Chapter 5 Drugs Addiction and Reward Lecture Date February 19 2015 Pages 125 133 Drug chemical substance that changes the body or its functioning Psychoactive drugs have psychological effects e g anxiety relief hallucinations Ex caffeine alcohol ethanol Agonist mimics or enhances the effect of a naturally occurring neurotransmitter NT Abuse Terminology Addiction Criteria below Have same effect on receptor lock and key match on postsynaptic dendrite soma as NT Increasing effect of NT on receptor can t substitute for NT NT has to be there facilitates or helps binding to receptor catalyzer Blocking reuptake NT removed from synaptic cleft and repackaged into vesicles or degradation of NT levels of NT build up stronger signal over time Speed up exocytosis presynaptic neuron releases NT into synaptic cleft Antagonist blocks or reduces the effect of a NT Binding to a receptor without activating it similar structure but doesn t affect permeability many toxins poisons work like this Reducing the availability of NT e g reducing production release of NT from presynaptic terminals Preoccupation with obtaining drug spends inordinate amount of time trying to get access to drug Compulsive use of drug realizes it s not beneficial still feel like they need access to it High tendency to relapse after quitting Oversimplified definition addiction is more than a physiological biological condition there are other factors just as powerful that have nothing to do with biology socio economic cultural Withdrawal negative reaction when drug use is stopped physiological or psychological Symptoms often the opposite of effects of drug e g withdrawal from elation producing drug depression doesn t work all the time but in many cases it does Tolerance increasing amounts of the drug are required to produce the same results Physiological level due to receptors for drug in postsynaptic membrane being sensitive to concentration receptors will decrease in number sensitivity over time and exposure Drug Types Opiates derived from opium poppy Opium Morphine Heroin ab used since around 4000 BC Early 1800 s effective treatment of intense pain Created as technology caught up Most commonly prescribed high level pain killer Very powerful very addictive very dangerous Late 1800s initially sold as an over the counter analgesic didn t know its dangers at first Called this because it makes you feel like a hero Easy to overdose due to its power Recently many states have seen a rise in heroin addiction because more people have become addicted to other opiates such as morphine or codeine products Codeine Variety of Effects Cough suppressant sold over the counter up until the past few decades stopped so children wouldn t be more vulnerable to opiate addictions later on Analgesic pain relieving morphine most effective as this Hypnotic sleep inducing doesn t take much with powerful ones Produce euphoria intense sense of happiness heroine most effective as this Side Effects addictive Heroine Highly soluble in lipids crosses the blood brain barrier easily Go straight to brain and have immediate effect Major danger is overdose Drug purer than what they re used to Tolerance may inject too much and end up shutting down systems Bind to opiate receptors act as agonists of endogenous opiates endorphins pain relief opiates come in and activate pain numbing circuitry artificially The drug is what we discovered first which is why the receptors and NT are named as such many NT discovered because drugs were studied and they found similar ones naturally in brain Depressants reduce activity of CNS doesn t mean they make the patient become depressed Ethanol ie alcohol ie booze Produced from fermented fruits grains etc ie waste product of bacteria Not the only species which can develop an addiction to this wild elephants in Africa will return to a tree which tends to hold fermented fruit water in its hollow pass down this info Complex action high doses sedative calming hypnotic low doses stimulant inhibits prefrontal cortex which deals in decision making and part that handles limbic system Addictive one of the most dangerous ones in terms of withdrawal symptoms Withdrawal tremors anxiety mood and sleep disturbances delirium tremens in worst cases hallucinations seizures even death needs to be a gradual process Acts as an antagonist of glutamate most prevalent excitatory NT Acts as an agonist of GABA most prevalent inhibitory NT by binding to GABAA receptors cannot substitute for GABA but bind to channel at different area and makes effect greater when GABA binds as well Facilitates opening of Cl channels hyperpolarization of postsynaptic membrane Barbiturates derivatives of barbituric acid Complex action high doses sedative and hypnotic low doses inhibits cortical centers that inhibit behavior talkativeness Antagonist of glutamate Agonist of GABA by binding to GABAA In high doses can open Cl channels even without GABA potentially very dangerous even coma or death Used in medicine as a sedative used to be and sometimes still used as anti anxiety medication Benzodiazepines 1950s Similar to barbiturates but safer Cannot open chloride channel on their own Produce anxiolytic anxiety reducing sedative anti seizure and muscle relaxing effects Sold today as anti anxiety prescriptive drug Addictive Stimulants increase activity of CNS Cocaine derived from coca plant s resin Indigenous people used the leaves to treat altitude sickness help with hunger Considered miracle drug when it first came out mid late 1800s Freud became addicted realized it and reportedly quit Produces euphoria increased alertness relief from fatigue Used to be legal as an ingredient in over the counter medications and Coca Cola 1 part in 50 000 000 Acts as an agonist of dopamine and serotonin by blocking their reuptake Addictive Withdrawal symptoms include depression and anxiety usually not as severe as symptoms for alcohol withdrawal but enough to keep people addicted Long term use can cause neurotoxic effects brain damage seizures and psychotic symptoms Amphetamines Synthetic drugs Methamphetamine speed crank crystal Produce euphoria increase in confidence alertness and concentration Acts as an agonist of dopamine and norepinephrine by increasing their release in the synaptic cleft exocytosis