Inhibition of gastric functions by stimulation of rat locus coeruleus

To investigate the possible role of central noradrenergic neurons in the regulation of gastric functions, electrical stimulation of the locus coeruleus [LC] and microinjection of noradrenaline [NA] into the ala cinerea (area of the dorsal motor nucleus of the vagi [NDV] and the nucleus tractus solitarius [NTS]) were given to urethane-anesthetized rats. Unilateral electrical stimulation of the LC decreased both the basal levels and the lateral hypothalamic area [LHA]-induced increases in gastric acid output and mucosal blood flow. Microinjection of NA 0.1 and 0.5 micrograms/animal into the ala cinerea also decreased the basal levels of these gastric parameters. From these results, combined with neuroanatomical data from the literature, it is concluded that central noradrenergic inhibitory mechanisms originating from the LC seem to be involved in the regulation of gastric functions, probably at the level of the brain-stem ala cinerea.