Central noradrenergic pathways are not involved in the pressor response to intracerebroventricular substance P

Intracerebroventricular (i.c.v.) pretreatment of Wistar rats with the catecholaminergic neurotoxin, 6-hydroxydopamine, significantly reduced noradrenaline in the pons/medulla (by 73%) and almost abolished the noradrenaline levels in the spinal cord (by 89%). The pressor response of these animals to i.c.v. angiotensin II (ANGII, 10 ng) was significantly attenuated. In contrast, there was no significant effect on the pressor response to i.c.v. substance P (SP, 100 ng). The results provide evidence that different central pathways mediate the pressor response to ANGII and SP.