Tissue-type plasminogen activator is not required for kainate-induced motoneuron death in vitro

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• Spinal motoneurons are susceptible to kainate excitotoxicity.
• Tissue-type plasminogen activator (tPA) and plasmin have been implicated in kainate-induced neuronal death in the hippocampus.
• The role of tPA in spinal motoneuron excitotoxicity remains unclear.

Purpose of the Study:

• To investigate whether tPA mediates kainate-induced death of spinal motoneurons in vitro.
• To determine if the plasmin system contributes to kainate excitotoxicity in spinal motoneurons.

Main Methods:

• Primary cultures of motoneuron-enriched populations from wild-type (WT) and tPA-deficient (tPA-/-) mouse embryos.
• Co-culturing of neurons and spinal glial feeder layers from WT and tPA-/- mice.
• Exposure to kainate and assessment of neurotoxicity.
• RT-PCR for tPA expression analysis.
• Treatment with the plasmin inhibitor alpha2-antiplasmin.

Main Results:

• Kainate-induced neurotoxicity was comparable between WT and tPA-/- motoneuron cultures.
• The plasmin inhibitor alpha2-antiplasmin did not provide protection against kainate-induced injury in WT neurons.
• tPA expression was confirmed in WT co-cultures via RT-PCR.

Conclusions:

• The plasmin system, including tPA, does not appear to mediate kainate-induced excitotoxicity in spinal motoneurons in vitro.
• These findings suggest that the mechanisms of kainate excitotoxicity may differ between neuronal populations.
• The plasmin system is not a universal mediator of kainate-induced excitotoxicity.