Neurotrophins are a family of polypeptide growth factors that are required for the proliferation, differentiation, survival, and death of neuronal cells. A growing body of evidence suggests that they may have broader physiological roles in various non-neuronal tissues. The testicles are complex non-neuronal organs in which diverse cell types interact to achieve correct spermatogenesis. Both neurotrophins and their receptors have been detected in various cell types from mammalian testes, suggesting that neurotrophins may regulate or mediate intercellular communication within this organ. This review summarizes the existing data on the cellular distribution and possible biological roles of neurotrophins in the testes. The data reported in the literature indicate that neurotrophins affect somatic cell growth and spermatogenesis and imply that they play a role in regulating testicular development and male reproduction.
Chunjin Li and Xu Zhou
Chubin Qin, Li Xu, Yalin Yang, Suxu He, Yingying Dai, Huiying Zhao and Zhigang Zhou
To increase the knowledge of probiotic effects on zebrafish (Danio rerio), we compare the effects of two probiotic strains, Lactobacillus rhamnosus CICC 6141 (a highly adhesive strain) and Lactobacillus casei BL23 (a weakly adhesive strain), on zebrafish reproduction and their offsprings' innate level of immunity to water-borne pathogens. During probiotics treatments from 7 to 28 days, both the Lactobacillus strains, and especially L. casei BL23, significantly increased fecundity in zebrafish: higher rates of egg ovulation, fertilization, and hatching were observed. Increased densities of both small and large vitellogenic follicles, seen in specimens fed either Lactobacillus strain, demonstrated accelerated oocyte maturation. Feeding either strain of Lactobacillus upregulated gene expression of leptin, kiss2, gnrh3, fsh, lh, lhcgr, and paqr8, which were regarded to enhance fecundity and encourage oocyte maturation. Concomitantly, the gene expression of bmp15 and tgfb1 was inhibited, which code for local factors that prevent oocyte maturation. The beneficial effects of the Lactobacillus strains on fecundity diminished after feeding of the probiotics was discontinued, even for the highly adhesive gut Lactobacillus strain. Administering L. rhamnosus CICC 6141 for 28 days was found to affect the innate immunity of offspring derived from their parents, as evinced by a lower level of alkaline phosphatase activity in early larval stages. This study highlights the effects of probiotics both upon the reproductive process and upon the offsprings' immunity during early developmental stages.
Jingjing Guo, Hongyu Zhou, Zhijian Su, Bingbing Chen, Guimin Wang, Claire Q F Wang, Yunfei Xu and Ren-Shan Ge
The objective of this study was to purify cells in the Leydig cell lineage following regeneration after ethane dimethanesulfonate (EDS) treatment and compare their steroidogenic capacity. Regenerated progenitor (RPLCs), immature (RILCs), and adult Leydig cells (RALCs) were isolated from testes 21, 28 and 56 days after EDS treatment respectively. Production rates for androgens including androsterone and 5α-androstane-17β, 3α-diol (DIOL), testosterone and androstenedione were measured in RPLCs, RILCs and RALCs in media after 3-h in vitro culture with 100 ng/ml LH. Steady-state mRNA levels of steroidogenic enzymes and their activities were measured in freshly isolated cells. Compared to adult Leydig cells (ALCs) isolated from normal 90-day-old rat testes, which primarily produce testosterone (69.73%), RPLCs and RILCs primarily produced androsterone (70.21%) and DIOL (69.79%) respectively. Leydig cells isolated from testes 56 days post-EDS showed equivalent capacity of steroidogenesis to ALCs and primarily produced testosterone (72.90%). RPLCs had cholesterol side-chain cleavage enzyme, 3β-hydroxysteroid dehydrogenase 1 and 17α-hydroxylase but had almost no detectable 17β-hydroxysteroid dehydrogenase 3 and 11β-hydroxysteroid dehydrogenase 1 activities, while RILCs had increased 17β-hydroxysteroid dehydrogenase 3 and 11β-hydroxysteroid dehydrogenase 1 activities. Because RPLCs and RILCs had higher 5α-reductase 1 and 3α-hydroxysteroid dehydrogenase activities they produced mainly 5α-reduced androgens. Real-time PCR confirmed the similar trends for the expressions of these steroidogenic enzymes. In conclusion, the purified RPLCs, RILCs and RALCs are similar to those of their counterparts during rat pubertal development.
Xiaoyan Huang, Jun Zhang, Li Lu, Lanlan Yin, Min Xu, Youqun Wang, Zuomin Zhou and Jiahao Sha
Identification of genes specifically expressed in adult and fetal testis is important in furthering our understanding of testis development and function. In this study, a novel human transcript, designated human testis cAMP-responsive element-binding protein (htCREB), was identified by hybridization of adult and fetal human testis cDNA probes with a human cDNA microarray containing 9216 clones. The htCREB transcript (GenBank Accession no. AY347527) was expressed at 2.35-fold higher levels in adult human testes than in fetal testes. Sequence and ntBLAST analyses against the human genome database indicated that htCREB was a novel splice variant of human CREB. RT-PCR-based tissue distribution experiments demonstrated that the htCREB transcript was highly expressed in adult human testis and in healthy sperm, but not in testes from patients with Sertoli cell-only syndrome. Taken together, these results suggest that the htCREB transcript is chiefly expressed in germ cells and is most likely involved in spermatogenesis.
