Levels Of Testosterone Secretion Research Articles

On the problem of intersystem correlations in modern anthropology: the relationship between the somatic and hormonal indicators in Moscow youth

The work is dedicated to the study of the joint variability of somatic characteristics and level of sex hormones (estradiol and testosterone), as well as to the assessment of anthropometric indicators and steroid profile in Mos-cow students. The material of the study is represented by comprehensive anthropological survey of 152 people (18–22 year old): 122 females (average age — 19.9 years) and 30 males (average age — 20.2 years) of Moscow higher educational institutions. The analysis included data from respondents of Russian nationality permanently residing in Moscow and nearest Moscow region. The examination program included the measurement of total body sizes, the assessment of body composition, BMI, waist-to-hip ratio (WHR), sexual dimorphism index (by Tanner); indicators of the relative value of body components were calculated as well. In addition, the hormonal profile of the participants was obtained (total testosterone and total estradiol levels in blood serum), on the basis of which the estradiol-testosterone ratio (E/T) was calculated. The analysis of morphophysiological characteristics of modern Moscow young people revealed the presence of reliable correlations (r = 0.2–0.3) between hormonal production and soma parameters only in girls: estradiol is negatively associated with waist circumference and posi-tively with the proportion of active cell mass (a direct relationship with it was also found in the E/T ratio). The level of testosterone secretion is positively associated with the value of the sexual dimorphism index. The results of factor analysis reveal a consistent variability in the levels of sex steroids with morphological parameters: estradiol is associated with indicators of obesity, and testosterone — with the proportion of musculoskeletal mass and the value of sexual dimorphism. The revealed features of the shared variation of morphophysiological signs are cha-racteristic for both sexes, which indicates their stability and biological regularity. Increased testosterone secretion was recorded for 15.6 % of female students. The average values of morphological indicators in this group signifi-cantly differ from individuals with normal hormone secretion towards the increasing andromorphism of the phy-sique (due to an increase in the proportion of musculoskeletal mass and the value of sexual dimorphism index). It can be assumed that these results indicate an increased stress load within the metropolitan region.

ВАРИАБЕЛЬНОСТЬ СОДЕРЖАНИЯ СЫВОРОТОЧНОГО ТЕСТОСТЕРОНА У БЕЛУХ DELPHINAPTERUS LEUCAS РАЗНЫХ ВОЗРАСТОВ

Recently, the issues of a comprehensive study of the reproductive system of marine mammals, in particular the analysis of hormonal changes in the organism of cetaceans in the process of their growth and development has become urgent. In the present work, the content of serum testosterone in blood samples of male beluga whales Delphinapterus leucas was determined. The studies were carried out on belugas kept in semi-free conditions of an open-air marine enclosure complex in the Barents Sea. Venous blood samples were obtained from animals aged 5 to 10 years, while individuals under 7 years old were considered immature. A total of 5 belugas were examined, 43 samples were obtained. Blood sampling was carried out from the ventral or dorsal vein of the caudal fin using a vacuum blood sampling system in plastic vacuum tubes. The volume of the samples ranged from 3 to 12 ml of native blood. Blood serum for research was obtained by centrifuging the samples at 2000 rpm for 10-15 minutes. About 2.5-3 ml of serum was obtained from 8 ml of native blood. It was frozen, stored and transported to the laboratory at a temperature of -20 ° С. The testosterone content in the samples was determined by the method of heterogeneous enzyme-linked immunosorbent assay (ELISA). A comparative assessment of the concentration of this steroid hormone in young and mature animals showed a positive linear correlation between the level of testosterone secretion and the age of the animal. Studies have shown that the sexual maturity of male beluga whales occurs by the age of 8-10, when serum testosterone levels of 15 nmol / L or higher are reached.

Effect on Testosterone Production in Sprague-Dawley Rats of Gastrodia and Bee Pollen

Objectives: We investigated the effects of Korean gastrodia and bee pollen on testosterone production in Sprague-Dawley rats. Methods: This study measured the body weight, consumption of food and water, and serum testosterone concentration in SD rats fed for four weeks with gastrodia and bee pollen. Results: The average body weights after four weeks were <TEX>$375{\pm}2g$</TEX> for the control group, <TEX>$358{\pm}3g$</TEX> for gastrodia consumption, and <TEX>$354{\pm}2g$</TEX> and <TEX>$367{\pm}8g$</TEX> for acorn pollen and Siberian gooseberry pollen, respectively. The average food consumption in SD rats over the four weeks in the control was 23.6 g for gastrodia consumption, 24.3 g and 24.9 g for acorn pollen and Siberian gooseberry pollen, respectively. The average water consumption over the four weeks was 38.33 ml in the control group, 35.0 ml for gastrodia treatment, and 33.3 ml and 33.3 ml for acorn pollen and Siberian gooseberry pollen treatment, respectively. The testosterone secretion levels in the serum of male rats were increased by gastrodia, acorn pollen, and Siberian gooseberry pollen (2.68, 3.00, and 3.28 pg/ml, respectively) compared to the control group (2.23 pg/ml). Conclusions: These results suggest that gastrodia or bee pollen may be developed as a complementary medicine to improve sexual hormone production.

