EFFECTS OF 6-HYDROXYDOPAMINE LESIONS OF THE MEDIAL PREFRONTAL CORTEX ON LOCAL CEREBRAL BLOOD-FLOW AND D-1 AND D-2 DOPAMINE-RECEPTOR BINDINGIN RATS - A QUANTITATIVE AUTORADIOGRAPHIC STUDY

The effects of lesions of the dopamine (DA) nerve terminals in the med ial prefrontal cortex (MPFC) on local cerebral blood flow (LCBF) and D A receptor binding in rats were investigated. 4 mu g of 6-hydroxydopam ine (6-OHDA) was infused stereotaxically into the area of the bilatera l MPFC of rats pretreated with desmethylimipramine, and control rats r eceived a vehicle solution. Twenty-four days after the operation LCBFs of 23 brain regions were measured using the quantitative autoradiogra phic N-isopropyl-p-[I-125]iodoamphetamine technique. D-1 and D-2 DA re ceptor binding in various brain regions was also quantified autoradiog raphically using [H-3]SCH 23390 and [H-3]YM 09151-2 as the respective ligands. 6-OHDA lesions of MPFC produced significant increases in LCBF of the nucleus accumbens, the dorsolateral portion of the caudate-put amen and the anterior cingulate cortex. The lesioned animals did not s how decreased LCBF in MPFC per se. D-1 and D-2 DA receptor binding was not affected in any brain region examined. These results suggest that lesions of the DA nerve terminals in MPFC induce an enhancement of fu nctional activity in the terminal regions of the subcortical DA system s, and that hypofunction of the mesocortical dopamine system does not elicit reduced metabolic activity in the prefrontal cortex.