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Biomedical subjects

A G Reznikov

Publications and source records attributed to A G Reznikov.

At least 55 records · Page 3Linked to original sources
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[Preventive effect of inhibitors of catecholamine synthesis, serotonin and adrenoblockaders on anovulatory syndrome development in neonatally androgenized rats. 2].

Administration to female rats of 250 micrograms of testosterone propionate (TSP) on the 3rd day of postnatal life led to reduction of estradiol, progesterone, and, to a lesser degree, of lutropin in the blood plasma of these animals at the age of 3 months. There was an increase of the lutropin content in the adenohypophysis and of luliberin in the hypothalamus. Combined with TSP administration of alpha-methyl-p-tyrosine, p-chlorphenylalanine or droperidol promoted preservation of cyclic changes in the hypothalamic gonadotropin activity and partially prevented disturbances of estradiol and progesteron secretion caused by neonatal androgenization. The mechanisms of participation of biogenic monoamines in sex differentiation of the hypothalamus are discussed.

Animals↗
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[Antiandrogens].

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Acne Vulgaris↗
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[The role of testosterone metabolism in the hypothalamus in regulating the gonadotropic function of the hypophysis in male pre- and postpubertal rats].

Experiments were staged on immature (21 days) and mature (3.5 mos.) Wistar male rats to investigate the influence of the aromatase inhibitor 1, 4, 6-androstatriene-3, 17-dione on the activity of the aromatase and 5 alpha-reductase enzymatic complexes of the hypothalamus and the blood levels of LH and testosterone (T). The formation of 5 alpha-dehydrotestosterone against a background of aromatase activity inhibition was increased in mature rats and was unchanged in immature animals. The blood levels of LH and T were increased, the reaction of LH in immature animals being more marked. A conclusion has been made of a role of T aromatic transformations in the hypothalamus in tonic inhibition of LH secretion by endogenous T and a possible involvement of this mechanism in the maturation of male rats.

Androstatrienes↗
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[Testosterone metabolism in discrete areas of the brain in rat fetuses].

Experiments in vitro with further thin-layer chromatography of steroids were staged to investigate changing of 3H-testosterone into 3H-estradiol-17 beta and 3H-5 alpha-reduced metabolites in a fraction of 1000 g of homogenates of the medial preoptic area (MPA), the paraventricular nuclei (PVN), the dorsal vagal complex (DVC) of the lower cerebral trunk, the rostral and caudal parts of the amygdaloid complex (ACr and ACc) of the brain of 21-day male and female rat fetuses. The activity of aromatase (AA) and 5 alpha-reductase (AR) was detected in all investigated areas. AA was maximum in PVN of females and minimum in ACc of males and females. The production of 5 alpha-dehydrotestosterone prevailed among 5 alpha-reduced products in PVN, DVC and ACr, 5 alpha- and rostane-3 alpha and 17 beta-diol--in MPA and ACr, AR in ACr was much higher than in ACc. AR in DVC of females was slightly higher than in males. Sex differences in the other cerebral areas were undetectable. The results of the investigation suggest that the above cerebral structures are dependent on sex hormones.

Animals↗
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[Preventive action of catecholamine and serotonin synthesis inhibitors and of adrenergic blockaders on the occurrence of the anovular syndrome in neonatally androgenized rats. I].

Administration of catecholamine synthesis inhibitors (alpha-methl-p-tyrosine) or serotonin (parachlorphenylalanine) simultaneously with testosterone propionate prevented the anovular sterility in the majority of the neonatally androgenized rats. Preventive action of adrenoblockers (droperidol and propranolol) on the effects of early androgenization were weak. The data obtained pointed to the participation of catecholamines and serotonin in the realization of the masculinizing action of androgen on the neuroendocrine centres of the gonadotropin hormones secretion control.

Adrenergic alpha-Antagonists↗
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[Problems of pathogenesis of ovarian and idiopathic hirsutism].

The content of total testosterone (T), dehydrotestosterone (DHT), androstenedione (A), estradiol (E2), luteotropin (LH) and follicle-stimulating hormone (FSH) was studied in patients with ovarian and idiopathic hirsutism by a radioimmunoassay. The level of T-E-binding globulin (TEBG) was determined by 3H-DHT binding. Concentrations of free and TEBG-unbound T, DHT and E2 were calculated on the basis of the mass action law. The level of free and TEBG-unbound T and DHT was found to be the most reliable marker of the excessive production of androgens in hirsutism. The level of total T and DHT was raised in 50-60% of patients with hirsutism. Patients with hirsutism of ovarian genesis were characterized by considerable blood elevation of LH and FSH with still greater values in patients with menstrual disturbance, and by a rise of an A level. Difference found in hormonal indices can be used in differential diagnosis of ovarian and idiopathic hirsutism.

Adolescent↗
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[Nonsteroidal antiandrogen inhibition of testosterone metabolism in the prostate].

The effect of prolonged administration of antiandrogen flutamide (FT) on testosterone (T) metabolism in the prostate (P) of intact and castrated rats and animals receiving androgens with substitution purpose was studied. In intact animals the production of dehydrotestosterone from labeled T in vitro was decreased in 30 days by 50%. The influence of FT on 5 alpha-reductase was shown to be determined by the blockade of androgenic effects. Proceeding from the results of experiments with FT and its hydroxylated metabolite added to incubated homogenates of the prostate of intact animals it was assumed that FT hydroxylated metabolite mediated FT influence on T metabolism.

Androgen Antagonists↗
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[New functional test using the antiandrogen niftolid for studying the gonadotropic reserves of the hypothalamo-hypophyseal system].

A study was made of a possibility to use a nonsteroidal antiandrogen flutamide to investigate the gonadotropic reserves of the hypothalamo-hypophysial system. In healthy males aged 12 to 36, the intake of flutamide tablets at a dose of 10 mg/kg bw for 3 or 5 days was accompanied by an increase in the LH excretion and general gonadotropic activity in the daily urine by 1.5-2 times and more. An elevation of the gonadotrophin level in morning urine portions was less noticeable. The LH level in the blood plasma did not change, that of FSH and testosterone increased but in certain age groups. For purposes of functional diagnosis it was suggested that the gonadotrophin level in the daily urine should be studied prior to and after 3- or 5-day of flutamide intake.

Adolescent↗
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[Use of the antiandrogen niftolide for studying reserves of the hypothalamo-hypophyseal system in patients with male hypogonadism].

A study was made of a possibility to use a test with the administration of the nonsteroid antiandrogen flutamide to male patients with testicular hypogonadism to evaluate the gonadotropic reserves in this pathology and differential diagnosis of the pathogenetically different forms of this diseases in male patients aged 12 to 33. Flutamide was prescribed for internal use, 10 mg/kg a day for 5 days. Functional reserves of the hypothalamo-hypophyseal-gonadal system were estimated by the change of LH secretion with morning and daily urine after 3 and 5 days as well as by the LH, FSH and T content in the blood plasma. A significant rise of LH excretion with morning and daily urine was noted in patients with primary hypogonadism receiving flutamide. On the contrary, no significant changes in LH secretion under the influence of flutamide were detected in secondary hypogonadism. It is suggestive of the preservation of the gonadotropic reserves in primary hypogonadism and their absence in secondary hypogonadism. The test is proposed for differential diagnosis in diagnostic difficulties. The most accurate results are obtained by using LH in the urine collected for 3 days of flutamide intake.

Adolescent↗