Effects of levonorgestrel butanoate alone and in combination with testosterone buciclate on spermatogenesis in the bonnet monkey

Abstract

The spermatogenic effects of levonorgestrel butanoate were studied in adult male bonnet monkeys when administered alone and in combination with testosterone buciclate. Levonorgestrel butanoate (0.25, 1.0 and 2.5 mg kg(-1)) given as two injections on days 0 and 60 (groups II, III, IV) resulted in thickening and folding of the basement membrane and disruption of cell associations in groups III and IV (on day 120). In group II, no apparent changes in testicular histology were observed. When these doses of levonorgestrel butanoate were combined with 40 mg of testosterone buciclate (groups V, VI, VII), maximum changes were seen in group VI in which all stages of spermatogenesis were absent on day 120 except for a small number of spermatogonia. The changes caused by lower dose (group V) and higher dose (group VII) of levonorgestrel butanoate were less prominent than in group VI. A significant decrease in the number of dark A (Ad) and B spermatogonia was observed in all groups except for Ad spermatogonia on day 120 in group V, B spermatogonia on day 60 in group IV and B spermatogonia on day 120 in group III. A significant decrease in pachytene spermatocytes was seen on day 120 in groups V only. Early spermatids showed a significant decrease only in groups V and VII on day 120 of treatment. Advanced spermatids were suppressed significantly in group IV on day 60 and in groups IV and V on day 120. These data indicate that levonorgestrel butanoate (1.0 mg kg(-1)) in combination with 40 mg of testosterone buciclate was the most effective treatment in suppressing spermatogenesis. The site of action of this combination regimen is at the level of renewing Ad spermatogonia.