REORGANIZATION OF SYMPATHETIC PREGANGLIONIC CONNECTIONS IN CAT BLADDER GANGLIA FOLLOWING PARASYMPATHETIC DENERVATION

Journal of Physiology, 1989 · DOI: · Published: January 1, 1989

Simple Explanation

The study investigates how the sympathetic nervous system reorganizes its connections to the bladder after the parasympathetic nerves, which normally control bladder emptying, are damaged. After parasympathetic denervation, the sympathetic nerves, which usually inhibit bladder contractions, start to cause bladder contractions. This is due to the sympathetic nerves reinnervating the denervated parasympathetic ganglion cells. This change in nerve function may contribute to the development of an overactive bladder that is often seen after spinal cord injuries or other conditions that damage the nerves controlling the bladder.

Study Duration

2 weeks to 22 months

Participants

Thirty-five adult cats (twenty-five females, ten males)

Evidence Level

Not specified

Key Findings

1
Chronic parasympathetic denervation leads to hypogastric nerve stimulation causing large and sustained bladder contractions, in contrast to the small transient contractions seen in intact bladders.
2
These contractions after denervation are mediated by muscarinic and nicotinic cholinergic synapses, as they are blocked by atropine and hexamethonium.
3
Following extensive denervation, stimulation of the intact pelvic nerve can elicit firing in vesical postganglionic nerves on the denervated side, indicating a crossed excitatory pathway.

Research Summary

This study examined the reorganization of sympathetic pathways to the cat urinary bladder following chronic parasympathetic denervation. Hypogastric nerve stimulation after denervation elicited large bladder contractions mediated by cholinergic synapses, unlike the normal inhibitory response. Contralateral pelvic nerve stimulation induced postganglionic firing on the denervated side after extensive denervation, suggesting a crossed excitatory pathway.

Practical Implications

Understanding Bladder Dysfunction

The findings help explain the mechanisms behind autonomous hyperactive bladder, which occurs after nerve damage.

Therapeutic Targets

Identifying the cholinergic involvement suggests potential therapeutic targets for managing bladder hyperactivity.

Rehabilitation Strategies

The study provides insight for developing rehabilitation strategies that may prevent or reverse the maladaptive neural reorganization after bladder denervation.

Study Limitations

1
The study was conducted on cats, and the results may not be directly applicable to humans.
2
The study focuses on the effects of denervation and does not address other potential causes of bladder dysfunction.
3
The exact mechanisms underlying the sprouting and reinnervation of nerve fibers were not fully elucidated.

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