Journal article

SEASONAL AND STEROID-DEPENDENT EFFECTS ON THE MODULATION OF LH-SECRETION IN THE EWE BY INTRACEREBROVENTRICULARLY ADMINISTERED BETA-ENDORPHIN OR NALOXONE

RJE HORTON, H FRANCIS, IJ CLARKE

JOURNAL OF ENDOCRINOLOGY | J ENDOCRINOLOGY LTD | Published : 1989

Abstract

The natural opioid ligand, beta-endorphin, and the opioid antagonist, naloxone, were administered intracerebroventricularly (i.c.v.) to evaluate effects on LH secretion in ovariectomized ewes and in ovariectomized ewes treated with oestradiol-17 beta plus progesterone either during the breeding season or the anoestrous season. Ovary-intact ewes were also studied during the follicular phase of the oestrous cycle. Jugular blood samples were taken at 10-min intervals for 8 h and either saline (20-50 microliters), 100 micrograms naloxone or 10 micrograms beta-endorphin were injected i.c.v. after 4 h. In addition, luteal phase ewes were injected i.c.v. with 25 micrograms beta-endorphin(1-27), a p..

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