Exogenous vaspin suppresses germ cell proliferation, apoptosis, and promotes autophagy in pubertal mouse testes

The expression of vaspin and GRP78 has been shown in the testis and ovary. The postnatal testis undergoes several changes in the expression of different proteins. The expression of vaspin and GRP78 has not been shown in the postnatal testis. It has also been shown that modulation of adipokine function could affect testicular germ cell proliferation and apoptosis. Whether vaspin regulates testicular proliferation and apoptosis in the early pubertal stage is still unknown. The aim of this study was to determine the expression of vaspin/GRP78 in postnatal testes of mice. Next, we investigated the effects of vaspin on cell proliferation and cell death (apoptosis, ferroptosis, and autophagy) in the pubertal testis. Immunohistochemistry and western blot analyses revealed that vaspin and GRP78 exhibit dynamic expression levels through developmental stages. In the testis, both proteins showed mild to moderate immunostaining in Leydig cells at early stages (PND7 and 14), with increasing intensity at PND21 and 42 in Leydig cells and spermatocytes, and round and elongated spermatids. The expression of vaspin and GRP78 was significantly down-regulated at postnatal day 21 (PND21). Moreover, exogenous vaspin treatment (PND21 to PND35) suppressed germ cell proliferation (BrdU labelling, PCNA, and GCNA) and apoptosis (decreased expression of active caspase-3 and TNFα) in the testis. The marker of autophagy, LAMP2, was elevated by vaspin treatment. Furthermore, vaspin treatment showed both stimulatory and inhibitory effects on markers of ferroptosis. In conclusion, vaspin/GRP78 could be a new regulator of cell proliferation and cell death in pubertal mouse testes.