mGluR5

Metabotropic glutamate receptor 5 (mGluR5) is a Gq-coupled Group I receptor that modulates excitatory synaptic transmission and intracellular calcium signaling in neurons^[1][2]. Mechanistically, mGluR5 activation influences synaptic plasticity by regulating long-term potentiation (LTP) and long-term depression (LTD) through protein synthesis-dependent pathways, particularly in hippocampal CA1 neurons^[3][4]. Compared with mGluR1, mGluR5 exhibits higher intracellular localization in neurons, favoring postsynaptic compartments and extrasynaptic sites, which affects receptor trafficking and signaling specificity^[5][6]. In developmental and adult cerebellar Purkinje cells, mGluR5 can substitute for mGluR1 to restore motor coordination and synapse elimination, indicating functional overlap despite temporal expression differences^[2]. In respiratory network neurons, mGluR5 activation modulates TRPC channel-mediated currents, enhancing regularity of inspiratory rhythms, whereas mGluR1 primarily regulates frequency^[7]. Disease relevance is highlighted in addiction models, where mGluR5 antagonism reduces ethanol self-administration, and in autoimmune encephalitis, where anti-mGluR5 antibodies are associated with psychiatric symptoms^[8][9]. Agonists such as CHPG and DHPG potentiate mGluR5 signaling in experimental systems, while selective antagonists like MPEP and LY344545 inhibit receptor activity, enabling mechanistic studies of synaptic plasticity and behavioral modulation^[1][3][10].