Variations in amino acid neurotransmitters in the rat ventral spinal cord after hindlimb unloading

We have measured by HPLC the neurotransmitter content in L4 and L5 spinal segmental levels in CONT rats, after 7 (HU7) and after 14 days (HU14) of hindlimb unloading. These segments are known to contain the hindlimb muscle motoneurons. The main result is the increase of two neuroexcitators (glutamate and aspartate) and two neuroinhibitors (glycine and GABA) at the L5 spinal segmental level in HU7 group. Our data indicated that the neurotransmitter changes are restricted to spinal segmental level containing motoneurons from muscles which are strongly modified by HU condition.