ABSTRACT
Objective To explore the modulation roles of gamma-aminobutyric acid A(GABAA) receptor on respiratory rhythmical discharge activity in brainstem slice of neonatal rats.Methods Experiments were performed on in vitro neonatal rats brainstem slices.The slices containing the medial region of the nucleus retrofacialis(mNRF)with the hypoglossal nerve rootlets retained was prepared in which the respira-tory-related rhythmic discharge activity(RRDA)were recorded from hypoglossal nerve rootlets by suction electrode.The possible role of GABAA receptor on RRDA was investigated by administration of GABA and its antagonist bicuculline in modified Kreb′s solution(MKS),for perfusion of the brainstem slices.Eighteen slices positive of RRDA were randomly divided into three equal groups:the first group of slices was perfused with different concentrations(10,20,40,60 ?mol/L) GABA and the most effective concentration was selected;the second group of slices was perfused with 10 ?mol/L bicuculline;the third group of slices was perfused with 10 ?mol/L bicuculline plus 40 ?mol/L GABA.The RRDA in 3 groups were observed.Results GABA decreased RRDA,40 ?mol/L was the most effective concentration.It shortened inspiratory time(TI),decreased integral amplitude(IA),prolonged respiratory cycle(RC) and expiratory time(TE) respectively.By contrast,10 ?mol/L bicuculline produced opposite effects on RRDA,it prolonged TI,increased IA,shortened RC and TE respectively.40 ?mol/L GABA plus 10 ?mol/L bicuculline had no significant effects on RRDA.Conclusion GABA plays an important role in modulate RRDA of neonatal rats via GABAA receptor.