Robert E Sorge

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It is well established that stress induces reinstatement of drug seeking in an animal model of relapse. Here we studied the role of the medial prefrontal cortex (mPFC) and orbitofrontal cortex (OFC) in foot-shock stress-induced reinstatement of cocaine seeking. Groups of rats were trained to self-administer cocaine (0.5 mg/kg per infusion, i.v., 3 h/day for(More)
Facial expression is widely used as a measure of pain in infants; whether nonhuman animals display such pain expressions has never been systematically assessed. We developed the mouse grimace scale (MGS), a standardized behavioral coding system with high accuracy and reliability; assays involving noxious stimuli of moderate duration are accompanied by(More)
We recently demonstrated the utility of quantifying spontaneous pain in mice via the blinded coding of facial expressions. As the majority of preclinical pain research is in fact performed in the laboratory rat, we attempted to modify the scale for use in this species. We present herein the Rat Grimace Scale, and show its reliability, accuracy, and ability(More)
Attempts to explain tobacco addiction have relied heavily on the assumption that each cigarette puff delivers a bolus of nicotine to the brain within seconds. However, nicotine transits from lungs to brain much more gradually than once thought. Nevertheless, animal self-administration studies continue to use rapid (e.g., <3-s) infusions, as well as high(More)
Chronic pain is highly variable between individuals, as is the response to analgesics. Although much of the variability in chronic pain and analgesic response is heritable, an understanding of the genetic determinants underlying this variability is rudimentary. Here we show that variation within the coding sequence of the gene encoding the P2X7 receptor(More)
Postoperative pain management in animals is complicated greatly by the inability to recognize pain. As a result, the choice of analgesics and their doses has been based on extrapolation from greatly differing pain models or the use of measures with unclear relevance to pain. We recently developed the Mouse Grimace Scale (MGS), a facial-expression-based(More)
Using the place-preference conditioning paradigm, we evaluated the potential of the two most prominent cannabinoids found in marijuana, the psychoactive component Δ9-tetrahydrocannabinol (Δ9-THC) and the nonpsychoactive component cannabidiol (CBD), to potentiate extinction of a cocaine-induced and an amphetamine-induced conditioned place preference in rats.(More)
Dopaminergic modulation of neuronal function has been extensively studied in the prefrontal cortex, but much less is known about its effects on glutamate-mediated synaptic transmission in the entorhinal cortex. The mesocortical dopamine system innervates the superficial layers of the lateral entorhinal cortex and may therefore modulate sensory inputs to(More)
There is reason to think that footshock stress-induced reinstatement of cocaine may be affected by the history of drug use and time since termination of drug taking. Here, we assessed the contribution of daily access (hours per day) and duration (number of days) of cocaine self-administration to propensity to reinstate drug seeking following footshock(More)
Buprenorphine reduces both heroin and cocaine intake in opioid addicts, but the mechanisms remain unclear. To determine the effects of chronic buprenorphine treatment on intake of heroin and/or cocaine and measure nucleus accumbens (NAc) dopamine (DA) levels during self-administration. In experiment 1, plasma levels of buprenorphine were determined in rats(More)