Drug Addiction: From Mice to Men and Back

Transcription

1 Drug Addiction: From Mice to Men and Back Clinical Neurosciences Training Program Mariella De Biasi, Ph.D. Department of Psychiatry Perelman School of Medicine Philadelphia, PA, USA

2 Understanding behavior in health and disease

3 When things go wrong genetics, environmental insults/stresses, injuries Neurodegenerative diseases - Alzheimer s, Mild Cognitive Impairment, Parkinson s Disease, Huntington s Disease, ALS Neuropsychiatric disorders - depression, bipolar disorder, OCD, schizophrenia Disorders of decision-making - addiction, substance abuse, alcoholism, risky behaviors Neurodevelopmental disabilities - mental retardation, autism spectrum disorders, ADHD, seizure disorders Brain injury and repair - stroke, traumatic brain injury and spinal cord injury, neural prostheses brain-machine interfaces Immune, inflammatory, glial disorders - multiple sclerosis, brain inflammation and infection, glioblastoma, chronic pain

4 Incidence and costs of Brain Disorders in the U.S. ( ) Disorder Total # of cases (x millions) annual cost (x billion $) Parkinson s disease stroke spinal cord injury traumatic brain injury Alzheimer s disease multiple sclerosis epilepsy and seizures depression bipolar disorder alcoholism nicotine addiction (attributable conditions) neurodevelopmental disorders (ASD, CP, MR) chronic pain Total 120 million cases $765 billion

5 Incidence and costs of Brain Disorders in the U.S. ( ) Disorder Total # of cases (x millions) annual cost (x billion $) Parkinson s disease stroke spinal cord injury traumatic brain injury Alzheimer s disease multiple sclerosis epilepsy and seizures depression bipolar disorder alcoholism nicotine addiction (attributable conditions) neurodevelopmental disorders (ASD, CP, MR) chronic pain Total 120 million cases $765 billion

6 The Dopaminergic System Food, Sex.. Activation of the VTA results in the release of dopamine

7 Nicotine is addictive Nicotine in tobacco Alters synaptic function Produces neural adaptations Changes behaviors

8 Nic nachrs Binding of nicotine to nachrs in the VTA results in the release of dopamine

9 Addiction: the hijacking of the mesolimbic dopamine system

10 Drug Dependence 1. Impaired control over use of the drug. 2. Strong desire (or craving ) to take it. 3. Much time taken obtaining/using/recovering. 4. A high priority given to drug use relative to other activities. 5. Continued use of the drug despite the harm that it causes. 6. Development of tolerance to the effects of the drug. 7. Withdrawal symptoms on cessation of use.

11 Nicotine-withdrawal Symptoms in Humans Affective Depressed mood Irritability Anxiety Frustration Difficulty concentrating Craving for tobacco Somatic (physical) Bradycardia Insomnia Gastrointestinal discomfort Increased appetite leading to weight gain A general dysphoric state

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13 Nicotine Withdrawal Symptoms in Rodents Non-somatic signs Hyperalgesia Anxiety-like responses Conditioned place aversion Elevated brain stimulation reward threshold Somatic Signs Head nodding Wet dog shakes Paw tremors Excessive grooming Excessive scratching

14 The Neuronal Nicotinic Receptor α 11 genes encoding α & β nachr subunits ACh binding pocket β β α β out α α α α α in gate

15 The α5 and β4 nachr Subunits are Expressed in the MHb and IPN. α5 In Situ hybridization β4 In Situ hybridization CA1 MHb MHb VTA IPN IPN

16 α5 Subunit Necessary for Physical Manifestations of Nicotine Withdrawal Total withdrawal signs α5+/+ Saline * α5 +/+ Nicotine α5 -/- Saline α5 -/- Nicotine Salas et al. (2009) J.Neurosci.

17 β4 Subunit Necessary for Physical Manifestations of Nicotine Withdrawal * Total withdrawal signs β4 +/+ Saline β4 +/+ Nicotine β4 -/- Saline β4 -/- Nicotine Salas et al. (2004) J. Neurosci.

18 β2 Subunit Not Necessary for Physical Signs of Nicotine Withdrawal Total withdrawal signs * β2 in situ hybridization * +/+ Saline +/+ Nicotine β4 -/- Saline β4 -/- Nicotine β2 -/- Saline β2 -/- Nicotine Salas et al. (2004) J. Neurosci. Salas et al., Journal of Neuroscience 24 (2004), pp

19 Microinjection of Mecamylamine Precipitates Withdrawal ONLY in MHb and IPN α5 α5 β4 v β4 Salas et al. (2009) J. Neurosci.

