Conj 556 “Addiction: Mechanisms, Prevention, Treatment” Charles Chavkin Department of Pharmacology University of Washington

>150 faculty Major grants from NIAAA, NIDA, and NIMH UW Centers: Addictive Behaviors Research Center Alcohol and Drug Abuse Institute Center for Drug Addiction Research Center for Functional Genomics & HCV-Related Liver Disease Center for Healthcare Improvement for Addictions, Mental Illness and Medically Vulnerable Populations Center for the Study of Health & Risk Behaviors Fetal Alcohol and Drug Unit Fetal Alcohol Syndrome Diagnostic & Prevention Network Innovative Programs Research Group Social Development Research Group

Societal structure and legal system Family structure and risky behaviors - initiation of drug use Underserved populations at risk College-age binge consumption, pre-addiction behaviors Co-morbid psychiatric and addictive disorders Sequelae of drug abuse: teratogenesis, HIV, HepC Molecular pharmacology of abused drugs Animal models of addictive behavior MACRO SCALE INDIVIDUAL NEURONAL

What does it mean to be a ‘broadly trained’ scientist studying the basis of addiction: mechanisms, prevention & treatment ?

What are the mechanisms of addictive drug action? How do the drugs affect the brain to produce craving and drug compulsion? How does the underlying brain chemistry affect the response to drugs? -- molecular and neuronal basis of behavior

What does it mean to be a ‘broadly trained’ scientist studying the basis of addiction: mechanisms, prevention & treatment ? What are the risk factors controlling initiation? What are the social factors sustaining drug use? What are the external forces controlling relapse? What is ‘harm reduction’, and who are ‘at-risk-youth’? What are the social, biological and genetic factors controlling addiction risk ?

What does it mean to be a ‘broadly trained’ scientist studying the basis of addiction: mechanisms, prevention & treatment ? How do we predict which interventions are likely to be effective? How do we design clinical trials that assess treatment efficacies? What new behavioral or pharmacological interventions need to be considered?

What is Addiction? Compulsive, out-of-control drug use, despite adverse consequences. Substance dependence/abuse. Specific DSM-IV criteria. Voluntary intake Voluntary intake EuphoriaTolerance Physical dependence Sensitization Involuntary - compulsive intake Involuntary - compulsive intake cravings, obsession, self-destructive behavior Addiction readily reversible - high relapse risk

DSM-IV Criteria for Substance Dependence A maladaptive pattern of substance use, leading to clinically significant impairment or distress, as manifested by three (or more) of the following, occurring at any time in the same 12-month period: Tolerance Withdrawal Loss of intake control, Craving Substance acquisition, use and recovery consumes a major proportion of the affected person’s time Reduction in alternative activities Use is continued despite objective evidence of harm

What are the goals of this course? We want you to understand the major Research themes: Social forces that control access and initiation of drug use Individual factors that confer vulnerability Effective treatment options Neurobiological effects on brain structure and function

Goals of the course con’t: What does it mean to be broadly trained? Be able to intelligently discuss the question: “What would a CURE for addiction look like?”

What addictive substances will we be considering? Alcohol Psychostimulants (cocaine & amphetamine) Marijuana and hashish Opiates (heroin, morphine, oxycodone) Others: nicotine, caffeine, inhalants, hallucinogens, other prescription drugs… Behaviors: gambling, over-eating, sex….

Alcohol (ethyl alcohol) Basic Pharmacology of Alcohol (ethyl alcohol) Non-potent compound: 80 mg/dL (0.08%) Nonspecific compound: (1) Potentiates the inhibitory effects of the transmitter GABA by altering the conformation of the heteropentameric GABA A receptor and increases Chloride ion entry into neurons. (2) Inhibits the activation of NMDA-type glutamate receptors reducing Sodium and Calcium ion entry into neurons.

Alcohol (con’t) Basic Pharmacology of Alcohol (con’t) Acute: produces dose-dependent intoxication, loss of behavioral inhibition, sedation, impaired judgment, slurred speech, ataxia. At higher doses: loss of consciousness, anesthesia, coma, respiratory depression, cardiovascular depression. Chronic: hepatitis and cirrhosis, gastrointestinal bleeding, hypertension, thiamine deficiency. Teratogenicity: fetal alcohol spectrum disorders.

