OBJECTIVETo observe the effect of glycine on the discharge activities of inspiratory neurons in the medulla oblongata slices of neonatal rats.

METHODSNeonatal rat medulla oblongata slices including the medial region of the nucleus retrofacialis (mNRF) with the hypoglossal nerve rootlets retained were prepared. The activity of the inspiratory neurons in the mNRF and the respiratory rhythmical discharge activity (RRDA) of the hypoglossal nerve rootlets were simultaneously recorded using microelectrodes and suction electrodes, respectively. The effect of glycine on the rhythmical respiration was investigated by administration of glycine receptor agonist and its specific antagonist strychnine (STR) into a modified Kreb's perfusion solution (MKS).

RESULTSGlycine significantly shortened the inspiratory time (TI) and integral amplitude (IA) of the inspiratory neurons and decreased the peak frequency (PFn). By contrast, STR induced a decrease in the expiratory time (TE) and respiratory cycle (RC) of the inspiratory neurons, but the peak frequency was not significantly affected.

CONCLUSIONGlycine and its receptor play a role in the modulation of the rhythmical respiration, and glycine is probably involved in the phase-switching between expiration and inspiration by affecting the inspiratory neurons.