Role of GABAA receptors in sevoflurane-induced inhibition of discharge activities of inspiratory neurons in medullary respiratory center of neonatal rats

Abstract

Objective To evaluate the role of GABAA receptors in sevoflurane-induced inhibition of the discharge activities of inspiratory neurons in the medullary respiratory center of neonatal rats. Methods The medulla oblongata slices of neonatal rats(aged 0-4 days)including the medial region of the nucleus retrofacialis with the hypoglossal nerve rootlets retained were prepared.The slices were perfused with artificial cerebrospinal fluid(ACSF), and the activity of the inspiratory neurons in the medial region of the nucleus retrofacialis and the respiratory rhythmical discharge activity of the hypoglossal nerve rootlets were simultaneously recorded using microelectrodes and suction electrodes, respectively.The ACSF, 5% sevoflurane, GABAA receptor blocker bicuculline 10 μmol/L and combination of 5% sevoflurane and 10 μmol/L bicuculline were added to the perfusion liquid after the discharge activity was stable.The respiratory cycle(RC), inspiratory time(TI), integral amplitude(IA)and changes in peak frequency(PFn)of the inspiratory neurons were recorded. Results Compared with that after giving ACSF, RC was significantly prolonged, TI was shortened, and IA and PFn were decreased after giving sevoflurane, and RC was significantly shortened, IA and PFn were increased(P 0.05). Compared with that after giving sevoflurane, RC was significantly shortened, TI was prolonged, and IA and PFn were increased after giving sevoflurane and bicuculline(P<0.05). Conclusion Sevoflurane inhibits the discharge activities of inspiratory neurons through GABAA receptors in the medullary respiratory center of neonatal rats. Key words: Anesthetics, Inhalation; Respiratory Center; Neurons