Androgen Excess Increases Food Intake in a Rat Polycystic Ovary Syndrome Model by Downregulating Hypothalamus Insulin and Leptin Signaling Pathways Preceding Weight Gain.

BACKGROUND: Polycystic ovary syndrome (PCOS) is a common reproductive and metabolic disorder characterized by high androgen levels. The aim of this study was to evaluate the effects of hyperandrogenism on the hypothalamus and subsequently on the food intake and obesity in females. METHODS: A dihydroxy testosterone (DHT)-induced rat model was established to recapitulate the hyperandrogenism features of PCOS patients. Body weight and food intake of the rats were recorded. The food intake of DHT-induced rats was restricted by pair feeding to exclude possible effects of weight gain on the hypothalamus. The expression levels of relevant proteins and mRNAs in the hypothalamus and primary hypothalamic neurons exposed to DHT were analyzed by Western blotting and RT-PCR, respectively. The leptin levels in the serum and cerebrospinal fluid (CSF) were measured, and leptin was injected via the intracerebroventricular (ICV) route to test the leptin sensitivity of the hypothalamus. RESULTS: The excessive prepuberty androgen levels in the DHT-induced rats markedly elevated food intake prior to weight gain. Consistent with this, the expression of neuropeptide Y and agouti-related peptide mRNAs was upregulated, which occurred prior to obesity and even with restricted food intake. In addition, the hypothalamic sensitivity to insulin and leptin was also impaired in the DHT-induced rats before obesity and with restricted food intake. DHT significantly reduced the leptin levels in the CSF, and ICV injection of leptin inhibited the DHT-induced increase in food intake. CONCLUSIONS: Androgen excess increased food intake in rats and promoted obesity by downregulating insulin and leptin signaling in the hypothalamus, most likely by suppressing leptin levels in the CSF.

Folate deficiency and aberrant expression of DNA methyltransferase 1 were associated with cervical cancerization.

DNA methyltransferase 1 (DNMT1) plays a significant role in maintaining DNA methylation. Aberrant DNA methylation is a recognized feature of human cancers and folate is directly involved in DNA methylation via one-carbon metabolism. Previous reports also have suggested that folate deficiency was associated with many cancers. The aim of the present study was to evaluate the effect of folate deficiency and aberrant expression of DNA methyltransferase 1 (DNMT1) on cervical cancerization. The expression of DNMT1 protein and mRNA and levels of serum folate were detected in 238 women with a diagnosis of normal cervix (NC，n = 53), cervical intraepithelial neoplasia (CIN I, n = 52; CIN II/III, n = 53), and squamous cell carcinoma of the cervix (SCC; n = 80). In addition, the expression of DNMT1 protein and mRNA was measured in cervical cancer cells (Caski and C33A) treated by different concentration of folate. Serum folate levels decreased and expression levels of DNMT1 protein and mRNA increased gradually with progressive severity of the cervix lesions (P<0.001). It was found that folate was able to reduce the viability of Caski or C33A cell (r=0.978, P=0.002; r=0.984, P<0.001) and regulated aberrant expression of DNMT1 protein (r=-0.859, P=0.01; r=-0.914, P<0.001) and mRNA (r=-0.297, P=0.159; r=0.433, P=0.034) in vitro. Our findings indicated that the low-level of serum folate and high-expression of DNMT1 protein or mRNA was significantly associated with cervical carcinogenesis. Folate deficiency and aberrant expression of DNA methyltransferase 1 had additive effect on cervical cancerization. Folate supplement and recovery of aberrant DNA methylation status may offer a new strategy for prevention and therapy of cancers.