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Biomedical subjects

L V Osadchuk

Publications and source records attributed to L V Osadchuk.

32 records · Page 2Linked to original sources
PubMedDate not supplied

[Testosterone production by the fetal testes of silver foxes selected for their domesticated behavior].

Testosterone content was determined by radioimmune assay in the testes of silver foxes between the 31st and 50th days of gestation. Small quantities of testosterone were found in the testes already at the 31st day of prenatal life, gradually increasing up to a maximum value at the 50th day. No significant difference in testosterone content was found between domesticated and undomesticated silver foxes during prenatal life. It is suggested that selection for domesticated behaviour affects rather central control of endocrine functions than steroid biosynthesis in the testes.

Animals↗
PubMedDate not supplied

[The testosterone level in the testes of silver foxes during prenatal development].

The level of testosterone in serum and testes of the silver fox fetuses on days 31, 35, 40, 45, and 50 of gestation was determined using radioimmunoassay. In testes, testosterone was first detected at day 31; then its level gradually increased. Serum testosterone was detected only at day 40. Subsequent increase in its concentration was insignificant. Human chorionic gonadotropin stimulated testicular testosterone production in vitro beginning from day 40. We suggest that in the silver fox, testes are capable of responding to gonadotropins already by the day 40 of prenatal development but the formation of pituitary-gonadal axis proceeds until the end of embryogenesis.

Animals↗
PubMedDate not supplied

[Effect of prenatal stress on the pituitary-adrenal axis in blue foxes].

Handling is a source of stress for farm bred blue foxes. The influence of handling during the late gestation period on the pituitary--adrenal axis was studied in 10-day old male and female blue foxes. Cortisol and progesterone were measured by radioimmunoassay in the plasma, adrenal homogenates, and in vitro incubates from animals of both sexes. Adrenals were incubated in vitro in the absence or presence of ACTH. In addition, the adrenal weight and plasma concentration of ACTH were assessed. In cubs of both sexes, the adrenal weight was decreased after prenatal stress. The plasma concentration of progesterone and the adrenal cortisol in vitro production were elevated in the prenatally stressed female cubs, as compared to the control, along with the adrenal progesterone in vitro production in prenatally stressed male cubs. The adrenal cortisol and progesterone content and plasma ACTH and cortisol concentrations were not affected by prenatal stress. In conclusion, the results of this study suggest that the prenatal stress induced by handling pregnant vixens can affect the pituitary--adrenal axis in neonatal offspring, this effect being more pronounced in female cubs.

Adrenal Glands↗
PubMedDate not supplied

[The experimental model of establishment and maintenance of social hierarchy in laboratory mice].

The goal of the investigation is to establish a new experimental model of social hierarchy in laboratory mice. The important feature of the model is a group of two males only placed into the special experimental cage. The cage consists of two nestling chambers and central chamber. Observations were made 3 times per day (20 min each) throughout 5 days. Aggression, defence and sniffing behaviours of both partners were recorded during each observation period using video camera. Social rank was detected by asymmetry in aggressive behaviour. It was shown that social hierarchy was established during the first four tests limited by the first 24 h after pairing. After this period aggression and defence behaviours were greatly decreased. After the first 5 tests a stabilization in aggression (number of wins, active attacks and not direct aggression) and defence (number of vertical defensive postures and escapes) as well as sniffing behaviours took place. But a strong asymmetry in mentioned here behaviours in males of different ranks (dominants and subordinates) was kept up. Thus we offer a new experimental model of minimal society, which entirely reproduces a pattern of establishment and maintenance of social hierarchy. Our model demonstrates significant differences in agonistic, defence and sniffing behaviours between males of different social rank.

Aggression↗
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[Relationship between the hypophyseal-adrenal and the genital systems in silver-black foxes].

Interaction between the hypophysial-adrenal system (HAS) and the hypophysis-gonad system was studied. For this purpose the foxes were subjected to total gonadectomy 8 months before they were sacrificed. Functional activity of the HAS was judged by the hypophysis ACTH content, corticosteroid production by the adrenal cortex in vitro, and by the glucocorticoid concentration in the peripheral blood. Castration of male foxes foxes failed to influence the activity of various HAS links. Gonadectomy of females was accompanied by changes in the activity of individual HAS links in different direction--some reduction of ACTH in the hypophysis, a sharp and significant fall of the peripheral blood glucocorticoid level and a marked significant elevation of hydrococortisone production in the adrenal cortex in vitro.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

[Gonadal endocrine function in female silver foxes selected for domesticated behavior].

