Glucocorticoid-Dependent Neuroplasticity: Fueling the Cycle of Stress and Addiction

1. Glucocorticoid-Dependent Neuroplasticity: Fueling the Cycle of Stress and Addiction John Mantsch, Ph.D. Department of Biomedical Sciences Marquette University Milwaukee, WI

2. PERSONALITY TRAITS GENETIC POLYMORPHISMS GENETICS DRUG EFFECTS ENVIRONMENT DRUG-ASSOCIATED CUES DRUG-ASSOCIATED CONTEXT STRESS RISK FACTORS FOR COCAINE ADDICTION ACUTE REWARDING EFFECTS WITHDRAWAL EFFECTS DRUG-INDUCED NEUROPLASTICITY

3. CLINICAL EVIDENCE FOR A LINK BETWEEN STRESS AND COCAINE ADDICTION: • High incidence of anxiety/mood disorders in cocaine-addicted populations. • Link between drug dependence and post-traumatic stress disorder (PTSD) • Personalized stress imagery precipitates cocaine craving in recovering cocaine addicts.

4. COCAINE IV DRUG SELF-ADMINISTRATION • Surgical implantation of silastic catheter into jugular vein • Exit via head- or back-mounted cannula port • Drug delivery line attached to a counter-balanced leak-proof swivel to allow unrestricted movement • Tested in operant chamber (modified Skinner box) - experimenter-controlled environment • Pressing a response lever activates a pump resulting in infusion of set volume of drug solution • In general - drugs with abuse potential in humans will be self-administered by rats (e.g., cocaine, heroin, alcohol, benzodiazepines,methamphetamine, nicotine, and cannabinoids).

5. POSITIVE REINFORCING (EUPHORIC) EFFECTS OF DRUGS: MAINTENANCE PROTOCOLS PREDISPOSITION TO USE DRUGS: ACQUISITION PROTOCOLS LOSS OF CONTROL OVER DRUG USE (ADDICTION): ESCALATION PROTOCOLS RELAPSE OF DRUG USE/DRUG CRAVING: REINSTATEMENT PROTOCOLS

6. Acute Stress Reinstates Extinguished Cocaine-Seeking Behavior in Rats 1. Self-Administration 2. Extinction 3. Reinstatement In syringe: Cocaine (1.0 mg/kg/inf) Saline Saline Ahmed and Koob 1997 Erb et al 1997 Mantsch et al 1999

7. CHRONIC STRESS

8. COCAINE AND STRESS EFFECTS OF CHRONIC-STRESS ON COCAINE-INDUCED NEUROPLASTICITY COCAINE ALONE

9. MODELING HUMAN ADDICTION HUMANS • LOSS OF CONTROL OVER DRUG USE • LONG-TERM SUSCEPTIBILITY TO DRUG RELAPSE • RATS • ESCALATING PATTERNS OF DRUG SELF-ADMINISTRATION • AUGMENTED REINSTATEMENT OF EXTINGUISHED COCAINE-SEEKING BEHAVIOR

10. Five Minutes Intermittent Electric Footshock 3 x 0.6 mA shocks; 100 msec duration/frequency Average of 45 sec EFFECTS OF REPEATED ELECTRIC FOOTSHOCK (EFS) STRESS ON COCAINE SELF-ADMINISTRATION 4 X 30-min Cocaine Self-Administration Sessions 0.5 mg/kg/inf; Fixed-ratio 4 schedule • Groups (tested for 14 days): • EFS: received footshock during 5-min components • No EFS: did not receive footshock during 5-min components

11. CHRONIC STRESS PRODUCES AN ESCALATION OF COCAINE BUT NOT FOOD SELF-ADMINISTRATION BY RATS • EFS: Electric footshock in the SA chamber at the time of SA testing • No EFS: control group Cocaine Mantsch and Katz, 2007; Neuropsychopharmacology Food

12. EFS ONLY ESCALATES SA IF DELIVERED AT THE TIME OF SA TESTING WITHIN THE SA ENVIRONMENT • EFS/SA Context/SA: Electric footshock in the SA chamber at the time of SA testing • EFS/Non-SA Context/Post-SA: EFS in a non-SA context at the time of SA testing. • EFS/SA Context/Post-SA: EFS the SA context at the time of SA testing. • No EFS: control Mantsch and Katz, 2007; Neuropsychopharmacology

13. THE CHRONIC VARIABLE STRESS PROTOCOL • Chronic: 14 days; twice daily exposure • Mild: non-noxious stressors • Variable: 7 stressor presented in randomized sequence References: JP Herman et al (1995) Neuroendocrinology 61: 180-90; WE Cullinan et al (2000) Brain Research 887: 118-124.

