[Dependence of changes in the luliberin level in the synaptosomal fraction of the olfactory bulbs and various areas of the hypothalamus on the level of sexual activity in male rats]. / Zavisimost' izmenenii soderzhaniia liuliberina v sinaptosomal'noi fraktsii oboniatel'nykh lukovits i nekotorykh oblastei gipotalamusa ot urovnia polovoi aktivnosti u samtsov krys.

The paper is devoted to a study of the level of LH-RH in the synaptosomal fraction of the olfactory bulbs, preoptic area and mediobasal hypothalamus, and the blood level of HL in adult male rats with sexual activity after noradrenergic denervation of the preoptic area using 6-hydroxydopamine. A neurotoxic effect of 0.1% solution of ascorbic acid, preventing 6-hydroxydopamine disintegration, was noted. Both sexual activity and the level of LH-RH in synaptosomes of the preoptic area were lowered in male rats with noradrenergic denervation of the preoptic area. The maximum blood level of LH was observed during exposure to a recipient female rat. LH-RH concentration in the synaptosomal fraction of the olfactory bulbs being raised, that in the mediobasal hypothalamus lowered. The results were indicative of the involvement of HL-RH-synthesizing cerebral neurons with terminals in the olfactory bulbs, preoptic area and mediobasal hypothalamus in the regulation of sexual behavior, and the interaction of LH-RH-containing terminals with noradrenergic nerve endings at the level of the preoptic area.

[Hypothalamic receptors of sex hormones in the mechanism of the sexual differentiation of the brain in rats]. / Gipotalamicheskie retseptory polovykh gormonov v mekhanizme polovoi differentsirovki mozga u krys.

Studies have been made on the content of receptors of estradiol (E2) and testosterone (T) in cytoplasmic and nuclear fractions of the hypothalamus of male and female rats during neonatal development, as well as in adult females after androgenization in neonatal period and adult males castrated within 3 days of postnatal life. It was shown that both E2 and T are present in the blood serum of male and female newborn rats. In female hypothalamus, only E2 receptors were found, whereas in males both types of receptors were revealed, their content being higher than in females. In adult animals subjected to changes in the level of sex hormones in the blood during early neonatal period, changes in concentration of the receptors in the hypothalamic centres of regulation of tonic and cyclic secretion of gonadotropins were found. The data obtained presumably reveal the role of receptors of sex hormones in sex differentiation of the brain.

[Effect of a calcium channel blocker on the hypophyseal secretion of luteinizing hormone in intact and castrated rats of both sexes]. / Vliianie blokatora kal'tsievykh kanalov na sekretsiiu liuteiniziruiushchego gormona gipofizom u intaktnykh i kastrirovannykh krys oboego pola.

The effect of verapamil on luteinizing hormone secretion by pituitary body was studied in normal and castrated male and female rats. Intragastric verapamil administration at a dose of 10 mg/g body weight two hours prior to decapitation decreased luteinizing hormone serum and pituitary levels in female rats only in proestrus. It is suggested that preovulatory luteinizing hormone secretion depends partially on estradiol-stimulated calcium transport.

[Relation between the modulating effect of estradiol on the secretion of the pituitary luteinizing hormone and calcium ions in ovariectomized animals]. / Zavisimost' moduliruiushchego deistviia éstradiola na sekretsiiu liuteiniziruiushchego gormona gipofizom ot ionov kal'tsiia u ovariéktomirovannykh zhivotnykh.

The effect of verapamil, the blocker of calcium channels, on estradiol modulation of the LH-RH effect on the secretion of the luteinizing hormone was studied in experiments on ovariectomized rats. It was shown that verapamil influenced neither the basal nor the LH-RH activated secretion of the hormone from the pituitary gland. However verapamil inhibited the effect of estradiol increasing the secretory response to LH-RH. Hence, the modulating effect of estradiol on the secretion of the luteinizing hormone depended on the transport of extracellular calcium into hypophyseal cells.

[Sex hormone receptors in the hypothalamus and their role in the sexual differentiation of the brain of male rats]. / Retseptory k polovym gormonam v gipotalamuse i ikh rol' v polovoi differentsirovke mozga u krys-samtsov.

The content of receptors to estradiol and testosterone was determined in cytoplasmic and nuclear fractions of hypothalamus and brain cortex of male rats in the early postnatal period. Receptors to both estradiol and testosterone were revealed in cytosol and nuclear fractions, with the decrease in their concentration observed from days 1 to 5. The data obtained demonstrate that receptors to sexual hormones take part in the brain differentiation and regulation of hypophysis gonadotropic function by male or female type.

[Interrelations between monoamines and luliberin in the synaptosomes of the medio-basal hypothalamus and its separate structures]. / Vzaimosviaz' monoaminov i liuliberina v sinaptosomakh medial'no-bazal'nogo gipotalamusa i ego otdel'nykh strukturakh.

