Photoperiodic modulation of testicular LH receptors in the bank vole (Clethrionomys glareolus)

The temporal changes in testicular binding of 125I-labelled hCG in juvenile bank voles (18 days of age, born and reared in a 18L:6D photoperiod) exposed to a long (18L:6D, Group L) or short (6L:18D, Group S) photoperiod for 0, 3, 7, 14 and 42-56 days were investigated. During testicular maturation, in Group L, there was a slight initial decrease in LH receptor numbers per testis followed by a marked prepubertal rise during the initial phase of rapid testicular growth after which a decrease took place. In Group S, during testicular regression, the temporal changes in LH receptor numbers per testis resembled those of Group L except that the corresponding increase in hCG binding during the initial week was considerably less marked and the receptor numbers remained thereafter at a significantly lower level than in Group L. Leydig cell count indicated that the observed changes in LH receptors per testis were due to changes in the number of Leydig cells as well as in LH receptors per Leydig cell. The present results indicate, that (1) photoperiod is an important modulator of testicular LH receptor numbers in this species, (2) photoperiod or age has no significant effect on the binding affinity of LH receptors, (3) short photoperiods arrest the induction of LH receptors as well as the increase in Leydig cell numbers associated with normal testicular maturation, and (4) changes in LH receptor numbers per testis correlate well with the photoperiod-induced changes in androgen biosynthesis, spermatogenesis and Leydig cell morphology observed in our previous studies.     

Hormonal regulation of oestrogen formation by Leydig cells in vitro: immunocytochemical approach

The ability of the testis to convert androgens into oestrogens is related to the presence of a microsomal enzyme, aromatase, in testicular cells. The aim of this study was to show whether the supplementation of culture media with LH or an aromatase inhibitor could affect the process of aromatisation in Leydig cells of the bank vole in vitro. This was investigated by means of immunocytochemistry and radioimmunological assays. In control cultures of Leydig cells, both steroid hormones secretion as well as immunoreactivities for aromatase and oestrogen receptor were weaker than in those treated with LH. On the contrary, the addition of aromatase inhibitor into the culture medium resulted in a decreased intensity of immunocytochemical stainings in comparison with the control. Concomitantly, the androgen level was slightly higher, whereas that of oestrogen significantly lower than in the control cultures. Additionally, to check whether steroid hormones are able to regulate aromatase or oestrogen receptor immunoexpressions, some of the Leydig cell cultures were enriched with testosterone or oestradiol, respectively. Strong immunoreactivities for both aromatase and oestrogen receptor were observed. This suggests that Leydig cells in vitro are able to regulate directly the secretion of oestrogens by active aromatase. Finally, it is concluded that oestrogen formation in bank vole Leydig cells in vitro can be influenced by various factors. It should be stressed, however, that the effect of hormone stimulation or aromatase inhibitor action appeared to be dependent on the length of light cycles that bank voles were exposed prior to the isolation of Leydig cells.     

Immunolocalization of androgen receptors in testicular cells of prepubertal and pubertal pigs

In the testis, androgen receptors are known to mediate autocrine and paracrine effects of androgens on Leydig cell function and spermatogenesis. The pig presents some unusual features with regard to the synthesis of testosterone and estrogens in the male gonads. In testes from prepubertal males, testosterone level was lower than in testes from adult boars, while estrogen secretion was relatively high and comparable to that of mature porcine gonad. Immunolocalization of androgen receptors and intensity of immunohistochemical staining was age-dependent. In testis sections from adult boars, androgen receptors were found in nuclei of all somatic cells such as Leydig cells, Sertoli cells, and peritubular-myoid cells, whereas in sections from immature pigs only in the Leydig cell cytoplasm showed positive immunoreaction for androgen receptors. In control tissue sections incubated with omission of the primary antibody, no positive staining was observed. Detection of the androgen receptors in testicular cells of the pig is important for understanding of their central role in mediating androgen action.     

