RE-INNERVATION OF GUINEA-PIG SUPERIOR CERVICAL GANGLION CELLS BY PREGANGLIONIC FIBRES ARISING FROM DIFFERENT LEVELS OF THE SPINAL CORD

J. Phy8iol., 1977 · DOI: · Published: January 31, 1977

Physiology Neurology Regenerative Medicine & Stem Cells

Simple Explanation

This study investigates how nerve cells re-establish connections after nerve damage, focusing on the mammalian peripheral sympathetic system. Researchers examined preganglionic axons from different spinal cord levels and their ability to reconnect with neurones in sympathetic ganglia after nerve section. The study found that while the general pattern of reconnection is restored, some abnormalities occur, such as fewer connections and disproportionate weakness in connections from certain spinal segments.

Study Duration

4-9 Months

Participants

24 guinea-pigs

Evidence Level

Not specified

Key Findings

1
The general distribution of segmental contributions to the superior cervical ganglion was restored after nerve regeneration, but each ventral root innervated a smaller fraction of neurones.
2
The average number of spinal segments contributing innervation to a neurone was reduced after re-innervation, and discontinuities in the sequence of innervating segments were more frequent.
3
Re-innervated cells tended to be innervated in a graded fashion by a subset of contributing spinal segments, with the strongest innervation from a single ventral root and diminishing influence from adjacent segments.

Research Summary

This study examined the re-establishment of synaptic connections in the guinea-pig superior cervical ganglion after section of the cervical sympathetic trunk. In vivo stimulation showed generally normal end-organ responses, and intracellular recordings revealed a largely normal segmental pattern of innervation of ganglion cells. However, abnormalities were observed, including a reduced number of innervating segments per neurone, more discontinuities in the innervation pattern, and a disproportionately weak innervation by caudal segments.

Practical Implications

Understanding Nerve Regeneration

The study provides insights into the mechanisms of nerve regeneration and the factors that influence the specificity of synaptic connections.

Clinical Applications

The findings may have implications for the development of strategies to promote nerve regeneration and improve functional recovery after nerve injury.

Chemo-affinity

The research supports the concept of chemo-affinity in nerve regeneration, where specific chemical signals guide the formation of appropriate synaptic connections.

Study Limitations

1
The study observed slight abnormalities of end-organ responses after re-innervation, but the significance of these irregularities is uncertain.
2
It is unclear whether the disproportionately poor performance of caudal preganglionic fibres during re-innervation is due to regeneration failure or other factors.
3
The mechanisms underlying the establishment of appropriate synaptic contacts during development and re-innervation are not fully understood.

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