A study was made of the mechanism of interrelationship of neuromediators (biogenic amines) and LH-RH at the level of separate hypothalamic regions involved in the regulation of gonadotropic function of the hypophysis as well as at the synaptosomal level of the mediobasal hypothalamus (MBH). The steroid-dependent nature of LH-RH response in the investigated structures to monoamine administration has been shown. Noradrenaline and dopamine lowered the LH-RH level in intact animals in the area of arcuate nuclei and MBH synaptosomes, the LH level in the blood increased under the influence of noradrenaline only. Castration caused an increase in the LH-RH content in the arcuate area and its decrease in MBH synaptosomes; under such experimental conditions the LH level in the blood did not change. Serotonin in intact animals lowered the LH-RH level in the area of arcuate nuclei and MBH synaptosomes whereas in castrated animals the LH-RH level in the area of arcuate nuclei increased and decreased in synaptosomes.

[Cytoplasmic and nuclear receptors of estradiol in the hypothalamus and cerebral cortex of female rats in the neonatal period]. / Tsitoplazmaticheskie i iadernye retseptory éstradiola v gipotalamuse i kore golovnogo mozga samok krys v neonatal'nom periode.

The content of estradiol receptors (E2) was studied in the cytoplasmic and nuclear fractions of the female rat hypothalamus and cortex during neonatal development. In the cytosol the E2-binding proteins, having a high capacity, include both true estradiol receptors and proteins identical with alpha-fetoprotein. True E2 receptors were found in the nuclear fraction: their concentration underwent almost no changes in hypothalamus and decreased from the 1st to the 5th day of postnatal development in cortex.

[Luliberin of the synaptosomal fraction of the mediobasal hypothalamus in male rats and a change in its level as affected by monoamines]. / Liuliberin sinaptosomal'noi fraktsii mediobazal'nogo gipotalamusa krys-samtsov i izmenenie ego urovnia pod deistviem monoaminov.

Investigation of the effects of injecting monoamines (noradrenaline, dopamine and serotonin) into the third ventricle of the brain on the LH-RH content in the synaptosomal fraction of the mediobasal hypothalamus in intact and castrated male rats has demonstrated that all the three monoamines are involved in the regulation of synthesis and secretion of LH-RH and that their effects on LH-RH-producing neurons are steroid-dependent.

[Intracellular distribution of estradiol-binding sites in the hypothalamus of female rats during the estrous cycle]. / Vnutrikletochnoe raspredelenie éstradiolsviazyvaiushchikh mest v gipotalamuse samok krys v khode éstral'nogo tsikla.

The content of cytoplasmic and nuclear receptors for estradiol (E2) in the preoptic anterior hypothalamus (PO) and arcuate nucleus-medial eminance (ARC-ME) at varying day time (10, 13, 15 and 18 hours) of each stage of the estrous cycle was examined. The most pronounced changes in the concentrations of estradiol-binding sites in both hypothalamic regions, having high affinity for E2, was seen at the second half of the day of diestrus-2 and proestrus. The association constant values for cytoplasmic and nuclear receptors in PO and ARC-ME were slightly changed during the cycle. It is suggested that the receptors for E2 in both hypothalamic regions participate in regulating the luteinizing hormone preovulatory release.

[Cytoplasmic and nuclear testosterone receptors in the hypothalamus of androgenized female and castrated male rats]. / Tsitoplazmaticheskie i iadernye retseptory k testosteronu v gipotalamuse u androgenizirovannykh samok i kastrirovannykh samtsov krys.

Receptors for testosterone (T) in the preopticoanterior hypothalamus (PO) and in the arcuate nucleus and median eminence (ARC + ME) were examined in neonatally androgenized female and neonatally castrated male rats. As a result of neonatal castration of males, the concentration of cytoplasmic and nuclear receptors for T in the PO dropped to an undetectable level. In the ARC + ME, the number of T-binding sites in the cytosole fraction remained unchanged, while that in the nuclear fraction decreased 2-fold. In the cytosole fraction of neonatally androgenized females, receptors for T were detectable only in the ARC + ME, the level of binding being not different from that seen in this hypothalamic area in intact and neonatally castrated males. At the same time in the nuclear fraction, receptors for T were detectable in both hypothalamic areas, the number of T-binding sites in the ARC + ME being 1.5 times less than in the PO. The data obtained attest to the involvement of receptors for T in sexual differentiation of the brain and regulation of gonadotropic function of the hypophysis.

[Dynamics of the changes in the content of testosterone and estradiol receptors in the hypothalamus of male rats in the course of sexual development]. / Dinamika izmeneniia soderzhaniia retseptorov k testosteronu i éstradiolu v gipotalamuse samtsov krys v khode polovogo razvitiia.

