"Fatigue" of medullary but not mesencephalic raphe serotonergic neurons during locomotion in cats

Casimir A. Fornal, Francisco J. Martín-Cora, Barry L. Jacobs

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Single unit activity of presumed serotonergic neurons in the medulla [n. raphe obscurus (NRO) and pallidus (NRP)] or the mesencephalon [n. raphe dorsalis (DRN)] was recorded in adult male cats during prolonged treadmill locomotion. Treadmill speed was set at a moderate level (0.4 m/s) in order to induce long-duration locomotion. The typical time to "fatigue" (failure to keep pace, falling behind and reluctance to continue) was ∼ 40 min in both groups, at which point cats typically displayed marked panting and vocalization. The activity of DRN neurons was unchanged from baseline during the locomotion trial and during the recovery phase. By contrast, the activity of NRO/NRP neurons decreased steadily across the locomotion trial, reaching a mean decrease of ∼50% (during the first min after the treadmill was turned off). Full recovery of single unit activity to a level approximating the baseline discharge rate required 30-45 min. Possible mechanisms underlying these changes are discussed as is the role of serotonin and fatigue in human pathology.

Original languageEnglish (US)
Pages (from-to)55-61
Number of pages7
JournalBrain Research
Volume1072
Issue number1
DOIs
StatePublished - Feb 9 2006

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

Keywords

  • Brain stem
  • Exercise
  • Fatigue
  • Serotonin
  • Single unit activity
  • Treadmill

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