CHANGES IN PRIMARY AFFERENT DEPOLARIZATION OF SENSORY NEURONES DURING PERIPHERAL NERVE REGENERATION IN THE CAT

J. Phyaiol, 1981 · DOI: · Published: January 1, 1981

Physiology Neurology Regenerative Medicine & Stem Cells

Simple Explanation

This study investigates how nerve regeneration affects the way sensory neurons communicate in the spinal cord. Specifically, it looks at primary afferent depolarization (p.a.d.), a process where the central terminals of sensory neurons become more excitable. The researchers found that after nerve injury, p.a.d. is reduced, meaning the sensory neurons are less able to be excited. This reduction is due to both a decrease in the number of neurons showing p.a.d. and a slight decrease in the magnitude of p.a.d. in those neurons that do show it. The study suggests that nerve damage causes the central terminals of sensory neurons to retract or atrophy, and that these terminals must re-form as the nerve regenerates. This re-formation process doesn't necessarily depend on the neuron re-establishing a connection in the skin.

Study Duration

1-9 Months

Participants

Adult cats (2.5-6.5 kg)

Evidence Level

Not specified

Key Findings

1
After nerve injury, the excitability changes associated with primary afferent depolarization were significantly less than in control animals.
2
The proportion of nerve fibers showing no evidence of primary afferent depolarization increased significantly after nerve injury.
3
Even when primary afferent depolarization was present, the magnitudes of the effects were slightly but significantly decreased compared with control values.

Research Summary

Micro-electrode recordings were made from normal and regenerating sural nerve fibres in cats to assess changes in primary afferent depolarization after nerve injury. The study found a significant reduction in primary afferent depolarization of regenerating sural nerve fibres, due to a combination of fewer fibres exhibiting depolarization and a decrease in the magnitude of the effect when present. The researchers suggest that the central terminals of damaged nerve fibres retract or atrophy after injury, and then re-form during regeneration, influencing the observed changes in primary afferent depolarization.

Practical Implications

Understanding Nerve Regeneration

The study provides insights into the central changes that occur during peripheral nerve regeneration, specifically regarding primary afferent depolarization.

Potential Therapeutic Targets

Identifying the mechanisms behind the loss and re-establishment of primary afferent depolarization could lead to new therapeutic strategies for improving sensory recovery after nerve injury.

Central Plasticity

The findings suggest that the central nervous system exhibits plasticity in response to peripheral nerve damage, potentially allowing for the re-organization of sensory pathways.

Study Limitations

1
The study was conducted on cats, and the findings may not be directly applicable to humans.
2
The exact mechanisms underlying the observed changes in primary afferent depolarization were not fully elucidated.
3
The study focused on sural nerve fibres, and the results may not be representative of other types of sensory nerves.

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