-related SI similar to SI in intact adult female rats. This effect of juvenile castration on SI in male rats was prevented by chronic exposure to testosterone propionate (TP) over Days 30 through 60. SI in male rats castrated in adulthood, on the other hand, was not altered either 2 or 4 weeks postcastration. The results from this study indicate that pubertal secretions of gonadal androgen(s) are necessary for the development of environment-related SI in male rats. In contrast, secretions of gonadal androgens in adulthood do not appear to be critical for the continued expression of environment-related SI, as suggested by the observation that environment-related SI in male rats remains unchanged by castration in adulthood.  相似文献   

10.
It has been widely reported that gonadal hormones influence the display of aggression in Syrian hamsters; conversely, much less is known about whether gonadal hormones modulate submissive/defensive behaviors in these animals. Following social defeat, male hamsters no longer display normal territorial aggression but instead display submissive/defensive behavior in the presence of a smaller opponent, a phenomenon we have termed conditioned defeat (CD). The purpose of the present study was to examine the effect of gonadal hormones on the display of CD in male hamsters. In Experiment 1, males were castrated or sham-operated. The castrated males were significantly more submissive following social defeat relative to their intact counterparts. The increased submissive behavior in the castrated males during CD testing was particularly surprising, given the fact that they were attacked significantly less during CD training. In Experiment 2a, males were castrated and given hormone replacement. Castrated males treated with testosterone or dihydrotestosterone displayed significantly less submissive behavior following social defeat than did those treated with cholesterol or estradiol. Finally, in Experiment 2b, there was no effect of hormone replacement on aggressive behavior in non-defeated hamsters suggesting that the decrease in submissive behavior in males treated with dihydrotestosterone or testosterone is specific to being previously defeated. Taken together the data indicate that the presence of androgens reduces the display of submission in defeated male hamsters. More importantly, these findings suggest that androgens may have a protective effect against the development of depression-like or anxiety-like behaviors following exposure to an ethologically relevant stressor.  相似文献   

11.
12.
Gonadal toxicity of short term chronic endosulfan exposure to male rats   总被引:3,自引:0,他引:3  
Endosulfan was studied for its effect on rat testicular toxicity in relation to the enzymes of androgen biosynthesis, viz. 3 beta-hydroxysteroid dehydrogenase (EC 1.1.1.145, 3 beta-HSD) and 17 beta-hydroxysteroid dehydrogenase (EC 1.1.1.64, 17 beta-HSD); cytosolic conjugation enzyme, glutathione-S-transferase (EC 2.5.1.18); and testicular as well as serum testosterone levels at the dose levels of 2.5, 5.0, 7.5 and 10 mg/kg body weight fed orally for 7 and 15 days. Organ and body weights of the treated animals did not change significantly, however, the testicular protein contents were found to be increased appreciably after 7 days treatments. The activity profile of cytosolic conjugation enzyme showed much remained low during 7 days treatment, however, the two steroidogenic enzymes showed much individual variations in response to endosulfan treatments. An overall varied response with respect to testosterone biosynthesis and its secretion to serum was observed suggesting nevertheless, a profound hormonal imbalance caused by this insecticide to male gonads on short term chronic exposures.  相似文献   

13.
Ismail Bhai and Pandey A. K. 1982. Gonadal hormones in experimental Ancylostoma caninum infections in male Swiss albino mice. International Journal for Parasitology12: 589–591. Orchiectomy in mice increased their resistance to Ancylostoma caninum infection. Testosterone propionate increased the susceptibility of castrated animals to infection and also increased the survival of larvae in muscles, compared with sham-operated placebo-treated controls with intact testes. Estradiol benzoate increased the resistance of castrated mice as demonstrated by differential larval recoveries. The possible involvement of the small intestine as a barrier to infection and the influence of testosterone on host susceptibility to infection is discussed.  相似文献   

