Summary
The role of ascending noradrenergic pathways in the mediation of central opiate-induced cardiovascular effects has been investigated. The effects of selective χ- and δ-opiate agonists microinjected into the nucleus tractus solitarius (NTS) of urethane anaesthetized rats were compared following 6-hydroxydopamine lesions of either the dorsal (DNAB) or ventral (VNAB) noradrenergic bundles. In sham lesioned animals both opiates elicited a significant pressor effect and a variable but consistent bradycardia. The δ-agonist responses were not modified in lesioned rats. In marked contrast the pressor effect of the χ-agonist was abolished in both DNAB and VNAB lesioned rats. The bradycardic response was not significantly modified. These findings are consistent with previous observations that the cardiovascular effects of χ- and δ-opiates in the NTS are mediated via different mechanisms, and provide evidence for selective functional actions of endogenous opioids within brain nuclei.
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Carter, D.A., Lightman, S.L. Selective mediation of ℵ-opioid central cardiovascular effects by ascending noradrenergic pathways. Exp Brain Res 65, 699–702 (1987). https://doi.org/10.1007/BF00235997
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DOI: https://doi.org/10.1007/BF00235997