TY - JOUR T1 - Effect of Estrogen on Baroreflex Sensitivity through Autonomic Tone in Male Rats TT - نقش استروژن بر روی حساسیت بارورفلکس از طریق سیستم اتونومیک در موش های صحرایی نر JF - umsha JO - umsha VL - 15 IS - 2 UR - http://sjh.umsha.ac.ir/article-1-364-en.html Y1 - 2008 SP - 11 EP - 18 KW - Atropin KW - Baroreflex KW - Estrogen KW - Propranolol KW - Solitary Nucleus N2 - Introduction & Objective :Studies have shown that estrogen has important cardiovascular protective role. Nucleus tractus solitarii (NTS) is the termination point for all afferent of baroreceptor fibers that is important in regulation of heart function and circulation. For recognizing the estrogen mechanisms the role of estrogen through autonomic system in NTS have been evaluated. Hypertension state, estrogen increases baroreflex sensivity in NTS through autonomic system in rats. Materials & Methods: Present study was an experimental-interventional study performed on 32 male rats. After introduction of anesthesia, ovariectomy and capsulation was happened. After two weeks their femoral artery and vein cannulated to recorded mean arterial blood pressure (MAP) and heart rate (HR), also for infusion of phenylephrin (as a vasoconstrictor). Then NTS by drugs (Propranolol, Atropin, Saline) have injected and ΔHR and ΔMAP recorded before & after injection of phenylephrin. For evaluating of baroreceptors sensivity, BRS index (Δ HR/Δ MAP) was employed. Results: HR and MAP in estrogen received groups , without phenylephrine "rest state", had no significant statistical differences in comparison with control group. Estrogen in acute hypertension state "after injection of phenylephrine" enhanced reflex bradycardia and inhibited rising of MAP. ΔHR in estrogen received group was less than control group (p M3 ER -