Development of DA and 5HT neurons involved in reward-associated behavior in zebrafish

1. Development of DA and 5HT neurons involved in reward-associated behavior in zebrafish Su Guo, Ph.D. University of california, San Francisco

2. Basal forebrain DA and 5HT neurons 3-day old zebrafish labeled with anti-TH and 5HT antibodies

3. Questions • Do zebrafish have reward-associated behavior? • Experience-dependent morphine preference • Do the basal forebrain DA/5HT neurons play a role in this behavior? • The too few mutant • How is the development of basal forebrain DA/5HT neurons regulated? • The foggy mutant

4. Zebrafish: a vertebrate genetic model organism Small-size High fecundity Rapid development In vivo tracing of biological processes Easy to maintain In large numbers Optically transparent

5. What is reward-associated behavior? • A prior exposure to a substance elicits a preference behavior for the substance: • Spend more time in the substance-paired side (CPP) • Self-administer the substance

6. Studying reward-associated behavior in larval zebrafish • Larval zebrafish are amenable to genetic analysis and the study of cellular mechanisms • Larval zebrafish are free-living (food hunting, escaping) • The nervous system of larval zebrafish is more plastic than adult zebrafish.

7. drug water Pre-expose larval Zebrafish to the drug draining Test their preference for the drug in the choice chamber Choice chamber

8. Larval zebrafish show experience-dependent preference for morphine

9. Morphine preference is dependent on opioid receptors

10. The too few mutant

11. The basal forebrain DA/5HT neurons are required for morphine preference behavior

12. tfu Zebrafish: adapted from Rink and Wullimann, 2002 Mammals: adapted from Kandel’s Principles of Neural Science Functional analogy of zf basal FB to mammalian MB DA neurons

13. How is the development of basal FB DA and 5HT neurons regulated? • Will the mechanisms be homologous to mammalian FB or MB neurons? • What are the genes and pathways involved in the development of these neurons?

14. Mutagenesis screen

15. Mutations affecting the development of basal FB DA/5HT neurons • too few • motionless • twin-of-motionless • foggy

16. The foggy mutant WT foggy

17. foggy encodes a regulator of transcription elongation

18. The importance of regulating transcription elongation during development promoter Transcription initiation Transcription elongation

19. foggy expression

20. Activator Repressor The foggy mutation selectively disrupts its repressor activity

21. Question • What genes are de-repressed that leads to defects in DA/5HT neuron development? • Micro-array study • How is foggy’s repressor activity regulated during development? • Focus on the function of the C-terminal domain, where the foggy mutation resides.

22. Summary • Zebrafish is an attractive genetic model organism to study: • the development of specific neuronal types. • The developmental alteration that leads to abnormal reward-associated behavior.

23. Acknowledgements Reward-associated behavior in larval zebrafish Sandrine Bretaud Brent Lockwood Foggy downstream tergets Keerthi Krishnan Foggy regulation Jae-yeon Jeong Arnon Rosenthal (Rinat Neuroscience) Mark Fishman (Novartis) Wolfgang Driever (University of Freiburg)