“Drinking in the dark” (DID) procedures: A model of binge-like ethanol drinking in non-dependent mice
Section snippets
DID procedures and influencing factors
Rhodes and colleagues tested a variety of factors that influence the amount of ethanol consumed by mice using variations of the DID procedure. Variations included ethanol concentration, the length of time into the dark cycle that ethanol was offered, the source from which the experimental mice were obtained, and mouse sex and strain (Rhodes et al., 2005). The general DID procedure implemented by Rhodes et al. (2005) was to house C57BL/6J mice (or other strains under consideration) individually
The advantages of DID procedures in modeling binge-like ethanol drinking
One of the clear advantages of DID is that it promotes pharmacologically meaningful BECs in an experimenter-defined limited access time frame (Crabbe et al., 2011). Because ethanol access is limited to a relatively short period of time, one can more easily assess the effects of pharmacological compounds on binge-like ethanol intake, especially in cases where the actions of a drug are short-term (i.e., 4 h or less). Further, as noted above, mice exhibit behavioral intoxication with DID and
Considerations for the DID model
While there are clear advantages to the DID procedure relative to other models of binge-like ethanol consumption/exposure, there are potential limitations with the model which should be considered. As noted above, the DID procedure takes advantage of a time in the animal's circadian rhythm associated with high levels of ingestive behavior. Clearly, administration of ethanol within the animal's dark cycle is a key component to the high level of ethanol intake associated with DID procedures. In
Future directions with DID procedures
Additional research is needed to a) further characterize and potentially improve DID procedures, b) understand the neurobiology and mechanisms that modulate binge-like ethanol drinking with DID procedures, and c) discover ways to expand the utility of the DID procedure. As noted above, much has been done to characterize the factors that influence the level of binge-like ethanol drinking with DID procedures. Thus, providing 20% ethanol in place of water for 2–4 h beginning 3 h into the dark
Acknowledgments
This work was supported by National Institute of Health grants AA022048, AA013573, and AA015148.
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