Effects of Anticholinesterase Agents on Synaptic Transmission in the In Vitro andIn Vivo Pontine Reticular Formation. An Electrophysiological Characterization of Medical Pontine Reticular Formation (mPRF) Neuronal Response to Cholinergic and Serotonergic

摘要

Carbachol treatment of medial pontine reticular formation neurons(mPRF) neuronsresulted in depolarization associated with an increase in input resistance. The inward current elicited was dependent on extracellular potassium. Carbachol also elicited a hyperpolarization associated with a conductance increase also dependent on potassium. Muscarinic responses were relatively insensitive to pirenzepine indicating mediation by non-M1 receptors. Nicotinic agonists elicited a depolarization in 77% of neurons with an inward current and conductance increase. This response was sensitive to dihydro-B-ethroidine, an antagonist of neuromuscular type nicotinic responses. Application of soman resulted in depolarization and excitation of mPRF neurons. This action was absent in the presence of tetrodotoxin. Methacholine, responses were enhanced, consistent with mediation of the soman excitation by the blockage of esterase activity. Serotonin excited 62% of the neurons, associated with inward current. These responses had a reversal potential close to that expected for potassium, consistent with a decrease in potassium conductance. The remainder became hyperpolarized.