Pseudoephedrine, a sympathomimetic agent, induces Fos-like immunoreactivity in rat nucleus accumbens and striatum

The pharmacological properties of the ephedrine derivative pseudoephedrine were investigated at the nuclear level. Following intraperitoneal injection of Sprague-Dawley rats with pseudoephedrine, Fos induction was measured in various brain areas by Western blots and immunocytochemistry. Pseudoephedr ine induced Fos-like immunoreactivity in the nucleus accumbens and striatum in a time and concentration-dependent manner with maximal effect at 60 mg/ kg 2 h after injection. Immunocytochemical studies confirmed that the major ity of the signal was detectable in the nucleus accumbens and striatum. Pre -injection with the D-1 dopamine receptor antagonist SCH23390 partially and completely blocked pseudoephedrine-induced Fos-like immunoreactivity in th e striatum and nucleus accumbens, respectively, suggesting that the action of pseudoephedrine is mediated via dopamine release and results in the acti vation of D-1 dopamine receptors. With the exception of the higher doses re quired, the actions of pseudoephedrine were similar to those previously des cribed for the psychostimulant amphetamine. (C) 1999 Elsevier Science Ltd. All rights reserved.