Activation of GABA-A receptor ameliorates homocysteine-induced MMP-9 activation by ERK pathway

Area of Science:

• Neuroscience
• Biochemistry
• Vascular Biology

Background:

• Hyperhomocysteinemia (HHcy) is a known risk factor for neuroinflammatory and neurodegenerative conditions.
• Homocysteine (Hcy) contributes to redox stress and blood-brain barrier dysfunction by activating matrix metalloproteinase-9 (MMP-9).
• The specific role of GABA-A receptors in Hcy-induced cerebrovascular remodeling remains unclear.

Purpose of the Study:

• To investigate the role of GABA-A receptors in Hcy-induced cerebrovascular remodeling.
• To determine if Hcy affects cerebrovascular remodeling via redox stress, MMP-9 activity, and the ERK signaling pathway.
• To elucidate the interaction between Hcy, GABA-A receptors, and oxidative stress.

Main Methods:

• Assessed Hcy-induced reactive oxygen species (ROS) production using a fluorescent probe.
• Measured MMP-9 activity via gelatin zymography and ERK pathway activation through phosphorylation.
• Evaluated the effects of the GABA-A receptor agonist, muscimol, on Hcy-induced changes.

Main Results:

• Hcy increased ROS production, MMP-9 activity, and ERK phosphorylation, while decreasing thioredoxin and tissue inhibitors of metalloproteinase-4 (TIMP-4).
• Hcy also altered inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) expression, reducing NO bioavailability.
• Muscimol treatment ameliorated Hcy-mediated MMP-9 activation and restored TIMP-4 levels, suggesting a protective role.

Conclusions:

• Hcy appears to interfere with GABA-A receptors, triggering an oxidative stress pathway that activates ERK signaling.
• This mechanism contributes to cerebrovascular remodeling and dysfunction in HHcy.
• Targeting GABA-A receptors may offer a novel therapeutic strategy for managing Hcy-related neurological disorders.