Many environmental changes impact sleep, such as exposure to drugs, social isolation, and varying temperatures. We are subjecting a wild-derived panel of flies to four different psychotropic drugs. This panel of lines, the Drosophila Genetic Research Panel (DGRP), is fully sequenced and polymorphisms both within and among these lines are known.
Aim 1. We are now in the process of generating dose response curves for four psychotropic drugs with different pharmacological profiles. We based the nominal drug dosage for the flies on the usual dosage given to humans, corrected for body weight. Using a subset of DGRP lines with long and short-sleeping phenotypes, we tested the viability of the flies after chronic exposure to each drug and determined the Lethal Dose 50% (LD50). We are currently generating the dose response curve for a set of concentrations lower than the LD50 for each drug. From these curves we will choose an appropriate dosage at which to measure the entire DGRP population for each drug.
Aim 2. We will measure sleep in the entire DGRP in flies exposed to the drug dosages determined in Aim 1. We will then perform a genome-wide association study on the effects of drug exposure on sleep. The results of this study will then be compared to a genome-wide association study on sleep that was previously performed under normal conditions. We will identify those gene networks that are robust during different environmental exposures, and those gene networks that are plastic and perhaps unique to each drug environment.
Aim 3. Little is known about the pharmacokinetics and molecular pharmacology of the four psychotropic drugs in flies. We will therefore quantify the concentrations of each drug and their active metabolites in the head and/or body of each fly, and relate these measurements to the observed effect on sleep. To integrate information on the molecular targets of these drugs available from studies in vertebrates, we will perform drug binding assays in fly tissue homogenates.