Changes in the characteristics of pulsatile luteinizing hormone secretion during the oestrous cycle and after ovariectomy and oestrogen treatment in female rats.
Changes in the characteristics of LH secretory pulses in female rats were determined in different hormonal conditions; during the oestrous cycle and after ovariectomy and oestrogen treatment. The frequency and amplitude of the LH pulses were stable during the oestrous cycle except at oestrus when a pattern could not be discerned because of low LH concentrations. These were significantly lower than those measured during other stages of the cycle. Mean LH concentrations and LH pulse amplitudes increased with time up to 30 days after ovariectomy. The frequency of the LH pulse was unchanged 4 days after ovariectomy when mean LH levels had already increased. The frequency increased 10 days after ovariectomy and then remained stable in spite of a further increase in mean serum LH concentrations. Oestradiol-17 beta injected into ovariectomized rats caused a decrease in LH pulse amplitude but no change in pulse frequency. One day after treatment with oestradiol benzoate no LH pulse was detectable, probably because the amplitude was too small. A generator of pulsatile LH release is postulated and an oestrogen effect on its function is discussed.
D000818:Animals; D002369:Castration; D004958:Estradiol / Q000494:pharmacology*; D004971:Estrus; D005260:Female; D007986:Luteinizing Hormone / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D012636:Secretory Rate / Q000187:drug effects
D004958:Estradiol; D007986:Luteinizing Hormone