Receptor for gastrin-releasing peptide (GRP) (PubMed:1671171, PubMed:1707129, PubMed:9345264, PubMed:12526815, PubMed:26658875). Signals via association with G proteins that activate a phosphatidylinositol-calcium second messenger system, resulting in Akt phosphorylation (PubMed:26658875). Contributes to the regulation of food intake (PubMed:12176666). Contributes to the perception of prurient stimuli and transmission of itch signals in the spinal cord that promote scratching behavior, but does not play a role in the perception of pain (PubMed:28280205, PubMed:17653196, PubMed:26658875). Contributes primarily to nonhistaminergic itch sensation (PubMed:28280205). In one study, shown to act in the amygdala as part of an inhibitory network which inhibits memory specifically related to learned fear (PubMed:12526815). In another study, shown to contribute to disinhibition of glutamatergic cells in the auditory cortex via signaling on vasoactive intestinal peptide-expressing cells which leads to enhanced auditory fear memories (PubMed:34610277). Contributes to the induction of sighing through signaling in the pre-Botzinger complex, a cluster of several thousand neurons in the ventrolateral medulla responsible for inspiration during respiratory activity (PubMed:26855425). Detected in pancreas and brain (PubMed:1671171, PubMed:9345264). Detected in suprachaismatic nucleus neurons (PubMed:28280205). Detected in neurons in the dorsal horn of the spinal cord (PubMed:17653196). Detected in inhibitory GABAergic interneurons in the lateral nucleus of the amygdala (PubMed:12526815). Detected in approximately 160 neurons of the pre-Botzinger complex (PubMed:26855425). Within the pre-Botzinger complex, there is some overlap with neurons expressing Nmbr with some cells expressing only Grpr or Nmbr while some cells express both (PubMed:26855425). Detected in cells throughout the cortex where it is coexpressed in most of these cells with vasointestinal peptide (VIP) (PubMed:34610277). Mice are born at the expected Mendelian rate, are viable and fertile (PubMed:9345264). They do not decrease their food intake in response to gastrin-releasing peptide (PubMed:12176666). Mice consume more food per meal, but the overall food intake per day remains unchanged (PubMed:12176666). Still, they display increased body weight relative to wild-type (PubMed:12176666). Contrary to wild-type mice, their body temperature remains nearly constant when exposed to cold (4 degrees Celsius) after intracerebroventricular injection of gastrin-releasing peptide (PubMed:9345264). Mutant mice show increased locomotor activity and increased social interactions (PubMed:9345264). They do not show any change in the perception of painful stimuli, but show reduced scratching in response to pruritogenic treatments (PubMed:17653196). Contrary to wild-type, mutant mice do not display imitative scratching after observing spontaneous scratching behavior in another mouse (PubMed:28280205). In one study, mutant mice display normal performance in a water maze, but show decreased inhibition of principal neurons by the interneurons, enhanced long-term potentiation (LTP), and greater and more persistent long-term fear memory (PubMed:12526815). Another study showed that mutants display reduced long-term fear memory (PubMed:34610277). Reduced basal sigh rate (PubMed:26855425). Conditional knockout in the auditory cortex results in diminished auditory fear memories with no significant effect on auditory discrimination (PubMed:34610277). Belongs to the G-protein coupled receptor 1 family.