Ovine luteinizing hormone heterogeneity: androgens increase the percentage of less basic isohormones.

The heterogeneity of luteinizing (LH) is hormonally regulated with androgens having been reported to increase the percentage of extremely basic LH isohormones in the ovine pituitary. This study re-examined the effects of androgens on the heterogeneity of LH in the ovine pituitary because the extremely basic isoforms of LH reported previously were subsequently demonstrated to be artifacts resulting from the conditions used for chromatofocusing. Pituitary extracts from wethers, rams, and dihydrotestosterone (DHT)-implanted wethers were desalted by flow dialysis and chromatofocused on pH 10.5 to 7.0 gradients. LH was quantitated by radioimmunoassays. When compared with rams, wethers had increased percentages of LH isoforms eluting between pH 9.6 and 10. Patterns of intrapituitary LH isohormones were comparable in rams and DHT-implanted wethers except that rams had a higher percentage of LH eluting at pH 9.2 (20.9 +/- 2.1% vs. 13.3 +/- 1.3%). In contrast to what was previously reported, rams and DHT-implanted wethers had higher percentages of ovine LH isoforms eluting at pH's 9.4 or lower. Thus, androgens alter LH heterogeneity yielding increased percentages of isohormones eluting at pH's of 9.4 or lower.