Aromatization and antioxidant capacity in the testis of seasonally breeding bank voles: Effects of LH, PRL and IGF-I

Aromatization and antioxidant strategies in the male gonads are important processes, which are involved in control of normal fertility. The objective of this study was to show whether luteinizing hormone (LH), prolactin (PRL), and insulin-like growth factor-I (IGF-I) as well as the length of photoperiod are able to exert an effect on aromatase expression, steroid hormone levels, and antioxidant concentrations in testes of bank voles, seasonally breeding rodents. Mature bank voles that were kept under short light cycles or long light cycles served as the animal model. Testicular sections were used for immunohistochemical visualization of aromatase expression, whereas testicular homogenates were used for radioimmunological measurement of steroids, biochemical determination of superoxide dismutase activity, total antioxidant status (TAS) and protein content. In the testes of hormone-treated voles a stronger immunostaining for aromatase was concurrent with the increase in testosterone and estradiol levels, and total antioxidant status compared with the controls. In contrast, there was a decrease in superoxide dismutase (SOD) activity. The strongest effect on aromatase immunoexpression and steroid hormone levels was detected after combined doses of LH and IGF-I, indicating a stimulatory role of these hormones on estrogen synthesis in the bank vole. An increase in total antioxidant status in testes of hormone-treated bank voles suggests the presence of testicular defense, whereas a decrease in superoxide dismutase activity indicates a protective role of administered hormones against toxic oxygen radicals. The present study also demonstrates a significant, photoperiod-dependent relationship between aromatization and antioxidant capacity in the testis of the bank vole.     

Photoperiodic elevation of testicular zinc protects seminiferous tubules against fluoride toxicity in the bank vole Clethrionomys glareolus

Recent work has shown that a high fluoride (F) intake in rodents leads to histopathologic changes in the germinal epithelium of testes and to zinc deficiency in the testis and several other organs. The purpose of the present study was to determine whether an elevation of testicular zinc concentration during fluoride exposure could protect the testes of bank vole from damage. The elevation of testicular zinc was achieved by exposing the bank voles to a long photoperiod (16 hr light/8 hr dark). The zinc concentration in the testes of bank voles kept under the long photoperiod was 38% higher than that in animals exposed to a moderate photoperiod (12 hr light/12 hr dark). Fluoride exposure (200 μg F/ml drinking water) during 4 months decreased additionally p > 0.05 zinc concentration in the testes of bank voles kept under the moderate photoperiod. The same animals also exhibited histopathologic changes in the germinal epithelium. By contrast, these disturbances were not observed in animals maintained in the long photoperiod. This experiment suggests that an increase in testicular zinc due to a long photoperiod prevents seminiferous tubules from a damage induced by fluoride in bank voles. The protective effects of zinc (or a long photoperiod) did not appear to be related to a decrease in testicular fluoride accumulation or lipid peroxidation.     

Variations in testicular androgen receptors and histology of the lamb testis from birth to puberty

Changes in testicular androgen receptor numbers were studied in lambs from 25 to 100 days of age. During this period, cytoplasmic receptors increased from 5 to 80 pmol/testis and nuclear receptors from 1 to 12 pmol/testis, while the total volume of Leydig cells increased 7-fold. The total number of Sertoli cells doubled between 25 and 40 days of age. From 40 days onward their number remained constant while their cellular and nuclear sizes increased by a factor of 3 and 1.5 respectively. Cytoplasmic receptor concentration was positively correlated with the number of Sertoli cells per section of seminiferous tubule, and negatively correlated with the number of germinal cells per cross section. One explanation for these results could be that Sertoli cells are the main androgen target cells in lamb seminiferous tubules.     

Morphofunctional alterations in testicular cells of deslorelin-treated boars: an immunohistochemical study

In this study we thoroughly scrutinized testes morphology and investigated whether treatment of recipient boars with gonadotropin-releasing hormone (GnRH)-agonist deslorelin could alter the expression of 3beta-hydroxysteroid dehydrogenase (3beta-HSD), luteinizing hormone receptors (LHRs), and androgen receptors (ARs) in testicular cells. An implant containing 4.7 mg of the GnRH-agonist deslorelin was subcutaneously inserted into crossbred male pigs at 91 and 147 days of age. Testicular traits, morphology of the testes, the proteins' expression, and testosterone concentration in blood plasma were analyzed in all boars after slaughter at 175 days of age. Histological analysis revealed significant alterations in both the interstitial tissue and seminiferous tubules of experimental animals after 28 and 84 days of deslorelin treatment. The intensity of the AR immunostaining within the testis appeared as a function of the severity of testicular dysgenesis. Time-dependent action of deslorelin on the expression of LHR and 3beta-HSD in Leydig cells was also detected. Staining for LHR and 3beta-HSD was very weak or the Leydig cells were immunonegative. Concomitantly, a significant decrease in plasma testosterone level was found in both groups of deslorelin-treated boars when compared with the control group. This is the first report showing the cellular distribution of AR, LHR, and 3beta-HSD in testicular cells of deslorelin-treated boars. It is concluded that morphological and immunohistochemical studies are important for the evaluation of testicular histoarchitecture and steroidogenic function. Subsequently, the endocrine control of reproduction in the GnRH-agonist deslorelin-treated males will be better understood.     

