Intra-arcuate opiate actions stimulate GRF-dependent and protein-selective feeding

Growth-hormone releasing factor (GRF) induces feeding and growth hormone (GH) release. Opiates activate GRF neurons regulating GH release. This study sought to determine whether opiate actions on GRF neurons would also stimulate feeding. In Experiment 1, Wistar male rats received intra-arcuate morphine (0, 1, 10, and 20 micrograms/0.5 milligrams) which increased protein intake/feeding activity. In Experiment 2, this effect was blocked when Wistar male rats received intra-SCN/MPOA pretreatments with GRF antiserum followed by intra-arcuate morphine (1 microgram/0.5 milligrams) injections. The data suggest that an opioid trigger may stimulate complementary central (feeding effects) and peripheral (GH release) GRF actions via the arcuate nucleus.