Selective mediation of kappa-opioid central cardiovascular effects by ascending noradrenergic pathways.
The role of ascending noradrenergic pathways in the mediation of central opiate-induced cardiovascular effects has been investigated. The effects of selective kappa- and delta-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 delta-agonist responses were not modified in lesioned rats. In marked contrast the pressor effect of the kappa-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 kappa- and delta-opiates in the NTS are mediated via different mechanisms, and provide evidence for selective functional actions of endogenous opioids within brain nuclei.
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001921:Brain / Q000502:physiology*; D002320:Cardiovascular Physiological Phenomena; D004723:Endorphins / Q000502:physiology*; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology; D008845:Microinjections; D009294:Narcotics / Q000494:pharmacology; D009638:Norepinephrine / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D004723:Endorphins; D009294:Narcotics; D009638:Norepinephrine