Neurotensin increases extracellular striatal dopamine levels in vivo

• Published in: Neuropeptides (Edinburgh) Vol. 22; no. 3; pp. 175 - 183
• Main Authors: Chapman, M.A., See, R.E., Bissette, G.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.07.1992; Elsevier
• Subjects: 3,4-Dihydroxyphenylacetic Acid - metabolism; Animals; Biological and medical sciences; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Cocaine - pharmacology; Consciousness; Corpus Striatum - drug effects; Corpus Striatum - metabolism; Dialysis; Dopamine - metabolism; Ergolines - pharmacology; Extracellular Space - drug effects; Extracellular Space - metabolism; Female; Fundamental and applied biological sciences. Psychology; Homovanillic Acid - metabolism; Microinjections; Neurotensin - antagonists & inhibitors; Neurotensin - pharmacology; Nucleus Accumbens - drug effects; Nucleus Accumbens - metabolism; Quinpirole; Rats; Rats, Sprague-Dawley; Vertebrates: nervous system and sense organs; Dopamine; Rat; Rodentia; Central nervous system; Corpus striatum; Basal ganglion; Neurotensin; Catecholamine; Extracellular; Neuropeptide; Nucleus accumbens; In vivo; Vertebrata; Mammalia; Microdialysis; Brain (vertebrata)
• ISSN: 0143-4179; 1532-2785
• DOI: 10.1016/0143-4179(92)90160-X

This study employed intracranial microdialysis to assess the effects of neurotensin (NT) infusion on extracellular dopamine (DA) and DA metabolite concentrations in the rat striatum and nucleus accumbens, and the effects of NT on alterations in extracellular DA levels induced by cocaine and the DA D-2 receptor agonist, quinpirole. Direct NT infusion (.10, 1.0, 10.0 μM) did not significantly affect extracellular DA in the nucleus accumbens, but did produce a significant increase in the DA metabolite homovanillic acid (HVA). In contrast, direct NT infusion produced an increase in striatal DA levels, without altering DA metabolites. Neurotensin infusion (.10 μM) into the striatum significantly attenuated the peak DA increase induced by an intraperitoneal (IP) injection of a low dose (10.0 mg/kg) but not a high dose (30.0 mg/kg) of cocaine. Neurotensin infusion (.10 μM) did not affect the decrease in DA and its metabolites induced by an IP injection of a low dose of quinpirole (.03 mg/kg), but did alter the decrease in HVA induced by a high dose of quinpirole (.10 mg/kg). These results suggest that NT differentially affects in vivo DA release in the striatum and nucleus accumbens, and further strengthens the assertion that NT is an important modulator of dopaminergic function.