14. THE CHRONIC VARIABLE STRESS PROTOCOL… 1. Does not affect body weight or produce noticable changes in health/vitality 2. Produces physiological signs of chronic stress 3. Does not result in attenuation of the stress response with repeated exposure

15. Room Temp Swim Cocaine SA/Injection Restraint 8 AM 12 PM 4 PM A. A sample experimental test day SA TESTING/ EXTINCTION/ INDUCTION WITHDRAWAL 14 DAYS +/- CVS 14 DAYS No CVS SA TRAINING/ HABITUATION REINSTATEMENT/ DRUG CHALLENGE B. General experimental time-line EFFECTS OF CVS ON COCAINE-INDUCED NEUROPLASTICITY

16. CHRONIC VARIABLE STRESS ACROSS A PERIOD OF COCAINE ADMINISTRATION POTENTIATES COCAINE-INDUCED LOCOMOTOR SENSITIZATION Withdrawal D12 Challenge: • CVS across a period of cocaine administration augments cocaine-induced locomotor sensitization • CVS does not produce locomotor sensitization when delivered in the absence of cocaine

17. CHRONIC VARIABLE STRESS DURING BUT NOT AFTER A PERIOD OF COCAINE SA AUGMENTS LATER COCAINE-INDUCED REINSTATEMENT # # #

18. The Hypothalamic Pituitary Adrenal (HPA) Axis Corticotropin Releasing Hormone/Factor PVN of the Hypothalamus Corticosterone (in rats) Adrenocorticotropic Hormone KIDNEY

19. STRESS WHY GLUCOCORTICOIDS? • Glucocorticoids = mediate adaptational responses to stressors (physiological and behavioral) • Neurocircuitry underlying drug-seeking behavior is a direct and indirect target of glucocorticoids

20. CIRCADIAN AND EFS-INDUCED CORT SECRETION IN ADX RATS WITH DIURNAL CORT REPLACEMENT AND SHAM-TREATED CONTROLS • Sham surgery • 100% cholesterol pellet • 0.9% NaCl for drinking water • Surgical adrenalectomy • Subcutaneous 25% CORT Pellet Implantation • Inclusion of CORT (0.25%) in drinking water (0.9% NaCl)

21. THE ESCALATION OF COCAINE SELF-ADMINISTRATION BY REPEATED STRESS REQUIRES STRESSOR-INDUCED GLUCOCORTICOID SECRETION ADX/C = surgical adrenalectomy with diurnal CORT replacement

22. CORT ADMINISTRATION RESTORES BUT DOES NOT REPRODUCE THE ESCALATING EFFECTS OF EFS ON SA IN ADX/C RATS ADX/C +: • IP CORT (3.0 mg/kg) to ADX/C rats alone or prior to EFS • IP CORT does not escalate cocaine SA by itself • IP CORT given along with EFS restores the escalating effects of EFS on cocaine SA Plasma CORT after 3.0 mg/kg IP CORT Injection

23. Summary • Stress promotes cocaine-induced neuroplasticity that may be pathogenic for addiction: • Repeated exposure to a stressor (EFS) produces a context/timing-dependent escalation of cocaine SA that is specific to drug-seeking behavior. • Exposure to chronic variable stress (CVS) across a period of experimenter-delivered or self-administered cocaine exposure augments the expression of behavioral sensitization or cocaine-induced reinstatement after a stress-free withdrawal period. • The escalating effects of repeated EFS are prevented by eliminating the corticosterone response to EFS. • EFS-induced corticosterone secretion is necessary but not sufficient for the escalation of cocaine SA by repeated EFS. • Corticosterone functions as an “enabler” that permits stressors to promote cocaine-seeking behavior and addiction. • Cocaine-induced corticosterone secretion is NOT required for the escalation of cocaine SA under LgA conditions but does facilitate SA under long-access conditions. • CORT is likely functioning as an enabler of stressor-induced neuroplasticity and appears to be working in concert with other neurobiological mediators that are active during periods of stress.

