Conclusions
These data, coupled with previous studies on the effects of morphine and amphetamine, demonstrate that galanin normally attenuates drug reinforcement, potentially via modulation of the mesolimbic dopamine system.
Methods
Mice lacking the neuropeptide galanin (Gal -/-) and wild-type (Gal +/+) controls were used to analyze the effects of galanin in an unbiased conditioned place preference paradigm. We then examined cocaine-induced activation of extracellular signal-regulated kinase (ERK) activity as a marker of intracellular signaling in the mesolimbic dopaminergic pathway induced by acute cocaine administration
Objective
In the current study, we present evidence that galanin modulates neurochemical and behavioral correlates of cocaine response.
Results
Gal -/- mice showed significantly greater conditioned place preference at a threshold dose of cocaine (3 mg/kg) than Gal +/+ mice, and this was reversed by administration of the galanin receptor agonist galnon. Consistent with the results of behavioral experiments, there was a significant increase in ERK activation in the ventral tegmental area (VTA) and nucleus accumbens (NAc) of Gal -/- mice but not Gal +/+ mice following acute, systemic cocaine injection at the threshold dose. In the NAc, but not VTA, this effect was reversed by administration of galnon. Conclusions: These data, coupled with previous studies on the effects of morphine and amphetamine, demonstrate that galanin normally attenuates drug reinforcement, potentially via modulation of the mesolimbic dopamine system.