Some gamma-motoneurons contain gamma-aminobutyric acid in the rat cervical spinal cord

Brain Res. 2008 Mar 27;1201:78-87. doi: 10.1016/j.brainres.2008.01.056. Epub 2008 Feb 2.


Gamma-aminobutyric acid (GABA) is utilized in the peripheral as well as central nervous system. In this study, fibers immunoreactive for 67 kDa isoform of glutamic acid decarboxylase (GAD67), an enzyme which synthesizes GABA, were found to terminate in the intercapsular region of muscle spindles of the upper limb. GABA-containing fibers were also found in the ventral roots of C5 to T5 spinal segments, brachial plexus, and radial nerve. These fibers were thin and immunoreactive for choline-acetyl transferase (ChAT). After transection of the brachial plexus, GABA immunoreactivity disappeared completely in the ipsilateral triceps brachii muscle (TBM). After the injection of fluorogold into the TBM, some retrogradely labeled medium-sized neurons were positive for GAD67, but not VGAT mRNA. All these observations clearly indicate that GABA-containing gamma-motoneurons in the lower cervical spinal cord send their fibers to muscle spindles in the upper extremities. Since we detected neither GABAA nor GABAB receptors in the TBM by RT-PCR, the function of the GABA-containing gamma-motoneurons remains unclear.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcholine / metabolism
  • Animals
  • Axons / metabolism
  • Axons / ultrastructure
  • Biomarkers / metabolism
  • Brachial Plexus Neuropathies / metabolism
  • Brachial Plexus Neuropathies / physiopathology
  • Cervical Vertebrae
  • Choline O-Acetyltransferase / metabolism
  • Denervation
  • Glutamate Decarboxylase / genetics
  • Glutamate Decarboxylase / metabolism
  • Immunohistochemistry
  • Male
  • Motor Neurons, Gamma / cytology
  • Motor Neurons, Gamma / metabolism*
  • Muscle Spindles / cytology
  • Muscle Spindles / enzymology*
  • Muscle Tonus / physiology
  • Muscle, Skeletal / innervation*
  • Muscle, Skeletal / physiology
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Wistar
  • Spinal Cord / cytology
  • Spinal Cord / metabolism*
  • Spinal Nerve Roots / cytology
  • Spinal Nerve Roots / metabolism
  • Stilbamidines
  • gamma-Aminobutyric Acid / metabolism*


  • 2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt
  • Biomarkers
  • RNA, Messenger
  • Stilbamidines
  • gamma-Aminobutyric Acid
  • Choline O-Acetyltransferase
  • Glutamate Decarboxylase
  • glutamate decarboxylase 1
  • Acetylcholine