Hypothalamic control of the post-castration rise in serum LH concentration in rams

in Reproduction

Summary. Sexually mature rams were left intact, castrated (wethers), castrated and implanted with testosterone, or castrated, implanted with testosterone and pulse-infused every hour with LHRH. Serum concentrations of LH increased rapidly during the first week after castration and at 14 days had reached values of 13·1 ± 2·2 ng/ml (mean ± s.e.m.) and were characterized by a rhythmic, pulsatile pattern of secretion (1·6 ± 0·1 pulses/h). Testosterone prevented the post-castration rise in serum LH in wethers (1·0 ± 0·5 ng/ml; 0 pulses/h), but a castrate-type secretory pattern of LH was obtained when LHRH and testosterone were administered concurrently (10·7 ± 0·8 ng/ml; 1·0 pulse/h). We conclude that the hypothalamus (rather than the pituitary) is a principal site for the negative feedback of androgen in rams and that an increased frequency of LHRH discharge into the hypothalamo—hypophysial portal system contributes significantly to the post-castration rise in serum LH.

If the inline PDF is not rendering correctly, you can download the PDF file here.


An official journal of

Society for Reproduction and Fertility

Index Card


Google Scholar

Related Articles



All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 45 45 10
PDF Downloads 183 183 33