We are using Drosophila melanogaster as a model system to understand the acute side-effects of exposure to organic solvent inhaLants. These inhalants, which are abused by a startling large number of adolescents, are commonly found components of many household cleaning solutions and fuels. In general, solvent inhalants owe much of their ability to intoxicate on their anesthetic-like qualities. Abuse of these compounds can have severe side effects. We have observed that Drosophila knocked out by low level exposure to benzyl alcohol vapor recover in approximately 6 hours. This occurs even though one can demonstrate that the solvent in the exposure chamber can still knock out naive flies. Furthermore, the acutely-resistant animals show cross-resistance to the abused solvent toluene. Concomitant with recovery we have observed that mANA from the slowpoke Ca2+-activated K+ channel gene increases in abundance. Because of our many mutant animals and animals carrying various transgenes we will be able to determme the biological meaning of these observations. SpecificalLy, we will determine if cross-resistance and slowpoke mRNA induction is a response common to different abused solvents. During solvent exposure the animals first become hyperexcitable and then 'unconscious'. We would like to know, to which phase, the acute resistance and channel mRNA induction is a response. Using a temperature sensitive mutation in a sodium channel gene which reversibly blocks neural signaling we can answer this question. We will 'turn off' neural signaling during each phase of solvent exposure and determine if the solvent-induced changes occur. Furthermore, using slowpoke mutants we will determine if the change in slowpoke expression is involved in the recovery from solvent-anesthesia. Using our large bank of slowpoke transgenes, which have small lesions in their transcriptional control regions, we will determine if the mRNA abundance change is the result of changed transcriptional regulation and if it results in increases in the channel protein. Finally, we will determine if other ion channel genes shows the same response. We have already shown that a sodium channel gene does not. Future directions include a mutagenic screen to isolate mutations that interfere with the acquisition of acute resistance.
| Ghezzi, Alfredo; Al-Hasan, Yazan M; Larios, Leo E et al. (2004) slo K(+) channel gene regulation mediates rapid drug tolerance. Proc Natl Acad Sci U S A 101:17276-81 |
