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Biomedical subjects

I Vermes

Publications and source records attributed to I Vermes.

At least 109 records · Page 6Linked to original sources
PubMed1979

In vitro effects of a synethetic enkephalin analogue (D-Met2,Pro5)-enkephalinamide on the hypothalamus-pituitary--testis function in rats.

The effects of (D-Met2,Pro5)-enkephalinamide, a synthetic analogue of the natural opioid pentapeptides, were investigated on the hypothalamus-pituitary-testis axis using in vitro tissue and isolated cell incubation systems. (D-Met2,Pro5)-enkephalinamide in a concentration range 10(-7)--10(-5) M did not alter the testosterone production and the troph-hormone sensitivity of the isolated Leydig cells, or the gonadotroph hormone release and the luteinizing-hormone--releasing hormone (LH-RH) sensitivity of the isolated anterior pituitary cells. However 10(-5)--10(-5) M synthetic enkephalin analogue induced a dose-dependent inhibition of LH-RH content and release of the mediobasal hypothalamus, which was prevented by equimolar concentrations of naloxone.

Animals↗
PubMed1979

Action of androgenic steroids on brain neurotransmitters in rats.

The effects of androgenic steroids on the dopamine (DA), noradrenaline (NA) and 5-hydroxytryptamine (5-HT) contents of different brain regions have been studied in order to elucidate the possible involvement of neurotransmitters in the negative feedback action of androgens. Administration of testosterone propionate (TP); (100 micrograms/kg or 5 mg/kg, i.p.) increased plasma testosterones, which reached a maximum at about 30 min following injections. TP (100 micrograms/kg) decreased the DA level in the hypothalamus to a minimum after 30 min and returned to normal level after 120 min. There was no effect in the amygdala, striatum and mesencephalon. Subsequent to 5 mg/kg i.p. TP administration, the minimum in the DA level was observed between 90 and 120 min in the hypothalamus, and after 120 min in the amygdala, but the treatment was without effect in the striatum and mesencephalon. Both doses of TP were ineffective as regards for in altering NA and 5-HT levels in the brain areas studied. In a dose of 5 mg/kg, androgens of different activities, such as norandrostenolone, dihydrostestosterone and androstenedione, decreased the DA contents of the hypothalamus and amygdala regions, but pregnenolone was ineffective. None of the androgens affected the NA and 5-HT levels in the brain areas studied. The data suggest that some of the actions of androgens are mediated via a dopaminergic mechanism in which not only the hypothalamus but also the amygdala is involved.

Androgens↗
PubMed1979

Effects of drugs on brain neurotransmitter and pituitary-testicular function in male rats.

The effects of different drugs influencing brain neurotransmitter contents have been tested on the pituitary-testicular function in male rats. L-dopa (200 mg/kg body weight, i.p.) increased the dopamine and noradrenaline contents of the hypothalamus, amygdala, striatum and mesencephalon, but it was ineffective as regards the 5-hydroxytryptamine contents of the same brain areas, and increased the plasma testosterone level. alpha-Methyl-p-tyrosine (250 mg/kg b.w., i.p.) decreased the dopamine and noradrenaline contents of these brain areas, but it was ineffective to 5-hydroxytryptamine, and decreased the plasma testosterone level. Diethyldithiocarbamate (400 mg/kg b.w., i.p. twice a day) increased the dopamine levels in the hypothalamus, amygdala, striatum and mesencephalon, decreased the noradrenaline contents in the same brain regions but had no effect on the 5-hydroxytryptamine contents of these brain areas or on the testosterone level in the peripheral blood. p-Chlorophenylalanine (300 mg/kg b.w., i.p.) decreased the 5-hydroxytryptamine contents of the different brain areas, while it had no effect on the dopamine and noradrenaline levels or on the plasma testosterone level. 5-Hydroxytryptophan (200 mg/kg b.w., i.p.) increased the 5-hydroxytryptamine contents of all brain areas studied, but was without effect on the dopamine and noradrenaline contents or the plasma testosterone level. The data suggest that both dopamine and noradrenaline may be involved in the regulation of the pituitary-testicular function, and the ratio of the two transmitters might be more important that their actual levels in definite brain areas.

