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Biomedical subjects

L Debeljuk

Publications and source records attributed to L Debeljuk.

At least 73 records · Page 4Linked to original sources
PubMed1983

Prolonged treatment with gamma-aminobutyric acid (GABA)-mimetic substances in prepubertal male rats.

The effect of chronic treatment with a gamma-aminobutyric acid (GABA)-mimetic compound, progabide, and an inhibitor of GABA-transaminase, gamma-acetylenic GABA (GAG), was tested in prepubertal male rats. The effect of gamma-butyrolactone (GBL), given orally, was also tested. The rats treated with progabide did not show any difference in body, testicular, or seminal vesicle weights or serum prolactin levels, as compared with control rats. Treatment with GAG, at both dose levels used, did not significantly affect body weight. Testicular weight was significantly lower in the group of rats treated with the low dosage of GAG (5 mg/kg), and serum prolactin was significantly lower in the rats treated with the high dosage of GAG (20 mg/kg) as compared with control rats. In the first experiment performed with GBL, the rats given this compound had significantly lower body and testicular weights as compared with control rats. In the second experiment, GBL-treated rats had body weights similar to those of control rats, but testicular weights were significantly decreased. Prolonged treatment with GABA mimetics may affect the hypothalamic-pituitary-testicular axis.

4-Butyrolactone↗
PubMed1981

Pituitary response to luteinizing hormone-releasing hormone during haloperidol-induced hyperprolactinemia.

The effects of a 6-hour infusion with haloperidol on serum prolactin and luteinizing hormone (LH) levels was studied in a group of male subjects. Five hours after starting the infusions, a study of the pituitary responses to LH-releasing hormone (LH-RH) was carried out. Control patients received infusions of 0.9% NaCl solution. During the course of haloperidol infusions, significant hyperprolactinemia was found, together with an abolished pituitary response to LH-RH, as compared with responses of control subjects.

Animals↗
PubMed1981

Effects of a superactive analogue of LH-RH on the hypothalamo-pituitary-testicular axis in male rats pretreated with estrogens.

The effect of a highly active agonistic analogue analogue of LH-RH on testicular weight an pituitary gonadotropin levels was studied in male rats previously treated with estrogens. These steroids induced a considerable depression of testicular weight. In the first experiment the treatment with a high dose (4 microgram daily) of D-Ala-6-des-Gly-10-LH-RH-ethylamide, the superactive analogue used, further depressed testicular weight and pituitary gonadotropins. In a second experiment, the treatment with lower doses (100 ng daily) of the analogue in estrogen-treated rats induced a slight but significant stimulatory effect on testicular weight and pituitary FSH content. In the third experiment none of the three doses of the analogue used (1, 10, or 100 ng daily) modified testicular weight when the treatment was started shortly after the administration of estrogens. It is concluded that, according to the dose of the analogue used, it is possible to observe inhibitory or stimulatory effect on testes and pituitary gonadotropin levels.

Animals↗
PubMed1981

Effect of inhibitors of catecholamine synthesis on the pituitary response to LH-RH.

Cathecolamines have an important role in the regulation of LH secretion. The effect of two selective blocking drugs of cathecolamines synthesis upon pituitary response to LH-RH was studies. Basal levels of serum LH in rats treated with alpha-methyl-p-tyrosine and diethyldithiocarbamate were significantly lower than those of control rats. Diethyldithiocarbamate induced a greater decrease of LH levels than alpha-methyl-p-tyrosine. The rats treated with diethyldithiocarbamate showed an LH increase after LH-RH stimulation that was significantly higher as compared with control group as well as in alpha-methyl-p-tyrosine treated group.

Animals↗
PubMed1980

Effect of cycloheximide on the LH release induced by a superactive analog of LH-RH.

The effect of cycloheximide on the pituitary response to a superactive analog of LH-RH (D-Ala-6-des-gly-10-LH-RH-ethylamide) was studied in intact male rats. Cycloheximide did not modify the LH release induced by the LH-RH analog within 1 hr after its injection, but produced significant supression between 1 and 4 hr. It is concluded that the early release of LH observed after the administration of the analog occurs from the readily releasable pool of LH in the pituitary gland, which is not affected by cycloheximide. The subsequent LH release that can be suppressed by cycloheximide comes from the second pool of LH.

Animals↗
PubMed1978

Biosynthesis of gonadotropins by rat pituitary cells in culture and in pituitary homogenates: effect of gonadotropin-releasing hormone.

