[Effect of neurotensin in locus coeruleus of rat on vagus-pressor response].

The effect of neurotensin (NT) was studied by method of radioimmunoassay, microinjection and spectrophotofluorometry in locus coeruleus of rat on vagus-pressor response. The results were as follows: (1) The contents of neurotensin immune reactivity (NT-IR) in the nucleus of the tractus solitarius (NTS), LC and hypothalamus were significantly increased by stimulation of the central end of vagi (P less than 0.05); (2) The vagus-pressor response was significantly weakened by NT injection into the LC (P less than 0.01), being dose-dependent; (3) The vagus-pressor response was significantly potentiated by antineurotensin serum injected into the LC (P less than 0.01); (4) The content of noradrenaline (NA) was increased by stimulation of the central end of vagi after microinjection of NT into the LC. The results indicate that endogenous and exogenous NT in the locus coeruleus of the rat may modulate vagus-pressor response, possibly mediated by the increase in the content of NA in LC.