Effects of intranigral substance P and neurokinin A injections on extracellular dopamine levels measured with microdialysis in the striatum and frontoparietal cortex of rats

Reid, M.S.; Herrera-Marschitz, M.; Ungerstedt, U.

Journal of Neurochemistry 57(3): 970-974

1991


ISSN/ISBN: 0022-3042
PMID: 1713616
DOI: 10.1111/j.1471-4159.1991.tb08245.x
Accession: 007277609

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Abstract
Extracellular levels of dopamine (DA) and its metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), in the sriatum 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 .mu.l) into the substantia nigra pars reticulata (SNR) increased DA and DOPAC levels .apprx. 30% in the ipsilateral striatum and .apprx. 50% in the ipsilateral frontoparietal cortex. Injections of neurokinin A (0.09 nmol/0.2 .mu.l) into the SNR increased DNA and DOPAC levels .apprx. 30% in the ipsilateral striatum but did not significantly affect DA levels in the ipsilateral frontoparietal cortex, although DOPAC levels were increased by .apprx. 50%. It is suggested that striatal and cortical DA release is regulated differently by nigral substance P and neurokinin A terminals.

Effects of intranigral substance P and neurokinin A injections on extracellular dopamine levels measured with microdialysis in the striatum and frontoparietal cortex of rats