In a recent study GABAa
receptors, with and without the gamma subunit, were expressed in Xenopus
oocytes.In a recent study GABAa
receptors, with and without the gamma subunit, were expressed in Xenopus
oocytes.
The ability of diazepam (a benzodiazepine) to potentate GABA was examined (review use of Xenopus oocytes in electrophysiology?).
In the case where alpha, beta and gamma were coexpressed (i.e. mRNA
for all three subunit types were injected into the oocyte), a receptor was created which
was clearly sensitive to diazepam at 20 nM.
In the case where mRNA for the gamma subunit was omitted from the RNA mixture injected into the oocyte, the resulting receptor, while still sensitive to GABA, displayed a remarkably reduced ability to be potentated by diazepam.
In this case the first clear potentiated response was seen at 20,000 nM diazepam.
Clearly, subunit composition is important to the behavior of the receptor with respect to potentiation to benzodiazepines.
Walters et al. Nature Neuroscience 3: 1274-1281, 2000