The incorporation of labeled amino acids and glucosamine into LH and FSH by cultured rat anterior pituitary cells and anterior pituitary homogenates is reported. There was a significant augmentation in this incorporation by cells after 6 days of culture in the presence of GnRH. Tritiated LH and FSH were found in the cell extracts as well as in the media by the method of immunoprecipitation. An increase of approximately 7--13-fold in the release of LH and FSH into the cell incubation medium was observed in the presence of GnRH (3 ng/ml). The rate of incorporation of [3H]proline was higher than that of [3H]glucosamine into LH and FSH. At the same time a higher incorporation of labeled amino acids was observed in the case of FSH than with LH. Cycloheximide inhibited completely the incorporation of labeled proline but the inhibition was partial for the incorporation of labeled glucosamine. Freshly dispersed cells, short-time cultures maintained for 20 h and pituitary homogenates also incorporated labeled amino acids into LH and FSH, but GnRH had no effect on this incorporation. Pituitary homogenates also incorporated [3H]glucosamine into LH and FSH with an optimal incorporation after 30 min of incubation. Three different concentrations of GnRH had no effect on the incorporation of [3H]proline by homogenates. Cycloheximide and puromycin inhibited this incorporation completely.

Amino Acids↗
PubMed1978

Effect of pimozide and sulpiride on the release of LH and FSH by pituitary cells in culture.

A culture of dispersed rat anterior pituitary cells was used to test the ability of pimozide and sulpiride to affect the basal gonadotropin release and their effects on the response to Gn-RH. Sulpiride did not alter either the basal or the Gn-RH-induced release of LH, and the lowest dose (500 ng/ml) seemed to potentiate the Gn-RH-induced FSH release. On the other hand, both doses of pimozide (100 ng/ml and 10 microgram/ml) significantly inhibited the release of FSH and LH induced by Gn-RH but did not affect the basal release of the two gonadotropins. From these results it is evident that pimozide, at the doses used, is a powerful inhibitor of the pituitary response to Gn-RH in vitro. Sulpiride on the other hand had no effect on the pituitary response to Gn-RH in vitro, except on FSH release, using the lower dose.

Animals↗
PubMed1978

Release of prolactin during pregnancy: effect of sulpiride.

The aim of this trial was to study the prolactin-releasing capacity of the pituitary during pregnancy by means of an acute stimulation with sulpiride. Thirty women with normal pregnancies were included in the study (first trimester, nine women; second trimester, eleven women thir trimester, ten women). Each woman received an intramusclar injection of 100 mg of sulpiride sulfate between 8 and 9 A.M. Three similar groups received injections of a saline solution. Blood samples were obtained before and 30 and 60 minutes after the injection. In each sample the prolactin concentration was determined by radioimmunoassay. Basal prolactin levels increased during pregnancy. Significant responses to sulpiride were observed during the three stages of pregnancy, and the levels in the second and third trimesters were higher than those in the firsttrimester. The prolactin-releasing capacity of the pituitary, as judged by the response to sulpiride, seems to be maintained during pregnancy.

Adult↗
PubMed1978

Effects of gonadal steroids and cycloheximide on the release of gonadotrophins by rat pituitary cells in culture.

The effects of oestradiol-17beta, testosterone and progesterone alone and together with cycloheximide on the basal and gonadotrophin releasing hormone (Gn-RH)-induced release of gonadotrophins were studied in cultured dispersed rat pituitary cells. In the control group (no steroid treatment), GnRH significantly stimulated the release of LH and FSH; cycloheximide partially inhibited this response, although it had no effect on the basal secretion of gonadotrophins. A dose of 5 ng oestradiol/ml had no significant effect on the response to GnRH; at a dose of 100 ng/ml the GnRH-induced release of LH was significantly augmented whereas the release of FSH was inhibited. Cycloheximide blocked the augmenting effect of oestradiol. The basal release of LH was slightly but significantly inhibited in response to 10 ng testosterone/ml and increased in response to progesterone (200 ng/ml). Testosterone at both dose levels and progesterone significantly inhibited the GnRH-induced release of LH and FSH and in testosterone and progesterone-treated groups, the response to GnRH was inhibited by cycloheximide, but not beyond the levels observed in the control group. It is concluded that steroids can act directly on the pituitary cells, that oestradiol stimulates the GnRH-induced release of LH and that cycloheximide blocks this stimulatory effect. Testosterone and progesterone, on the other hand, partially inhibit the response to GnRH.

Animals↗