Individual Features of the Hypothalamic-Pituitary-Thyroid Axis Functioning during Aging in Non-Human Primates

Individual features of age-related changes in the function of the neuroendocrine systems are an important problem as the basic component of a personalized approach to predicting and treating age-related pathologies. We studied the age-related features of the function of the hypothalamic-pituitary-thyroid axis in laboratory primates with depression- and anxiety-like behavior (DAB). It was found that in young female rhesus monkeys with DAB, the basal and thyrotropin-releasing hormone-stimulated levels of thyroid-stimulating hormone were significantly lower than in young animals with standard behavior (control). During aging, the levels of thyroid-stimulating hormone increased in DAB animals and free thyroxine concentrations decreased both at baseline (fasting) and in response to the thyrotropin-releasing hormone test, while in animals with standard behavior, only a trend towards similar hormonal changes was revealed.

Effect of Constant Illumination on the Function of the Hypothalamic-Pituitary-Adrenal Axis in Nonhuman Primates

We studied the effect of constant illumination on the effects of administration of arginine vasopressin (AVP), one of the most important regulators of the key adaptive hypothalamic-pituitary-adrenal (HPA) axis under basal conditions and during stress, as well as on the circadian rhythm of activity of HPA axis and the pineal gland in laboratory primates. In young adult female rhesus monkeys exposed to constant illumination for 7 weeks, the rise in the concentration of ACTH and cortisol in response to administration of AVP was markedly reduced in comparison with both the basal period and with the control group of animals. In addition, a destructive effect of constant lighting on circadian rhythm of cortisol secretion was observed in the absence of significant circadian changes in melatonin secretion. The inhibitory effect of constant illumination on the function of the HPA axis under basal conditions and under conditions of its activation can reduce the body's adaptive abilities.

[Features of endocrine function of the pancreas with aging in nonhuman primates with various types of adaptive behavior.]

An increasing number of studies are devoted to the study of the relationship of mental disorders, such as depression and anxiety, with the risk of developing type 2 diabetes mellitus. However, in the literature there are practically no publications on the study of the relationship of the features of higher nervous activity, in particular, adaptive behavior, in healthy individuals with the risk of developing age-related dysfunction of the pancreatic islet apparatus (PIA). The purpose of this study was to investigate features of the functioning of the PIA during aging in individuals with normal standard behavior (SB), as well as anxiety- and depressive-like behavior (DAB) in experiments on nonhuman primates. 76 physically healthy young mature and old female rhesus monkeys with SB and DAB were used in the experiments. Old animals were divided into subgroups with normal (NW) and excess (EW) body weight. All young animals were characterized by NW. The function of PIA was assessed using a glucose tolerance test. Intergroup differences in the functioning of the PIA in young animals were revealed, which were characterized by signs of impaired early insulin response, apparently due to a decrease in the sensitivity of β-cells of the pancreas to glucose. With aging, the function of the PIA was damaged in all animals, but the features of its changes depended on both the affiliation to a particular behavioral group and the animal's body weight. During aging in animals with SB, the development of relative insulin resistance of peripheral tissues was observed, accompanied by impaired glucose tolerance and a compensatory increase in the secretory activity of the PIA, which were more pronounced in animals with EW. Age-related dysfunction of the PIA in animals with DAB and NW was similar with age-related changes in the PIA function in animals with SB and NW. At the same time, with aging, animals with DAB and EW showed a more significant peak concentration of glucose than that of old animals with SB and EW, accompanied by a minimum «disappearance» rate of glucose from the circulation and significantly lower insulin secretion than this in animals with SB and EW. Thus, age-related dysfunctions of the PIA in primates with SB and DAB are unidirectional with the development of insulin resistance, impaired glucose tolerance and a compensatory increase in insulin secretion, which, however, in old animals with DAB and EW are accompanied by exhaustion of the PIA function, increasing the risk of developing type 2 diabetes mellitus.

