The sensitivity of gonadotrophic cells to steroid and peptide hormones
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The results obtained during the studies on the effects of gonadal steroid (estradiol dipropionate, EDP) and peptide hormones (luteinizing-releasing hormone, LHRH) on gonadotrophic cell in female rats during different periods of life are summarized. Our results show that gonadotrophic cells are sensitive to a single dose of neonatally administered EDP, so that a serious defect in follicle stimulating hormone (FSH)-, luteinizing hormone (LH)- and prolactin (PRL)-producing cells, and their regulation within the pituitary during infantile, peripubertal and adult period was evident. A reciprocal relationship between the number of gonadotrophic and luteotrophic (PRL) cells during these periods was characteristic. The degree of sensitivity gradually decreased, i.e. it was less conversaly related to the duration of the interval after estrogen treatment. Chronic EDP application to ageing female rats inhibited gonadotrophic cell function, while stimulating hyperplasia and hypertrophy of chromophobes and PRL cells. The suppression of gonadotrophic cell function following LHRH agonist treatment depends on the regimen and dose administration. We showed that maximal suppression of all examined parameters of gonadotrophic cells was achieved by a combined chronic EDP and LHRH treatment.