Inhibitory effect of GABA on phrenic discharge activity of rabbit through microinjection into nucleus tractus solitarii

Abstract

In 53 anesthetized, paralyzed and artificially ventilated rabbits with bilateral vagotomy and section of sinus nerves, the effects of GABA and related drugs on respiratory performances induced by microinjection of the drugs into nucleus tractus solitarii (NTS) were studied by recording phrenic nerve discharges. GABA significantly depressed respiratory output after injection, diazepam, a drug which potentiates GABAnergic transmission, produced the fame effect as GABA; GABA receptor antagonists, bicuculline methiodide and picrotoxin, augmented phrenic nerve discharges. Neither thyrotropin-releasing hormone nor methionine-enkephaline caused any change in the pattern of phrenic nerve discharges. The results suggest that central endogenous GABAnergic transmission system might be involved in inhibitory regulation of respiration in rabbits and that NTS is a possible acting site of GABAnergie system.

Keywords

GABA / microinjection / nucleus tractus solitarii / inhibition / central regulating mechanism of respiration