Effects of GABA and L-glutamic acid on the potassium-evoked in vitro release of substance P- and neurokinin A-like immunoreactivities are different in the rat striatum and substantia nigra.
Slices of the rat substantia nigra and striatum were superfused in vitro to measure release of tachykinins (TKs). Potassium (30 and 60 mM) infusion caused a 3- to 10-fold outflow of both substance P-like immunoreactivity (SP-LI) and neurokinin A-like immunoreactivity (NKA-LI) in the substantia nigra as well as in the striatum as measured by radioimmunoassay. The potassium-evoked release of SP-LI and NKA-LI was significantly, but not completely (by 25-70%) inhibited by simultaneous perfusion with L-glutamic acid (50 microM) and gamma-aminobutyric acid (GABA, 50 microM) in the substantia nigra. No significant inhibition was, however, observed in the striatum. The present data indicate a differential regulation of tachykinins in the striatum and substantia nigra by L-glutamic acid and GABA. The presynaptic regulation of TK release may therefore differ in the dendritic and terminal region of the striatonigral pathway.
Humpel
C
C
Department of Psychiatry, University Hospital Innsbruck, Austria.
Saria
A
A
D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D005071:Evoked Potentials / Q000187:drug effects*; D005260:Female; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D066298:In Vitro Techniques; D015288:Neurokinin A / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013373:Substance P / Q000378:metabolism*; D013378:Substantia Nigra / Q000187:drug effects / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D005971:Glutamates; D013373:Substance P; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D011189:Potassium Chloride; D015288:Neurokinin A; D011188:Potassium