Development of Type 1 Diabetes in Wild Bank Voles Associated With Islet Autoantibodies and the Novel Ljungan Virus

Wild bank voles (Clethrionomys glareolus) may develop diabetes in laboratory captivity. The aim of this study was to test whether bank voles develop type 1 diabetes in association with Ljungan virus. Two groups of bank voles were analyzed for diabetes, pancreas histology, autoantibodies to glutamic acid decarboxylase (GAD65), IA-2, and insulin by standardized radioligand-binding assays as well as antibodies to in vitro transcribed and translated Ljungan virus antigens. Group A represented 101 trapped bank voles, which were screened for diabetes when euthanized within 24 hours of capture. Group B represented 67 bank voles, which were trapped and kept in the laboratory for 1 month before being euthanized. Group A bank voles did not have diabetes. Bank voles in group B (22/67; 33%) developed diabetes due to specific lysis of pancreatic islet beta cells. Compared to nondiabetic group B bank voles, diabetic animals had increased levels of GAD65 (P < .0001), IA-2 (P < .0001), and insulin (P = .03) autoantibodies. Affected islets stained positive for Ljungan virus, a novel picorna virus isolated from bank voles. Ljungan virus inoculation of nondiabetic wild bank voles induced beta-cell lysis. Compared to group A bank voles, Ljungan virus antibodies were increased in both nondiabetic (P < .0001) and diabetic (P = .0015) group B bank voles. Levels of Ljungan virus antibodies were also increased in young age at onset of newly diagnosed type 1 diabetes in children (P < .01). These findings support the hypothesis that the development of type 1 diabetes in captured wild bank voles is associated with Ljungan virus. It is speculated that bank voles may have a possible zoonotic role as a reservoir and vector for virus that may contribute to the incidence of type 1 diabetes in humans.     

Age-differential homing tendencies in displaced bank voles, Clethrionomys glareolus

Escape movements of three different age classes of encaged bank voles, Clethrionomys glareolus Schreber, were studied in modified Emlen funnels. While there was a concentration about the mean direction in the adult and overwintered subadult groups (i.e. homing) when tested in darkness, no such concentration was found when testing yearling subadult bank voles. When tested in the light no concentration about the mean direction occurred in any age class. The differences in homing tendencies between the tested age classes are consistent with known differences in their behaviour. While adults and overwintered subadults about to become adults have fixed home ranges, yearling subadults generally do not have well-defined activity areas and hence lack a homing goal. In the light, all animals behaved as if running for the nearest cover rather than in any particular direction.     

Hepatic and renal cadmium accumulation is associated with mass-specific daily metabolic rate in the bank vole (Clethrionomys glareolus)

Previous study has shown that photoperiod and age affect tissue accumulation of cadmium (Cd) in a small rodent, the bank vole. Since the body mass is also influenced by these factors, the present study was designed to determine whether mass-specific daily metabolic rate might be responsible for differential accumulation of Cd in the liver and kidneys of the short- and long-photoperiod bank voles as well as of the young and old animals. One- and five-month old male bank voles were held under short (8 h light/16 h dark) or long (16 h light/8 h dark) photoperiods and exposed to dietary Cd (100 microg/g) for 6 weeks. The bank voles raised under the short photoperiod and those injected subcutaneously with melatonin (7 micromol/kg/day) under the long photoperiod showed significantly higher concentrations of Cd in the liver (43-60%) and kidneys (40-47%) than the age-matched long-photoperiod animals. The old bank voles accumulated significantly less Cd in both organs than the young animals. These differences in Cd accumulation appeared not to be associated with the relative Cd intake. However, the hepatic and renal Cd levels followed a pattern similar to that of the mass-specific daily metabolic rate (or energy expenditure) and energy assimilation efficiency. These data indicate that mass-specific daily metabolic rate and energy assimilation efficiency (an indicative of digestive and absorptive processes) may be responsible for differential tissue Cd accumulation in the bank vole.     

