GABAA-rho (GABA-C) receptor!

[dopamimetic]

Just found that a third class of GABA receptors exists!

A second type of ionotropic GABA receptor, insensitive to typical allosteric modulators of GABAA receptor channels such as benzodiazepines and barbiturates, was designated GABAС receptor. Native responses of the GABAC receptor type occur in retinal bipolar or horizontal cells across vertebrate species.

The GABAA-ρ receptor (previously known as the GABAC receptor), like other GABAA receptors, is expressed in many areas of the brain, but in contrast to other GABAA receptors, the GABAA-ρ receptor has especially high expression in the retina.

Only three agonists are listed yet, with that strange anticonvulsant GABOB being one of them and the only one clinically used. Don't know if the GABA-rho contributes to it's effects or only side effects? Oh, and N2O is an antagonist here! I haven't experienced nitrous oxide yet, but this would implicate that it'd have an obvious impact on vision, or?

 

[Nagelfar]

Are these related to the GHB receptor perhaps? HOCPCA is an interesting one in that regard/capacity.

 

[dopamimetic]

Didn't know about HPCPCA, but I think the GABA-rho isn't really related to the excitatory GHB receptor, it mediates glutamate/dopamine release and is really somewhat interesting - GABA-rho seems to be inhibitory though(?).

 

[dopamimetic]

Just had to think about that irreversible GABA transaminase inhibitor / anti-epileptic vigabatrin that causes vision defects in maybe 50% of the cases, cell atrophy in the retina. These cells have a high occurrence of the GABA-rho receptor. I've always wondered how more GABA could lead to death of visual cells - but makes sense now ... just curious whether this is the cells dying from too little excitation then or if GABA is excitatory here!?

 

[Anxious.Individual]

The only effective GABAArho positive allorestic modulators are the barbiturates and at large doses only, but that's because they have rather strange non-selective Cl- channel opening properties. But yeah, GABOB is a substance worth taking a look at, although very little is known of it. Also, Muscimol is a GABAArho partial-agonist.