Expression and distribution of ghrelin in mouse testes during postnatal development periods

Ghrelin, a polypeptide hormone, is known to be secreted by endocrine cells from stomach and hypothalamus and to act via growth hormone secretagogue receptors (GHS-R1a) to alter food intake and energy homeostasis. Because of growing evidence of its involvement in reproductive function, the present study aims to investigate the ghrelin expression pattern in mouse testes during postnatal developmental (pubertal and adult) periods. For that, food intake, weight growth, serum ghrelin and testosterone concentrations were determined in pubertal (40 days old) and adult (75 days old) mice (10 animals in each group) and ghrelin expression in testes was analysed by immunohistochemistry and western blot analysis. Strong ghrelin immunoreactivity, restricted to cytoplasm as a granular pattern, was strictly evidenced in Leydig and Sertoli cells and the testicular hormone secretion appeared similar in pubertal and adult rodents. It was also observed a gradual increase in food intake and weight growth during development coupled to a slight decrease in serum ghrelin and testosterone concentrations. These results suggest a clear association between local and constitutive ghrelin synthesis and gonad development.