Molecular basis underlying GABA(A) responses in rat mesencephalic trigeminal neurons

We studied the molecular basis of GABA(A) receptor (GABA(A)R) expressed in the rat mesencephalic trigeminal (Vmes) sensory neuron using the immunohistochemical and single-cell RT-PCR methods. Using anti-GABA(A)R alpha2 subunit antibody, abundant GABA(A)Rs were visualized in Vmes neurons. A single-cell RT-PCR clarified that GABA(A)Rs expressed in Vmes neurons were predominantly composed of alpha2, alpha5, beta1, gamma1 and gamma2 subunits. Novel splicing variants in both alpha5 and beta1 were found invariably, and they lacked multiple amino acid sequence in the extracellular N-terminal portion. Known functional roles of both beta and gamma subunits in regulating the expression at the cell surface suggest that the unique subunit composition of GABA(A)Rs may be involved in the characteristics of GABA(A) response in Vmes neurons.