Major molecular pharmacological questions for Ethanol: How does its binding affect receptor functioning? Do different receptor isoforms differ in sensitivity? How does ethanol tolerance occur? Can a specific antagonist be designed based on an understanding of ethanol action? Neural Systems level question: How does ethanol activate the dopamine-reward pathways to cause changes in the brain that result in addiction?

Basic Pharmacology of Psychostimulants (cocaine & methamphetamine, dextroamphetamine, methylphenidate) Indirect acting sympathomimetics: block the reuptake of the neurotransmitters: dopamine, norepinephrine and serotonin Nerve terminal NT reuptake Vesicular repackaging Vesicular fusion and transmitter release

Basic Pharmacology of Psychostimulants (con’t) Acute: arousal, euphoria, agitation, restlessness, insomnia, anorexia, tachycardia, hyperthermia, seizures. Chronic: psychotic delusions and paranoia. dopamine - euphoria, motor control, sexual arousal norepinephrine - affect, arousal, euphoria, learning serotonin - affect, appetite, sleep, sexual behavior, anxiety, pain

Major molecular pharmacological questions for Psychostimulants: How do cocaine and amphetamine affect synaptic plasticity leading to long term potentiation (LTP) and cellular events underlying learning? How do the effects on dopamine, norepinephrine and serotonin contribute to the reinforcing and addictive effects of these drugs? Can these insights be used to develop new therapeutics able to block or reverse the addictive effects of psychostimulants?

Basic Pharmacology of Marijuana and hashish Marijuana  9 Tetrahydrocannabinol (THC) is the Active alkaloid from the cannabis plant Currently the most commonly used illegal drug in US Anandamide is the endogenous ligand Binds and activates abundant G-protein coupled receptors in brain (CB1 and CB2); reduces neuronal excitability by: - increasing K + conductance and - decreasing Ca + + conductance Rimonabant (Sanofi) is a specific antagonist

Major molecular pharmacological questions for THC: How does THC tolerance occur? How will rimonabant or related CB1 antagonists be incorporated as therapeutics? Neural Systems level question: How does THC activate the dopamine-reward pathways to cause effects resulting in addiction?

Basic Pharmacology of Opiates (heroin, morphine, oxycodone) Mu (  ), Kappa (  ), and Delta (  ) type opioid receptors Mu (  ), Kappa (  ), and Delta (  ) type opioid receptors Mu receptor activation induces euphoria, Kappa receptor activation produces dysphoria Mu receptor activation induces euphoria, Kappa receptor activation produces dysphoria Enkephalins, Endorphins and Dynorphins are the endogenous ligands that are released during stress to induce analgesia, immobility (sedation), euphoria or dysphoria. Enkephalins, Endorphins and Dynorphins are the endogenous ligands that are released during stress to induce analgesia, immobility (sedation), euphoria or dysphoria. Naloxone, Naltrexone, and Nalmefene are Mu antagonists Naloxone, Naltrexone, and Nalmefene are Mu antagonists Methadone and Buprenorphine are weak mu agonists used in opiate addiction treatment. Methadone and Buprenorphine are weak mu agonists used in opiate addiction treatment.

Major molecular pharmacological questions for Opiates: How does tolerance occur? What are the mechanisms of withdrawal? Neural Systems level question: How does morphine activate the dopamine-reward pathways to cause changes in the brain resulting in addiction? How does the dysphoria induced by kappa receptor activation affect the motivation to use drugs of abuse?

These are the basic ‘drug facts’ that every addiction researcher should know. More detail: see Wikipedia Addiction is a chronic relapsing disorder. What can we learn about the molecular pharmacology of relapse?

