Abstract
Pyrogultamylated arginine-phenylalanineamide peptide (QRFP) is strongly conserved across species and is a member of the family of RFamide-related peptides, with the motif Arg-Phe-NH(2) at the C-terminal end. The precursor peptide for QRFP generates a 26-amino acid peptide (QRFP-26) and a 43-amino acid peptide (QRFP-43), both of which bind to the G protein-coupled receptor, GPR103. Recently, QRFP has been characterized in rats, mice and humans and has been reported to have orexigenic properties. In rodents, prepro-QRFP mRNA is expressed in localized regions of the mediobasal hypothalamus, a region implicated in feeding behavior. Increased intake of a high fat diet contributes to increased weight gain and obesity. Therefore, the current experiments investigated the effects of QRFP administration in rats and the effects of a high fat diet on prepro-QRFP mRNA and GPR103 receptor mRNA levels. Intracerebroventricular administration of QRFP-26 (3.0nM, 5.0nM) and QRFP-43 (1.0nM, 3.0nM) dose-dependently increased 1h, 2h, and 4h cumulative intake of high fat (55% fat), but not low fat (10% fat) diet. In Experiment 2, hypothalamic prepro-QRFP mRNA levels and GPR103 receptor mRNA levels were measured in rats fed a high fat or a low fat diet for 21 days. Prepro-QRFP mRNA was significantly increased in the ventromedial nucleus/arcuate nucleus of the hypothalamus of rats fed a high fat diet compared to those fed a low fat diet, while GPR103 mRNA levels were unchanged. These findings suggest that QRFP is a regulator of dietary fat intake and is influenced by the intake of a high fat diet.