Modification of Acute Testosterone Responsiveness to Luteinizing Hormone by Follicle-Stimulating Hormone and Luteinizing Hormone in the Domestic Cockerel 1

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Abstract
Pretreatment of newly hatched cockerels with low doses of highly purified ostrich or ovine FSH (1 .mu.g/injection .times. 5 or 7 injections over 2.5 or 3.5 days) enhanced subsequent acute in vivo testosterone responses to a wide range of doses of NIH ovine luteinizing hormone (LH). Similar pretreatment with corresponding LH preparations or with much higher doses of NIH-LH (25 .mu.g/injection) enhanced responses to moderate and high doses of NIH-LH, but had no effect on responses to low doses. When combined with FSH in pretreatment, the high doses of NIH-LH suppressed the stimulatory effect of FSH on these latter responses. The effects of FSH preparations on responsiveness to LH were not due to LH contamination: the activity of the ovine FSH was not reduced by immunoneutralization of its LH contamination, and very low doses of ovine LH, equivalent to amounts that might have contaminated the effective doses of the FSH preparation, had no effect on responsiveness to LH. In slightly older cockerels, pretreatment with highly purified ovine FSH (1 .mu.g/injection .times. 14 injection over 7 days, from days 4-10 after hatching) had effects similar to those in the younger cockerels. Similar pretreatment with NIH-LH (25 .mu.g/injection) suppressed the acute testosterone response to a low dose of NIH-LH, but seemed to enhance that to a higher dose (though this latter effect was not statistically significant). In the cockerel, FSH can enhance responsiveness of the testis to acute LH stimulation of testosterone production and LH can also modulate testicular responsiveness to itself.