Striatal dopamine and glutamate release: effects of intranigral injections of substance P.
The levels of extracellular striatal dopamine and glutamate were measured simultaneously in halothane-anaesthetized rats using microdialysis. Unilateral injections of substance P (0.07 nmol) into the substantia nigra, pars reticulata enhanced the levels of dopamine and glutamate in the ipsilateral striatum. Intranigral injections of neurokinin A (0.09 nmol) enhanced the levels of striatal dopamine, and intranigral injections of gamma-aminobutyric acid (300 nmol) or dynorphin A (0.5 nmol) decreased the levels of striatal dopamine, but none of these had any effect on the levels of striatal glutamate. Local perfusion with the dopamine agonists apomorphine (D1/D2), SKF 38393 (D1) or pergolide (D2) (each at 10(5) M) decreased the levels of striatal dopamine and enhanced the levels of striatal glutamate. In unilateral 6-hydroxydopamine-lesioned rats, basal striatal glutamate levels were decreased bilaterally. Furthermore, on the denervated side intranigral substance P stimulation of striatal glutamate levels was enhanced, while on the intact side intranigral substance P stimulation of striatal dopamine and glutamate levels was similar to that seen in normal rats. These findings suggest that striatonigral substance P provides a stimulatory regulation of ipsilateral striatal glutamate release. Furthermore, it is indicated that striatal glutamate release can also be regulated by dopamine terminals.
Reid
M S
MS
Department of Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Herrera-Marschitz
M
M
Kehr
J
J
Ungerstedt
U
U
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D003714:Denervation; D004298:Dopamine / Q000378:metabolism*; D015259:Dopamine Agents / Q000008:administration & dosage; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D006892:Hydroxydopamines; D008297:Male; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D013373:Substance P / Q000008:administration & dosage; D013378:Substantia Nigra / Q000187:drug effects / Q000502:physiology
D015259:Dopamine Agents; D005971:Glutamates; D006892:Hydroxydopamines; D015102:3,4-Dihydroxyphenylacetic Acid; D013373:Substance P; D018698:Glutamic Acid; D016627:Oxidopamine; D004298:Dopamine