Methamphetamine-associated cleavage of the synaptic adhesion molecule intercellular adhesion molecule-5

Area of Science:

• Neuroscience
• Molecular Biology
• Addiction Research

Background:

• Methamphetamine (MA) is a neurotoxic psychostimulant with high addictive potential.
• Matrix metalloproteinase (MMP) inhibitors reduce addiction-related behaviors in animal models.
• Polymorphisms in synaptic cell-adhesion molecules (CAMs), MMP substrates, are linked to human addiction.

Purpose of the Study:

• To investigate if MA stimulates the cleavage of intercellular adhesion molecule-5 (ICAM-5), a synaptic CAM.
• To explore the consequences of ICAM-5 shedding in relation to synaptic plasticity.

Main Methods:

• In vitro assays to assess MA's effect on ICAM-5 ectodomain cleavage, with and without MMP inhibitors.
• In vivo administration of MA to mice, followed by analysis of ICAM-5 cleavage in hippocampus and striatum.
• Biochemical assays to examine the interaction of shed ICAM-5 ectodomain with β(1) integrins and cofilin phosphorylation.

Main Results:

• MA directly stimulates ICAM-5 ectodomain cleavage in vitro, an effect blocked by MMP inhibitors.
• Acute MA administration in vivo induced ICAM-5 cleavage in murine hippocampus and striatum within 6 hours, accompanied by increased MMP-9.
• The shed ICAM-5 ectodomain interacts with β(1) integrins, promoting cofilin phosphorylation linked to spine maturation.

Conclusions:

• MA induces cleavage of the synaptic CAM ICAM-5 via MMPs, both in vitro and in vivo.
• MA-induced ICAM-5 shedding may contribute to synaptic plasticity changes associated with methamphetamine addiction.
• MMPs are implicated as effectors of synaptic plasticity, providing a potential mechanism for MA's neurobiological impact.