Effects of oestrogen and Cimicifuga racemosa on the cardiac noradrenaline pathway of ovariectomized rats.

What is the central question of this study? We investigated the effects of oestrogen and Cimicifuga racemosa on the stellate ganglion, cardiac noradrenaline pathway and Ca2+ -calmodulin-dependent protein kinase II in ovariectomized rats. What is the main finding and its importance? The right stellate ganglion, but not the left, may be associated with decreased left ventricular noradrenaline content in ovariectomized rats. Oestrogen can reverse all changes caused by ovariectomy. Cimicifuga racemosa did not affect left ventricular noradrenaline, but decreased protein expression of β1 -adrenergic receptor and Ca2+ -calmodulin-dependent protein kinase II. The results might explain potential effects of C. racemosa on the cardiovascular system and provide new insights into cardiovascular protection. The aim of this study was to investigate the effects of oestrogen and Cimicifuga racemosa on the stellate ganglion, cardiac noradrenaline (NA) pathway and Ca2+ -calmodulin-dependent protein kinase II (CaMK II). Forty adult female Sprague-Dawley rats were randomly divided into the following four groups: sham operated (SHAM); ovariectomized (OVX); ovariectomized with oestrogen treatment (E2); and ovariectomized with C. racemosa treatment (iCR). After 4 weeks of treatment, the NA content was determined by high-performance liquid chromatography, and dopamine β-hydroxylase (DBH) and noradrenaline transporter (NET) expression were detected by immunohistochemistry. Western blotting was used to determine NET, β1 -adrenergic receptor (β1 -AR) and CaMK II expression. Compared with the SHAM group, body weights, DBH and NET expression in the right stellate ganglia, and NET, β1 -AR and CaMK II expression in the left ventricles of the OVX group were increased, whereas left ventricular NA content was decreased; DBH and NET expression in the left stellate ganglion was not significantly different. The indexes of the E2 group were similar to those of the SHAM group. Moreover, in the iCR group, DBH, NET, β1 -AR and CaMK II expression was decreased; NET expression and NA content of the left ventricle remained unchanged. Our conclusions are as follows. First, the right stellate ganglion, but not the left, may be associated with decreased left ventricular NA content in OVX rats. Second, oestrogen increases the left ventricular NA 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. Third, C. racemosa does not affect left ventricular NA, but decreases the protein expression of β1 -AR and CaMK II.