The effects of selenium on peripheric nevre injury in ovariectomized rats

There have been reports on the adverse effects of the decrease in the levels of all sex hormones, mainly estrogen, in menopause on nerveous system. Studies have shown that there menopause is linked with some disorders such as depression, headache and Alzheimer's disease. Previous studies have investigated the effects of menopause on central nervous system, menopause induced oxidative damage on central nervous system and the menopause induced disorders that originate from this oxidative damage. However, there is a limited knowledge in literature on the the effects of menopause on the structure and function of peripheral nervous system. One important cause of the observed changes in menopuasal conditions is the decrease in antioxidant enzyme levels, changes in the antioxidant-free radical balance in the body and the increase in the level of free radicals due to the decrease in the amount of sex hormones in menopause. The adverse effects of free radicals on many different systems in the body including the nervous tissue have been postulated previously. Regarding these information in the literature, this study has been adressed to investigate the effects of menopause and the nevre injury state in menopause on the structure and function of sciatic nerve which is a member of the peripheral nervous system. In addition, the role of selenium treatment on the recovery of these effects has been investigated by the use of two different doses of selenium administration, namely a normal dose (1μmol/kg) and a high dose (5μmol/ kg) selenium treatment. The results demonstrated that menopausal conditions which were induced by ovariectomy has resulted in the decrease in the nerve conduction velocities and variations in sciatic functional index values in ovariectomized groups that reveals the neurodegeneration in the sciatic nerves in menopause. Moreover, the sciatic nevre injury in menopausal conditions have enhanced the effects of menopause on nerve conduction velocities and sciatic functional index values. Both normal (1μmol/kg) and high dose (5μmol/ kg) selenium treatment was observed to decrease these adverse effects increasing nerve conduction velocities and normalizing sciatic functional index values. These results have shown that selenium treatment led to a recovery on menopause induced alterations in structure and function of sciatic nerves. The results implicated that selenium treatment prevented the oxidative stres induced mitochondrial functional disorders, inhibited the apoptotic pathways induced by mitochondrial damage and eventually led to the survival of neurons in sciatic nerves increasing the nerve conduction velocities and distal latancies. Moreover, the results have revealed that selenium treatment in menopause have led to an increase in serum estradiol levels in ovariectomized rats. Further studies are needed to more clearly evaluate the molecular effects of selenium treatment on nervous tissue in menopause.