What are the neurobiological mechanisms controlling relapse? Drug consumption time escalation crash Stress or Cue driven Stress releases endogenous opioids - drives relapse Kappa opioid antagonists block stress-induced relapse buprenorphine is a kappa antagonist. Compulsive, out-of-control drug use, despite adverse consequences. tolerance withdrawal relapse

Dynorphins Endogenous opioid peptides first detected in early 1970’s 1973 Goldstein first detected dynorphin in pituitary extracts 1979 & 1981 Goldstein reported the sequence of dynorphin A 1982 Numa cloned and sequenced the dynorphin precursor NeoendorphinYGGFLRKYPK Dynorphin AYGGFLRRIRPKLKWDNQ Dynorphin BYGGFLRRQFKVVT Dynorphins act at kappa opioid receptors  neo Dyn-ADyn-B  signal seq

How do the dynorphins modulate behavior? (Pliakas et al., 2001)

Immobility (sec) Trial Vehicle treated nor-BNI treated (10 mg/kg i.p.) 5 Day 1 Day 2 * * * * Immobility (sec) Trial 5 Day 1Day 2 Dynorphin KO Dynorphin WT * * McLaughlin et al, 2003

Day 1 Day 2 McLaughlin et al, 2003 Forced swim stress-induced analgesia is blocked by prodynorphin gene disruption Dynorphin is a stress hormone; stress affects drug abuse risk; how does dynorphin release affect cocaine reward?

Day: Preference test, 30 min Cocaine conditioning, 30 min Vehicle conditioning, 30 min Forced swim stress exposure McLaughlin et al, 2003

Forced swim stress potentiation of cocaine conditioned-place preference (CPP) mediated by endogenous dynorphins Prodynorphin gene knockout Similar block with KOR-/-

- - Drug Box Preference (post-pre, sec) Control norBNI KOR-/- Extinction Footshock Cocaine Prime preference Redila, unpublished observations

Kappa opioid receptor activation by endogenous dynorphins during repeated forced swim, chronic social stress, footshock, and chronic pain produces: Stress-induced immobility Stress-induced immobility Stress-induced analgesia Stress-induced analgesia Stress-induced potentiation of cocaine-CPP Stress-induced potentiation of cocaine-CPP Stress-induced reinstatement of craving Stress-induced reinstatement of craving blocked by norBNI, prodyn-/-, KOR-/- blocked by norBNI, prodyn-/-, KOR-/- Since KOR activation produces dysphoria in humans and aversion in rodents, how does it potentiate reward mechanisms?

Pre cocaine Post cocaine  m is the hypothetical rewarding valence of cocaine Mood state Stressed Normal  m (DA, NE + 5HT?) Hypothetical model to explain negative reinforcement prior to cocaine training

U50488 (5mg/kg) cocaine ( 15 mg/kg) time cpp Kappa receptor activation prior to cocaine potentiates (McLaughlin et al, 2006)

Does swim stress create KOR dependent dysphoria?  Cannot use classical CPA conditioning because of the swim  Pair swim with a smell (olfactory cue); test in a different environment with access to smell Olfactory cue

Where in the brain are dynorphins acting to produce their behavioral effects? (how is the stress-circuit organized?) What cell types mediate the effects, (immunohistochemistry) What signal transduction mechanisms are involved, and How is the processing within the neuronal circuit affected? (electrophysiology) Activated kappa opioid receptors are phosphorylated at serine- 369 by G-protein receptor kinase. Phosphoselective antibody KOR-P developed to identify sites of dynorphin action in brain.

Increased KOR-P in GFAP-ir astrocytes and GABAergic neurons in nAcc

a b c e d Land et al, unpublished

a b SA CRF CRF+ KOR NorBNI (-/-) KORp d 65Kda e Saline CRF c 200  m 50  m

Behavioral stress (forced swim, social defeat, neuropathic pain) induce dynorphin release and KOR activation following CRF-R2 receptor activation. Dynorphin/KOR activation seems to encode the aversive (dysphoric) component of chronic stress by p38 MAPK activation. Stress/CRF activates dynorphin-KOR systems broadly in the CNS Therapeutically, KOR antagonism may potentially reduce stress-induced addictive drug craving and reduce relapse risk.

Thanks: Jay McLaughlin Mike Bruchas Ben Land Shuang Li Mei XuMegumi Aita Van RedilaDan Messinger Julia LemosErica Melief