714 EFFECT OF GHRELIN ON PRESERVATION OF ENDOCRINE AND SPERMATOGENIC FUNCTION OF SURGICALLY CRYPTORCHID MICE

Abstract

INTRODUCTION AND OBJECTIVES: Cryptorchidism is associated with progressive germ cell loss and impaired spermatogenesis. Effective approaches to protect or improve testis function after cryptorchidism are not known. We demonstrated that the orexigenic hormone ghrelin can help prevent endocrine impairment and spermatic function loss from cisplatin mediated testicular injury in mice. We asked if ghrelin could prevent testicular damage from surgically-induced cryptorchidism in mice. METHODS: 8–10 week old C57BL6 male mice were isolated from females for two weeks prior to undergoing laparotomy and suture fixation of the testicles to the abdominal wall. Starting post-operative day 3 twice daily injections of ghrelin or phosphate buffered saline were administered to the mice. After six weeks the mice were sacrificed and hormone levels evaluated. Testes were evaluated using light microscopy of hematoxylin and eosin-stained paraffin sections. Quantitative PCR was used to evaluate gene expression for specific endocrine and spermatogenic markers. Flow cytometry of Annexin-FITC signaling with single cell preparations were used to evaluate the relative proportions of viable and apopototic cell populations between the saline and ghrelin groups. RESULTS: Post-operatively weight loss was greater in the control group with the ghrelin-treated mice recovering their body weight more quickly. After six weeks testicular weights in the control and ghrelin group were 35.1 mg and 52.3 mg (p 0.02). Testosterone concentration was 1.5 fold higher in the ghrelin group compared to control while LH was 3.8 fold higher in the ghrelin group and FSH was similar in both groups. Hematoxylin and eosin-stained paraffin sections demonstrated a disruption of spermatogenesis with vacuolization and decreased cellularity in the PBS group with preservation of spermatogenesis and improved seminiferous tubular architecture in the ghrelin treated group. Quantitative PCR revealed relative gene expression of steroidogenic marker (StAR) and Sertoli cell marker (GDNF) to be similar between treatment groups. Flow cytometry showed a larger proportion of late apopototic cells in the saline group in comparison to the ghrelin group. CONCLUSIONS: Experimentally cryptorchid mice exhibit a dramatic loss of spermatogenesis and impairment of endocrine function. Ghrelin administration to surgically cryptorchid mice increased testosterone production. This suggests a possible mechanism by which ghrelin may limit the testicular damage from cryptorchidism.