NGF Rescues Spermatogenesis in Azoospermic Mice

Nerve growth factor (NGF) plays an important role in regulating the hypothalamus-pituitary-gonadal (HPG) axis. However, the effects of NGF on spermatogenesis remain unclear. This study aimed to assess the potential application of NGF with nasal delivery on spermatogenesis in azoospermic mice. We established a model with azoospermia induced by a single intraperitoneal (i.p.) injection of busulfan. NGF pre-encapsulated with liposomes (25, 50, and 100 μg/kg) was delivered via internasal administration. Three weeks after busulfan injection, NGF treatments were performed twice a week for 8 weeks; the change of sperm quality, testis and epididymis histopathology, and androgenic hormone were analyzed to evaluate sperm regeneration. Furthermore, 30 mg/kg busulfan injection caused severe testicular atrophy of the seminiferous tubules, characterized by a loss of spermatogenic elements and sperms. NGF with nasal administration could significantly upregulate the markers expressing meiotic spermatogonia (Stra8) and spermatocytes (SYCP3), restore spermatogenesis, and improve sperm quality in busulfan-treated mice by increasing the secretion of sexual hormones. The convenient and noninvasive nasal delivery of NGF may be a new potential therapy for spermatogenesis via activating the HPG axis and elevating androgenic hormones. This study opened a new horizon for NGF application in reproductive endocrine.