Increased activity in the form of endurance training increases calcitonin gene-related peptide content in lumbar motoneuron cell bodies and in sciatic nerve in the rat.
The relative content of calcitonin gene-related peptide in lumbar motoneuron cell bodies (semiquantitative immunohistochemistry) and sciatic nerve was examined in rats who had previously undergone a 16-week period of endurance training on a motor-driven treadmill. Soleus motoneurons were identified in the spinal cord by their fluorescence following injection of FluoroGold into the muscle one week before killing. In sedentary rats, calcitonin gene-related peptide was detectable in 76-90% of motoneurons, with no difference in the proportions of negative cells, or in the mean staining intensity of positive cells, between soleus and neighbouring (presumptive fast hindlimb muscle) unlabelled moto-neurons. In endurance-trained rats, the estimated content of calcitonin gene-related peptide was significantly increased (90%) in cell bodies of soleus and neighbouring motoneurons, with no training-induced alterations in the proportions of calcitonin gene-related peptide-positive cells in either sample. The content of the neuropeptide was also significantly higher (37%) in sciatic nerve of endurance-trained rats. Relative accumulation of calcitonin gene-related peptide proximal to a sciatic nerve ligature applied 4 h before, however, was unchanged. The increases in calcitonin gene-related peptide in motoneuron cell bodies and sciatic nerve axons following endurance training may indicate an up-regulation of the synthesis, transport and terminal release of this neuropeptide, which could play a significant role in other morphological and functional adaptations which are known to occur at the neuromuscular junction following this chronic change in activity level.
Gharakhanlou
R
R
Department of Kinesiology, Université de Montréal, Québec, Canada.
Chadan
S
S
Gardiner
P
P
D000818:Animals; D001370:Axonal Transport; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D005260:Female; D005456:Fluorescent Dyes; D009043:Motor Activity / Q000502:physiology*; D009046:Motor Neurons / Q000166:cytology / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000166:cytology / Q000502:physiology*; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*; D013266:Stilbamidines
C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D005456:Fluorescent Dyes; D013266:Stilbamidines; D015740:Calcitonin Gene-Related Peptide