A. Nunez et al., ELECTROPHYSIOLOGICAL PROPERTIES AND CHOLINERGIC RESPONSES OF RAT VENTRAL ORAL PONTINE RETICULAR NEURONS IN-VITRO, Brain research, 754(1-2), 1997, pp. 1-11
In order to characterize the electrophysiological properties of morpho
logically identified neurons of the ventral part of the oral pontine r
eticular (vRPO) nucleus and the effects of cholinergic agonists on the
m, intracellular recordings were obtained from 45 cells in a rat brain
-slice preparation. Intracellular staining was performed with 2% biocy
tin in potassium acetate (1 M)-filled micropipettes. Results demonstra
ted the presence of two types of vRPO neurons. Type I cells (n = 12, 2
4%) were characterized by a break with a decrease of the depolarizing
slope following hyperpolarizing pulses which delayed the return to the
resting V-m and subsequent spike-firing. The delay was antagonized by
4-AP (200-500 mu M) which specifically blocks the transient outward K
f-mediated current I,. Type II neurons (n = 38, 76%) displayed a typic
al depolarizing sag during hyperpolarizing current pulses which was bl
ocked by Cs+. This behavior is characteristic of the hyperpolarization
-activated current I-Q. These two neuronal types displayed different m
orphological features. Most type I and LI cells (100 and 73.7%, respec
tively) were depolarized by acetylcholine (1-15 mu M), carbachol(0.5-1
mu M) and muscarine (1-10 mu M) through the activation of post-synapt
ic muscarinic receptors. The remaining type II cells (26.3%) were hype
rpolarized (1-10 min, 3-15 mV) through the activation of post-synaptic
muscarinic receptors. Results are consistent with the hypothesis that
the vRPO could be a neuronal target of Cch in eliciting paradoxical s
leep because most of its neurons are activated by muscarinic agonists.
(C) 1979 Elsevier Science B.V.