Modulation of Chelidonii herba on GABA activated chloride current in rat PAG neurons

Modulation of Chelidonii herba on gamma -aminobutyric acid (GABA) activated chloride current in the acutely dissociated periaqueductal gray (PAG) neur on was studied by nystatin-perforated patch-clamp technique. High concentra tions of Chelidonii herba elicited ion current, that was blocked by bicucul line. Low concentrations reduced the GABA activated current in PAG. Two typ es of inhibitory action of Chelidonii herba on GABA activated current have been implicated in PAG. One is the inhibitory action of Chelidonii herba on GABA was abolished by naltrexone and the other is that of Chelidonii herba was potentiated by naltrexone. In addition, all of two types of action of Chelidonii herba are linked to pertussis toxin-sensitive GTP-binding protei ns. These results suggest that the inhibitory modulation of Chelidonii herb a on GABA activated current via G-proteins in PAG neuron is an important an algesic mechanism.