[Correction of impaired glucose tolerance using tetrapeptide (Pancragen) in old female rhesus monkeys]

The aim of the investigation was comparative study of the influence tetrapeptide Pancragen (St. Petersburg Institute of Bioregulation and Gerontology, St. Petersburg) on hormonal function of the pancreas compared to the effect of widely used hypoglycemic drug - glimepiride. The investigation involved 9 old (20-25 years) clinically healthy rhesus monkey females (Macaca mulatta). Five of them were injected with Pancragen (0,05 mg/animal per day during 10 days, intramuscularly) for 10 days; 4 animals received glimepiride (4 mg/animal per day during 10 days, per os). Blood samples were taken from all the animals with subsequent analysis of glucose, insulin and C peptide levels; the manipulation was performed before administration of the drugs, on the background of their administration and after their withdrawal in basal conditions, as well as during glucose tolerance testing. Pancragen and glimepiride administration induced the decrease of blood glucose basal levels in both groups of old monkeys. Pancragen also normalized insulin and C peptide levels suggesting its recovering effect on the disturbed tolerance to glucose in old animals. At the same time, glimepiride administration led to a more expressed and delayed hypoglycemic effect and C peptide secretion stimulation without any significant effect on insulin secretion. The data suggest that Pancragen is effective and safe for correction of age-related imbalance of endocrine pancreatic function, and can be used for elderly patient with disturbed glucose tolerance.

[Impact of tetrapeptide pancragen on endocrine function of the pancreas in old monkeys]

Significant increase of the elderly in the demographic structure of a modern society is one of the main reasons for increase in the number of patients with diabetes type 2 and impaired glucose tolerance. The purpose of this research was to study impact of Pancragen (tetrapeptide Lys-Glu-Asp-Trp) on endocrine function of the pancreas of non-human primates, female rhesus monkeys, and to elucidate the possibil- ity of its use for correction age-related dysfunction of pancreatic islet apparatus. In old animals after the glucose administration (standard dose) in control period, a reduced glucose "disappearance" rate and a higher values of insulin and C-peptide peaks (5 and 15 min after the glucose injection) were observed in comparison with young animals in similar experiments. Pancragen administration (50 μg/animal per day during 10 days, intramuscularly) to old monkeys caused markedly increased the glucose "disappear- ance" rate, normalized the plasma insulin and C-peptide dynamics in response to glucose administration. The recovering effect of Pancragen on the function of the pancreas partially remained 3 weeks after discontinuation of the drug. Thus, Pancragen is a promising factor for restoring the age-related endocrine dysfunction of primates.

Repeated moderate stress stimulates the production of dehydroepiandrosterone sulfate (DHEAS) and reduces corticosteroid imbalance in old Macaca Mulatta

Young (6-8 years) and old (21-30 years) Macaca mulatta females were subjected to gentle immobilization (2 h daily at 15.00) for 10 days. Blood specimens were collected before the exposure and 15, 30, 60, 120, 240 min and 24 h after the beginning of exposure on days 1, 3, and 10. The adrenocortical reaction to stress was maximum on day 1 in all animals. The increase of cortisol (F) and dehydroepiandrosterone sulfate (DHEAS) concentrations in young monkeys decreased on days 3 and 10, DHEAS drop being less pronounced in comparison with F, as a result of which F/DHEAS molar concentration ratio changed negligibly. In old monkeys the basal DHEAS levels were lower, while the F/DHEAS ratio was higher than in young animals. Repeated immobilizations inhibited F elevation on day 3, caused no changes in DHEAS reaction, led to increase of basal DHEAS levels and to a reduction of F/DHEAS ratio on days 2, 3, 4, 10, 11. Hence, chronic moderate stress stimulated the production of DHEAS and reduced the corticosteroid imbalance in old monkeys.

[Age-related changes of the hypothalamic-pituitary-adrenal axis in individuals with various types of adaptive behaviour]

The purpose was to study age-related changes of the hypothalamic-pituitary-adrenal (HPA) axis function and their interrelations with features of cognitive aging in individuals with various type of adaptive behaviour on model of laboratory primates. Plasma cortisol (F) and dehydroepiandrosterone sulfate (DHEAS) levels in basal conditions (0900h and 2100h of day) and under acute psycho emotional stress (2-hour moderate restraint) were estimated in blood plasma of 34 young (6-8 years) and 34 old (20-27 years) female rhesus monkeys with various types of adaptive behaviour (aggressive, adequate, depressive-like). We have found that the age-related changes in HPA of monkeys of the depression-like behavior were accompanied by the maximal absolute and relative hypercortisolemia in the basal conditions as well as in the stress conditions. These disturbances in HPA are apparently associated with the higher age-related cognitive disturbances. Moreover, the young aggressive monkeys in comparison with the young monkeys of other behavior groups, demonstrated the higher levels of DHEAS and the minimal molar ratios between F and DHEAS plasma levels. For old animals with the aggressive behavior, these inter-group differences have leveled off. The minimal age-related changes in HPA and the minimal cognitive disturbances have been revealed for the monkeys with the adequate behavior. These results establish that the age-related damage of the HPA axis and the relevant age-related changes in the cognitive processes are the characteristic individual peculiarities of the animals associated with their individual features in the adaptive behavior strategy.

