Spermatogenesis in rat: effect of L-tryptophan loading.

Abstract

The present experiment was designed to assess the role of enhanced central 5-HT level on testicular steroidogenesis and spermatogenesis of rat. L-tryptophan, a precursor in the synthesis of 5-HT in brain, was injected in male rats on a short-term (7-days) and a long-term (21-days) basis. The short-term treatment had no effect on the spermatogenic pattern (Stage - VII of the cycle of the seminiferous epithelium), while the long-term treatment showed a degenerative change (reduced count of the germ cells). Both modes of treatment reduced the activity of testicular delta 5-3 beta-HSD without affecting NADH2-linked Diaphorase activity. Histological study of the Leydig cells' nuclear area also revealed a marked reduction after both the modes of treatment. Human chorionic gonadotropin supplementation in the long-term treatment restored the spermatogenesis, delta 5-3 beta-HSD activity and Leydig cells' nuclear area towards the vehicle treated control. The inhibition of spermatogenesis and steroidogenesis reflects a decrease in the pituitary gonadotropin release under the influence of enhanced 5-HT synthesis in brain, after L-tryptophan loading.