Role of the Medial Preoptic Area in Electroacupuncture Treatment of Reproductive Dysfunction in Ovariectomised Rats

Abstract

Objective To investigate the role of the medial preoptic area (MPOA) of the hypothalamus in electroacupuncture (EA) treatment of reproductive dysfunction in ovariectomised (OVX) rats and to examine the underlying mechanisms of action. Methods 62 female Sprague-Dawley rats (200–220 g) underwent bilateral ovariectomy (OVX). Three weeks later, 32 rats assigned to experiment 1 were randomly divided into four groups: two groups underwent MPOA lesioning (n=16) followed by EA at CV4, CV3, SP6 and bilateral Zigong (30 min per day) for 3 days (OVX+MPOA+EA group, n=8) or no treatment (OVX+MPOA group, n=8); and two groups underwent sham (S) surgery (n=16) followed by EA (OVX+SMPOA+EA group, n=8) or no treatment (OVX+SMPOA group, n=8). Plasma oestradiol and luteinising hormone (LH) were measured by radioimmunoassay and mature vaginal epithelial cells stained and quantified post-treatment. 30 rats assigned to experiment 2 were randomised to receive EA (OVX+EA group, n=15) or remain untreated (OVX group, n=15), following which push-pull perfusion in combination with high pressure liquid chromatography/electrochemical (HPLC-EC) detection was used to measure neurotransmitter release in the MPOA. Results EA significantly increased the percentage of mature vaginal epithelial cells and plasma oestradiol levels in sham MPOA-lesioned rats compared with MPOA-lesioned OVX rats (p<0.05). In sham MPOA-lesioned OVX rats, EA significantly decreased plasma LH levels compared with no treatment (p<0.01). HPLC-EC results showed that γ-aminobutyric acid (GABA) and β-endorphin levels in the MPAO were significantly increased in OVX rats following EA (p<0.01). Conclusions The present study suggests that the MPOA plays a crucial role in EA treatment of abnormal reproductive function in OVX rats.