Qian Chen, Yong Fan, Xiaowei Zhou, Zheng Yan, Yanping Kuang, Aijun Zhang and Chen Xu
Some studies have demonstrated that the implantation rate of fresh transfer cycles is lower in the gonadotropin-releasing hormone antagonist (GnRH-ant) protocol than in the GnRH agonist (GnRH-a) protocol during in vitro fertilization (IVF). This effect may be related to endometrial receptivity. However, the mechanisms are unclear. Here, endometrial tissues obtained from the mid-secretory phase of patients treated with GnRH-a or GnRH-ant protocols and from patients on their natural cycle were assessed. Endometrial expression of B-type creatine kinase (CKB), which plays important roles in the implantation phase, was significantly reduced in the GnRH-ant group. At the same time, expression of the endometrial receptivity marker HOXA10 was considerably reduced in the GnRH-ant group. GnRH-ant exposure in endometrial epithelial cells (EECs) in vitro decreased CKB expression and ATP generation and blocked polymerization of actin. Furthermore, in vitro GnRH-ant-exposed Ishikawa cells showed enhanced F-actin depolymerization, and these effects were rescued by CKB overexpression. Similar effects were observed after CKB knockdown, and these effects were rescued by CKB overexpression. Moreover, cell migration was decreased in CKB-knockdown Ishikawa cells compared with that in control cells, and this effect was also rescued by CKB overexpression. Overall, these findings showed that GnRH-ant affected CKB expression in EECs, resulting in cytoskeletal damage and migration failure. These results provide insight into the roles and molecular mechanisms of GnRH-ant treatment in the endometrium.
Xuan-Tong Liu, Hui-Ting Sun, Zhong-Fang Zhang, Ru-Xia Shi, Li-Bing Liu, Jia-Jun Yu, Wen-Jie Zhou, Chun-Jie Gu, Shao-Liang Yang, Yu-Kai Liu, Hui-Li Yang, Feng-Xuan Xu and Ming-Qing Li
It has been reported that the impaired cytotoxicity of natural killer (NK) cells and abnormal cytokines that are changed by the interaction between ectopic endometrial cells and immune cells is indispensable for the initiation and development of endometriosis (EMS). However, the mechanism of NK cells dysfunction in EMS remains largely unclear. Here, we found that NK cells in peritoneal fluid from women with EMS highly expressed indoleamine 2,3-dioxygenase (IDO). Furthermore, IDO+NK cells possessed lower NKp46 and NKG2D but higher IL-10 than that of IDO-NK. Co-culture with endometrial stromal cells (nESCs) from healthy control or ectopic ESCs (eESCs) from women with EMS led to a significant increase in the IDO level in NK cells from peripheral blood, particularly eESCs, and an anti-TGF-β neutralizing antibody suppressed these effects in vitro. NK cells co-cultured with ESC more preferentially inhibited the viability of nESCs than eESCs did, and pretreating with 1-methyl-tryptophan (1-MT), an IDO inhibitor, reversed the inhibitory effect of NK cells on eESC viability. These data suggest that ESCs induce IDO+NK cells differentiation partly by TGF-β and that IDO further restricts the cytotoxicity of NK cells in response to eESCs, which provides a potential therapeutic strategy for EMS patients, particularly those with a high number of impaired cytotoxic IDO+NK cells.
Qiaoge Niu, Maosheng Cao, Chenfeng Yuan, Yuwen Huang, Zijiao Zhao, Boqi Zhang, Xin Wang, Yameng Wei, Wenjing Fan, Xu Zhou and Chunjin Li
Nerve growth factor (NGF) has been proved to play important roles in male reproductive physiology, but the molecular mechanisms of NGF action remain unclear. In this study, the effects of NGF on the growth of newborn bovine testicular Sertoli (NBS) cells and the related signaling pathways were investigated. The NBS cells were treated in vitro with NGF (100 ng/mL) for 18 h. The expression levels of cell proliferation related genes, INHBB, and cytoplasmic specialization related gene were determined using real-time PCR and Western blot. The roles of PI3K/AKT and MAPK/ERK pathways in NGF-induced cell proliferation were investigated. It was found that NGF regulates proliferation and function of NBS cells via its receptor NTRK1 by activating the PI3K/ATK and MAPK/ERK signaling pathways. The study will help to further understand the role of NGF in male reproduction and provide new therapeutic targets for reproductive dysfunctions in male animals.
Xihua Chen, Bin Wu, Shufang Wang, Jianbing Liu, Haijun Gao, Fang Zhou, Nan Nan, Bonan Zhang, Jiedong Wang, Xiangbo Xu and Bin He
Menstruation is a specific physiological phenomenon that occurs in women. However, molecular mechanisms underlying this phenomenon are still unclear. According to the classical theory, tissue hypoxia resulting from vasoconstriction of the spiral arteries after progesterone (P4) withdrawal initiates the breakdown of the endometrium at the earliest stage of menstruation. However, this theory has been challenged by previous studies that have questioned the function and even the existence of hypoxia during menstruation. In this study, we not only provide convincing evidence that hypoxia exists during endometrial breakdown, but also further explore the role of hypoxia and hypoxia-inducible factor 1 (HIF1) in this process. Based on mouse menstrual-like model and experiments with human decidual stromal cells, we observed that P4 withdrawal induced both hypoxia and HIF1 activation; however, endometrial breakdown was triggered only by P4 withdrawal. Hypoxia significantly enhanced the mRNA expression of specific matrix metalloproteinases (MMPs) under the conditions of P4 withdrawal. In conclusion, hypoxia is involved but not an essential component of endometrial breakdown during menstruation.