Effect of testosterone on testicular steroidogenesis in the hypogonadal (hpg) mouse

Previous studies have shown that androgens have direct inhibitory effects on steroidogenesis in active Leydig cells. It is not clear what effect androgens have on inactive Leydig cell either through direct action on the cell itself or indirectly through stimulation of Sertoli cell activity. The hpg mouse has undetectable levels of circulating gonadotrophins and the gonads fail to develop post-natally. The effect of androgen treatment on testicular steroidogenesis and morphology was examined in these animals. Treatment with testosterone propionate for two weeks significantly increased testicular and seminal vesicle weight. Seminiferous tubules showed marked development in androgen-treated animals, indicating increased Sertoli cell activity, but the abnormal Leydig cell morphology of the hpg testis was unchanged. Androgen production per testis in vitro was low in control hpg animals and remained unaffected by treatment with androgen. Similarly, the pattern of [3H]pregnenolone metabolism was not significantly affected by androgen treatment. The androgen content of the testis was higher in androgen-treated animals but this could be accounted for by uptake of administered steroid from the circulation. It is concluded that androgens have no direct trophic effect on Leydig cells and that stimulation of Sertoli cell activity is not, in itself, sufficient to affect Leydig cell function.     

Assay of primate seminiferous tubule androgen receptors using [3H]mibolerone

The synthetic radiolabelled androgen mibolerone (7 alpha, 17 alpha-dimethyl-19-nortestosterone) was used to characterize androgen receptor binding in the seminiferous tubules from Cynomolgus monkey testis. Mibolerone binding was of high affinity (Kd = 0.6-5.4 nM) and limited capacity (37-50 fmol/mg protein), and was androgen specific. Sucrose density gradient centrifugation using a vertical tube rotor permitted the identification of a 9S molybdate-stabilized receptor under low salt conditions. The receptor bound to DEAE-cellulose. Methyltrienolone, but not mibolerone, also bound to a low affinity high capacity binding site in tubule cytosol, which probably represents glucocorticoid receptor binding, since it could be displaced by excess dexamethasone. However, occupancy of this low-affinity binding site by dexamethasone in an androgen receptor assay with [3H]methyltrienolone lead to a 33% underestimation of receptor binding, which appeared to relate to radioactive decomposition. Mibolerone, as well as methyltrienolone, bound to a progestin-binding protein in seminiferous tubule cytosol. These studies provide methods for the study of seminiferous tubule androgen receptors in subhuman primates and indicate that, due to its greater stability and lack of binding to glucocorticoid receptor, mibolerone is a useful new ligand in the study of androgen receptors in testis and its constituent cells.     

Effects of competition and season on survival and maturation of young bank vole females

In territorial microtines intra-specific density dependent processes can limit the maturation of individuals during the summer of their birth. This may have demographic consequences by affecting the number and the age distribution of breeding individuals in the population. Little is known about this process on a community level, though populations of many northern microtine species fluctuate in synchrony and are known to interfere socially with each other. We experimentally studied the influence of the field vole Microtus agrestis on maturation, breeding, space use and survival of weanling bank voles, Clethrionomys glareolus. Two additive competition experiments on bank vole populations were conducted in large outdoor enclosures, half of them additionally housing a field vole population. In a mid-summer experiment low population density and absence of older breeding females minimised intra-specific competition. Survival was not affected by the presence of field voles. Season had a significant effect on both the probability of maturation and breeding of the weanlings. Competition with field voles significantly delayed breeding, and coupled with seasonal effects decreased the probability of breeding. In a late-summer experiment breeding and survival of bank vole weanlings were studied for three weeks as part of a high density breeding bank vole population. Weanlings did not mature at all nor were their space use and survival affected by the presence of field voles. Our results show that competition with other species can also have an impact on breeding of immatures. In an extreme seasonal environment, even a short delay of breeding may decrease survival chances of offspring. Seasonal and competition effects together may thus limit the contribution of year born females to reproductive output of the population. Other studies have shown that adult breeding bank voles suffer lower survival in the presence of field voles, but this study showed no survival effects on the weanlings. Thus it might be beneficial for weanlings to stay immature especially in the end of the breeding season and postpone reproduction to the next breeding season if densities of competing species are high.     

Male reproductive defects caused by puromycin-sensitive aminopeptidase deficiency in mice

Male reproductive performance is composed of two principal elements, copulation and spermatogenesis. A wealth of literature has described the intricate web of endocrine events underlying these biological processes. In the present study we show that puromycin-sensitive aminopeptidase (Psa)-deficient mice are infertile, lack copulatory behavior, and have impaired spermatogenesis. The reproductive deficits of the mutants are not restored by androgen administration, although no aberrant localization of the sex steroid receptors was detectable in their brains and testes. Considering the strong expression of the Psa gene in the brain and Sertoli cells and the degenerative morphology of Sertoli cells in Psa-deficient mice, Psa may participate in testosterone-mediated reproductive signal pathways in the brain and testis.     

