SIGMA-RECEPTORS - PUTATIVE LINKS BETWEEN NERVOUS, ENDOCRINE AND IMMUNE-SYSTEMS

The sigma-receptor is a neuronal substrate that binds several psychoactive compounds. These include cocaine, some steroids, dextromethorphan, phencyclidine (PCP), and benzomorphans such as pentazocine and N-allyl-normatezocine (SKF-10047). Many newer atypical antipsychotic drugs also bind to the sigma-receptor. The sigma-receptor, however, is not the PCP receptor. The sigma-receptor exists in the central nervous system, endocrine, immune and certain peripheral tissues. Progesterone and certain steroids have been shown to represent endogenous ligands for the sigma-receptor. The sigma-receptor resides likely in the nonsynaptic region of the plasma membrane. The sigma-receptor exists in two forms: high-affinity and low-affinity. The solubilized sigma-receptor retains all of the pharmacological characteristics of a membrane-bound receptor. A major physiological role of the sigma-receptor may involve the modulation of a tonic potassium channel.