QRFP in female rats: effects on high fat food intake and hypothalamic gene expression across the estrous cycle

Pyroglutamylated arginine-phenylalanineamide peptide (QRFP) is a neuropeptide involved in feeding behavior. Central administration of QRFP selectively increases the intake of a high fat diet in male rats. QRFP administration also stimulates the hypothalamic-pituitary-gonadal axis via gonadotrophin-releasing hormone in male and female rats. Prepro-QRFP mRNA is expressed in localized regions of the mediobasal hypothalamus which are abundant in neurotransmitters, neuropeptides and receptor systems important for food intake regulation and reproductive behaviors. The current experiments were conducted to investigate the effects of centrally administered QRFP-26 on the intake of a high fat diet (HFD, 60% kcal from fat) in female rats and to investigate alterations in hypothalamic prepro-QRFP and its receptors, GPR130a and GPR103b, mRNA levels over the estrous cycle. In Experiment 1, female rats were administered QRFP-26 (intracerebroventricular; 0.3 nmol, 0.5 nmol, 1.0 nmol) in rats consuming either a HFD or a low fat diet. All doses of QRFP-26 selectively increased the intake of the HFD in female rats. These data suggest that QRFP-26 regulates the intake of energy dense foods in female rats, which is similar to previous findings in male rats. In Experiment 2, hypothalamic levels of prepro-QRFP mRNA and its receptors were assessed during diestrus, proestrus, or estrus. The level of prepro-QRFP mRNA in the ventromedial/arcuate nucleus (VMH/ARC) of the hypothalamus was increased during proestrus, which suggests that endogenous estrogen levels regulate QRFP expression in the VMH/ARC. These data suggest that QRFP may play a role in coordinating feeding behaviors with reproductive function when energy demand is increased.