CHPG

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CHPG is a selective mGlu5 metabotropic glutamate receptor agonist.

The mGlu family of G-protein-linked glutamate receptors currently comprises eight members. 3,5-dihydroxyphenylglycine can activate specifically Group I mGlu receptors, which have been found to regulate multiple effects in the vertebrate brain.

In vitro: (R,S)-2-Chloro-5-hydroxyphenylglycine [CHPG] selectively activated mGlu5a receptors with no activation of mGlu1a receptors. This selective mGlu5 receptor agonist also enhances NMDA-induced depolarizations in rat hippocampalslices. CHPG may be used to study the role of mGlu5 receptors in the CNS [1].

In vivo: To compare the effects of treatment with the newly developed selective mGluR5 antagonist MPEP and the selective mGluR5 agonist CHPG in a rat intraluminal filament model of temporary middle cerebral artery occlusion (MCAo), rats, after induction of ischemia for 2 h, were administered MPEP or CHPG (i.c.v.) beginning 15 or 135 min. measured After either 22 or 70 h of reperfusion measured infarct size, and quantified neurological function at 2, 24, 48 and 72 h. 24 h infarct volumes after treatment with MPEP or CHPG at 15 min were reduced by 61 and 44%, respectively. The neuroprotective effects were dose-dependent. The neuroprotective effects were eliminated by delaying MPEP treatment until 135 min. In other studies, with early MPEP treatment (15 min) at optimal doses, infarct volume was reduced by 44% at 72 h, being correlated with significant neurological recovery [2].

Clinical trial: Clinical study has been conducted.

References:
[1] Doherty AJ, Palmer MJ, Henley JM, Collingridge GL, Jane DE.  (RS)-2-chloro-5-hydroxyphenylglycine (CHPG) activates mGlu5, but no mGlu1, receptors expressed in CHO cells and potentiates NMDA responses in the hippocampus. Neuropharmacology. 1997 Feb;36(2):265-7.
[2].  Bao WL, Williams AJ, Faden AI, Tortella FC. Selective mGluR5 receptor antagonist or agonist provides neuroprotection in a rat model of focal cerebral ischemia. Brain Res. 2001 Dec 20;922(2):173-9.