14.
Selection for domesticated behavior in female silver fox is accompanied by a number of changes in endocrine function of ovaries. Significant changes in peripheral blood estradiol and progesterone levels and their production by gonads during anestrous may be an endocrine basis for out-of-season activation of reproductive system and earlier beginning of seasonal reproduction in domesticated females. The increase in the hormone level during preimplantation period of pregnancy and before parturition in tame foxes may influence their productivity.  相似文献   

15.
16.
Using 30 years of demographic data from 15 groups, this study estimates how harem size, female fertility, and offspring survival may contribute to variance in the siring rates of dominant male mountain gorillas throughout the Virunga Volcano Region. As predicted for polygynous species, differences in harem size were the greatest source of variance in the siring rate, whereas differences in female fertility and offspring survival were relatively minor. Harem size was positively correlated with offspring survival, even after removing all known and suspected cases of infanticide, so the correlation does not seem to reflect differences in the ability of males to protect their offspring. Harem size was not significantly correlated with female fertility, which is consistent with the hypothesis that mountain gorillas have minimal feeding competition. Harem size, offspring survival, and siring rates were not significantly correlated with the proportion of dominant tenures that occurred in multimale groups versus one-male groups; even though infanticide is less likely when those tenures end in multimale groups than one-male groups. In contrast with the relatively small contribution of offspring survival to variance in the siring rates of this study, offspring survival is a major source of variance in the male reproductive success of western gorillas, which have greater predation risks and significantly higher rates of infanticide. If differences in offspring protection are less important among male mountain gorillas than western gorillas, then the relative importance of other factors may be greater for mountain gorillas. Thus, our study illustrates how variance in male reproductive success and its components can differ between closely related species.  相似文献   

17.
18.
The development and differentiation of the gonads of embryonic alligators incubated at 30 °C (100% female producing) and 33 °C (100% male producing) was investigated histologically. The stage of development of the gonad and differentiation into an ovary or a testis occurred at essentially the same time at both temperatures. This contrasts with the overall development of the embryos which was slower at the lower temperature. A few days prior to differentiation, gonads grew more quickly at 33 °C than they did at 30 °C. However, once differentiated into a presumptive testis, gonads reduced in volume so that at hatching presumptive testes were smaller than presumptive ovaries. It is hypothesized that synchrony/asynchrony of development of the gonad and the rest of the embryo may account for temperature-dependent sex determination.  相似文献   

19.
Three experiments were conducted to test whether testicular hormones secreted during puberty masculinize and defeminize the expression of adult reproductive behavior. Experiment 1 tested the hypothesis that gonadal hormones during puberty masculinize behavioral responses to testosterone (T) in adulthood. Male hamsters were castrated either before puberty (noTduringP) or after puberty (TduringP). All males were implanted with a 2.5-mg T pellet 6 weeks following castration and tested once for masculine reproductive behavior 7 days after the onset of T replacement. TduringP males displayed significantly more mounts, intromissions, and ejaculations than noTduringP males. Experiment 2 tested the hypothesis that gonadal hormones during puberty defeminize behavioral responses to estrogen (EB) and progesterone (P). Eight weeks following castration, noTduringP and TduringP males were primed with EB and P and tested for lordosis behavior with a stud male. Behavioral responses of males were compared to that of ovariectomized (OVX) and hormone primed females. NoTduringP males and OVX females displayed significantly shorter lordosis latencies than TduringP males. Experiment 3 investigated whether prolonged T treatment or sexual experience could reverse the deficits in masculine behavior caused by the absence of T during puberty. Extending the T treatment from 7 to 17 days did not ameliorate the deficits in masculine behavior caused by absence of T during puberty. Similarly, when the level of sexual experience was increased from one to three tests, the deficits in masculine behavior persisted. These studies demonstrate that gonadal hormones during puberty further masculinize and defeminize neural circuits and behavioral responsiveness to steroid hormones in adulthood.  相似文献   

20.
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