Morphology and Function of Testis in Growth Deprived Mature and Immature Male Rats

Choi, Hak Ryong; Lee, Soo Hyung; Lee, Moo Sang; Lee, Jin Moo

Abstract

Growth hormone(GH) plays a major role in growth and its effects are mainly mediated by insulin like growth factor-I ( IGF-I). However the role of GH in the regulation of testicular function especially in spermatogenesis is still under debate. Though there were several studies using GH-deficient mutant mice, results are conflicting. Furthermore they are not proper to find out any exact role of GH in normal adults. We have therefore used somatostatin analogue (Sandostatin) for 1 week to block the effect of GH and it's mediator IGF-I, in mature and immature Sprague-Dawley male rats. In immature rats the delayed maturation was recovered after ceasing somatostatin in several weeks and the testicular parameters became normal after maturation. Post-pubertal rats showed diminished spermatogenesis especially in the number of pachytene spermatocytes and round spermatids of stage VII. These results seems to be associated with decreased systemic IGF-I. But the Leydig cell function in other words, testosterone production, remained normal. Somatostatin administered Leydig cells showed strong positive reactions like normal control on IGF-I immunohistochemical stain. We concluded that GH mediated IGF-I plays a major role in spermatogenesis especially on pachytene spermatocytes of post-pubertal male rats and there are GH independent IGF-I actions in Leydig cells.