c-fos expression and NADPH-d reactivity in spinal neurons after fatiguing stimulation of hindlimb muscles in the rat

Alexander I. Pilyavskii, Vladimir A. Maisky, Ivana Kalezic, Milos Ljubisavljevic, Alexander I. Kostyukov, Uwe Windhorst, Håkan Johansson

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26 Citations (Scopus)


The distribution of Fos-immunoreactive (Fos-ir) and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d)-reactive neurons in the rat lumbar spinal cord was examined following muscle fatigue caused by intermittent high-rate (100 s-1) electrical stimulation of the triceps surae muscle or the ventral root L5 (VRL5) for 30 min. Following both types of stimulation, the fatigue-related c-fos gene expression was more extensive in the L2-L5 segments on the stimulated side, and the majority of Fos-ir neurons were concentrated in the dorsal horn. After direct muscle stimulation, the highest number of Fos-ir neurons were detected in two regions: layer 5, and superficial layers (1 and 2o), although many labeled cells were also found in layers 3, 4, 6, and 7. In response to VRL5 stimulation, the maximal density of Fos-ir neurons was detected in the middle and lateral parts of layers 1 and 2o, the zone of termination of high-threshold muscle afferents. Statistically significant prevalence of Fos-ir cell number was also found in layers 5 and 7 on the stimulated side. A few Fos-ir neurons were detected in the ventral horn (layer 8 and area 10) on both sides. The lamellar distribution of NADPH-d-reactive neurons was similar over all experimental groups of animals. In the L3-L6 segments, such reactive cells were arranged in two distinct regions: dorsal horn (layers 2i, 3, and 5) and area 10; in the L1 and L2 segments, an additional cluster of NADPH-d positive cells was found in the intermediolateral cell column (IML). Double-labeled cells were not detected. We suggest that c-fos expression in response to muscle fatigue reveals activity of functionally different types of spinal neurons which could operate together with NOS-containing cells in pre-motoneuronal networks to modulate the motoneuron output.

Original languageEnglish
Pages (from-to)91-102
Number of pages12
JournalBrain Research
Issue number1-2
Publication statusPublished - Dec 27 2001
Externally publishedYes


  • Fos immunoreactivity
  • Muscle fatigue
  • NADPH-d positive neuron
  • Spinal cord

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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