Parental care and testosterone in males of the bank vole (Myodes glareolus): Sensitization and androgenic stimulation of paternal behavior

The relationship between parental responsiveness of bank vole males and their body weight, testes mass, and plasma and gonadal testosterone levels were examined. Two groups of voles were studied: Group I consisted of 14 breeding pairs where females gave birth to young within a month after formation of pairs, and Group II represented 13 pairs without offspring and signs of pregnancy in females. Males in Group I, unlike those in Group II, had contact with pups before the tests on parental responsiveness. In Group I, males were found to have larger testes and to exhibit a higher level of care-giving activity (pup retrieval) as compared to males in Group II. Both the plasma and gonadal testosterone levels in males exhibiting pup retrieval were revealed to be significantly higher than those for males exhibiting infanticide. Thus, promiscuity, competition for receptive females, and a higher level of testosterone secretion, which are characteristic of bank vole males during the breeding season, are not out of the realm of possibility of the males that care for young. Our findings suggest that factors promoting parental responsiveness in bank vole males are sensitization due to contact with pups and an increase in testosterone secretion. Obviously, there is a need to reexamine the role that testosterone plays in regulating rodent parental behavior.

The effect of exposure to oestrous ewes on rams' sexual behaviour, plasma testosterone concentration and ability to stimulate ovulation in seasonally anoestrous ewes

Previous research has shown that the proportion of seasonal anoestrous ewes that ovulate in response to the introduction of rams (‘ram effect’) is dependent upon pheromonal and sexual behavioural stimuli emitted by the rams. Close contact with oestrous ewes is likely to increase the rams' libido and level of testosterone secretion, which in turn has been suggested to positively influence the production of pheromones. Thus, the sexual stimulation of rams could be used to improve the efficacy of the ‘ram effect’. In the present experiment, 272 ewes were introduced (1) to rams without recent experience of oestrous ewes, (2) to rams recently exposed to oestrous ewes, (3) and (4) to oestrous ewes and rams with or without recent experience with oestrous ewes, or (5) remained isolated from rams. Serum testosterone concentration of rams was elevated equally ( P<0.05) when oestrous or anoestrous were introduced. Exposure to oestrous ewes before or after introduction increased ( P<0.05) the various measures of ram sexual behaviour directed towards anoestrous ewes. However, there was no statistical evidence that increased sexual activity resulted in an improvement in the ability of rams to stimulate ovulation in anoestrous ewes.

Testosterone productivity and histostructural changes of autotransplanted rat Leydig cells.

To investigate the possibility of in vivo transplantation of Leydig cells as a new biologic androgen replacement therapy, the Leydig cells procured from 6 week-old male Sprague-Dawley rats were autotransplanted, and the level of testosterone secretion and histostructural changes were observed. The renal subcapsular and intraperitoneal transplant showed higher levels of testosterone compared to subcutaneous or scrotal counterparts, and the number of transplanted cells was correlated with the level of measured testosterone. Furthermore, if the Leydig cells were transplanted intraperitoneally after the uptake on synthetic collagen, testosterone levels were higher than the ones simply transplanted without synthetic collagen uptake, resulting in 27 fold increase at 3 months. The activity of 125I-hCG decreased 20 to 40% at each month after transplantation compared to the normal levels, but no statistical significance was noted among different periods. The histologic examination revealed neovascularized capillaries and well demarcated sheet-like group of eosinophilic Leydig cells were observed at 4 weeks. But the evidence of destructive changes such as a focal inflammation with central dystropic ossification could be noted after 3 month. On electron microscopy, the marked indentation of nucleus and presence of lipochrome pigment were seen, and the number and size of smooth endoplasmic reticulum and mitochondria were reduced after 3 month. In conclusion, testosterone output could be increased to the physiologic range by increasing the number of transplant cells or utilizing collagen uptake but further effort is necessary on delaying or preventing the structural and functional decrement of Leydig cells.

