Self-stimulation from the mesencephalon following intraventricular interleukin-2 administration

Intracranial self-stimulation was evaluated among CD-1 mice responding for brain stimulation from the dorsal and ventral aspects of the ventral tegmental area (VTA), Intraventricular interleukin-2 (IL-2) administration (5 ng) in a 1-mu l volume elevated the stimulation frequency required to effect half-maximal responding for brain stimulation from the dorsal A10 region 15 min, 24 h, 48 h, and 1 week following drug administration relative to vehicle-treated animals. Intraventricular IL-2 administration did not influence responding for brain stimulation from the ventral A10 area, and performance of these animals was indistinguishable from the performance of vehicle-challenged animals implanted with a stimulating;electrode in the ventral A10 area. These data suggest that central IL-2 administration reduces the value of previously rewarding brain stimulation from subregions of the VTA. The implications of these data for behavioural pathology are discussed. (C) 1998 Elsevier Science Inc.