DIFFERENTIAL-EFFECTS OF YM-14673, A THYROTROPIN-RELEASING-HORMONE ANALOG, ON DOPAMINE RELEASE IN THE DORSAL AND VENTROLATERAL DIVISION OF THE STRIATUM OF RATS

The effects of the thyrotropin-releasing hormone analogue, N-alpha-[{( S)-4-oxo-2-azetidinyl} -carbonyl]-L-histidyl-L-prolinamide dihydrate ( YM-14673), on extacellular levels of dopamine, L-3,4-dihydroxyphenylac etic acid (DOPAC) and homovanillic acid (HVA) in the dorsal and ventro lateral parts of the striatum were studied in freely moving rats using in vivo microdialysis. Local injection of YM-14673 (0.1 mu g/0.5 mu l ) into the dorsal striatum through a cannula secured alongside a micro dialysis probe produced a 36 % increase in dopamine efflux, whereas th e treatment did not significantly affect extracellular levels of DOPAC and HVA. A similar injection of YM-14673 into the ventrolateral stria tum produced a 46 % increase in dopamine efflux and a slower-onset gra dual increase in both DOPAC and KVA levels. The results suggest that t he dorsal and the ventrolateral parts of the striatum are differential ly involved in the effects of YM-14673 on striatal dopamine release.