Effects of Black Cohosh and Estrogen on the Hypothalamic Nuclei of the Ovariectomized Rats at Different Temperatures
Dr. Wenpei Bai
Beijing, China 
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9 slide(s) – English – 2012-03-28
Objectives: To observe the changes in c-Fos protein expression in the hypothalamic nuclei of four groups of rats: a sham-operated group (SHAM), ovariectomised (OVX) group, OVX+E group (OVX group treated with estrogen) and ovariectomised group of rats treated with an isopropanol extract of Cimicifuga racemosa (OVX+ICR), and to investigate the mechanism of black cohosh and estrogen in the hypothalamic nuclei of ovariectomized rats.
Methods: Fifty rats from each of the four groups were placed in incubators at 4°C, 10°C, 25°C, 33°C and 38°C for 2 h. They were then anesthetized, and their brains removed after heart perfusion. c-Fos expression in the hypothalamic nuclei was detected by an immunohistochemical method.
Results: For the SHAM groups in the median preoptic nucleus (MnPO), ventromedial preoptic nucleus (VMPO), suprachiasmatic nucleus (SCh); for the four groups in the anterior hypothalamic area (AH) and supraoptic nucleus (SO); and for the SHAM, OVX and OVX+E groups in the paraventricular nuclei (PVN), c-Fos positive cell densities changed in the same way—that is, at <25°C, the cell density decreased with the temperature rise; when >25°C, the density increased with the temperature rise, showing a V-type curve, with 25°C as the lowest point. Other nuclei change irregularly. The positive cell densities for the SHAM, OVX + E and OVX + ICR groups in the MnPO, AH and PVN were greater than that for the OVX group at all temperatures, except 25°C. Positive cell densities for the SHAM, OVX + E and OVX + ICR groups were greater than that for the OVX groups in the medial preoptic area (MPA) at 25°C, in the VMPO at 4°C, 33°C and 38°C, in the SO at 4°C, 10°C and 38°C and in the SCh at 33°C.
Conclusion: Under different stimulation temperatures or the same temperature stimulation in the four groups, the positive cell densities in the OVX groups are lower than those in the SHAM groups of the MnPO, MPA, VMPO, AH, SCh, SO and PVN. After black cohosh and estrogen intervention, the positive cell densities in the OVX groups increased and became close to, or exceeded, those of the SHAM groups, suggesting that these two drugs may act on the hypothalamic nuclei and have therapeutic effects on menopausal symptoms.
Key words: black cohosh; estrogen; temperature stimulation; c-Fos protein; ovariectomized rats; immunohistochemistry
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