Serotonergic fiber sprouting to external anal sphincter motoneurons after spinal cord contusion

Gregory Holmes, Montina J. Van Meter, Michael S. Beattie, Jacqueline C. Bresnahan

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

The present study analyzed the anatomical plasticity of serotonergic immunoreactive projections to external anal sphincter (EAS) motoneurons, and the behavioral plasticity of EAS reflexes, penile erection, and locomotion in rats with spinal contusion injury (SCI) or complete spinal cord transection (TX). Electromyographic activity of the EAS, penile erection latency, and BBB locomotor score exhibited parallel recovery over the 6-week recovery period after contusion SCI. This pattern of recovery was not observed in TX animals. While locomotor scores demonstrated a small increase after TX, erectile and anorectal function remained at abnormal levels established immediately after injury. Serotonergic immunofluorescent (5-HT-IF) staining at the lesion site identified a small number of fibers spared after SCI that may provide a substrate for functional recovery. Pixel density measurements of 5-HT-IF in the vicinity of retrogradely labeled EAS and unlabeled pudendal motoneurons necessary for penile erection provide indirect evidence of serotonergic sprouting that parallels the observed functional recovery in animals with SCI. No 5-HT-IF was detected caudal to the injury site in TX animals. These studies indicate: (1) lumbosacral eliminative and reproductive reflexes provide a valid means of studying the mechanisms of post-SCI plasticity; (2) the similar recovery curves suggest similar return of descending control, perhaps through sprouting of descending serotonergic fibers; (3) the observed deficits after TX likely represent the permanent removal of descending inhibition and reflect reorganization of segmental circuitry.

Original languageEnglish (US)
Pages (from-to)29-42
Number of pages14
JournalExperimental Neurology
Volume193
Issue number1
DOIs
StatePublished - Jan 1 2005

Fingerprint

Contusions
Anal Canal
Motor Neurons
Spinal Injuries
Spinal Cord Injuries
Penile Erection
Serotonin
Reflex
Wounds and Injuries
Locomotion
Staining and Labeling

All Science Journal Classification (ASJC) codes

  • Neurology
  • Developmental Neuroscience

Cite this

Holmes, Gregory ; Van Meter, Montina J. ; Beattie, Michael S. ; Bresnahan, Jacqueline C. / Serotonergic fiber sprouting to external anal sphincter motoneurons after spinal cord contusion. In: Experimental Neurology. 2005 ; Vol. 193, No. 1. pp. 29-42.
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Serotonergic fiber sprouting to external anal sphincter motoneurons after spinal cord contusion. / Holmes, Gregory; Van Meter, Montina J.; Beattie, Michael S.; Bresnahan, Jacqueline C.

In: Experimental Neurology, Vol. 193, No. 1, 01.01.2005, p. 29-42.

Research output: Contribution to journalArticle

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