Effects of intranigral substance P and neurokinin A injections on extracellular dopamine levels measured with microdialysis in the striatum and frontoparietal cortex of rats.
Extracellular levels of dopamine (DA) and its metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), in the striatum and frontoparietal (sensorimotor) cortex in halothane-anesthetized rats were analyzed simultaneously using in vivo microdialysis. Basal DA levels, measured from the microdialysis perfusate, were 6.4 +/- 0.8 nM (n = 15) in the striatum and 0.9 +/- 0.1 nM (n = 15) in the frontoparietal cortex. Subcutaneous injections of d-amphetamine (2 mg/kg) increased DA levels 10-fold in the striatum and fivefold in the cortex. Injections of substance P (0.07 nmol/0.2 microliters) into the substantia nigra pars reticulata (SNR) increased DA and DOPAC levels approximately 30% in the ipsilateral striatum and approximately 50% in the ipsilateral frontoparietal cortex. Injections of neurokinin A (0.09 nmol/0.2 microliter) into the SNR increased DA and DOPAC levels approximately 30% in the ipsilateral striatum but did not significantly affect DA levels in the ipsilateral frontoparietal cortex, although DOPAC levels were increased by approximately 50%. It is suggested that striatal and cortical DA release is regulated differently by nigral substance P and neurokinin A terminals.
Reid
M S
MS
Department of Pharmacology, Karolinska Institute, Stockholm, Sweden.
Herrera-Marschitz
M
M
Ungerstedt
U
U
D000818:Animals; D002540:Cerebral Cortex / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003342:Corpus Striatum / Q000737:chemistry / Q000378:metabolism*; D003956:Dialysis / Q000379:methods; D004298:Dopamine / Q000032:analysis / Q000378:metabolism*; D007276:Injections, Intraventricular; D007279:Injections, Subcutaneous; D008297:Male; D015287:Neurokinin B / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013373:Substance P / Q000494:pharmacology*; D013378:Substantia Nigra / Q000737:chemistry / Q000378:metabolism
D013373:Substance P; D015287:Neurokinin B; D004298:Dopamine