In vivo neurochemical analysis, by push-pull perfusion, of the mesocortical dopaminergic system of the rat during self-stimulation.
The region immediately adjacent to a self-stimulation site in the medial prefrontal cortex of the unanesthetized rat was prelabeled with 0.5 mu Ci 14C-dopamine (DA) injected through an indwelling guide cannula. Then successive 5 min push-pull perfusions of the site with an artificial CSF were carried out at a rate of 25 microliter/min so that a washout curve of declining radioactivity was generated under control conditions. When square wave 100 Hz pulses were delivered to the contiguous self-stimulation site, the release of 14C-DA was enhanced either during the actual interval of electrical stimulation or in the perfusion sample collected immediately thereafter. In parallel experiments, however, self-stimulation by the rat of its ventral tegmental area failed to alter the kinetics of 14C-DA release from the cortex when homologous loci were perfused. Analyses by thin-layer chromatography of the perfusates for their content of catechol metabolities revealed that the homovanillic acid fraction declined during stimulation, whereas the level of DOPAC remained relatively elevated. Evidence was also obtained for the new synthesis and subsequent release of norepinephrine during the stimulation of the cortex of the rat. These results suggest that endogenous dopamine, because of the notable alterations in its release and metabolism, plays an important synaptic role in the mediation of self-stimulation behavior at the level of the cerebral cortex.
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D002395:Catecholamines / Q000378:metabolism*; D002540:Cerebral Cortex / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism*; D004558:Electric Stimulation; D006719:Homovanillic Acid / Q000378:metabolism; D008297:Male; D008781:Methyltyrosines / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D009647:Normetanephrine / Q000378:metabolism; D010477:Perfusion; D051381:Rats; D012653:Self Stimulation / Q000502:physiology*
D002395:Catecholamines; D008781:Methyltyrosines; D009647:Normetanephrine; D015102:3,4-Dihydroxyphenylacetic Acid; D004298:Dopamine; D009638:Norepinephrine; D006719:Homovanillic Acid