بررسی اثر تاموکسیفن بر روی فعالیت آنزیم نیتریک اکسید سینتاز(NOS) در تکامل هیپوکامپ موش صحرایی

Background & Aim: treatment, as an estrogen antagonist, induces cell death in rat's developing hippocampus. Estrogen has avariety of physiological effects on the nervous system, including regulation of cognitive functions, learning,aging, angiogenesis, neurogenesis, and neuroprotective effects. In the present study, we demonstrated theeffects of TAM as an estrogen antagonist on nitric oxide synthase activity in rat's developing hippocampalpyramidal neurons.Maternal steroids modulate various functions in the developing brain. Tamoxifen (TAM)Material and Method: animals were divided randomly into control, experimental and sham groups. Each group contained full termembryo (Egroup received a total of four doses of TAM,i.e. 250 mg/kg TAM in propylene glycole was injectedintraperitoneally twice a day for two days. Their hippocampus was removed 6 hours after the last injection.Animals at the same gestational age were used as shams and controls. The latter received only propyleneglycole. The hippocampus was dissected out and stored in fixative and sucrose. Cryostat sections were thawmountedon gelatin slides. The sections were incubated for NADPH-diaphorase histochemistry by lightmicroscope. Independent sample t-test and SPSS version 11.0 were used to analyze the data.The present experimental study was conducted on twelve groups of adult rats. The22), one-day neonate (P1), one-week neonate (P7), and three -week neonate (P21). The experimentalResults: thickness increases so that the most thickness is seen in the third week after birth. Considering the short halftimeof TAM, it was observed that tamoxifen had its greatest effects on Eestrogen receptors. In the group that didn't receive tamoxifen, due to the presence of estrogen NADPHdiaphoraseactivity, which indicates NOS activity level, strengthened. On the other hand, the animals whichreceived tamoxifen in the early stage showed a decrease in NADPH-diaphorase activity owing to estrogenreceptor blockade. Furthermore, the number of neural cells in CA1 hippocampal region showed a decrease inproportion to the reduction in NOS activity level in this region. The decreased number of neural cells and NOSactivity, which was seen in EWe found that in the early stage of development cellular density decreases and gradually cellular22, P1 and P7 groups and blockaded22, P1 , P7 groups, seems to be due to the short half-time of tamoxifen.Conclusion: oxide-mediated growth and development of hippocampal pyramidal cells.These findings indicate that estrogen and selective estrogen modulators can influence nitric