Effects of microinjection of L-glutamate into locus coeruleus complex area on respiration

Abstract

The experiments were performed on 55 rabbits vagotomied, anesthetized with urethane and immobilized with flaxedil. Injection of L-glutamate (L-glu) into the locus coeruleus complex (Lc-Sc) area led to a marked increase in respiratory frequency (RF) and phrenic nerve discharge rate (phr. d) (16±3.5% and 6.5±2.5%;P<0.01 andP<0.05, respectively), a decrease in inspiratory and expiratory duration, and no obvious change in blood pressure (Bp) was observed. While prazosin (0.5 μg/μl), yohimbin (4 (μg/μl) and propranolol (2μg/μl) were preinjected into the nuclei tractus solitraii (NTS) respectively, the above-mentioned effects of L-glu on respiration was blocked. These results indicate that the excitation of neurons in the Lc-Sc can induce an increase in RF and phr d and the excitative effect of L-glu on RF was mediated by α₁,α₂ and β-receptors in the NTS, while the effect on phrd was mediated differently.

Keywords

locus coeruleus complex / nuclei tractus solitarii / L-glutamate / prazosin / respiration

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