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The influence of the D1 antagonist SCH 23390 on the motivational properties of rewarding (morphine, nicotine and diazepam) and aversive (naloxone, phencyclidine and picrotoxin) drugs was studied in the rat in a two-compartment place-conditioning paradigm, which included a pre-conditioning test for spontaneous place-preference. The specific D1(More)
In vivo microdialysis was used to assess the involvement of ventral tegmental area (VTA) mu, delta, and kappa opioid receptors in modulation of basal extracellular ventral striatal dopamine (DA) and DA-metabolite concentrations. Independent groups of chloral hydrate-anesthetized rats were given VTA microinjections of selective opioid agonists, and(More)
Extracellular dopamine and DOPAC (3,4-dihydroxyphenylacetic acid) levels in nucleus accumbens were sampled by microdialysis and quantified with high-performance liquid chromatography during intravenous heroin self-administration sessions in rats. Dopamine levels in 10 and 20 min samples were elevated following the first injection of each session, reaching a(More)
Microdialysis and high-performance liquid chromatography with electrochemical detection were used to determine extracellular levels of dopamine following ventral tegmental morphine injections into chloral hydrate-anesthetized rats. Morphine (13.2 nanomoles in 0.5 microliter of Ringer's solution) caused 50-150% increases in nucleus accumbens dopamine and(More)
The effect of two potent and specific antagonists of 5HT3 receptors, ICS 205-930 and MDL 72222, on the reinforcing properties of amphetamine, morphine and nicotine was studied in rats. Durg-induced reinforcement was assessed by measuring drug-conditioned place preference. ICS 205-930 and MDL 72222 dose-dependently reduced the place preference induced by(More)
Microdialysis and high pressure liquid chromatography were used to assess the effects of ventral tegmental area microinjections of the mu-opioid receptor antagonists D-Pen-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP) and beta-funaltrexamine (beta-FNA) on extracellular ventral striatal dopamine and metabolite concentrations. While CTOP is known to antagonize the(More)
In this paper we report on the effects of intra-VTA infusion of opioid agonists on rat ingestive behavior in a variety of experimental contexts. When the animals were tested outside of their home cages surrounded only by food-pellets (Experiment 1), the injection of the mu-opioid agonist DAMGO, but not the kappa-opioid agonist U-50,488H, into the ventral(More)
In this paper we report on the effects of microinjections of the mu-opioid antagonist CTOP (D-Pen-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2) into the ventral tegmental area (VTA) on activity and ingestive behavior in the rat. Intra-VTA CTOP (0.015, 0.15, and 1.5 nmol per side) dose-dependently increased activity, whereas it had no effect on feeding and drinking(More)