Changes in GABAA receptor subunit gamma2 in extensor and flexor motoneurons and astrocytes after spinal cord transection and motor training

Brain Res, 2009 · DOI: 10.1016/j.brainres.2009.03.060 · Published: June 1, 2009

Simple Explanation

This study investigates how GABA signaling, crucial for spinal cord response to injury and motor training, is affected by spinal cord injury and subsequent motor training. Researchers examined the γ2 subunit of the GABAA receptor, which is essential for benzodiazepine binding, a common treatment for muscle spasticity after spinal cord injuries. The study found that motor training can restore GABAA γ2 levels towards control values in motoneuronal pools of both muscles.

Study Duration

8 weeks

Participants

6 control rats, 6 spinal cord transected non-trained rats, and 6 spinal cord transected trained rats

Evidence Level

Not specified

Key Findings

1
Spinal rats had higher levels of γ2 in TA (tibialis anterior, ankle flexor) motoneurons and lower levels in soleus (ankle extensor) motoneurons compared to intact rats.
2
Step training restored GABAA γ2 levels towards control values in motoneuronal pools of both soleus and TA muscles.
3
γ2 levels were elevated in surrounding astrocytes of both motor pools in spinal rats, and step training had no further effect.

Research Summary

The study investigates changes in the γ2 subunit of GABAA receptors in muscle-specific motoneurons and astrocytes following spinal cord transection and motor training in rats. Researchers found that spinal cord transection differentially modulates γ2 immunoreactivity in soleus and TA motoneurons, with lower levels in soleus and higher levels in TA compared to intact rats. Step training normalized γ2 levels in motoneurons but had no effect on elevated γ2 levels in surrounding astrocytes, suggesting a specific effect on neurons directly involved in the motor task.

Practical Implications

Therapeutic Potential

Motor training can be a valuable tool to normalize GABAergic signaling after spinal cord injury.

Targeted Therapies

Further research should focus on the differential modulation of GABA receptors in specific motor pools to develop targeted therapies.

Astrocytic Involvement

Understanding the role of astrocytes in GABAergic signaling after spinal cord injury may provide new avenues for therapeutic intervention.

Study Limitations

1
The study used a neonatal spinal cord transection model, which may not fully reflect the adult injury response.
2
The specific mechanisms underlying the differential response of extensor and flexor motor pools remain unclear.
3
The study did not investigate other GABAR subunits, which may also contribute to the observed changes.

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