Dietary cadmium induces histopathological changes despite a sufficient metallothionein level in the liver and kidneys of the bank vole (Clethrionomys glareolus)

The objective of this study was to correlate hepatic and renal cadmium (Cd) accumulation, Cd-binding capacity of metallothionein (MT) and lipid peroxidation with the tissue injury in the male bank voles raised under short (8 h light/16 h dark) and long (16 h light/8 h dark) photoperiods that affect differently Cd accumulation and MT induction in these rodents. The animals were exposed to dietary Cd (0, 40 and 80 microg/g) for 6 weeks. The accumulation of Cd in the liver and kidneys appeared to be dose-dependent in bank voles from the two photoperiod groups; however, the short-photoperiod animals exhibited significantly higher concentrations of Cd in both organs than the long-photoperiod bank voles. Cd-Binding capacity of MT in the liver and kidneys of bank voles from the long photoperiod was sufficiently high to bind and detoxify all Cd ions, while in the animals fed 80 microg Cd/g under the short photoperiod, the concentrations of Cd in both organs exceeded (by about 10 microg/g) the MT capacity. However, similar histopathological changes in the liver (a focal hepatocyte swelling and granuloma) and kidneys (a focal degeneration of proximal tubules) occurred in Cd-80 bank voles from the two photoperiods. Likewise, in either photoperiod group, dietary Cd brought about a similar, dose-dependent decrease in the hepatic and renal lipid peroxidation, which paralleled closely that of the iron (Fe) concentrations. These data indicate that: (1) MT does not protect the liver and kidneys against Cd-induced injury in the bank vole exposed to the higher level of dietary Cd; and (2) lipid peroxidation cannot be responsible for the tissue damage. It is hypothesized that dietary Cd produces histopathological changes indirectly, through depressing the tissue Fe and Fe-dependent oxidative processes.     

Altered concentrations of gonadotrophin, prolactin and GnRH receptors, and endogenous steroids in the abdominal testes of adult unilaterally cryptorchid rats

Testicular descent was prevented unilaterally in newborn rats by cutting the gubernaculum testis. At 100 days of age, the number of Leydig and Sertoli cells per testis, the concentration of receptors for LH, FSH, prolactin and GnRH, and endogenous concentrations of progesterone and testosterone were determined. The weight of the abdominal testes was reduced by 80%, but in spite of this they contained as many Sertoli (32.8 +/- 1.3 X 10(6), mean +/- s.e.m., n = 6) and Leydig (28.2 +/- 1.7 X 10(6) cells as did scrotal testes (32.1 +/- 2.5 X 10(6) and 24.3 +/- 1.2 X 10(6) respectively). The numbers of receptors for LH (3.2 +/- 0.2 and 1.0 +/- 0.2 pmol/testis, mean +/- s.e.m., n = 11), FSH (358 +/- 11.0 and 96.3 +/- 12.6 fmol/testis) and prolactin (535 +/- 32.7 and 92.4 +/- 13.2 fmol/testis) were reduced (P less than 0.001) in abdominal testes, but the number of GnRH receptors was unaffected (8.9 +/- 1.4 and 12.1 +/- 1.8 fmol/testis, n = 6). Testicular testosterone concentration (30.9 +/- 4.4 vs 15.4 +/- 3.2 ng/g, n = 11, P less than 0.001), but not that of progesterone (0.87 +/- 0.10 vs 1.01 +/- 0.21 ng/g), was decreased in abdominal testes. The decreased receptor and androgen values reflect functional disturbances in the abdominal testes. The changed local milieu within abdominal testes may reduce hormone receptor concentrations which are then involved in the observed Leydig cell dysfunction.     

