Sm. Brudzynski et F. Barnabi, CONTRIBUTION OF THE ASCENDING CHOLINERGIC PATHWAYS IN THE PRODUCTION OF ULTRASONIC VOCALIZATION IN THE RAT, Behavioural brain research, 80(1-2), 1996, pp. 145-152
It has been well documented that cholinergic stimulation of the mediob
asal forebrain structures induces 20-30 kHz ultrasonic vocalization in
adult rats. If the cholinergic system plays a triggering role for ult
rasonic vocalization, the question arises as to where the source of th
e cholinergic fibres, which innervate the mediobasal forebrain and ind
uce vocalization, is located. In the present study, the role of the as
cending cholinergic projection from the ponto-mesencephalic cholinergi
c nuclei to the mediobasal hypothalamic-preoptic region in production
of 22 kHz calls was investigated. Cholinergic neurons were stimulated
by local injection of L-glutamate and eventual vocalization was record
ed by a S200 bat detector and analyzed sonographically. Intracerebral
injection of L-glutamate into the laterodorsal tegmental nucleus induc
ed short latency, 20-30 kHz ultrasonic calls. Sound frequency (pitch)
and single call duration of the L-glutamate-induced vocalization did n
ot differ from those obtained by cholinergic stimulation of the mediob
asal hypothalamic-preoptic region with carbachol. However, L-glutamate
stimulation of the laterodorsal tegmental nucleus was ineffective or
less effective in 70% of responses, when the terminal fields in the me
diobasal hypothalamic-preoptic region were pretreated with scopolamine
, a muscarinic antagonist. The results demonstrate that the ascending
cholinergic projection from the laterodorsal tegmental nucleus plays a
triggering role for 20-20 kHz vocalization in adult rats.