Effects of naloxone, an antiopiate on the hypophysial gonadotrophins in the cycling goats

Abstract

The effects of an antiopiate naloxone on hypophysial gonadotrophins during luteal phase were studied on 6 cycling goats (Alpine x Beetal). They were infused with saline through jugular vein for 4 hr@ 0.66 ml/min on day 11 and naloxone for 4 hr at the same rate on day 14 of the cycle. Naloxone treatment increased mean LH levels significantly (p<0.01) over saline treatment during infusion but levels in post-infusion samples did not show any significant difference between treatments. Mean number of LH pulses observed during naloxone infusion, was though high but not significantly different, whereas pulse magnitude was significantly high (P<0.05) compared to saline treatment. Follicle stimulating hormone levels remained unaffected both during infusion and post-infusion periods. Progesterone data confirmed that the animals were in the stated part of the cycle. The study reveals that naloxone can be employed to increase LH levels for short periods without affecting normal endocrinology in the animals primed with progesterone.