GPR88

GPR88 is an orphan G protein-coupled receptor (GPCR) of the class A rhodopsin family. GPR88 was originally identified as a striatum-specific receptor (designated Strg/GPR88) in both human and rodents, though it is also expressed at low levels in the cerebral cortex, central extended amygdala, lateral, cortical, hypothalamus, and other brain regions.

The specific brain signaling pathways and physiologic functions of GPR88 are largely unknown because the endogenous hormone or transmitter for the receptor has not yet been identified. However, several lines of evidence suggest that GPR88 may provide an important role regulating the excitability of glutamatergic and GABAergic neurons as well as modulating responses to dopaminergic neurons, based on the particularly robust expression of GPR88 in medium spiny neurons (MSNs) in the striatum. Conversely, glutamatergic and dopaminergic depletion differentially alters Gpr88 mRNA levels in distinct MSN subpopulations, indicating neurotransmission regulates Gpr88 gene expression. Consequently, GPR88 is implicated in many behavioral functions and responses, including cognition, mood, movement control, and cued response reward learning.