Biomedical subjects

R H Asch

Publications and source records attributed to R H Asch.

201 records · Page 12Linked to original sources

PubMedDate not supplied

Temporal changes in FSH and LH concentrations following the administration of a potent LH-RH inhibitory analogue ( [N-Ac-D-Trp1, 3, D-p-Cl-Phe2, D-Phe6, D-Ala10]-LH-RH) to oophorectomized rhesus monkeys.

A series of studies was performed in order to assess the antigonadotropic potency of an inhibitory analogue of LH-RH (IA-LH-RH) ( [N-Ac-D-Trp1, 3, D-p-Cl-Phe2, D-Phe6, D-Ala10]-LH-RH) in oophorectomized rhesus monkeys. I) Single administration of 1 mg IA-LH-RH im resulted in a prompt and significant decrease of serum levels of FSH and LH which lasted for at least 24 h. A specific rebound of serum LH to higher concentrations than baseline occurred in all animals at +48 or +72 h. II) Exogenous LH-RH at a dose of 150 micrograms was administered iv 2 or 18 h after the injection of 1 mg IA-LH-RH. Blood was drawn at 0, 10, 20, 30, 60, 120 and 180 min post LH-RH. The rise in LH and FSH levels observed in the control animals was not altered when LH-RH was administered 2 h after the antagonist, but it was significantly inhibited and delayed when LH-RH was given 18 h after the LH-RH inhibitory analogue. These results show that antagonistic analogues of LH-RH are potent inhibitors of gonadotropin concentrations in non-human primates. Their potential use in conditions in which inhibition of gonadotropin secretion and/or release is desired is discussed.

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PubMedDate not supplied

Dose response inhibition of the circhoral pulsatile secretion of LH and FSH in rhesus monkeys by the administration of a potent inhibitory analogue of LH-RH ( [N-Ac-D-Trp1, 3, D-p-Cl-Phe2, D-Phe6, D-Ala10]-LH-RH).

The pulsatility of luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion was evaluated in chronically ovariectomized rhesus monkeys before and after the administration of [N-Ac-D-Trp1, 3, D-p-Cl-Phe2, D-Phe6, D-Ala10]-LH-RH) (IA-LHRH). Animals were divided into three groups (n = 4, each group) receiving, s.c.: 1) vehicle only (controls); 2) 0.5 mg IA-LH-RH; and 3) 2 mg IA-LH-RH. Twelve hours following drug administration, animals were chair-restrained and blood samples drawn every 10 minutes over a period of 4 hours via indwelling femoral vein catheters. LH and FSH levels were measured by RIA to determine the frequency, amplitude and increment of the pulses. Twelve hours after the administration of 0.5 mg or 2.0 mg of IA-LH-RH, levels of LH were reduced by 30 per cent and 68 per cent (P less than 0.001) and those of FSH by 34 per cent and 53 per cent (P less than 0.001 and P less than 0.002), respectively. Doses of 0.5 mg IA-LH-RH decreased the amplitude (20 per cent; P less than 0.001), increment (17 ng/ml; P less than 0.001) and frequency (2 per 4 h; P less than 0.001) of LH pulses. Administration of 2 mg IA-LH-RH produced a fall of increment (8 ng/ml; P less than 0.001), frequency (1 per 4 h; P less than 0.001) and pulse amplitude (26 per cent; P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMedDate not supplied

Pituitary responsiveness to LH-RH during gestation and puerperium in the rhesus monkey.

Pituitary gonadotropin response to luteinizing hormone-releasing hormone (LH-RH; 150 micrograms, administered intravenously) was studied during pregnancy and the early postpartum period in rhesus monkeys. Challenge tests were performed approximately every three weeks during pregnancy and every two weeks after delivery, in breast-feeding and non breast-feeding animals. It was found that the response to the releasing factor was completely abolished as early as day 20 after conception. This absence of pituitary responsiveness to LH-RH continued throughout pregnancy. The return of the response during the puerperium occurred as early as day 15 post-delivery in non-breast-feeding monkeys, but remained abolished up of the response to LH-RH in FSH and LH concentration was observed, in that LH levels increased 70%-90%, whereas FSH levels increased only 20%-30%. Serum prolactin (PRL) levels in breast-feeding animals presented a slight increase the first week post-delivery and thereafter, and decreased gradually until they reached normal levels four weeks post-delivery. In contrast, concentrations of serum PRL in non-breast-feeding animals decreased abruptly to normal levels within the first week post-delivery. These results demonstrate that, due to its similarity to the human, the rhesus monkey is an excellent animal model in which to study pituitary function during pregnancy and the puerperium.

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