Ethanol increases extracellular dopamine concentration in the ventral striatum in C57BL/6 mice.
BACKGROUND
Mesolimbic dopamine is thought to play a role in the reinforcing properties of ethanol, but ethanol-induced changes in extracellular dopamine in the ventral striatum have not been well characterized in mouse models.


METHODS
Two experiments were used to characterize the pharmacodynamic response of ethanol in the ventral striatum in C57BL/6 mice. The first experiment determined the effect of ethanol on ventral striatal dopamine in male and female mice after intraperitoneal injection of either 2.0 g/kg ethanol or saline. The second experiment was a replication in males, except that the mice were habituated to intraperitoneal injections before the dialysis experiment.


RESULTS
Distinct patterns of dopamine activity in response to ethanol were demonstrated in male and female C57BL/6 mice. A significant increase in dialysate dopamine relative to saline injection was observed in females but not in males. With habituation to intraperitoneal injection before the dialysis experiment, ethanol administration caused a significant dopamine response in males as well. A linear decline was observed in dialysate ethanol concentrations after the peak concentration was reached. Concurrent analysis of the time course of dopamine and ethanol content showed that the dopamine response declined significantly faster than the ethanol concentrations.


CONCLUSIONS
The C57BL/6 mouse strain is a justifiable model system for studying the mechanisms involved in ethanol regulation of mesolimbic dopamine activity. Habituation to intraperitoneal injection should be used in male C57BL/6 mice for experiments in which the dopamine response is measured after intraperitoneal injection of a drug. The dissociation between dopamine and ethanol may indicate an acute neural adaptation to ethanol-induced dopamine response in the ventral striatum after a single ethanol injection.
Tang
Amanda
A
College of Pharmacy, University of Texas at Austin, USA.
George
Magnia A
MA
Randall
Judith A
JA
Gonzales
Rueben A
RA
D000818:Animals; D001479:Basal Ganglia / Q000187:drug effects* / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism / Q000494:pharmacology*; D045604:Extracellular Fluid / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL
D000431:Ethanol; D004298:Dopamine