GABA(B) receptors in Müller cells of the bullfrog retina.

GABA is a major inhibitory neurotransmitter in the vertebrate retina. Using GABA(B) receptor-specific antibody combined with glial fibrillary acidic protein (GFAP) antiserum, we demonstrated that primary processes, vitreal endfeet and somata of virtually all Müller glial cells in the bullfrog retina prominently showed GABA(B) receptor immunoreactivity by light and electron microscopy. This study provides the first evidence that glial elements in the vertebrate retina express GABA(B) receptors. Such receptors on Müller cells may play an important role in retinal information processing through regulating the conductance of the inward-rectifying K+ channels.