Hypothalamic-pituitary-adrenal system and enzymes of the glutathione-dependent antioxidant system during stress and aging

Activity of glutathione-dependent antioxidant enzymes (glutathione peroxidase, glutathione reductase, and glutathione transferase) in blood erythrocytes from female Macaca mulatta (6-8 and 20-26 years) was measured during activation of the hypothalamic-pituitary-adrenal system under conditions of acute psychoemotional stress (2-h restraint stress). Glutathione reductase activity increased during stress, depended on the time of day, and strongly correlated with blood corticosteroid level. Circadian variations in stress reactivity of glutathione reductase during aging were accompanied by similar changes in stress reactivity of the hypothalamic-pituitary-adrenal system.

[Stress, aging, hypothalamic-pituitary-adrenal axis and reliability of antioxidant enzyme defence]

The purpose of the investigation was to study age-related changes in reaction of the hypothalamic-pituitary-adrenal axis and erythrocyte antioxidant enzyme system in response to acute psychoemotional stress in non human primates. Ten young (6-8 years) and ten old (20-26 years) healthy female rhesus monkeys were subjected to acute moderate psycho-emotional stress (two hours squeeze cage restraint) at 15:00 h. Plasma cortisol (F), activities of superoxide dismutase (SOD), glutathione peroxidase, gluthatione reductase (GR), gluthatione-S-transferase, and lipid peroxidation products (TBARS) in erythrocytes were measured before stress and 30, 60, 120, 240 min and 24 h after beginning of the stress. In young monkeys SOD activity decreased in response to the stress while it increased in the half of old monkeys. Young animals also demonstrated essentially higher increase in plasma F level and GR activity in response to the restraint, in comparison with old monkeys. Level of TBARS did not change in response to the stress in young animals and significantly increased in old monkeys. The age-related alterations in F, SOD, and GR stress responsiveness lead to activation of peroxide oxidation of lipids that may be considered as an important factor of aging damage of erythrocyte functioning and reliability of oxygen transport to tissues under stress conditions.

[Normalizing effect of the pineal gland peptides on the daily melatonin rhythm in old monkeys and elderly people]

In the course of aging both monkeys and people reveal decreased night and average daily level of melatonin in the blood plasma and reduced hormone circadian rhythm amplitude, which evidence the disorder of the pineal gland melatonin releasing function. Peptide preparations of the pineal gland (Epithalamin--a complex of peptides isolated from the pineal gland and Epitalon--synthetic tetrapeptide) recover night release of endogenous melatonin and lead to the normalization of the hormone circadian rhythm in the blood plasma. In elderly people Epithalamin and Epitalon modulate pineal gland functional state: people with pineal gland functional insufficiency report an increase of night melatonin level. The preparations of the pineal gland, effectively increasing melatonin concentration and having no side effects, can be used in clinical geriatric practice.

Effect of aging on stress reactivity of the adrenal cortex in laboratory primates. Dependence on the time of day

Age-specific differences in the reaction of the hypothalamic-pituitary-adrenal system to acute psychoemotional stress (immobilization) was studied in female rhesus macaques aged 6-8 and 20-27 years at different time of the day. The reactivity of the hypothalamic-pituitary-adrenal system during immobilization at 15.00 was lower in old animals, while at 9.00 there were no age-specific differences or the reactivity was higher in old animals.

[Adrenal androgens: age-related changes of their synthesis and bioregulation of their production in man and non-human primates]

The article presents a review of literature data on one of topical problems of contemporary endocrinology, developmental biology and gerontology--age-related changes of synthesis of adrenal androgens (dehydroepiandrosterone and dehydroepiandrosterone sulphate), and bioregulation of their production in man and monkeys.

