H. Davidowa et al., CHOLINERGIC MODULATION OF NEURONAL RESPONSES TO CHOLECYSTOKININ IN ANESTHETIZED RATS, Brain research bulletin, 46(5), 1998, pp. 435-440
The aim of this study was to investigate whether the effects of the ne
uropeptide cholecystokinin on neuronal firing can be changed by acetyl
choline in various structures of the brain. Single unit activity was e
xtracellularly recorded in rats anesthetized with urethane, The neuron
s were located in several nuclei of the thalamus, the basal ganglia an
d the cerebral cortex. Neurons responding to the sulfated octapeptide
of cholecystokinin (CCK-8S) were mainly activated by the drug [Wilcoxo
n test (Wt) p < 0.0001, n = 113]. Thalamic neurons could also increase
the number of burst discharges (Wt p < 0.005, n = 39). Iontophoretica
lly administered acetylcholine could reduce the activating effects of
CCK-8S on firing and burst discharges. In its presence, even inhibitor
y effects of CCK-8S predominated (Wt p < 0.0001, n = 113), The suppres
sive action seemed not to depend on the direction of the effect of ace
tylcholine itself and concerned neurons of all locations studied. Atro
pine could diminish or block the suppressive action of acetylcholine.
In the presence of both drugs, CCK-8S mainly activated the neurons (Wt
p < 0.005, n = 43), Atropine itself did not significantly change the
responses to CCK-8S (Wt p > 0.05), It can be concluded that cholecysto
kinin may reduce neuronal firing instead of increasing it during activ
ation of the cholinergic system. (C) 1998 Elsevier Science Inc.