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.

Animals↗
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[Photoperiodic control of gonadal endocrine function in silver-gray foxes and its alteration during domestication].

Studies have been made on the level of estradiol and progesterone in domesticated and nondomesticated female silver foxes under different photoperiodic regime. The duration of the "light--darkness" cycle was equal to 24 h. Total duration of the light period was equal to 9 1/2 h; illumination was natural for 7 h, being artificial for the rest 2 1/2 h in a dark part of a day. It was demonstrated that additional illumination affects the hormonal level and sexual activity, the effect being dependent on the particular time of illumination. Nocturnal illumination significantly increased the level of sex hormones in the blood, domesticated animals being more sensitive as compared to nondomesticated ones.

Animals↗
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[The role of steroid hormones in the sexual and agonistic behaviors of male silver foxes].

Silver fox males were tested for sexual and agonistic behaviour after introduction of a female at different stages of the reproductive cycle. The high level of aggressive interactions between male and female and no mountings were observed out of the reproductive season. During the reproductive season, the introduction of anoestrus female did not affect the aggressive behaviour but increased the number of mountings while introduction of a receptive female reduced aggressive contacts and augmented sexual behaviour in pairs independently of mating. Considerable variations in testosterone and oestradiol but not cortisol plasma levels were observed between different stages of sexual activity. At the beginning of the reproductive season, silver fox males responded to anoestrus females with significant increase in their blood levels of testosterone and oestradiol. Contents of these two hormones did not change in males during the reproductive season when they encountered a receptive female. A female did not elicit any cortisol response in a male during different periods of the reproductive cycle. The data obtained suggest that the sexual behaviour in silver fox males can be facilitated by testosterone and oestradiol while aggressive interactions between male and female occur independently of these hormones.

Agonistic Behavior↗
PubMedDate not supplied

[The reproductive function of young male silver foxes Vulpes vulpes after long-term selection for domesticated behavior].

Sperm morphology of spermaries, testosterone plasma level and sexual activity of young silver fox males selected for domestic behavior have been studied. It is established that a number of spermatozoa in semen of males from selected population is lower as compared with the control one, whereas abnormal spermatogenesis level is significantly increased. The testosterone plasma level in males after a female introduction increased to the same extent in both groups. Sexual activity in males from selected population was lower than in the control one during the first mating season. The data obtained suggest a depressing effect of selection for domestic behavior on spermatogenesis and sexual activity in the young silver fox males and point to the hereditary changes of some chains of reproductive functions of males under the selection for domestic behavior.

Animals↗
PubMedDate not supplied

[The biosynthesis of cortisol and its regulation by the adrenocorticotropic hormone in the adrenals of silver fox embryos].

We studied the cortisol level in blood serum and adrenal homogenates, as well as the in vitro production of cortisol in adrenals of silver fox embryos of both sexes in response to exogenous adrenocorticotropic hormone (ACTH) stimulation. The level of cortisol in blood serum did not show any significant changes during the embryo development, while its level in adrenals and production by adrenals in vitro increased progressively from Day 35 to Day 50 of prenatal life. We found that ACTH is capable of stimulating cortisol biosynthesis and production in vitro during all studied periods of embryogenesis.

Adrenal Glands↗
PubMedDate not supplied

[Adrenal function in the mink Mustela vison selected for the type of behavior].

Glucocorticoid function of adrenals and its reactivity to stress caused by immobilization and to ACTH stimulation have been studied in the male minks selected both for domestic and aggressive behavior towards man. In autumn period the regression of cortisol content in adrenals was observed in domesticated males and particularly in aggressive ones compared with control. At the same period the increased level of cortisol in blood as the result of immobilization was noticed in aggressive minks compared with the domesticated and control ones. At ACTH stimulation in spring time the increase of cortisol level in blood was shown for animals of all the groups but it was more marked for the aggressive ones.

Adrenal Glands↗