Hormonal status of male reproductive system: androgens and estrogens in the testis and epididymis. In vivo and in vitro approaches

The purpose of this article was to summarize our results on the role of androgens and estrogens in human, rodent and equine testes and epididymides, in both, physiological and patological conditions, obtained in the space of the Solicited Project (084/PO6/2002) financially supported by the State Committee for Scientific Research during the last three years. Testosterone produced by Leydig cells of the testes is clearly the major androgen in the circulation of men and adult males of most mammalian species. However, androgen metabolites make up a significant fraction of total circulating steroids. Moreover, androgen metabolism may proceed to amplify the action of testosterone through its conversion to dihydrotestosterone (DHT) or its aromatization to estradiol. The distribution of androgen and estrogen receptors (ARs and ERs) within male reproductive tissues is important because of their crucial role in mediating androgen and/or estrogen action. Attempts were undertaken to discuss not only the role of aromatase and ERs in mediating the action of estrogens in the male, but also the importance of DHT in hormonal regulation of the epididymis. In the latter, alterations caused by finasteride treatment and lead-induced oxidative stress are described. Male reproductive function of the testis and epididymis reflected by the alterations in enzymatic activity, distribution of steroid hormone receptors, differences in steroid hormone levels and altered gene expression of antioxidant enzymes are also discussed.     

布氏田鼠种群生理年龄结构的研究

本文根据胴体重分布将布氏田鼠划分为越冬鼠与当年鼠两组,然后再根据生理学指标将当年鼠划分为性成熟鼠(成年)和性未成熟鼠(幼年)。由于生理年龄与时间年龄不一致,故本文并不强调各种形态指标来划分时间年龄组。5月下半月以前种群主体为越冬鼠,但在当年鼠出现地表面后,当年鼠取代越冬鼠成为种群主体,到7月下半月越冬鼠已降到10％以下。当年生的幼鼠春季生长发育旺盛,很快成为当年成鼠。晚夏和秋季出生的个体当年性不发育成熟。秋季种群主体为当年幼鼠。越冬鼠和大部分当年成鼠从种群中消失。比较种群数量上升与下降年份,春季越冬鼠胴体重的轻重与第一批当年鼠(K_1)出现规模可能是种群数量升降的重要指标。     

Androgen receptor in nuclei of rat testis.

Testis nuclei of hypophysectomized rats selectively accumulate labeled testosterone and 5alpha-dihydrotestosterone following the injection of tritiated testosterone in vivo. Testosterone and 5alpha-dihydrotestosterone are bound to macromolecules in nuclei and can be extracted with 0.5 M KCl. Accumulation of protein bound radioactive androgens in nuclei of isolated seminiferous tubules is similar to that of whole testis. The relative amounts of testosterone and dihydrotestosterone in purified nuclei were similar to the relative amounts bound to cytoplasmic receptors, suggesting that cytoplasmic androgen-receptor complexes may be transported into the nuclei. Binding of labeled androgen is saturable and inhibited by prior injection of unlabeled testosterone or cyproterone acetate. Nuclear binding sites are destroyed by the proteolytic enzyme pronase, but not by DNase. Like the cytoplasmic androgen-receptor complexes in rat testis, nuclear androgen-protein complexes are heat labile and dissociate slowly at 0 degrees C. androgens fail to accumulate in testis nuclei of the Stanley-Gumbreck androgen insensitive rat, a species lacking cytoplasmic androgen receptors in testis and other androgen target tissues.     

Age and androgen-related changes in morphological parameters, haematological indices and serum protein fraction in common vole (Microtus arvalis Pall.) growing in different photoperiods

In male voles raised under different light conditions (L:D = 24:0, L:D = 18:6, L:D = 6:18) the following results were obtained. In the young males erythropoiesis seemed to be greatest in voles growing in "winter" photoperiod. In this light condition RBC count showed a tendency to decrease with age while in other illuminations erythrocyte numbers increased. The age related changes in RBC count were very similar to those observed in common voles aging in the different natural seasonal generations. The androgen level was higher after birth and then decreased. After reaching sexual maturity (13-15 weeks of vole life) it showed a peak and then decreased progressively. The age related changes in alpha 2-globulins (considered to be a potential binding proteins for steroid hormones) and in androgen level suggested a regulating mechanism based on a balance of hormones--blood proteins. The correlations stated between androgens and the parameters studied indicated more steroid than age-related metabolic changes. The more androgens, the less beta-globulin and fibrinogen while the greater rate of body and testes weight, as well as of albumin level and of RBC count were observed. All those might affect the transmission of lipoproteins from blood to adipose tissue and less predisposition to fighting with potentially lower blood coagulation capacity and more effective anabolic (erythropoietic) processes in the more "androgenic", reproductively active male voles. A higher protein metabolism in constant light, i.e. the higher level of the majority of plasma protein fraction and small weight was suggested. The high level of androgens in "winter" photoperiod might condition the aggressiveness and prevent hibernation in natural winter conditions.