M. Fendt et M. Koch, Cholinergic modulation of the acoustic startle response in the caudal pontine reticular nucleus of the rat, EUR J PHARM, 370(2), 1999, pp. 101-107
The startle response is a useful behavioural model to assess drug effects o
n sensorimotor information processing in the mammalian central nervous syst
em. Prepulse inhibition of the acoustic startle response in rats is an oper
ational measure for sensorimotor gating mechanisms which may be necessary f
or attention and response selection. The caudal pontine reticular nucleus i
s a key element of the pathway that mediates the acoustic startle response
and receives an inhibitory cholinergic projection that might be important f
or prepulse inhibition. The present study tested whether prepulse inhibitio
n of acoustic startle is modulated by microinfusions of the muscarinic/nico
tinic acetylcholine receptor agonist carbachol and of the muscarinic acetyl
choline receptor antagonist scopolamine. Carbachol (0-40 nmol/0.5 mu l) dos
e dependently attenuated startle and enhanced prepulse inhibition. Scopolam
ine (0-40 nmol/0.5 mu l) dose-dependently enhanced startle and reduced prep
ulse inhibition at a dose of 10 nmol. Scopolamine (40 nmol) also increased
the spontaneous motor activity of the rats. These findings lend support to
the hypothesis that muscarinic acetylcholine receptors in the caudal pontin
e reticular nucleus inhibit the acoustic startle response and are involved
in the mediation of prepulse inhibition of startle. (C) 1999 Elsevier Scien
ce B.V. All rights reserved.