Acupuncture Attenuates Hyperglycaemia and Improves Ovarian Function in Female Rats Subjected to Continuous Light Exposure

Abstract

Objective 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 longterm continuous light exposure. Methods 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. Results 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. Conclusion 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. InTRoduCTIonHuman circadian rhythms are synchronised to light/dark cycles. Over time, organisms have adapted to diurnal variations in their physiology and metabolism. These rhythms are regulated by molecular circadian clocks. However, in recent years, humans have shifted away from the naturally occurring solar light cycle in favour of artificial, irregular light schedules produced by electrical lighting. Disruption of the core clock genes secondary to interference with these environmental considerations may lead to an increased risk of cardiometabolic disease.1 2 Genetic disruption of clock genes in mice induces metabolic dysfunction at distinct phases of the sleep/ wake cycle.3 Constant exposure to light induces alterations in melatonin levels, food intake, visceral adiposity and circadian rhythms in rats. 4 Exposure of adult female rats to continuous light leads to the gradual development of chronic anovulation.5 6 However, it remains unknown how continuous light exposure affects glucose levels in female rats.As contemporary exposure to artificial light environments is unlikely to change, there may be a potential role for complementary and alternative medicine (CAM) in allowing humans to enjoy the convenience of artificially lit environments, while reducing the potential side effects of light exposure to a minimum. Acupuncture is now widely practised in both East Asian an...

Continuous Light-Induced PCOS-Like Changes in Reproduction, Metabolism, and Gut Microbiota in Sprague-Dawley Rats

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Effect of transcutaneous electrical acupoint stimulation on protecting against radiotherapy- induced ovarian damage in mice

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The Effect of Acupuncture on Glucose Metabolism and Lipid Profiles in Patients with PCOS: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

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