Cs. Maldonadoirizarry et al., EFFECTS OF COCAINE AND GBR-12909 ON BRAIN-STIMULATION REWARD, Pharmacology, biochemistry and behavior, 48(4), 1994, pp. 915-920
Cocaine and GBR-12909, two dopamine reuptake blockers, were administer
ed in a multiple current rate-frequency curve-shift test of intracrani
al self-stimulation (ICSS) reward in rats with medial forebrain bundle
(MFB) electrodes. Acute injections of cocaine (0, 5, 15, 30 mg/kg, IP
) increased ICSS reward at all currents (501, 316, 200 mu Amps) as mea
sured by decrease half-maximal frequency threshold. Cocaine also incre
ased operant motor performance but only at the low current. In additio
n, cocaine increased dynamic interval at the highest dose at all curre
nts. Similar treatment with GBR-12909 (0, 5, 10, 20 mg/kg, IP) signifi
cantly increased ICSS reward (decreased threshold) especially at the m
edium dose in all currents and had no significant effects on operant m
otor performance or dynamic interval. The major novel finding of the p
resent study is that the rewarding effects of both drugs was not depen
dent on the choice of stimulation current, which is discussed as simpl
ifying future psychophysical testing of psychostimulant drugs in the I
CSS rate-frequency curve-shift paradigm.