Arturo R. Zavala Department of Psychology California State University, Long Beach

1. The Neuronal Circuitry Activated by Cocaine-Associated Cues in an Animal Model of Cocaine Craving: Involvement of AMPA Glutamate Receptors Arturo R. Zavala Department of Psychology California State University, Long Beach September 26, 2008 4th Annual Drug Abuse Research Symposium

2. Triggers Drug Craving and Relapse

3. Cocaine-seeking behavior: Animal model Self-Administration Abstinence Test Response-contingent cues No Extinction Alternative environment Response-contingent cues Cocaine infusion High rates of lever pressing • Lever pressing in the absence of cocaine reinforcement is defined as cocaine-seeking behavior What brain regions are activated during cocaine-seeking behavior? Incentive motivational and/or conditional reinforcing effects of the cocaine cues

4. Fos protein as a marker of neuronal activation • Fos is the protein product of the c-fos gene • Low basal expression • Transiently expressed by several stimuli – stress, hormones, neurotransmitters • Peak expression after induction 90-120 min • Expression is localized using immunohistochemistry procedures

5. Cocaine Cues Increase Fos Expression in the Basolateral Nucleus of the Amygdala Cocaine Extinction Cocaine No Extinction

6. Hypothesized circuitry for cocaine cue effects Motor Cortex and Spinal Cord Cocaine-seeking Behavior Prefrontal Cortex Anterior Cingulate Cocaine Cues Hippocampal Formation Basolateral Amygdala Nucleus Accumbens Mediodorsal Thalamus VP STN GPi SNr

7. Hypothesis Glutamate AMPA receptors are involved in cue-conditioned cocaine-seeking Predicted that the AMPA/Kainate receptor antagonist, NBQX, would: • decrease cue-conditioned cocaine-seeking behavior • block cue-conditioned Fos protein expression

8. Saline Saline NBQX NBQX Saline Saline NBQX NBQX Experiment design Self-administration Training (24 days) Cocaine Saline-Yoked Abstinence phase (24 days) Extinction No Extinction Extinction No Extinction Pretreatment (20 min) Test (90 min) Test Test Test Test Test Test Test Test Fos Fos Fos Fos Fos Fos Fos Fos

9. Pretreatment with NBQX had no effect on spontaneous locomotion

10. NBQX pretreatment on the test day attenuated cocaine-seeking behavior

11. NBQX pretreatment attenuates cue-elicited Fos expression in a region specific manner • NBQX pretreatment attenuates Fos expression 2. NBQX pretreatment had no effect on Fos expression 3. Cue-conditioned Fos was region specific

12. Summary and conclusions • Re-exposure to cocaine-associated cues on the test day resulted in robust cocaine-seeking behavior and cue-conditioned increases in Fos expression in limbic, striatal, and cortical regions in vehicle pretreated rats. • NBQX pretreatment on the test day attenuated cocaine-seeking behavior and Fos expression in the: • Orbitofrontal cortex • Anterior cingulate cortex • Nucleus accumbens core • Dorsal caudate-putamen • Basolateral amygdala • Not likely due to decreased motor activity or acute effects of NBQX (Saline or Cocaine-Extinction groups) Cue-elicited Fos expression involves AMPA receptor stimulation

13. Summary and conclusions • NBQX pretreatment did not affect Fos expression in the: • Prelimbic cortex • Infralimbic cortex • Nucleus accumbens shell • Ventral subiculum • Lack of effect in these regions does not preclude a role of AMPA receptors - AMPA signal transduction may involve molecular pathways that induce other immediate early genes. Cue-elicited Fos expression does not involve AMPA receptor stimulation

14. Future directions • Determine functional significance of AMPA receptor involvement: • Motivation • Conditioned reinforcement • Extinction learning • Memory • Emotional states (e.g., stress, anxiety)

15. Acknowledgements Dr. Janet Neisewander Dr. Sudipta Biswas Jenny Browning Erin Dickey