Discrete quinolinic acid lesions of the rat prelimbic medial prefrontal cortex affect cocaine- and MK-801-, but not morphine- and amphetamine-inducedreward and psychomotor activation as measured with the place preference conditioning paradigm
Tm. Tzschentke et Wj. Schmidt, Discrete quinolinic acid lesions of the rat prelimbic medial prefrontal cortex affect cocaine- and MK-801-, but not morphine- and amphetamine-inducedreward and psychomotor activation as measured with the place preference conditioning paradigm, BEH BRA RES, 97(1-2), 1998, pp. 115-127
As a part of the mesocorticolimbic system, the medial prefrontal cortex (mP
FC) is thought to participate in the regulation of locomotor activity, moti
vation and reward. The mPFC consists of at least three different subareas.
In previous lesion studies examining this region usually large parts of the
mPFC were destroyed, with little discrimination between the different suba
reas. Therefore, this study was designed to selectively lesion the prelimbi
c area of the mPFC using a relatively low dose of quinolinic acid. In a con
ditioned place preference (CPP) experiment, lesioned and control animals we
re treated with cocaine (15 mg:kg), amphetamine (4 mg/kg), morphine (10 mg/
kg) or MK-801 (0.3 mg/kg) to induce CPP. The lesion blocked the development
of CPP only in animals receiving cocaine, but not in animals receiving amp
hetamine or morphine. MK-801 failed to produce a CPP in both lesioned and u
nlesioned animals. During the conditioning experiment, the acute locomotor
response to the different drugs was also measured. Only the response (in te
rms of locomotion and rearing) to cocaine and MK-801 was reduced to a signi
ficant extent by the lesion, while the response to amphetamine and morphine
was not affected. Also, the lesions did not cause any changes in the spont
aneous activity of the animals when tested without drug. These results show
that even small lesions of the prelimbic subarea of the mPFC are sufficien
t to produce behavioral effects. However, these are apparent only when the
animals are challenged with cocaine or MK-801, but not with amphetamine or
morphine, or when drug-free. This suggests that the mPFC might have a speci
al role in mediating cocaine and MK-801 effects. (C) 1998 Elsevier Science
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