Pineal peptides restore the age-related disturbances in hormonal functions of the pineal gland and the pancreas

The purpose of this research was to study age-related changes in functioning of pineal and pancreatic glands of non-human primates, rhesus monkeys, and to elucidate the possibility of their corrections with the help of epitalon, a synthetic analogue of the pharmacopoeia drug epithalamin. In old (20-27 years) animals, the basal plasma levels of glucose and insulin were found to be higher, while the night melatonin level was lower in comparison with (6-8 years) young animals. After the glucose administration to old monkeys, a larger area under the curve of the plasma glucose response, a reduced glucose 'disappearance' rate, and a reduced insulin peak (5 min after the glucose administration) were observed in comparison with young animals in similar experiments. The epitalon administration to old monkeys caused the decrease in the basal levels of glucose and insulin and the increase in the basal night melatonin level. Additionally, in the case of old monkeys, epitalon decreased the area under the plasma glucose response curve, markedly increased the glucose 'disappearance' rate and normalized the plasma insulin dynamics in response to glucose administration. Yet, it has not affected the hormonal and metabolic changes in young animals. Thus, epitalon is a promising factor for restoring the age-related endocrine dysfunctions of primates.

Age-associated changes in hormonal function of the pancreas and regulation of blood glucose in monkeys

Age-associated changes in the concentrations of glucose, insulin, and DHEAS in peripheral blood plasma of female rhesus macaques were studied in intact animals and in response to a standard dose of glucose and insulin. Basal levels of insulin and glucose increased, insulin sensitivity and glucose tolerance decreased, and pancreatic reaction to glucose load was impaired in old monkeys. Insulin level positively correlated with glucose concentration, body weight, and abdomen circumference and negatively correlated with DHEAS level.

Peptide Correction of Age-Related Hormonal Dysfunction of the Pancreas in Monkeys

We studied the effect of Epithalon on the function of pancreatic islets and regulation of blood glucose level in female rhesus monkeys of various ages. Epithalon corrected the age-related decrease in glucose tolerance and restored the dynamics of insulin level in response to glucose load.

Age-Related Endocrine Dysfunction in Nonhuman Primates

Peculiarities of functioning of some parts of the endocrine system (the pineal gland, pancreatic gland, hypothalamic-pituitary-adrenal axis, and hypothalamic-pituitary-testicular axis) in an aging nonhuman primate model (Papio hamadryas and Macaca mulatta) are described in this article. It has been established that basal activity of some endocrine functions (glucocorticoid, corticotropic, pancreatic, male estradiol producing) varies little with age. Other functions significantly decrease (DHEA/DHEAS-producing, pineal, testicular) or increase (male gonadotropic) with age. In contrast with basal activity, pronounced age-related changes in response to specific stimuli were detected in all endocrine functions. Old baboons and rhesus monkeys exhibited a delay of the normalization of the pituitary-testicular axis, adrenal cortex, and pancreatic gland function after their activation in response to specific stimuli, such as LHRH, CRH, ACTH, and glucose. Old monkeys also demonstrate decreased HPA axis sensitivity to glucocorticoid regulation by negative feedback and the HPT axis to inhibitory effect of prolonged administration of LHRH agonist. Age-related changes in reactions of endocrine functions in response to specific stimulating and inhibiting stimuli indicate impaired resiliency of these functions. Age-related endocrine changes perhaps play a pathophysiological role in age function disorders of hormonocompetent tissues and organs and age pathology.

[Peptide correction of age-related pineal disturbances in monkeys]

Investigation of the age-related changes of the pineal gland function and possible ways for their overcoming on nonhuman monkey model was the purpose of this study. Hormonal function of the pineal gland was studied in 38 Macaca mulatta females of two age groups: 6-8 years old, n = 18 and 20-26 years old, n = 20. Pineal function was studied in basal conditions and after administration of pineal peptide preparations--epithalamin and epitalon, both developed in the St. Petersburg Institute of Bioregulation and Gerontology (Russia). It has been revealed that plasma melatonin concentration in monkeys has well expressed high amplitude diurnal rhythm. Minimum is manifested at 4 p.m. and maximum--at 10 p.m.-3 a.m. In aging the mean diurnal melatonin concentration decreases by 1.5-2 times as well as in different points of the day: 9 p.m., 10 p.m., 3 a.m. and 4 a.m. Administration of pineal peptides--epithalamin (at the dose 5 mg/animal/day intramuscularly during 10 consecutive days) or epitalon (at the dose 10 micrograms/animal/day intramuscularly during 7-10 consecutive days) induced significant increase in the night plasma melatonin in old monkeys, but the treatment did not change the melatonin level in young monkeys. Taking into consideration that melatonin is very important for regulation of the diurnal rhythm of functioning of some organs and systems it should be suggested that applying epithalamin and epitalon are perspective in the correction of age-related hormonal imbalance and age pathology.

