The effect of photomirex on the in vitro perfused ovary of the rat.

Photomirex, a photodegradation product of the insecticide mirex, is an environmental contaminant that has been identified in Great Lakes fish, soil, and human adipose tissue. Because of the potential for human exposure, the present study was designed to investigate the short-term effects of photomirex on the in vitro perfused ovary of the rat. Adult Sprague-Dawley rat ovaries were isolated and perfused for a total of 6 h with Medium 199.

The pituitary gonadotropin-releasing hormone (GnRH) receptor of the female rabbit: characterization and developmental aspects.

The aim of the present study was to characterize the pituitary gonadotropin-releasing hormone (GnRH) binding site in the rabbit and investigate its possible role in sexual maturation of the female rabbit. A radioligand binding assay was established, and the presence of specific 125I-labelled D-Ala6-des-Gly10-GnRH ethylamide (125I-DAl6EA) binding sites in the anterior pituitary gland of the rabbit was demonstrated. 125I-DAla6EA binding was saturable, specific, displaceable, reversible, correlated with increasing tissue concentrations, and susceptible to physiological manipulation.

Light-related melatonin changes in pituitary response to gonadotropin-releasing hormone during sexual development in the female rabbit.

Melatonin levels in the blood of female rabbits were determined from the time of weaning to adulthood in a longitudinal study. Blood samples were taken at 3 h after light onset and 1 h after dark onset and plasma was analysed for melatonin, LH and FSH by radioimmunoassay procedures. The animals were sacrificed on days 25, 32, 39, 51, 72, 91 and 120 days of life and pituitaries removed for in vitro incubation of slices to determine their response to GnRH.

Endurance exercise potentiates the stimulatory influence of oestrogen-progesterone on LH and FSH release in the rat.

Ovariectomized rats were treated with oestradiol benzoate and progesterone or GnRH. Prolonged exercise (running 4 days per week for 6 weeks) markedly potentiated the oestrogen/progesterone-induced release of LH and FSH, but the pituitary response to an injection of GnRH was unaffected. In contrast, at 24 h after a single exercise bout there was no apparent effect on steroid and GnRH stimulated LH and FSH responses although an acute exercise session given on the day of the LH surge inhibited steroid-induced LH release in some rats.