title: Pulsatile GnRH treatment of the ovariectomized rat and release of LH and FSH.
abstract: The effect of pulsatile GnRH administration on the levels of LH and FSH was investigated in rats that had been ovariectomized 2 weeks earlier. Also the asynchronous occurrence of endogenous and GnRH-induced LH and FSH pulses was analysed. A small pulse dose of GnRH (1.25 ng/100 g) was given iv at a frequency of once every 60 min or once every 120 min during 24 h. A larger dose of 5 ng/100 g was given once every 60 or 120 min during either 24 h or 96 h. Blood was sampled arterially every 5 min around the two first and last GnRH injections and LH and FSH were measured. Only the treatment with the larger GnRH pulse dose resulted in a change of LH and FSH plasma levels. LH levels declined under all circumstances, whereas FSH was found to be increased temporarily after 24 h of treatment. The pituitary LH response to pulses of GnRH (5 ng/100 g) decreased irrespective of the frequency or duration with which GnRH was administered. There was a marked asynchronicity between LH and FSH pulses and almost every injection of GnRH (5 ng/100 g) resulted in clear LH pulses but not in FSH pulses.
mesh_terms: D000818:Animals; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007262:Infusions, Intravenous; D007986:Luteinizing Hormone / Q000097:blood*; D010052:Ovariectomy; D010906:Pituitary Hormone-Releasing Hormones / Q000008:administration & dosage*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D010906:Pituitary Hormone-Releasing Hormones; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone