Acupuncture attenuates hyperglycaemia and improves ovarian function in female rats subjected to continuous light exposure.

Abstract

Exposure to unnatural light cycles is increasingly associated with obesity and the metabolic syndrome. The purpose of this study was to examine the effects of electroacupuncture (EA) on glucose metabolism and ovarian function in female rats subjected to long-term continuous light exposure. Female Sprague-Dawley rats (n=24) were divided into three experimental groups: an LD group that was maintained under a normal light-dark cycle (healthy control); an LL group that was exposed to continuous light for 21 weeks but remained untreated; and an LL+EA group that received EA at ST36 and SP6 during weeks 17 to 21 of continuous light exposure. Oestrous cycles of female rats kept in a continuously lit environment for 21 weeks were disordered and polycystic ovarian syndrome (PCOS)-like changes occurred, accompanied by increased fasting blood glucose (6.23±0.33 vs 5.27±0.40 mmol/L in week 17, p=0.015) and reduced fasting levels of serum testosterone (0.07±0.018 vs 0.12±0.058 ng/L, p=0.043) and insulin (0.89±0.20 vs 1.43±0.46 ng/L, p=0.006). After 5 weeks of EA treatment at ST36 and SP6, ovarian cycle disruption was mitigated and blood glucose levels showed a gradual decline (5.18±0.37 vs 5.80±0.55 mmol/L, p=0.017; and 5.73±0.31 vs 6.62±0.13 mmol/L, p=0.004; in the fourth and fifth weeks of EA treatment, respectively). EA also attenuated the reductions otherwise seen in serum insulin and testosterone levels. Prolonged exposure to light can lead to a decline in ovarian and pancreatic function. EA at ST36 and SP6 may reduce abnormally elevated blood glucose levels and improve ovarian and pancreatic hormone levels.