Adropin, a multifaceted peptide, was identified as a new metabolic hormone responsible for regulating gluco-lipid homeostasis. However, its role in the testicular function is not yet understood. We aimed to investigate the localization and expression of adropin and GPR19 during different phases of postnatal development. Immunohistochemical study revealed the intense reactivity of adropin in the Leydig cells during all phases of postnatal development, while GPR19 showed intense immunoreactivity in the pachytene spermatocytes and mild immunoreactivity in Leydig cells as well as primary and secondary spermatocytes. Western blot study revealed maximum expression of GPR19 in pre-pubertal mouse testis that clearly indicates maximum responsiveness of adropin during that period. So, we hypothesized that adropin may act as an autocrine/paracrine factor that regulates pubertal changes in mouse testis. To examine the effect of adropin on pubertal onset, we gave bilateral intra-testicular doses (0.5 and 1.5 µg/testis) to pre-pubertal mice. Adropin treatment promoted testicular testosterone synthesis by increasing the expression of StAR, 3β-HSD, and 17β-HSD. Adropin also promoted germ cell survival and proliferation by upregulating the expression of PCNA and downregulating the Bax/Bcl2 ratio and Caspase 3 expression resulting in fewer TUNEL-positive cells in adropin-treated groups. FACS analysis demonstrated that adropin treatment not only increases 1C to 4C ratio but also significantly increases the 1C (spermatid) and 1C to 2C ratio which demarcates accelerated germ cell differentiation and turnover of testicular cells. In conclusion, adropin promotes steroidogenesis, germ cell survival, as well as the proliferation in the pre-pubertal mouse testis that may hasten the pubertal transition in an autocrine/paracrine manner.

Adropin 是一种多面肽，被确定为一种负责调节糖脂稳态的新代谢激素。然而，其在睾丸功能中的作用尚不清楚。我们的目的是研究 adropin 和 GPR19 在出生后发育不同阶段的定位和表达。免疫组织化学研究显示，在出生后发育的所有阶段，Leydig 细胞中 adropin 均表现出强烈的反应性，而 GPR19 在粗线期精母细胞中表现出强烈的免疫反应性，而在 Leydig 细胞以及初级和次级精母细胞中表现出轻微的免疫反应性。蛋白质印迹研究揭示了青春期前小鼠睾丸中 GPR19 的最大表达，这清楚地表明了该时期 adropin 的最大反应性。因此，我们假设 adropin 可能充当调节小鼠睾丸青春期变化的自分泌/旁分泌因子。为了检查阿降品对青春期开始的影响，我们给青春期前的小鼠双侧睾丸内注射剂量（0.5 和 1.5 µg/睾丸）。Adropin 治疗通过增加 StAR、3β-HSD 和 17β-HSD 的表达来促进睾丸睾酮合成。Adropin 还通过上调 PCNA 的表达并下调 Bax/Bcl2 比率和 Caspase 3 表达来促进生殖细胞存活和增殖，从而导致 Adropin 治疗组中 TUNEL 阳性细胞减少。FACS 分析表明，adropin 处理不仅增加了 1C 与 4C 的比率，而且还显着增加了 1C（精细胞）和 1C 与 2C 的比率，这表明睾丸细胞的生殖细胞分化和周转加速。总之，adropin 促进类固醇生成、生殖细胞存活以及青春期前小鼠睾丸的增殖，这可能以自分泌/旁分泌方式加速青春期过渡。