1. Zebrafish: An emerging model in drug abuse research Kevin S. Jones, Ph.D. Assistant. Professor Pharmacology The College of Osteopathic Medicine of the Pacific Western University of Health Sciences Charles Drew University 4 th Annual Drug Abuse Research Symposium September 26,2008

2. What is a “zebrafish”?

3. The zebrafish, Danio rerio, is: Tropical, fresh water fish native of India. Member of the teleost class (bony fish). Well established model for vertebrate development. Readily accessible to transgenesis.

4. Zebrafish have 3 developmental stages ~30 hpf (hours post fertilization) 1 mm Embryonic > 3 months Adult 5 dpf 1 mm Larval

5. Zebrafish as a model organism AdvantagesDisadvantages 1.Small size 2.High fecundity 3.Sequenced genome 4.Optical transparency 5.External Development 6.Genetic manipulation 7.Automated analysis Evolutionarily distant from humans Limited behavioral repertoire

6. Larval zebrafish (10dpf) 96 well plate U.S. Penny

7. How can zebrafish be used to study drug abuse?

8. Recreational “Illy” (PCP) Smoker

9. pcp PCP (phencyclidine) blocks NMDA receptors PCP

10. kd < 5 nM MK-801 MK-801 is a potent analogue of PCP

11. Psychostimulants cause movement disorders Actions of psychostimulants Drug-treated HUMAN Drug-treated Rodents HallucinationsYES??? DelusionsYES??? Thought DisorderYES Movement Disorders YES

12. Zebrafish have NMDA receptors zNMDAR is ~90 % IDENTICAL to human NMDAR Expressed as early as 24 hpf Developmental Dynamics 2005 234: 756-766

13. Objective: Characterize the behavioral effects of NMDA receptor blockade in zebrafish

14. Individual zebrafish larvae are placed into single wells of a multi well plate Multi-plate illuminated from below with a 15w lightbox Larvae given 5 minutes to acclimate Subsequent activity recorded for 5 minutes on digital camera Data Acquisition Methods

15. Data Analysis Video recordings analyzed off-line with particle tracking software

16. Vehicle-treated MK-801-treated Prototypical Data

17. Dose Response of MK-801-induced locomotion EC 50 ~ 10.3 uM

18. Locomotor kinetics t (h) Speed (mm/sec)

19. Developmental Sensitivity

20. The antipsychotic, ziprasidone, attenuate the locomotor effects of MK-801

21. Ziprasidone targets several receptors Target Receptor D2D35HT2 A 5HT2 C 5HT1 A 5HT1 D α1α1 Ki4.87.20.41.33.4210

22. Dopamine antagonists do not disrupt MK-801-indcued locomotion

23. MPTP pre-treatment diminishes locomotor effects of MK-801 Δ SPEED (mm/sec) VEH500 uM MPTP1 mM MPTP

24. Summary Zebrafish retain the most reliable symptom of NMDA blockade… increased locomotion. Antipsychotic meds block behavioral effects in zebrafish. Zebrafish may prove useful for elucidating important molecular pathways of drugs of abuse

25. Future Directions Elucidate molecular mechanism(s). Examine developmental sensitivity. Probe for behavioral sensitization. Molecular neurotoxicology.

26. Acknowledgments Mr. John Chen (Pomona College) Ms. Roshni Patel (Pomona College) Biology Dept Pomona College Pomona College—Dean’s office