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Unformatted text preview: 1 Drugs & Addiction: Part 1: Return to Psychoactive drugs Section NOT covered on the Tests is in Gray I. Review of Basic Concepts and Definitions Psychoactive Drugs-any chemical substance that alters mood or behavior as a result of alterations in the functioning of the brain Tolerance-decreased sensitivity to the effects of a drug as a result of exposure Sensitization- increased sensitivity to the effects of a drug as a result of exposure Withdrawal Syndromes- typically effects opposite to those produced by the drug Addiction (one definition) - habitual drug use with adverse social and/or health effects that resists attempts to stop the drug use Physical dependenc y - the onset of withdrawal syndromes upon removal of the drug The mesolimbic dopamine system (AKA - mesotelencephalic DA system)- is often implicated as the basis of many of the rewarding aspects of drugs that are taken recreationally and that are abused This system originates in nuclei in the hypothalamus. Bundles of neurons here project to the ventral tegmental area (VTA). Dopamine releasing neurons in the VTA project to the nucleus accumbens , septum and prefrontal cortex . This system has been implicated in the reinforcing properties of some drugs. 2 II. Review of Synaptic Mechanisms of Drug Action A. Drugs can be: Agonists- drugs which mimic or enhance the effects of a neurotransmitter Antagonists- drugs which reduce or block the effects of a neurotransmitter B. Drug Effects on Synaptic Transmission- Drugs can influence -neurotransmitter synthesis -neurotransmitter release -receptor binding -receptor activation -neurotransmitter reuptake -neurotransmitter breakdown Drugs can also influence -cellular metabolism -numbers of receptors -efficacy of receptors -gene expression In addition to immediate effects on synaptic transmission, drugs can cause neuronal adaptation , e.g., receptor downregulation 2 II. Review of Synaptic Mechanisms of Drug Action II....
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This note was uploaded on 01/20/2010 for the course PSY 1 taught by Professor Staff during the Spring '08 term at University of Texas at Austin.
- Spring '08