PMID: 589437Nov 4, 1977

Differential effects of morphine and D-amphetamine on self-stimulation from closely adjacent regions in rat midbrain

Brain Research
J M Liebman, D S Segal


The effects of morphine were investigated on self-stimulation from numerous electrode placements in the area of the substantia nigra or in the ventral half of mesencephalic central gray matter. Before pharmacological testing, current intensity was reduced to yield stable, submaximal rates of self-stimulation. Rats were then injected daily with morphine for 10 days, and were tested three hours after injection. Between days 5 and 10 of treatment, many rats self-stimulated at more than 150% of baseline, but some others reduced self-stimulation to as little as 3% of baseline. Histological evaluation revealed that morphine facilitated self-stimulation when the electrode tip was located more than 0.3 mm from substantia nigra or more than 0.2 mm from the midline of central gray. In rats with electrode tips closer to substantia nigra or to the midline of central gray, morphine often reduced or failed to alter self-stimulation rates. The effects of a low dose of D-amphetamine (0.1 mg/kg) were investigated on electrode placements in the substantia nigra area. Placements close to the dorsal border of substantia nigra yielded less facilitation of self-stimulation by D-amphetamine than did placements located more dorsally or medially. Possi...Continue Reading


Jan 1, 1971·Acta Physiologica Scandinavica. Supplementum·U Ungerstedt
Dec 15, 1973·Biochemical Pharmacology·T J CiceroL G Sharpe
Sep 1, 1973·Behavioral Biology·J M LiebmanJ C Liebeskind
Sep 28, 1973·Psychopharmacologia·S A Lorens, C L Mitchell


Jan 1, 1981·Psychopharmacology·W T NelsonS J Ellman
Dec 1, 1980·Pharmacology, Biochemistry, and Behavior·R M StutzP A Harvan
Mar 1, 1981·Pharmacology, Biochemistry, and Behavior·J M NazzaroE L Gardner
Jan 1, 1982·Pharmacology, Biochemistry, and Behavior·R L PreshawR M Stutz
May 1, 1983·Pharmacology, Biochemistry, and Behavior·K B Franklin, F Vaccarino
Jul 1, 1992·Pharmacology, Biochemistry, and Behavior·D Corbett
May 25, 1979·Brain Research·R U EspositoC Kornetsky
Jan 1, 1982·Annals of the New York Academy of Sciences·C Kornetsky, G Bain

Related Concepts

Midbrain Structure
Morphine Sulfate (2: 1), Pentahydrate
Raphe Nuclei
Self Stimulation
Substantia Nigra Structure

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