Protective effect of GHRP-6 and estrogen supplementation against some cardiometabolic risk factors in ovariectomized rats

Abstract

This study was aimed to assess the effect of both the estrogen and growth hormone releasing peptide-6 (GHRP-6), on the cardiovascular and metabolic diseases in ovariectomized (OVX) rats. Four groups of adult female rats were used: sham operated, OVX, OVX plus estrogen supplemented, and OVX plus GHRP-6 supplemented. After 8 weeks, blood samples were collected from the retro-orbital plexus and total cholesterol (TC), triglycerides (TGs), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), glucose and insulin in serum were estimated. The ovariectomy resulted in significant increase of body weight gain, food intake, fasting serum glucose, insulin, insulin resistance, TC, and LDL-C as well as in significant decrease of serum TGs and HDL-C levels. Estrogen supplementation to OVX rats reversed the effect of OVX on all the above mentioned parameters. However, GHRP-6 supplemented to OVX rats failed to produce significant change in both the body weight gain and food intake, but reversed the effect of OVX on fasting serum glucose, insulin, insulin resistance, and the assessed lipid fractions. The decrease in ovarian hormones produced by OVX resulted in arising of several risk factors related to carbohydrate metabolism and cardiovascular system. It appeared that such negative effects of OVX can be reversed by estrogen or GHRP-6 supplementation. However, the effect of GHRP-6 on improving dyslipidemia after OVX was more potent than that of estrogen, while the effect of estrogen on improving carbohydrate metabolism after OVX was more potent than that of GHRP-6.