Effect of melatonin on intra-abdominal fat in correlation with endometrial proliferation in ovariectomized rats

In the context of endometrial cancer, visceral obesity as a risk factor is associated with a chronic inflammatory process, confirmed by an increase in inflammatory marker levels. Blood melatonin levels are inversely correlated with the tumor proliferation index in patients with endometrial cancer. The aim of this study was the experimental exploration of the effects of melatonin and melatonin associated with estrogen on metabolic changes, intraperitoneal fat and endometrial proliferation in female rats with surgically induced menopause.

The current study included 50 rats. At 14 days post-ovariectomy, the animals were exposed to estrogen replacement treatment and combined treatment of estrogen and melatonin. The duration of the administered treatment, with products and doses recommended for veterinary use, was 12 consecutive weeks. The endometrial thickness was ultrasonographically assessed. For statistical analysis, Student's t-test or the Mann-Whitney test, in the case of the non-parametric distribution, were used.

The groups receiving estrogen associated with melatonin had a lower body weight (222.20±3.34 g vs. 232.50±3.44 g, p<0.001), less intra-retroperitoneal fat (4.97±0.94 g vs. 7.93±0.64 g, p<0.001), and lower endometrial proliferation (0.122±0.010 vs. 0.133±0.009 p=0.04), compared to the control group.

The addition of melatonin to estrogen replacement treatment is associated with a decrease in endometrial proliferation and prevents the appearance of cellular atypia. The presented results suggest that melatonin supplementation may play an important role in the prophylaxis of endometrial cancer in menopause.