The pedunculopontine tegmental nucleus and the role of cholinergic neuronsin nicotine self-administration in the rat: A correlative neuroanatomical and behavioral study
Aj. Lanca et al., The pedunculopontine tegmental nucleus and the role of cholinergic neuronsin nicotine self-administration in the rat: A correlative neuroanatomical and behavioral study, NEUROSCIENC, 96(4), 2000, pp. 735-742
The objective of this study was to determine whether the pedunculopontine t
egmental nucleus plays a role in the maintenance of nicotine self-administr
ation, and whether the ascending cholinergic projection from this nucleus t
o midbrain dopamine neurons in the ventral tegmental area might be involved
. Studies were done with rats trained to self-administer nicotine intraveno
usly. Self-administration was examined before and after the pedunculopontin
e tegmental nucleus was lesioned with the ethylcholine mustard aziridinium
ion, a selective cholinergic toxin. Lesions were assessed qualitatively and
quantitatively in histological sections stained for either nicotinamide ad
enine dinucleotide phosphate-diaphorase histochemistry to identify choliner
gic neurons, or for Nissl. Self-administration was also tested after an acu
te manipulation in which microinfusions of the nicotinic cholinergic antago
nist dihydro-beta-erythroidine were made into the pedunculopontine tegmentu
m.
Infusions of neurotoxin into the pedunculopontine tegmentum reduced nicotin
e self-administration behaviour when tested weeks later. Toxin treatment re
duced the number of cholinergic neurons in the tegmentum, while largely spa
ring the non-cholinergic population in this area. Lesions were Limited to t
he pedunculopontine area and did not extend to the neighboring laterodorsal
tegmental nucleus or to the substantia nigra Acute manipulation of the ped
unculopontine tegmental nucleus with microinfusions of dihydro-beta-erythro
idine also produced an attenuation of nicotine self-administration.
Collectively these data show that the pedunculopontine tegmental nucleus is
part of the neuronal circuitry mediating nicotine self-administration, and
that the population of cholinergic neurons is likely a critical element. (
C) 2000 IBRO. Published by Elsevier Science Ltd.