Diverse psychotomimetics act through a common signaling pathway

Area of Science:

• Neuroscience
• Pharmacology
• Molecular Biology

Background:

• Distinct drug classes, including dopaminergic, serotonergic, and glutamatergic agents, can induce psychotomimetic states resembling schizophrenia symptoms in animal models.
• Identifying a common molecular mechanism underlying these drug-induced states is crucial for understanding schizophrenia pathophysiology.

Purpose of the Study:

• To investigate a shared signaling pathway responsible for mediating the psychotomimetic effects of D-amphetamine, LSD, and PCP.
• To determine the role of dopamine- and adenosine 3',5'-monophosphate (cAMP)-regulated phospho-protein of 32 kilodaltons (DARPP-32) in these drug-induced behaviors.

Main Methods:

• Utilized genetically modified mice lacking DARPP-32 or possessing point mutations in its phosphorylation sites.
• Administered D-amphetamine, LSD, and PCP to assess their effects on sensorimotor gating and repetitive movements.
• Examined the phosphorylation status of DARPP-32 and its impact on downstream effectors like protein phosphatase-1, GSK-3, CREB, and c-Fos.

Main Results:

• DARPP-32 undergoes phosphorylation/dephosphorylation at three key sites, leading to synergistic inhibition of protein phosphatase-1.
• Genetic deletion or mutation of DARPP-32 significantly attenuated the behavioral effects of D-amphetamine, LSD, and PCP.
• These findings suggest DARPP-32 is a critical mediator of drug-induced psychotomimetic behaviors.

Conclusions:

• A common signaling pathway converges on DARPP-32 to mediate the behavioral effects of diverse psychotomimetic drugs.
• DARPP-32 represents a potential therapeutic target for conditions associated with schizophrenia-like symptoms.