Effects of estrogen and Cimicifuga racemosa on the cardiac norepinephrine pathway of ovariectomized rats

Abstract

This study aimed to investigate the effects of estrogen and Cimicifuga racemosa on the stellate ganglion, cardiac norepinephrine pathway, and Ca²⁺/calmodulin-dependent protein kinase II (CaMK II). Forty adult female Sprague Dawley rats were randomly divided into four groups: SHAM, ovariectomized (OVX), ovariectomized with estrogen treatment (E2), and ovariectomized with Cimicifuga racemosa treatment (iCR). After 4 weeks of treatment, norepinephrine (NE) content was determined by high-performance liquid chromatography, and dopamine beta-hydroxylase (DBH) and norepinephrine transporter (NET) expression was detected by immunohistochemistry. Western blotting was used to determine NET, beta1-adrenergic receptor (β1-AR), and CaMK II expression. Compared with SHAM group, body weights, DBH, NET expression in the right stellate ganglia, and NET, β1-AR, CaMK II expression in left ventricles of OVX group were increased, whereas left ventricular NE content was decreased; DBH and NET expression in the left stellate ganglion was not significantly different. The indexes of E2 group were similar to those of SHAM group. Moreover, in iCR group, DBH, NET, β1-AR, and CaMK II expression was decreased; NET expression and NE content of left ventricle remained unchanged. There, 1) the right stellate ganglion, but not the left, may be associated with decreased left ventricular NE content in OVX rats. 2) Estrogen increases the left ventricular NE content and adjusts the expression of DBH and NET in the right stellate ganglion, and restores β1-AR and CaMK II protein expression to normal levels. 3) Cimicifuga racemosa does not affect left ventricular NE, but decreases β1-AR and CaMK II protein expression.

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