ABSTRACT
The medullary raphe are involved in the control of sympathetic activity during desynchonized sleep and in the modulation of nocicepotive sensory inpts. To determine the particpation cholinergic and opiate mechanisms in the control of sympathetic activity, we microinjected eserine, morphine and naloxone into the nucleus raphe obscurus (NRO) of urethane-anesthetized rats. Arterial blood pressure (BP) and renal nerve activity (RN) were recorded. Eserine and morphine induced significant reductions of RN and BP, while naloxone had no effect. It is suggested that cholinergic and opiate mechanisms particpate in the control of sympathetic activity by th NRO
Subject(s)
Rats , Animals , Male , Morphine/pharmacology , Naloxone/pharmacology , Raphe Nuclei/physiology , Parasympathomimetics , Physostigmine/pharmacology , Sympathetic Nervous System/physiology , Blood Pressure/drug effects , Microinjections , Morphine/administration & dosage , Naloxone/administration & dosage , Physostigmine/administration & dosage , Rats, WistarABSTRACT
Extracellular recordings were made from neurons located in the nucleous raphe obscurus (NRO), raphe magnus (NRM), and raphe pallidus (NRP) of urethane-anesthetized rats. Noxious cutaneous stimuli had excitatory, inhibitory or no effect on neurons of the nuclei. Most of the neurons were excited by noxious stimuli. The distribution of responses of noxiously activated units in the NRO is similar to that observed in the NRM. It is suggested that the NRO is also a component of the endogenous pain suppression system that originates in the NRM