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Estrogen modifies the baroreceptor-induced responses of supraoptic vasopressin neurons in the ovariectomized rat
1Department of Physiology, Niigata University, School of Medicine, Japan. akaishi@med.niigata.u.ac.jp
Abstract:
Effects of estrogen (E2) and estrogen plus progesterone (EP) on the baroreceptor-induced response of the spontaneous discharge activity in the supraoptic (SON) vasopressin (AVP) neurons were examined in ovariectomized (OVX) female rats. An increase or a decrease in arterial blood pressure induced by intravenous injection of phenylephrine or nitroprusside, resulted in an inhibition or an acceleration of the discharge activity in the identified AVP neurons. The slopes that were derived from a least squares regression line for the arterial blood pressure and baroreceptor-induced responses of AVP neurons in both OVX + E2 and OVX + EP rats were statistically smaller (P < 0.05) than that in the control OVX rat. These results suggest a functional relationship between ovarian endocrine and autonomic functions in the female rat.