Photosensitive inhibition of the GABA system in vitro

In the central nervous system (CNS), γ–aminobutyric acid A (GABA(A)) receptors mediate two types of inhibitory effects. Phasic inhibition involves the activation of synaptic GABA(A) receptors, and tonic inhibition is mediated by extrasynaptic GABA(A) receptors. GABA(A) receptors are important regulators of neuronal activity and are involved in a range of neurological disorders. In this study, we conducted sIPSCs recordings on hippocampal CA1 pyramidal neurons in WT SD rats and found that exposure to blue light could specifically block the tonic inhibition and sIPSCs, and regulate neuronal activity. These observations indicate the existence of a non-opsin photosensitive pathway that regulates the GABA inhibitory system in the CNS.