5-Hydroxytryptophan↗
PubMed1979

Changes of maternal and fetal pituitary-adrenocortical functions during human labour.

The results of maternal 11-hydroxycorticoid (11-OHCS) determination on blood obtained from four stages of 44 spontaneous labour cases showed a strong and time-related maternal adrenocortical activation during vaginal delivery. The high 11-OHCS level in the cord blood and the increase of the 11-OHCS concentration in the amniotic fluid suggested the same response of the fetal adrenal. However, in 14 cases of elective caesarean sections the 11-OHCS levels in the cord blood and the amniotic fluid did not rise in spite of the elevated maternal plasma 11-OHCS content.

11-Hydroxycorticosteroids↗
PubMed1979

Study of the effects of neurotransmitters on the hypothalamus-pituitary-testis function in in vitro cell suspension system.

The effects of different neurotransmitters were tested in vitro on a hypothalamic tissue, collagenase-digested isolated anterior pituitary and Leydig cell suspension system by measuring the testosterone production of the Leydig cells. Neurotransmitters were used in concentrations of 0.25, 1.0, 2.5, 5.0, and 10.0 micrograms/ml incubation medium. Dopamine in doses of 1.0, 2.5, and 5.0 micrograms/ml increased the hypothalamic tissue-induced pituitary-testis activation, while it had no direct effect on pituitary and Leydig cells. Noradrenaline in the concentration range 2.5--10.0 micrograms/ml decreased the luteinizing-hormone-releasing-hormone (LHRH) sensitivity of the pituitary cells. 5.0 and 10.0 micrograms/ml 5-hydroxytryptamine decreased the testosterone production and the hCG sensitivity of the isolated Leydig cells. Carbamylcholine and pilocarpine had no action on the in vitro system at the different levels studied.

Animals↗
PubMed1979

Technique for study of hypothalamus (-) pituitary (-) testis function in vitro.

An in vitro system consisting of the rat hypothalamic tissue, the collagenase-digested isolated anterior pituitary cells and the Leydig cells, has been employed, where the testosterone production of the incubated Leydig cells was measured as the end point. The method appeared to be highly sensitive and specific in studying the functional interrelations of hypothalamus-pituitary-testis system. The sensitivity of the Leydig cells to hCG was 0.1--1.0 mU per 10(6) cells, and that of the anterior pituitary cells to LHRH responding with LH release was in the range of 0.1--1.0 ng per 10(6) cells. Two hypothalamic blocks can release a sufficient amount of LHRH to produce LH secretion in the pituitary cell preparation. The described technique seems to be a suitable in vitro approach for measuring the functional activity of the system studied and for evaluation of the sites of response to various external agents.

Animals↗
PubMed1979

Effect of prostaglandins on hypothalamic-pituitary-testicular function in vitro.

The effect of prostaglandins (PG) A1, E1, E2 and F2 alpha in the concentration range of 10(-7)--10(-4) M were studied in vitro on a rat hypothalamic tissue, collagenase-digested isolated anterior pituitary cell and Leydig cell suspension system by measuring the testosterone production of incubated Leydig cells. PGs did not change the testosterone production and the hCG sensitivity of the Leydig cells, nor the LH secretion and the LHRH sensitivity of the anterior pituitary cells. PGE2 at concentrations of 10(-6), 10(-5) and 10(-4) M significantly increased the hypothalamic tissue-induced pituitary-testicular activation, and this stimulatory effect of PGE2 was dose dependent. PGA1, PGE1 and PGF2 alpha did not alter hypothalamic LHRH release measured in vitro. The results suggest that PGE2 has a direct stimulatory effect on hypothalamic LHRH release.

Animals↗
PubMed1977

A superfusion system technique for the study of the sites of action of glucocorticoids in the rat hypothalamus-pituitary-adrenal system in vitro. II. Hypothalamus-pituitary cell-adrenal cell superfusion.