24. EFFECTS OF COCAINE ON STRESS RESPONSES

25. STRESS COCAINE USE WITHDRAWAL Cocaine-Induced Neuroplasticity: Long-Term Effects of Cocaine SA on Responses to Stressors VICIOUS CYCLE OF ADDICTION

26. Studying Cocaine-Induced Neuroplasticity Using the Long-Access Cocaine Self-Administration Model References: Ahmed and Koob, 1998 Ahmed and Koob, 1999 Mantsch et al 2004

27. LgA Cocaine SA Produces a Persistently Heightened Susceptibility to Cocaine and Stressor-Induces Reinstatement Mantsch et al Neuropsychopharmacology, submitted

28. Activation of the HPA Axis by ShA and LgA Cocaine SA • Acute cocaine SA increases plasma CORT Lights off • Chronic cocaine SA produces adrenal hypertrophy and reduces thymus mass 21 days after 14 days of daily ShA, LgA or saline SA

29. ADX with Diurnal CORT Replacement Reproduces Circadian Fluctuations in CORT Levels but Prevents SA-Induced Increases in CORT Secretion Mantsch et al Neuropsychopharmacology, submitted

30. Eliminating SA-Induced Increases in CORT Slows but Does Not Prevent Escalating SA Patterns in LgA Rats and Has No Effect on ShA SA Mantsch et al Neuropsychopharmacology, submitted

31. ADX/C Prior To But Not After Repeated LgA SA Prevents the Augmentation of Cocaine- or EFS-Induced Reinstatement Without Altering Reinstatement in ShA Rats Mantsch et al Neuropsychopharmacology, 2007

32. Administration of 2.0 mg/kg CORT Immediately Prior to ShA SA Mimics the Effects of LgA SA on Plasma CORT Mantsch et al Neuropsychopharmacology, 2007

33. Reproduction of LgA-Induced Increases in Plasma CORT is Insufficient to Produce Escalation or Augment Reinstatement in ShA Rats Mantsch et al Neuropsychopharmacology, 2007

34. Summary • Daily cocaine SA under LgA conditions results in a progressive escalation of daily cocaine intake and a long-term heightened susceptibility to cocaine- and stressor-induced reinstatement. • These effects of LgA SA are the consequence of cocaine-induced neuroplasticity that likely contributes to addiction. • Elevated CORT lat the time of SA testing is at least partly required for cocaine-induced neuroplasticity in LgA rats but is not necessary for the acute reinforcing or reinstating effect of cocaine and/or stressors. • Administration of CORT using doses that reproduce increases in circulating CORT level observed in LgA rats alone is insufficient to induce escalate drug use or augment later cocaine-induced reinstatement. • CORT is likely functioning as an enabler of cocaine-induced neuroplasticity and appears to be working in concert with other neurobiological mediators that are active during LgA cocaine SA. .

35. OPEN-ARM ACTIVITY ON THE ELEVATED PLUS MAZE IS INCREASED 2 WEEKS AFTER LONG-ACCESS COCAINE SELF-ADMINISTRATION ShA = short-access rats LgA = long-access SAL = saline SA controls Elevated Plus Maze Mantsch et al Pychopharmacology, Submitted

36. SA Produces An Augmentation of Exploratory Behavior Measured Using the Light-Dark Box Model 2 Weeks After SA Repeated SA Testing Light-Dark Box Latency to Enter Light Time Spent in Light Number of Light Entries Mantsch et al Pychopharmacology, Submitted

37. SA Increases Center Activity, But Not Total Activity, Within A Novel Environment Measured 2 Weeks After Repeated SA Center Total Activity Center Activity Time Spent in Center Mantsch et al Pychopharmacology, Submitted

