Failure of magnesium to maintain self-administration in cocaine-naive rats.

Previous research has shown that magnesium interacts with cocaine in such a way that it potentiates its action in a variety of behavioral situations. More recently, it has been demonstrated that magnesium will dose dependently substitute for cocaine self-administration and reduce the intake of cocaine. It is of considerable interest to determine if magnesium would be self-administered in cocaine-naive animals. The results of two experiments demonstrate that magnesium is not self-administered by cocaine-naive rats since although responding for magnesium chloride is above hypertonic saline control levels on day 1 of access, this responding is not maintained on subsequent days, does not occur in a regularly spaced pattern over time, and is not inversely related to dose. Taken together these data indicate that magnesium is a substitute for cocaine that has low abuse potential.