GABA-benzodiazepin-chloride channel receptor

In the retina, homomeric receptors consisting of the p-subunit represent a particular class of GABA-gated chloride channels. Their GABA site is insensitive to bicuculline and baclofen and they are not modulated by barbiturates or benzodiazepines. Due to these distinctive features, the receptors are sometimes termed GABAc receptors (Bormann 2000), although they are be considered a homomeric class of GABAa receptors (Barnard et al. 1998). 

Perhaps the most well-known example is the acetylcholine receptor located on the postsynaptic membrane of the neuromuscular junction49 56 (Fig. 4-1). When bound by acetylcholine molecules, the receptor activates and opens a pore through the cell membrane, thereby increasing the permeability of the muscle cell to sodium.38 56 This action results in depolarization and excitation of the cell because of sodium influx. Another important example of a receptor-ion channel system is the gamma-aminobutyric acid (GABA)-benzodiazepine-chloride ion channel complex found on neuronal membranes in the central nervous sys-... 

In summary, avermectin has been found to interact directly with the chloride channel in the muscle and the central nervous system of the American cockroach. This action of avermectin appears to occur independently from GABA, benzodiazepine, and picrotoxinin receptors in this species ... 

The GABA-gated chloride ion channel is modulated by several classes of drugs that bind to allosteric sites on the receptor complex the benzodiazepines, barbiturates and related intravenous general anesthetics such as etomidate and propofol, as well as anesthetic steroids and endogenous neurosteroids. It appears that some types of GABAa receptor are directly enhanced by ethanol and volatile general anesthetics (Fig. 16-2) [7,8,20]. 

The receptor site for a benzodiazepine is adjacent to the GABA receptor sire, (a) A benzodiazepine cannot open up the chloride channel on its own. 

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