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Reward. Reward Psychopharmacology. Rewards can be chemical or natural f ood, exercise, sex, drugs Transiently or permanently alter neurochemical pathways d opamine , serotonin, GABA, glutamate This subsequently alters psychological, physiological, and behavioral pathways.
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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
Reward Pathways….are complicated………… 1. Mesocorticolimbic: Ventral tegmental area (hindbrain) Nucleus accumbens (forebrain) Prefrontal Cortex 2. Mesopontine: Ventral tegmental area PedunculopontineTegmentum (hindbrain) 3. Nigrostriatal: Ventral tegmental area Substantianigra (midbrain) Striatum (forebrain)
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
Heroin and Morphine (Opiates) • Act on GABA and µ-opiod pathways, particularly, in the brain, on medium spiny neurons
Cocaine and Ecstasy (Psychostimulants) • Act on dopamine and serotonin pathways, particularly on neurotransmitter reuptake transporters For serotonin: cocaine and ecstasy block SERT
Nicotine and Caffeine (Psychostimulants) • Act on cholinergic pathways, particularly increasing the rate and frequency of neuronal firing
Alcohol • Acts on GABA and glutamate pathways, particularly by acting pre- or post-synaptically
The Effects of Gene Expression on Drug Intake (Neural Genetics)
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
Per2-mutant mice drink more alcohol and crave alcohol more often
….and higher circulating levels of alcohol at all hrs of the day
What about in humans? • Humans with certain single-nucleotide polymorphisms of Per2 are more likely to become alcohol dependent