Age-associated endocrine dysfunctions and approaches to their correction

This review discusses age-specific functional changes in different components of the endocrine system (pituitary, epiphysis, adrenals, and gonads), their role in aging and age-specific diseases, and possible approaches to correction of endocrine disorders and prevention of accelerated aging.

Regulatory effect of Epithalon on production of melatonin and cortisol in old monkeys

The effect of Epithalon on melatonin and cortisol secretion in female rhesus monkeys of various ages was evaluated by enzyme immunoassay. Epithalon stimulated evening melatonin production and normalized circadian rhythms of cortisol production in old monkeys.

Functions of the hypothalamo-hypophyseal-adrenal system in aging in female monkeys

Comparative studies on the functioning of the adrenal cortex in female rhesus macaques (Macaca mulatta) of different ages are reported - animals were aged 6-9 years (young adults; n = 5) and 20-26 years (old adults; n = 5). Corticosteroid concentrations (cortisol (F) and dehydroepiandrosterone sulfate (DHEAS)) were determined by specific radioimmunological and immunoenzyme methods in basal conditions, after acute stress (insulin-induced hypoglycemia, 2-h movement restriction), and after administration of dexamethasone. Basal F levels showed no marked age differences, while DHEAS concentrations in older animals decreased sharply. These animals also demonstrated weakened adrenal cortex responses to movement restriction, giving rise to delays in reaching peak F and DHEAS levels and decreases in the areas under their response curves (AUC) during the 4-h study period. In the dexamethasone test, the hypothalamo-hypophyseal-adrenal system of monkeys aged 20-26 years was relatively resistant to the suppressing effect of glucocorticoids via the negative feedback mechanism. It is suggested that disruption of feedback in the system controlling adrenal cortex function may be at least partially due to the development of peripheral blood steroid dysbalance with aging, this consisting particularly of a decrease in the DHEA (DHEAS) level; this steroid is known for its neurological activity.

Changes of hormonal function of the adrenal and gonadal glands in baboons of different age groups

The purpose of this study was to characterize the changes of hormonal function of the adrenals and gonads during aging in male baboons (Papio hamadryas). Basal levels of plasma dehydroepiandrosterone, dehydroepiandrosterone sulfate, pregnenolone, and 17-hydroxypregnenolone progressively decrease with age from 10-15 years when analyzed by specific radioimmunoassay. However, no significant changes were found in cortisol and 11-desoxycortisol concentrations. The levels of sexual hormones did not differ in young and mature groups. In the 20-26-year-old animals, the concentration of testicular androgens showed a tendency to decrease, while the concentration of biologically active luteinizing hormone (LH) showed a tendency to increase. The old animals exhibited a decrease of plasticity of the pituitary testicular system, which was manifested in the deceleration of the decrease of LH and T concentrations after the peak values had been reached in response to luteinizing hormone-releasing hormone (LHRH) administration. The oldest male also developed some refractoriness of the pituitary gonadal system to the prolonged administration of LHRH agonist. The hormonal imbalance which develops with age may play an important role in the age-related involutional process.

[Age-related characteristics of the regulation of the dehydroepiandrosterone sulfate level in the peripheral blood plasma of monkeys]

The author presents the results of study of dehydroepiandrosterone sulfate (DEAS) regulation in the circulation of male monkeys (P. hamadryas) of different age groups young nature, 8-10, and old, 26 y.o.) by functional tests with chorionic gonadotropin, and a sensitive and specific direct radioimmunoassay of plasma DEAS level developed by the author. It has established that ACTE is the principal regulator of DEAS secretion in young nature monkeys. The level of DEAS secretion in old monkeys. Testicular DEAS secretion was also notes in young animals during hyperactivation of gonadal function. The author proposes the presence of a spare mechanism of activation of testicular steroidogenesis in monkeys (through on of sulfate conjugative precursors synthesis and their transformation into testosterone) which plays an important role in the androgenopoiesis in old animals.