The content of receptors to testosterone and estradiol in hypothalamus of the male rats was studied during their sexual maturation (7, 14, 21, 28, 35 and 42 days). In all the age groups of animals the concentration of receptors to testosterone in the cytoplasmic and nuclear fractions of hypothalamus was at a relatively constant level, except in 7 day old males in which the minimal concentration of cytoplasmic and the maximal concentration of nuclear receptors were noted. The highest values of estradiol-binding sites in cytosol of hypothalamus were observed on the 7th and 14th days and in the nuclear fraction on the 28th, 35th and 42nd days of life. The binding of both the hormones with their receptors is a specific process characterized by a high affinity. A suggestion is put forward that receptors both to androgens and estrogens take part in the brain sexual differentiation.

[Dynamics of the content of estradiol cytoplasmic and nuclear receptors in the rat hypothalamus in the course of the estrous cycle and postnatal development]. / Dinamika soderzhaniia tsitoplazmatichekikh i iadernykh retseptorov k éstradiolu v gipotalamuse krys v khode éstral'nogo tsikla i postnatal'nogo razvitiia.

The content of receptors to estradiol in the cytoplasmic and nuclear hypothalamus fractions was studied in female rats during the postnatal development and oestral cycle. In the cytosol of 7 and 14 days old females and in the nuclear fraction of 7 days old females, E2-binding proteins having high capacity were identified as L-fetoprotein. The appearance of true receptors to E2 in the cytosol was shown in the 21 day old females and in the nuclear fraction in the 14 days old ones. In the other age periods until the 35th day, the parallel decrease in the content of both cytoplasmic and nuclear receptors was observed. The binding capacity of the cytoplasmic and nuclear receptors to estradiol in the preoptical area and the arcuate nucleus and median eminence area suffered marked changes with respect to different stages of the oestral cycle, and, within each stage, to day time.

[Dynamics of changes in the estradiol receptor content in the nuclear fraction of the hypothalamus of female rats during ontogenesis]. / Dinamika izmeneniia soderzhaniia retseptorov k éstradiolu v iadernoi fraktsii gipotalamusa samok krys v khode ontogeneza.

Determination of estradiol receptors content in the nuclear fraction of the female rats' hypothalamus demonstrated their number to alter during the postnatal development. Numerous nuclear E2-binding sites were revealed in the hypothalamus of 14-day-old female rats. The E2-binding level fell by the 21st day after birth, persisting at this level up to sexual maturity. The nuclear receptor content was maximal at this age period. Estradiol receptors possessed a high degree of affinity to the recepted hormone, and also specificity. Estradiol nuclear receptors were revealed in the brain cortex only in 7-day-old rats.

[Dynamics of changes in the concentration of luteinizing hormone in the pituitary and plasma and estrogens in blood of female rats during sexual maturation]. / Dinamika izmeneniia soderzhaniia liuteiniziruiushchege gormona v gipofize i plazme krovi i éstrogenov v krovi u samok krys v khode polovogo sozrevaniia.

The dynamics of LH content in hypophysis and blood and oestrogen content in blood was studied in female rats from the 1st till the 42nd day of postnatal development. The two peaks of LH content in blood on the 18th and 22nd days correspond to the maximum accumulation of the hormone in hypophysis. The 3rd peak on the 41st day is somewhat behind the accumulation of the hormone in hypophysis (37th day). At the moment of vaginal opening, both the hormone synthesis and the secretion sharply decreased. The measurable quantities of oestrogens were found in blood beginning from the 8th day of life. The maximum level of oestrogens was noted from the 13th till the 16 day. These results suggest the absence of distinct interrelations of the feed-back type between hypothalamus, hypophysis and gonads.

[Change in testosterone content in the testes and peripheral blood in male rats during postnatal development]. / Izmenenie soderzhaniia testosterona v semennikakh i perifericheskoi krovi u samtsov krys v khode postnatal'nogo razvitiia

Changes in testosterone content have been studied in the testes and peripheral blood in male rats from the 1st till the 42nd day after birth. The correlation was established between the level of luteinizing hormones in the blood and that of testosterone in the testes during the first 5 days after birth.

[The dynamics of changes in the concentration of luteinizing hormone in the pituitary and the blood during postnatal development of male rats]. / Dinamika izmeneniia soderzhaniia liuteiniziruiushchego gormona v gipofize i krovi v khode postnatal'nogo razvitiia u samtsov krys

The authors describe a specific and sensitive biological method of determination of luteinizing hormone (LH). There was shown a linear relationship between the LH dose gradient and the amount of testosterone determined in the blood flowing from the testes. Sensitivity of the method--5 nanogram/ml. Linear dependence--5--45 nanogram/ml. Dynamics of the changes in the LH concentration in the hypophysis and the blood of male rats in the course of postnatal development--from the 1st to the 43rd day was studied. There were distinguished 6 peaks of increase in the LH content in the hypophysis: on the 4th, 7th, 19th, 27th, 37th and the 43rd day after birth; blood LH concentration persisted at a relatively constant level--within the range of 1.33--4.39 gamma per cent. No LH was revealed in the blood on the 4th, 19th, and 24th days after birth.