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Biomedical subjects

L Debeljuk

Publications and source records attributed to L Debeljuk.

At least 91 records · Page 5Linked to original sources
PubMed1976

Re-examination of porcine and bovine hypothalamic fractions for additional luteinizing hormone and follicle stimulating hormone-releasing activities.

More than 150 hypothalamic fractions were reassayed for luteinizing hormone-releasing hormone (LHRH) and follicle stimulating hormone-releasing hormone (FSHRH) activities in search for LHRH and FSHRH which differ from the decapeptide (pyro)Glu-His-Trp-Ser-Try-Gly-Leu-Arg-Pro-Gly-NH2 (I). Among the porcine fractions tested were those obtained: 1) from the isolation of thyrotropin-releasing hormone; 2) from two isolation procedures for LHRH; and 3) from methanolic and aqueous 2N acetic acid extracts which were subjected to Biogel P-2 filtration and partition chromatography. Some bovine hypothalamic fractions were also tested. Both in vivo and in vitro assays were used for measuring LHRH and FSHRH activities. The values obtained were in each case compared with those resulting from the administration of pure natural or synthetic LHRH decapeptide I. A radioimmunoassay for LHRH (I) was also utilized for some fractions. In all the purification steps the location of LHRH and FSHRH activity, as determined by in vivo assays, corresponded to that of the decapeptide I. Purification of hypothalamic extracts on Biogel P-2 and by partition chromatography separated a fraction from the decapeptide I, which released more FSH than LH in vitro from the pituitaries of immature female rats. However, this material was inactive in vivo and in other in vitro systems, so that its significance is obscure. The results suggest that if material with LHRH and FSHRH activity other than the decapeptide I is present in acid extracts of porcine hypothalami, then its FSHRH and LHRH activity would be a minor part of the total LHRH/FSHRH activity in the extracts. (Pyro)-Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2 appears to account for most of all of the LHRH and FSHRH activity found.

Animals↗
PubMed1976

Effect of sulpiride on serum prolactin levels in humans.

The effect of acute and chronic administration of sulpiride sulphate on serum prolactin levels in humans was studied. Six normal women and four normal men received an i.m. injection of 100 mg sulpiride at 0800 h. A control group received saline solution 0.9%. Blood samples were taken before and 30, 60 and 120 minutes after the injection. Serum prolactin was determined by a double antibody radioimmunoassay technique. Sulpiride induced in all subjects a quick and marked increment of serum prolactin levels with peak values at 30 minutes. At 120 minutes the levels remained high. In another experiment six post menopausal women received 150 mg of sulpiride orally during 10 days. Five of them had marked increments of circulating levels of prolactin at the end of treatment. It is suggested that sulpiride could be used in the dynamic functional exploration of hypothalamic-pitutiary system.

Adolescent↗
PubMed1976

Effect of melatonin on the basal and stimulated gonadotropin levels in normal men and postmenopausal women.

The effect of melatonin on LH and FSH secretion in basal conditions and after stimulation with synthetic LHRH was studied in 3 volunteer normal men and 3 women two to five years after menopause. During the first three days of study, blood samples were obtained at 8 AM. On the second day, an iv injection of 50 mug LHRH was performed; on the third day, 2 ml of 0.9% saline were injected. In both cases, blood samples were obtained 30 and 60 minutes after the injection. On the fourth day, the subjects began melatonin (10 mg daily im for 13 days). Blood samples at 8 AM were obtained after 5, 11, and 13 days of administration of the drug. On days 5 and 11 of the treatment, iv injections of 50 mug LHRH were performed and on day 13 an iv injection of saline 0.9% was given. Blood samples were obtained 30 and 60 minutes after each injection. In each sample LH and FSH levels were determined by radioimmunoassay. Melatonin treatment did not cause any significant change in basal or post-stimulation LH and FSH levels either in men or in post-menopausal women. These results do not support previous findings of an insults do not support previous findings of an inhibitory effect of melatonin on gonadotropin secretion, even with the same dose as the one used in this study. Further studies with higher doses of melatonin are needed to clarify the action of this drug on gonadotropin secretion.

Adult↗
PubMed1975

Variation of the pituitary response to LH-releasing hormone (LH-RH) during a 24-hour period in male, diestrous female and androgenized female rats.

The pituitary response to LH-RH was studied at 8 a.m., 4 p.m. and 12 p.m. in normal male rats, female rats on day 1 of diestrus and female rats injected with testosterone propionate on the 2nd day of life. Androgenized rats responded to LH-RH with a greater release of LH than did female diestrous and male rats. In the 3 groups the lowest response to LH-RH was observed at 12 p.m., and the highest at 8 a.m., with the exception of androgenized rats which responded with a similar magnitude of LH release at 8 a.m. and 4 p.m. The release of FSH after the injection of LH-RH was studied only at 4 p.m. and only normal male rats responded with a significant FSH release.