[Direct radioimmunoassay of the dehydroepiandrosterone sulfate level in blood plasma and its use for evaluation of the androgenic function of the adrenal cortex]

The author suggests a direct radioimmunoassay of dehydroepiandrosterone sulfate (DEA-S) in 0.05-2 microliters of human blood plasma, making use of an antiserum prepared by rabbit immunization with DEA-S hemisuccinate conjugate with bovine serum albumin and [7-3H]-DEA. The method is highly sensitive (0.039 mumol/l), specific, reliable, and easily reproducible. This method was used to measure plasma DEA-S concentrations in healthy subjects of various ages, in women in different phases of the cycle, after dexamethasone load, and in patients with the Stein-Loewenthal's syndrome and the adrenogenital syndrome. It is recommended for the diagnosis of retinopathies connected with adrenal and gonadal androgenic dysfunction.

[Hormonal function of the adrenal cortex in "medical castration" induced by prolonged infusion of luliberin agonists]

Time course of the major corticosteroid hormones and the precursors in the biosynthesis chain was studied, as was the type of corticosteroid complex formation with transcortin in the peripheral blood plasma in male papua hamadryas exposed to a 4-16 week infusions of LH releasing factor agonists (buserelin, Hoechst A. G., Germany, and surfagon, Cardiology Research Center of the Russian Academy of Medical Sciences) with the use of osmotic mini-pumps (Alza Corp., Palo Alto, USA). Suppression of the gonadal function resultant from prolonged infusion of LH releasing factor agonists was not associated with essential shifts in the adrenal steroidogenesis and in the specific corticosteroid transport. Such exposure induced a somewhat more marked activation of glucocorticoid and adrenal androgen secretion in response to acute stressor exposure (a single injection of insulin in a dose of 0.2 U/kg b. m.). One should bear in mind this fact when prescribing therapy with LH releasing factor agonists to patients with prostatic carcinoma, for the adrenal androgens are transformed into active androgens in the prostatic tissue.

[Effects of chronic surfagon administration on secretion of luteinizing hormone and morphofunctional state of the testes in Papio hamadryas]

The paper is concerned with the results of a study of the effects of chronic (12 weeks) subcutaneous infusion of surfagon (D-Ala6, des-Gly10-ethylamide of LH-RH, a daily dose of 3 micrograms/kg of body mass) using osmotic mini-pumps on hormonal function of the hypophyseogonadal system, spermatogenesis and testicular histology in experiments on Papio Hamadryas. Prolonged infusion of surfagon through short-term transient activation of the hypophyseogonadal system was shown to cause inhibition of the basal secretion of LH-RH and testosterone, induction of hypophyseal desensitization to native LH-RH, development of oligo- and azospermia. Inhibited function of the testes was accompanied by noticeable changes in their histological structure (suppression of germinative cell division, narrowing of the seminiferous tubules, moderately transient fibrosis of connective stroma). Neither focal block of spermatogenesis nor foci of calcification or necrosis (observed in rats subjected to prolonged infusion of LH-RH agonists) were observed in Papio Hamadryas. All changes in the reproductive system (including gonadal histology), induced by chronic infusion of surfagon, were of reversible nature.

[Regeneration of the function of the hypophyseal-gonadal system after its prolonged suppression with luliberin agonists]

The paper is concerned with the results of investigation into the nature of regeneration of function of the hypophyseo-gonadal system in 15 mature male Papio hamadryas, subjected to infusion of LH-RH agonists (buserelin, Hoechst A. G. Germany) and surfagon (All-Union Cardiology Research Center, USSR) using osmotic mini-pumps (Alzo Corp., Palo Alto, USA) for 5-16 weeks. Regeneration of this system was characterized by 3 main phases: latent; gonadal hyperfunction and return to the basal level of functioning. The time of phases was determined by a period of administration of the drug and individual features of functioning of the hypothalamo-hypophyseo-gonadal system. Unlike the sex glands, regeneration of hypophyseal gonadotropic function did not undergo the stage of hyperfunction but included the development of 2 phases of refractivity of gonadotropocytes to exogenous LH-RH, differing in the level of functional activity. Regeneration of function of the hypophyseo-gonadal system under basal conditions was followed by regeneration of a reaction of this system under the conditions of its activation.

