Research On The Expression Of Fsh And Its Protection Of Ischemia-Reperfusion Injury In Rat Spinal Cord

As a kind of gonadotropin, FSH is secreted by basophilic cells of anterior pituitary and has important roles in production of gonadal hormone and regulation of reproductive process. FSH receptors are G protein-coupled receptors, which are mainly expressed on Sertoli cells of testes and granular cells of ovaries. As the superior hormone of FSH in hypothalamus-pituitary-gonad (HPG) axis, GnRH is mainly secreted from hypothalamic neurons into the capillary plexus of median eminence and reaches anterior pituitary, combined with GnRH receptor to regulate secretion of FSH.With further study, FSH has been found in other non-HPG axis tissues such as prostate, breast, testis, placenta and stomach. Its receptors also exist in uterine tubal epithelium and cervix. The functions of FSH in these tissues are beyond reproduction.As part of central nervous system and non-HPG axis tissues, spinal cord has been explored to express some reproductive hormones and their receptors. For examples:luteinizing hormone receptors are expressed in gray matter and white matter of adult rat spinal cord. Both GnRH and GnRH receptor mRNA was detected in lamina X and motoneurons in the ventral horn of sheep spinal cord. Estrogen can be synthesized in dorsal horn of spinal cord. Estrogen receptor alpha and beta immunoreactive neurons were found in spinal cord of male and female mice. At the same time, as one of reproductive hormones, estrogen could exert non-reproductive functions such as protective effects in spinal cord. Studies have found that estrogen might inhibit cell apoptosis in spinal cord injury. Administration of estrogen before spinal cord injury could reduce the development of inflammation and tissue injury associated with spinal cord trauma. FSH is the upstream hormone of estrogen in HPG axis. However, there have been no reports concerning the expression and function of FSH in spinal cord.On the base of our previous research, we did the following experiments:in situ hybridization method was used to observe the expression of FSH in rat spinal cord; double-labeled immunofluorescence histochemical staining and confocal laser-scanning microscope were used to study the co-localization of FSH and FSH receptor, FSH and GnRH receptor in rat spinal cord; spinal cord ischemia injury model was building, TUNEL staining and immunohistochemistry staining together with cell counting were used to study the protection of ischemia-reperfusion injury by FSH and its relationship with Fas in rat spinal cord.Through these experiments, the results are as follows:some neurons and glias of rat spinal cord showed both FSH immunoreactivity and FSH mRNA positive signals; not only FSH and its receptor but also FSH and GnRH receptor co-located in some cells of both gray matter and white matter; treatment with certain concentration of FSH before ischemia-reperfusion injury, less TUNEL positive motor neurons and Fas positive motor neurons were found in ventral gray matter of rat spinal cord in FSH experiment group than that in control group.In conclusion, our research found that rat spinal cord could express FSH, spinal cord is also a target organ of FSH; FSH might exert functions through its receptor by paracrine or autocrine effects; GnRH in spinal cord might regulate FSH positive neurons through GnRH receptor; FSH might inhibit ischemia induced neuron apoptosis by down-regulating Fas expression in rat spinal cord.