Anticonflict-like effect of a prefrontal dopaminergic lesion in rats: permissive role of noradrenergic neurons.
The effects of a perfrontal dopamine (DA) lesion were compared to those induced by a combined DA and noradrenaline (NA) lesion, to investigate the permissive role of prefrontal NA terminals in the anxiolytic-like effect of a prefrontal DA lesion. Lesions consisted of bilateral microinjections of 6-hydroxydopamine into the medial prefrontal cortex in rats either given desipramine (25mg/kg) before surgery (DA lesion) or not pretreated with desipramine (combined DA and NA lesions). Three weeks post-surgery, water-restricted rats, given saline or diazepam (2mg/kg), were subjected to a single session in the punished drinking test. Prefrontal DA lesions significantly increased punished drinking in saline-treated rats. This effect was not observed in rats with the dual prefrontal lesions. The ability of diazepam to increase punished drinking was not modified by either lesion. These data suggest that the integrity of NA afferents to the prefrontal cortex is necessary for the anxiolytic-like effect induced by the prefrontal DA lesion. The results also indicate that the effect of diazepam is not mediated by the prefrontal catecholamine afferents.
Departement de Pharmacologie et INSERM U 302. Faculté de Médecine Pitié-Salpetriére, 91, Boulevard de l'Hopital, 75634 Paris Cedex 13, France.
S.
S
Ravard
D.
D
Hervé
M-H.
MH
Thiébot
P.
P
Soubrié
J-P.
JP
Tassin