Influence of photoperiod on the secretion of testosterone as a response to sexual stimulus in male goats

Monthly sexual behavior tests were carried out for 1 yr in a group of 19 male goats (10 Verata breed and 9 Malagueña breed) 12 mo of age. Simultaneously with the tests, 5 blood samples were collected, 2 before and 3 after contact with females, to determine the influence of sexual stimulus on the secretion of testosterone. By means of radioimmunoassay, it was determined that both breeds showed a significant increase in testosterone secretion as a result of the sexual stimulus during increasing daylength (Verata: P<0.01; Malagueña: P<0.05), when testosterone secretion levels prior to the stimulus were the lowest of the year. Moreover, the level of testosterone secretion was higher in the Verata than in the Malagueña breed (P<0.01). A significant though low correlation (P<0.05) between the rise of testosterone levels as a response to sexual stimulus and the degree of sexual behavior in the males was observed in the Verata breed. However, there was no correlation between these factors in Malagueña male goats.

Androgen Levels and Antler Development in Captive and Wild White-Tailed Deer

Blood samples were collected monthly from 5 captive adult male white-tailed deer (Odocoileus virginianus) over a 1-year period. A blood sample was also collected, at immobilization, from each of 55 wild adult (12 months old or older) male white-tailed deer captured over approximately 1 year in southwest Virginia. The antlers of each buck were classified according to stage of development at the time of sampling. Androgen levels and the antler cycles for the captive and wild deer were essentially similar and followed a distinct cyclic pattern. Plasma androgen levels (ng/ml) for the captive and wild deer were highest during November (14.03 ? 2.79 (SE) and 31.23 ? 11.03 (SE), respectively) and lowest during June (0.84 ? 0.14 (SE) and 1.14 t 0.36 (SE)). Androgen concentrations were low and antler growth had commenced and was proceeding rapidly in the velvet from March through July. Androgen concentrations were highest and antlers were hardened and polished during November when does are normally bred in southwest Virginia. By December and January, androgen concentrations had diminished substantially, coincident with the initiation of antler shedding. J. WILDL. MANAGE. 47(2):178-183 Antler growth and development are secondary sex characteristics and as such are under hormonal control. Testosterone has the general effect of promoting and maintaining antler maturation. Certain levels of testosterone secretion are necessary for full ossification of the antlers and death of the velvet (Wislocki et al. 1947). Studies of testosterone concentrations in red deer (Cervus elaphus, Lincoln et al. 1970) and roe deer (Capreolus capreolus, Short and Mann 1966) and with serum testosterone levels in white-tailed deer (McMillin et al. 1974) have shown antler shedding to be related to falling testosterone level, whereas velvet shedding results from a rising level. The white-tailed deer is a valuable trophy animal, so appropriate management should include plans for sustained harvests and suitable trophies. Such a management approach must include a greater understanding of the hormonal relationship involved in the annual reproductive and antler cycle of the male. Previous studies neither considered the hormonal characteristics of captive and wild deer separately, nor provided sample sizes large enough for statistical analysis. Because the relationship between androgens other than testosterone and the antler cycle was never studied, it was important in the present investigation to examine androgens as they relate to the antler cycle. The objectives of this investigation were: (1) to measure monthly variation in plasma androgen levels in captive and wild whitetailed deer and (2) to relate these levels to changes in the antler cycles of the same animals. 1 This study was supported by McIntire-Stennis Project No. 636201. Contribution No. FIW 76-03 from the Department of Fisheries and Wildlife Sciences. 2 Present address: Oregon Cooperative Fishery Research Unit, Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon 77331. 178 J. Wildl. Manage. 41(2):1977 This content downloaded from 157.55.39.141 on Mon, 18 Jul 2016 05:49:02 UTC All use subject to http://about.jstor.org/terms ANDROGEN LEVELS IN WHITE-TAILED DEER ? Mirarchi et al. 179 We thank the personnel of the Radford Army Ammunition Plant for their cooperation, and the Virginia Cooperative Wildlife Research Unit for its financial assistance in maintaining the captive animals, and the use of its vehicles. Technical assistance from J. T. Jones, W. Morehead, and H. Lysy is acknowledged.

Postnatal development of the testes in the cuis, Galea Musteloides.

Testicular development to 9 months of age has been studied. Seminiferous tubule diameter increased in a linear manner between 13 and 65 days of age, and there was a steep increase in testicular weight with age. At about 9 months the animals weighed 400-500 g and total testicular weight was about 10 g. This relatively large testicular size was correlated with high sperm density in the semen. Spermatogenesis commenced at about 21-25 days of age, when the first spermatids were found. Spermatozoa appeared in a small proportion of seminiferous tubules by 31-35 days of age, and were seen in the epididymides of an animal of 31 and another of 34 days. Epididymal spermatozoas were consistently present in large numbers after 60 days and this correlated with the increased frequency of mature seminiferous tubules. Leydig cell size increased rapidly from 13 to about 60 days, then remained constant. Inferences have been drawn from this and the study of spermatogenesis about the level of testosterone secretion. The results indicate that the male cuis is almost fully grown and sexually mature by about 90 days of age.