Circulating estradiol and hypothalamic corticotrophin releasing hormone enhances along with time after ovariectomy in rats: Effects of electroacupuncture

Repeated electroacupuncture (EA) stimulation is known to enhance the circulating level of estrogen in the ovariectomized rats by stimulating the activity of the hypothalamus-pituitary-adrenal axis. To explore the mechanism of EA in promoting the homeostasis in ovariectomized rats, the hypothalamic CRH content and its mRNA expression as well as the circulating estradiol in the rats along with time after ovariectomy were detected. Female rats were divided into fourteen groups: 1 month after ovariectomy (OVX1M), OVX2M, OVX3M, OVX4M, OVX5M, OVX6M; intact 1 month (INT1M), INT2M, INT3M, INT4M, INT5M, INT6M; OVX1M with EA (OVX1M+EA) and intact 1 month with EA (INT1M+EA). The blood concentrations of estradiol (E2) and total contents of hypothalamic CRH were measured by radioimmunoassay. The expressions of CRHmRNA were semiquantified by RT-PCR. The results showed that the blood E(2) concentrations increased gradually along with time after ovariectomy in the rats. The level was higher in OVX1M+EA than those in OVX1M, 2M, 3M (p < 0.05), which was near to the level in OVX6M. The total content (ng/g tissue) of hypothalamic CRH and the CRHmRNA expressions in the OVX6M rats were higher than other groups (p < 0.05). The CRH content or mRNA expression in the OVX1M+EA increased significantly compared with that in OVX1M (p < 0.05), and it was close to the level in the OVX4M and OVX5M. The results suggested that the circulating E2 and hypothalamic CRH enhances along with time after ovariectomy in rats, and the EA stimulation might speedup the process.