A putative sigma(1) receptor antagonist NE-100 attenuates the discriminative stimulus effects of ketamine in rats

Ketamine, one of the dissociative anaesthetic agents, has been shown to pro duce psychotomimetic effects. It has been well documented that activation o f sigma receptors is responsible for the pathogenesis of some psychiatric d isorders. In the present study, the effects of NE-100, a putative sigma(1) receptor antagonist, was investigated in rats trained to discriminate betwe en ketamine (5 mg/kg, i.p.) from saline under a fixed-ratio 10 food-reinfor ced procedure. Here we report for the first time that NE-100 (1 mg/kg) prod uced a shift to the right in the dose-response curve for ketamine's discrim inative stimulus effects. These results suggest that the sigma1 receptor is , at least in part, involved in the discriminative stimulus effects of keta mine.