Basal and stimulated CRF release by hypothalamic blocks was studied by coupling the effluent of superfused hypothalamus tissue to a joint pituitary cell-adrenal cell superfusion system and measuring corticosterone production. Log dose-response curves of the adrenal cells for ACTH and of the pituitary cell-adrenal cell system for CRF were linear over the ranges used. Ca++-independent basal CRF release by the hypothalamus could be blocked in vitro by 0.2 mug/ml dexamethasone in the medium, or in vivo by treating the hypothalamus donor rats with corticosterone, 1 mg/rat ip 30 min before decapitation. These treatments did not impair CRF release caused by Veratridine (5 x 10(-6)M or by electrical stimulation. Adrenalectomy increased only basal but not stimulated CRF release. These results indicate that glucocorticoids have a hypothalamic site of action.

Adrenal Glands↗
PubMed1977

Effect of stress on activity of the serotoninergic system in limbic brain structures and its correlation with pituitary-adrenal function in the rat.

Fifteen min after ether stress, the 5-hydroxytryptamine (5-HT) content of the rat hypothalamus decreased, while after electric shock no decline was noted in the mesencephalon and the hypothalamus. At 30 min an increase occurred in the mesencephalon and amygdala and at 60 min in the hypothalamus after both stressors. Fifteen min after electric shock the 5-hydroxyindoleacetic acid (5-HIAA) content was increased in the amygdala, while after both stressors in the mesencephalon and hypothalamus 30 min and after ether stress in the amygdala. In the hippocampus and the septum the 5-HT or 5-HIIA content was unaffected by either type of stress. 5-HT turnover decreased between 10 and 20 min after ether stress in the hypothalamus and after electric shock in the mesencephalon and hypothalamus. Between 50 and 60 min after electric shock, 5-HT turnover increased in the mesencephalon. Other brain areas showed no significant difference from the control 5-HT value. 3H-5-HT uptake decreased in the mesencephalon and hypothalamus 20 min after ether stress, but returned to normal after 60 min. The plasma corticosterone level was highest at 30 min after both stressors and returned to normal 90 min after stress. Therefore, the stress-induced decrease of serotoninergic activity in certain limbic brain structures, especially in the hypothalamus, suggests an inverse relationship with pituitary-adrenal activity. This finding would further support the concept that the serotoninergic system plays an inhibitory role in pituitary-adrenal function.

Animals↗
PubMed1975

Effect of adrenocortical hormones on activity of the serotoninergic system in limbic structures in rats.

A single dose of corticosterone (1 mg/kg b.w.i.p.) increased the 5-hydroxytryptamine (5-HT) content in the mesencephalon, amygdala and hypothalamus. The maximum was observed at 15 min following administration. The 5-HT level returned to normal between 60 and 180 min. The 5-hydroxyindoleacetic acid (5-HIAA) content decreased in the mesencephalon and hypothalamus at 15 min, and then increased to the maximum at 30 min in the mesencephalon and at 45 min in the hypothalamus and amygdala. There were no changes in the septum and hippocampus either in 5-HT or in 5-HIAA content following corticosterone administration. Desoxycorticosterone administration (1 mg/rat i.p.) was ineffective. Tritiated 5-HT uptake did not change in the hypothalamus and mesencephalon tissue in vitro after corticosterone or desoxycorticosterone treatment. Adrenalectomy caused a decrease in the 5-HT content in all brain areas studies. 5-HIAA decreased only in the hypothalamus. Corticosterone administration normalized the 5-HT and 5-HIAA content in the hypothalamus and mesencephalon in adrenalectomized rats. Tritiated 5-HT uptake was lower in the hypothalamus and mesencephalon in adrenalectomized rats. Corticosterone administration increased the activity back to normal in the hypothalamus, however desoxycorticosterone was ineffective. The data suggest that the plasma corticosterone level plays a role in the regulation of the activity of the serotoninergic system in certain limbic brain structures.

Adrenal Glands↗