38. Role of Corticotropin Releasing Factor (CRF) • CRF mediates behavioral responses to stressors (Dunn and Berridge 1990, Brain Res Rev 15: 71-100). • CRF underlies stressor-induced reinstatement of cocaine seeking (Sarnyai et al 2001, Pharmacol Rev 53:209-243). • Potential sites of CRF-induced drug seeking include: • The CeA (Richter and Weiss 1999, Synapse 32: 254-261; Fu et al 2007, J Neurophysiol 97: 937-41) • The BNST via CRF projections originating in the CeA (Erb et al 2001, Psychopharm 158: 360-65; Erb et al 1999; J Neurosci 19: RC35) • The VTA presumably via CRF projections originating in the CeA (Wang et al 2005; J Neurosci 25: 5389-5396)

39. Post-Restraint CRF mRNA in the BNST is not Altered As a Consequence of Prior Cocaine SA Determined using in situ hybridization Unpublished findings (J Mantsch, D Ziegler, W Cullinan)

40. Guide Cannula Lateral Ventricle Reinstatement by ICV CRF is Augmented in LgA Rats Mantsch et al Pychopharmacology, Submitted

41. Summary • Cocaine SA alters anxiety-related behaviors in a manner dependent on the amount and/or pattern of cocaine intake. • When measured several weeks into withdrawal SA promotes a shift from a more passive response pattern when confronted with a stressful situation to a more active reponses patterns as measured using: • The elevated plus maze • The light-dark box • Testing in a novel environment • This more active response pattern during times of stress may be manifest as drug use/drug-seeking behavior. • Changes in stressor-responsiveness may be attributable to altered responsiveness to CRF. • Reinstatement by ICV CRF was augmented by LgA cocaine SA, suggesting a recruitment or augmentation of CRF regulation of neurocircuitry underlying cocaine-seeking behavior.

42. EFFECTS OF COCAINE ON STRESSOR-INDUCED HPA FUNCTION

43. Glucocorticoid and PVN CRH mRNA Responses to Restraint are Augmented During Acute (24-h) Withdrawal from Chronic Experimenter-Delivered Cocaine Administration Plasma CORT PVN CRH mRNA Mantsch et al Neurosci Lett 2007

44. Cocaine SA Intake-Dependently Augments the Stressor-Induced CORT Secretion and Impair Dexamethasone Suppression of Plasma CORT Levels Mantsch et al submitted Brain Res Measured approx 3 weeks after SA testing

45. GR Protein is Selectively Reduced in the Doromedial Hypothalamus (includes the PVN) of LgA Other Regions Examined: Ventromedial Hypothalamus, Pituitary, Amygdala, Dorsal Hippocampus, Ventral Subiculum, Medial Prefrontal Cortex Mantsch et al submitted Brain Res

46. Basal or Restraint-Induced Increases in CRH mRNA in the PVN is not Altered by Cocaine SA • Measured 1.5 hrs after 30 min of restraint • 21 day after 14 days of ShA, LgA, or SAL SA Mantsch et al submitted Brain Res

47. Summary • The response of the HPA axis to stressors is augmented by prior cocaine exposure. • Long-term augmentation of HPA responsiveness to stressors may be partly attributable to impaired negative feedback regulation due to reduced GR protein expression in the hypothalamus. • However long-term augmentation of stressor-induce CRH mRNA in the PVN measured at a single time-point following restraint was not oberved. • Augmented HPA responsiveness during times of stress may promote glucocorticoid-dependent plasticity, thus fueling the addiction cycle.

48. Acknowledgements NIDA Grant Number DA 15758 Collaborators David Baker William Cullinan M. Behnam Ghasemzadeh Dana Ziegler Research Assistants Lee Tang Eric Katz Michael Hoks Students Tayyiba Khan David Francis Joe Serge Tanveer Sajan Loren Cooper

49. Medial Prefrontal Cortex Nucleus Accumbens CRF, GLUCORTICOIDS DOPAMINE GLUTAMATE Ventral Tegmental Area CRF-R2 Receptor DRUG-SEEKING BEHAVIOR

50. Medial Prefrontal Cortex Nucleus Accumbens STRESS DOPAMINE CRF, GLUCORTICOIDS GLUTAMATE DRUG CRAVING/USE Ventral Tegmental Area CRF-R2 Receptor