Phencyclidine (PCP) acts at sigma sites to induce c-fos gene expression

Area of Science:

• Neuroscience
• Molecular Biology
• Pharmacology

Background:

• Phencyclidine (PCP) is a dissociative anesthetic with psychotomimetic effects, proposed as a model for schizophrenia.
• The immediate-early gene c-fos is rapidly expressed in neurons following stimulation, serving as a marker for neural activity.
• Sigma receptors are implicated in various neurological processes and are targets for drugs affecting behavior.

Purpose of the Study:

• To investigate the brain regions affected by PCP-induced c-fos expression.
• To determine if PCP-induced c-fos expression is mediated through sigma receptors.
• To explore the potential role of sigma receptor subtypes in PCP's neurobiological effects.

Main Methods:

• Administration of Phencyclidine (PCP), 1,3-di(2-tolyl)guanidine (DTG), and pentazocine to induce c-fos expression.
• Immunohistochemical analysis to detect c-fos expression in various brain regions.
• Administration of rimcazole, a sigma receptor antagonist, to assess its effect on c-fos induction.

Main Results:

• PCP, DTG, and pentazocine induced c-fos in similar patterns, primarily in the cortex and thalamus/hypothalamus, sparing the hippocampus.
• Rimcazole partially inhibited PCP- and DTG-induced c-fos expression in specific cortical areas.
• Pentazocine, a sigma1-selective ligand, had its c-fos induction unaffected by rimcazole, suggesting a role for sigma2 receptors in PCP's effects.

Conclusions:

• PCP-induced c-fos expression occurs in brain areas associated with emotional behavior, distinct from NMDA receptor-mediated effects.
• Sigma receptors, particularly sigma2, appear to mediate a significant portion of PCP's c-fos induction.
• These findings support the use of sigma ligands in understanding PCP's neurobiological mechanisms and potential therapeutic targets for schizophrenia-like behaviors.