Toni Shaun Shippenberg

Learn More
The mesolimbic dopaminergic system has been implicated in mediating the motivational effects of opioids and other drugs of abuse. The site of action of opioids within this system and the role of endogenous opioid peptides in modulating dopamine activity therein remain unknown. Employing the technique of in vivo microdialysis and the administration of highly(More)
An unbiased conditioned place preference paradigm was used to examine the neuroanatomical substrates mediating the reinforcing and aversive effects of mu and kappa opioid agonists. Unilateral microinjection of the selective mu agonist DAMGO into the ventral tegmental area (VTA), the origin of the mesolimbic and mesocortical dopamine (DA) systems, resulted(More)
Dopaminergic afferents arising from the ventral tegmental area (VTA) are crucial elements in the neural circuits that mediate arousal, motivation, and reinforcement. Two major targets of these afferents are the medial prefrontal cortex (mPFC) and the nucleus accumbens (NAc). Whereas dopamine (DA) in the mPFC has been implicated in working memory and(More)
Repeated intermittent administration of cocaine has been shown to sensitize animals to the locomotor-activating effects of this agent. The neurobiochemical basis of this phenomenon, however, remains only partially understood. The present study sought to characterize basal dialysate dopamine (DA) concentrations within the nucleus accumbens (NAc), 2, 12 or 22(More)
An involvement of the mesolimbic dopamine (DA) system in mediating the motivational effects of opioids has been suggested. Accordingly, the present study employed the technique of in vivo microdialysis to examine the effects of selective mu-, delta-, and kappa- opioids on DA release in the nucleus accumbens (NAC) of anesthetized rats. Microdialysis probes(More)
  Rationale: Previous research has shown that kappa-opioid receptor agonists decrease intravenous cocaine self-administration. These agents also block the development of sensitization that occurs following repeated exposure to cocaine, which is thought to be important in the maintenance and reinstatement of compulsive drug-seeking behavior. Objectives: This(More)
The dopamine transporter (DAT) terminates dopamine (DA) neurotransmission by reuptake of DA into presynaptic neurons. Regulation of DA uptake by D(2) dopamine receptors (D(2)R) has been reported. The high affinity of DA and other DAT substrates for the D(2)R, however, has complicated investigation of the intracellular mechanisms mediating this effect. The(More)
The magnitude and duration of dopamine (DA) signaling is defined by the amount of vesicular release, DA receptor sensitivity, and the efficiency of DA clearance, which is largely determined by the DA transporter (DAT). DAT uptake capacity is determined by the number of functional transporters on the cell surface as well as by their turnover rate. Here we(More)
This study examined a possible peripheral site of action of opioids in the modulation of the response to noxious pressure on inflamed tissue. Rats developed a unilateral localized inflammation upon injection of Freund's complete adjuvant into one hindpaw. 4-6 days after inoculation, intraplantar administration of mu, delta and kappa selective agonists(More)
In HEK 293 cells expressing the human dopamine transporter (DAT), a 10-min incubation with 10 microM cocaine followed by extensive washing resulted in a 30% increase in [3H]dopamine (DA) uptake as well as an increase in cell surface DAT in biotinylation experiments. Consistent with this novel regulation, [3H]DA uptake into synaptosomes prepared from the(More)