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Published byLaureen Leonard Modified over 9 years ago
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Reward
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Reward Psychopharmacology Rewards can be chemical or natural –food, exercise, sex, drugs Transiently or permanently alter neurochemical pathways –dopamine, serotonin, GABA, glutamate This subsequently alters psychological, physiological, and behavioral pathways
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Reward Pathways….are complicated………… 1. Mesocorticolimbic: Ventral tegmental area (hindbrain) Nucleus accumbens (forebrain) Prefrontal Cortex 2. Mesopontine: Ventral tegmental area Pedunculopontine Tegmentum (hindbrain) 3. Nigrostriatal: Ventral tegmental area Substantia nigra (midbrain) Striatum (forebrain)
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Reward pathways confer type of drug-seeking These types of parameters are used to measure the extent of drug-seeking and likelihood of full-blown addiction
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Self-administering drugs
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Hedonic Substitution: replacing one reward with another
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Diverse Effects of Drugs of Abuse on Neurochemical Pathways
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Heroin and Morphine (Opiates) Act on GABA and µ-opiod pathways, particularly, in the brain, on medium spiny neurons
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Cocaine and Ecstasy (Psychostimulants) Act on dopamine and serotonin pathways, particularly on neurotransmitter reuptake transporters For serotonin: cocaine and ecstasy block SERT
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Nicotine and Caffeine (Psychostimulants) Act on cholinergic pathways, particularly increasing the rate and frequency of neuronal firing
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Alcohol Acts on GABA and glutamate pathways, particularly by acting pre- or post- synaptically
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The Effects of Gene Expression on Drug Intake (Neural Genetics)
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Under-expression of Per2 enhances alcohol intake and craving We created mice that had normal Per2 transcription, but less PER2 translation Measured sleep/wake rhythms, circulating alcohol levels, and overall daily alcohol intake
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Per2-mutant mice drink more alcohol and crave alcohol more often
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….and higher circulating levels of alcohol at all hrs of the day
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What about in humans? Humans with certain single-nucleotide polymorphisms of Per2 are more likely to become alcohol dependent
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