[The development of a variant immunoenzyme method for determining testosterone and its use for assessing gonadal androgenic activity]

The authors have summed up the results of development of enzyme immunoassay (EIA) for the determination of testosterone (T) in human and animal blood plasma. The method is based upon the use of rabbit antiserum to testosterone-3-(O-carboxymethyl) oxim with bovine serum albumin as a binding system, a conjugate of T with horse-radish peroxidase as a marker, and the formation of the antigen-antibody complex was registered with a spectrophotometer of Cf-4a, Cf-16 and Cf-26 types. The method is highly sensitive (6.25 pg/test), specific and is characterized by high indices of precision. Close correlation between EIA and RIA results for the determination of a T level in human and simian plasma under physiological conditions as well as in some pathological conditions, associated with disturbed production of androgens, indicates the correctness of this method.

[The function of the hypophyseo-gonadal system in hamadryas baboons during the tonic infusion of a luliberin agonist--buserelin]

The authors presented the results of a study of hormonal function of the hypophyseal-gonadal system in Papio hamadryas males subjected to continuous infusion of buzereline (LH-RH agonist) at a daily dose of 3 micrograms/kg of body mass for 4-6 weeks with the help of subcutaneously implanted osmotic mini-pumps. A two-phasic response of the system to the drug was established. Activation of the secretion of hypophyseal gonadotrophins and testicular androgens in the first days of buzereline infusion was followed by sharp inhibition of endocrine function of the hypophyseal-gonadal system. Functional tests with the administration of LH-RH (100 micrograms) and human chorionic gonadotrophin (1500 U) to experimental animals demonstrated the leading role of the development of adenohypophyseal desensitization in the mechanism of antifertile drug action.

[Polymorphism of the response of the hypophyseo-gonadal system to the long-term administration of an agonist of luliberin]

The paper is concerned with the results of experiments on male Papio hamadryas aimed at the investigation of their hypophyseal and gonadal endocrine function by intravenous drip with the help of subcutaneously implanted osmotic mini-pumps of buzerelin, a superactive LH-RH analog. A 2-phase response of the hypophyseal-gonadal system was revealed. The stimulation of the secretion of LH and testicular androgens in the first 5-7 days of buzerelin administration was followed by sharp suppression of gonadotropic function of the pituitary gland and testosterone production. Individual differences in the sensitivity of animals to the drug were noted in parallel with the general regularities of hormonal functional changes of the hypophyseal-gonadal system in response t prolonged administration of the LH-RH agonist. Individual polymorphism of the body response to the LH-RH agonist was determined by the initial individual differences in the type of functioning of the hypothalamo-hypophyseal-gonadal system.

[Adrenal cortical function in chronic diseases]

The results of a study of the nature of adrenocortical function in 40 patients with tumorous and nontumorous diseases and in 22 monkeys (P. hamadryas) suffering from hemoblastosis with raised glucocorticoid activity of the adrenal glands were presented. A tendency to a decrease in the levels of pregnenolone, 17-hydroxypregnenolone and 17-hydroxyprogesterone (precursors in steroid hormones biosynthesis) and a significant decrease in the level of dehydroepiandrosterone were revealed against a background of high blood levels of cortisol. A conclusion was made that these changes were determined by the utilization of precursors in cortisol biosynthesis and a decrease in dehydroepiandrosterone synthesis. The authors emphasized the similarity of the revealed changes with hormonal imbalance in laboratory primates subjected to chronic stress. A conclusion was made of the nonspecific and adaptive nature of the above changes aimed at the maintenance of a high level of cortisol secretion (during chronic stress) playing an important role in the integration of body nonspecific adaptive processes.

[Reaction of the system of specific cortisol transport to a hemoblastosis process]

The nature of interaction of cortisol with corticosteroid-binding globulin was studied in the blood plasma of normal subjects and patients with leukemia and lymphoma. Sex-dependent differences in cortisol interaction with corticosteroid-binding globulin were found in hemoblastosis patients. Male patients showed a decrease in the binding capacity of corticosteroid-binding globulin and an increase in the affinity constant and index of free cortisol. In females no significant changes were observed.