In vivo studies on the enhancement of cholecystokinin release in the rat striatum by dopamine depletion.
The release of cholecystokinin-8-like (CCK) immunoreactivity from the rat striatum has been studied in vivo using brain microdialysis. A basal efflux of CCK-like immunoreactivity was not detectable in the majority of experiments. Intrastriatal infusion of veratrine (100 micrograms/ml) increased striatal dialysate levels of CCK-like immunoreactivity above detection limits, representing an overflow into the interstitial fluid. High concentrations of potassium caused similar but less consistent effects. Extracellular dopamine depletion using alpha-methyl-p-tyrosine or reserpine also increased the dialysate content of CCK-like immunoreactivity. In contrast, inhibition of peptidases reported to hydrolyse CCK in vitro did not affect either basal or evoked efflux of CCK-like immunoreactivity. These data demonstrate that CCK-like immunoreactivity may be released from neuronal elements within the striatum by depolarizing stimuli in vivo, and suggest that increased overflow of CCK-like immunoreactivity is associated with dopamine depletion.
Butcher
S P
SP
Department of Pharmacology, University of Edinburgh, U.K.
Varro
A
A
Kelly
J S
JS
Dockray
G J
GJ
D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism / Q000502:physiology*; D008781:Methyltyrosines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012110:Reserpine / Q000494:pharmacology; D012844:Sincalide / Q000378:metabolism*; D014701:Veratridine / Q000494:pharmacology; D019805:alpha-Methyltyrosine
D008781:Methyltyrosines; D019805:alpha-Methyltyrosine; D014701:Veratridine; D012110:Reserpine; D012844:Sincalide; D004298:Dopamine