[Glycine is involved in the modulation of respiratory rhythmical discharge activity in neonatal rat medullary brain slices].

ABSTRACT

OBJECTIVE: To determine the role of glycine (Gly) in the generation and modulation of basic respiratory rhythm. METHODS: Neonatal (0-3 days) SD rats of either sex were used in this study. The medulla oblongata brain slice containing the medial region of the nucleus retrofacialis (mNRF) and the hypoglossal nerve rootlets was prepared, and the surgical procedure was performed in the modified Kreb's solution (MKS) with continuous carbogen (95% O(2) and 5% CO(2)) within 3 min. The rhythmical respiratory discharge activity (RRDA) of the hypoglossal nerve rootlets was recorded using suction electrode. Eighteen medulla oblongata slice preparations were divided into 3 groups and treated for 20 min with Gly receptor specific agonist Gly (10 micromol/L), Gly receptor antagonist strychnine (STR, 1 micromol/L), or Gly+STR after a 20 min Gly application. The changes in RRDA of the hypoglossal nerve rootlets were observed. RESULTS: Gly significantly decreased the inspiratory time and integral amplitude (IA), but the changes of respiratory cycle (RC) and expiratory time (TE) were not statistically significant. STR induced a decrease in expiratory time and respiratory cycle without significantly affecting the inspiratory time or integral amplitud. The effect of Gly on the respiratory rhythm was partially reversed by additional application of STR. CONCLUSION: Gly may play an important role in the modulation of RRDA in the medulla oblongata slice of neonatal rats.