Promoting effect of licorice extract on spermatogonial proliferation and spermatocytes differentiation of neonatal mice in vitro.

Licorice (glycyrrhiza uralensis) is known as an herb with detoxication, and it has been widely used in clinical prescription of Oriental herbal medicine. Studies on the effects of licorice in the reproductive system were very rare, especially in spermatogenesis. In order to elucidate the effects of licorice on spermatogonial proliferation and spermatocyte differentiation during neonatal mice spermatogenesis, the organ culture model of testis tissue from neonatal C57BL/6N mice (born 6 d) was established. Then, in the presence of licorice extract (LE), the proliferation activity of spermatogonia was identified with the positive rate quantitative analysis of 5-bromo-2-deoxyuridine (BrdU) and anti-proliferating cell nuclear antigen (PCNA) antibody by immunohistochemical staining. The results showed that, compared to the control group, the percentage of positive cells by BrdU staining enhanced dramatically and that the expression of PCNA protein increased significantly in the spermatogonia from the LE group and showed a concentration-dependent manner (P < 0.05). This indicated that the LE can significantly promote the proliferation of spermatogonia in the spermatogenesis of neonatal mice. Furthermore, proteins related to spermatocyte differentiation, synaptonemal complex protein 3 (SCP3) and meiotic recombinant protein Spo11, were detected by immunohistochemical staining. The results showed that the differentiated spermatocyte in the LE group was significantly increased compared with that of the control group and showed a concentration-dependent manner (P < 0.05). The above results suggested that the LE can significantly accelerate the proliferation of spermatogonia and the differentiation of spermatocytes in the testicular tissue of the neonatal mice, which may be a potential drug for male infertility.