RESUMO
Objective The occurrence of perimenopausal hot flashes involves many theories, among which the study of neurotransmitter mechanism has attracted much attention. This study aims to investigate the changes of α1 and α2 adrenoreceptors in the preoptic area of the hypothalamus(POAH) in ovariectomized rats after 4 weeks treatment with estradiol valerate, and explore the potential neurotransmitter mechanism of perimenopausal hot flashes. Methods 30 female Sprague-Dawley rats, weighing 230±10 g and aged 6-8WK, were divided into three groups: ovariectomy (OVX)group , sham group, and ovariectomy plus estradiol valerate (OVX+E2) group, each 10. Rats in sham-operated group opened pelvic cavity to find ovaries, but did not remove them. The other rats underwent bilateral ovariectomy under sterile conditions. Rats in OVX group and (OVX+E2) group received bilateral ovariectomy, rats in OVX group received isotonic saline gavage (10 mg/kg), and rats in (OVX+E2) group received estradiol valerate gavage (0.8 mg /kg). Anesthesia, cardiac perfusion and paraffin section were made after taking the brain. The expression of α1 and α2 adrenoreceptors in POAH of the rats was detected by immunohistochemistry. Results After 4 weeks’ treatment, the number of α1[(54.0±3.9)/100μm2] and α2[(89.0±2.4)/100μm2] adrenoreceptor positive cells in POAH of OVX group significantly decreased compared with that in sham group[(66.3±4.0)、(71.0±2.2)/100μm2](P<0.01),while the number of α1 and α2 [(63.7±4.5)、(73.1±3.5)/100μm2)] adrenoreceptor positive cells in POAH of（OVX+E2 ）group significantly increased compared with that in OVX group(P<0.01). The difference was statistically significant. Conclusion The expression of two adrenergic receptors in the POAH of ovariectomized rats changed. The central noradrenergic system may be involved in the mechanism of perimenopausal hot flashes,which need further studying.