Correlation between reactive sprouting and microtubule protein expression in epileptic hippocampus

Area of Science:

• Neuroscience
• Cell Biology

Background:

• Temporal lobe epilepsy (TLE) in humans and rats involves hippocampal mossy fiber collateral sprouting, forming abnormal recurrent synaptic connections.
• Previous research indicated that increased alpha-tubulin expression in granule cells precedes mossy fiber synaptic remodeling in a rat model of TLE.

Purpose of the Study:

• To investigate the role of microtubule-associated proteins (MAPs), specifically MAP2 and TAU, in the axonal sprouting of mossy fibers during experimental temporal lobe epilepsy.
• To determine if the expression patterns of MAP2 and TAU correlate with the observed alpha-tubulin changes and subsequent mossy fiber sprouting.

Main Methods:

• Utilized in situ hybridization to quantify messenger RNA levels of MAP2 and TAU in rat hippocampal granule cells following kainate-induced seizures.
• Assessed MAP2 and TAU protein expression and localization using immunohistochemistry in the experimental model.

Main Results:

• Kainate treatment led to increased MAP2 messenger RNA in granule cell bodies and dendrites, alongside elevated MAP2 immunoreactivity in dendrites.
• TAU messenger RNA levels rose in granule cell bodies, with increased TAU immunoreactivity observed in their axons (mossy fibers).
• The temporal profile of MAP2 and TAU expression changes paralleled alpha-tubulin increases and occurred before and during mossy fiber sprouting.

Conclusions:

• The study suggests that elevated expression of alpha-tubulin, MAP2, and TAU contributes to microtubule formation.
• Overexpression of these microtubule-associated proteins likely plays a significant role in the pathological mossy fiber sprouting observed in epilepsy.