20 Microinjection into Other Areas Does Not Elicit Withdrawal Behaviors Salas et al. (2009) J. Neurosci.

21 The MHb Comprises Cholinoceptive & Cholinergic Neurons DG 3V DG vmhb MHb LHb LHb Thal 125 I-Epibatidine CHAT-ChR2 MHb

22 Electrophysiological recordings in the MHb Coronal brain slices with MHb (250 µm) Whole-cell patch clamp electrophysiology Intrinsic Excitability +50 pa +40 pa +30 pa +20 pa +10 pa

23 A) Nicotine Enhances Excitability of MHb Neurons B) 2 s Baseline Nicotine DG 3V MH LHb b Thal LHb DG +50 pa +40 pa +30 pa +20 pa C) Initial 500 ms Baseline Nicotine +10 pa +50 pa +40 pa +30 pa +20 pa D) E) Firing Rate (Hz) s Baseline Nicotine Step Amplitude (pa) *** Firing Rate (Hz) Initial 500 ms Baseline Nicotine Step Amplitude (pa) *** +10 pa F) Mecamylamine Firing Rate (Hz) s Baseline Nicotine n.s Step Amplitude (pa) G) Mecamylamine Firing Rate (Hz) Initial 500 ms Baseline Nicotine n.s Step Amplitude (pa) Blocks nachrs Dao et al. (under revision)

24 Null Mutation of α5 nachr Subunit Blocks Facilitation of Excitability by Nicotine α5 -/- β2 -/- β4 -/- Firing Rate (Hz) Baseline Nicotine n.s. Firing Rate (Hz) Baseline Nicotine Baseline Nicotine ** Firing Rate (Hz) Baseline Nicotine Baseline Nicotine *** Step Amplitude (pa) Step Amplitude (pa) Step Amplitude (pa) Dao et al. (under revision)

25 Neurokinin Receptor Antagonists Block Nicotine-induced Facilitation of Excitability Blocks NK1R Blocks NK3R Blocks both A) L-732,138 B) SB C) L-732,138+SB Firing Rate (Hz) n.s. Firing Rate (Hz) Baseline Nicotine n.s. Firing Rate (Hz) Baseline Nicotine n.s Step Amplitude (pa) Step Amplitude (pa) Step Amplitude (pa) Dao et al. (under revision)

26 New Functional Pathway + α5- nachrs Substance P &/or NKB NK1R MHb Cell IP 3 Smooth endoplasmic reticulum [Ca 2+ ] in Gq PLC PLC PKC Raf MEK MAPK ERK Fos Gene Regulation

27 Habenular microinjection of neurokinin receptor antagonists induces somatic signs of withdrawal in mice chronically treated with nicotine Withdrawal Score ** ** ** 0 Vehicle L-732,138 SB L-732,138 +SB Dang Dao & Erika Perez

28 Other Drugs?

29 α5- and β4-containing nachrs Influence the Physical Manifestations of Morphine Withdrawal Total Signs ** SALINE MOR ## ** Total Signs ** SALINE MOR ## ** Wild Type α5 null 0 Wild Type β4 null Erika Perez & Damaj lab **p>0.01 Compared to Saline Control, #p>0.01 Compared to Wild type

30 From Mice to Men... & Women!

31 Single Nucleotide Polymorphism in the Human α3 α5 β4 gene cluster

32 α5 Gene Variant Associated with Substance Abuse Alters Receptor Function CHRNA x rs SNP Mr. Big CHRNA3 CHRNB4 C Extracellular (Bierut et al 2008) M1 M2 M3 M4 Intracellular D398N (Modified from Improgo et al 2010)

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34 Back to Mice.

35 Critical role of the a5 nachr Subunit in Intravenous Nicotine Self Administration CHRNA5- WT CHRNA5 NULL Re-expression of α5 WT and α5 rs in the ventral tegmental area CHRNA5- WT CHRNA5-rs In collaboration with Fauvre & Maskos

36 Tobacco Smoking Causes 1/3 of cancer-related deaths in developed countries Global epidemic: 4-5 million annual deaths from smoking-related causes Predictions: increase to 10 million annually by 2030 Leading cause of preventable death worldwide Vineis et al., 2004; Mathers et al., 2006; Giovino et al., 2012; Kabir et al., 2013

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38 Conclusions part 1 The MHb is a fundamental structure for the expression of the physical signs of nicotine and ethanol withdrawal. a5 * and β4 * nachrs are necessary for the manifestations of the physical signs of abstinence from nicotine and, in part, from morphine.

39 Conclusions part 2 The MHb acts as a gatekeeper in the control of drug consumption, especially of doses that are normally aversive The contribution of α5 and β4 subunits is critical for this function.

40 Conclusions part 3 Mouse models and human genetics can work hand in hand to address the molecular mechanisms of disease.

41 De Biasi Lab: Erika Perez Dang Dao Edwin Alexander Ian McLaughlin Michael Paolini Peter Reese Fei Cao, M.D/Ph.D. Aaron Lauver, Ph.D. ` Nooshin Rezvani, M.D./Ph.D. Yanfen Teng, Ph.D. Collaborators: John Dani s Lab Kazu Oka s Lab Acknowledgements Funding: NIDA, NCI,CPRIT, Helis Foundation