Animals↗
PubMed1975

Effect of castration upon hypothalamic luteinizing hormone releasing factor (LH-RF).

The effect of castration upon hypothalamic LH-RF synthesis and content was determined in mature male rats. In each single experiment 20 hypothalami from both normal and 60-day-castrated rats were bisected into symmetrical portions. For the determination of LH-RF synthesis 20 hypothalamic halves were incubated for 120 min. After incubation the tissue was homogenized in medium containing 1 N acetic acid, and centrifuged; 1.0 ml of the supernatant was used to test LH-RF activity. In the other 20 halves, hypothalamic LH-RF content was determined: the samples were homogenized without incubation in 1 N acetic acid, centrifuged, and LH-RF activity was tested in 1.0 ml of the supernatant. LH-RF activity was determined in vivo in ovariectomized rats pre-treated with estrogen-progesterone by measuring, by radioimmunoassay, the LH modifications in serum after the i.v. administration of the extracts. Hypothalamic LH-RF content was significantly higher in control than in castrated rats (p is less than 0.001). After incubation there were no changes in the LH-releasing potency of control hypothalami compared with non-incubated tissue, whereas a significant increase (616%) was found after the incubation of hypothalami from castrated rats. On the other hand, after incubation LH-RF activity was higher (p is less than 0.02) in castrated than in control hypothalami. These results suggest that castration stimulates the release and synthesis of hypothalamic LH-RF in male rats.

Animals↗
PubMed1975

Serum follicle-stimulating hormone and luteinizing hormone levels in male rats with experimentally induced damage of the germinal epitheilum.

The effect of the depletion of germinal cells from the seminiferous tubules on serum follicle-stimulating (FSH) and luteinizing (LH) was studied in young male rats. A single administration of 1-(N,N-diethylcarbamylmethyl)-2-4-dinitropyrrole (ORF 1616) seemed to damage primary spermatocytes and especially young spermatids. Whenever young spermatids (stages 1-8) were absent or at least decreased in number, a significant increase in serum FSH, and in some cases serum LH, was detected. The administration of another drug, bis (dichloroacetyl) diamine (WIN 18446) for 21 consecutive days induced a depletion of primary spermatocytes in the seminiferous tubules, which was followed by a depletion of spermatids, due to the lack of spermatocytes to generat them. By the time the seminiferous tubules showed partial or total disapperance of young spermatids, serum FSH and in some cases also serum LH levels were significantly raised. It is concluded that the germinal epithelium of rat testes exerts some kind of control on serum gonadotrophin levels. Young spermatids seem to be involved in this regulation.

Animals↗
PubMed1975

Acute and chronic effects of sulpride on serum prolactin and gonadotropin levels in castrated male rats (38581).

The effect of the acute or chronic administration of sulpiride on serum prolactin and gonadotropin levels was studied in castrated male rats. Sulpiride administered in acute intravenous injections induced a quick increase in serum prolactin levels and no significant changes in serum gonadotropins. The peak in serum prolactin was observed 30 min after the injection of sulpiride, with a decrease of serum prolactin levels at 60 and 120 min. The subcutaneous administration of sulpiride for 13 days induced a significant increase in serum prolactin levels at the end of the treatment, and no significant changes in serum FSH and LH levels.

Animals↗
PubMed1975

Effect of a long-acting estrogen on the pituitary response to LH-releasing hormone (38582).

The effect of Quinestrol, an estrogenic substance of long-lasting activity, on the pituitary responsiveness to LH-RH was studied in ovariectomized rats. Quinestrol administered as a single 200 pg-dose significantly augmented the pituitary response to LH-RH 36 hr, 9 days, and although not significantly, also at 24 days after its oral administration. No effect could be detected 36 days after its administration. At a 20 pg-dose Quinestrol significantly augmented the pituitary response to LH-RH only at the 36 hr-period studied, this effect not being apparent in later time periods.

Animals↗
PubMed1975

Effect of actinomycin D and estradiol on the response to LH-releasing hormone in neonatally androgenized femal rats.

The effect of estradiol, actinomycin D, or both, on pituitary response to LH-RH was studied in 6-month-old female rats which had been injected with testosterone propionate on the 2nd day of life. Estradiol significantly augmented the pituitary response to LH-RH. Actinomycin D did not significantly modify basal serum LH levels and pituitary response to LH-RH but did significantly inhibit the augmenting effect of estradiol on such a response.

Animals↗