A role for interleukin-2 in the regulation of striatal dopaminergic function.

The present study determined whether interleukin-2 (IL-2) is endogenous to the normal adult rat striatum and whether IL-2 regulates striatal dopaminergic tone. IL-2 mRNA (1.5 kb size), endogenous IL-2 and IL-2 receptors were found to be distributed throughout the rat striatum in moderate densities. Application of exogenous IL-2 to striatal slices in in vitro produced significant increases in both spontaneous and potassium (25 mM)-evoked [3H] dopamine release. The modulatory effect of IL-2 was dependent on the presence of external calcium and required axonal nerve activity, since IL-2 was unable to increase transmitter release under low external calcium conditions or in the presence of tetrodotoxin. Overall, this study indicates that IL-2 may be an endogenous neurokine that regulates striatal dopaminergic function in normal animals.