Spontaneously active GABAergic interneurons in the subfornical organ of rat slice preparations

Inhibitory postsynaptic currents (IPSCs) were recorded from subfornical org an (SFO) neurons in slice preparations of rats, using whole-cell voltage cl amp techniques. Some SFO neurons showed bimodal distributions in amplitude with the large and small IPSCs. The large IPSCs vanished in the tetrodotoxi n perfusion medium, but the small did not. Both sizes of the IPSCs were com pletely abolished by application of bicuculline and picrotoxin. Further sub population of SFO neurons with the bimodal distributions showed intermitten t bursts of the large IPSCs. Immunohistochemical approach revealed existenc e of gamma-aminobutyric acid (GABA)-immunoreactive neurons and axons in the SFO. These suggest that spontaneously-active and intermittently-burst-firi ng GABA interneurons affect other SFO neurons in slice preparations of rats . (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.