Immunoreactive Change of Neuropeptides in Gastrocnemius Muscle and Dorsal Root Ganglia of Rat Followed by Ischemia

ABSTRACT

There are much evidences to indicate that muscles and its tendon are inserted during the reperfusion phase of ischemia-reperfusion insults. However, until now the alterations of neurotransmitter induced by ischemia- reperfusion have not been examined in peripheral nervous system. This study reports the alterations of calcitonin gene-related peptide(CGRP) and substance P(SP) in the hindlimb ischemic model by immunohistochemical methods. In the control group, the CGRP and SP immunoreactivity was observed in nerve terminals of gastrocnemius muscle and its tendon. In the dorsal root ganglia, CGRP immunoreactivity was shown in the large A cell and small B cell. On the other hand, SP immunoreactvity was predominantly detected in small B cells. The CGRP immunoreactivity in the gastrocnemius muscle increased significantly in 2 hour ischemic group, but decreased in its tendon. The SP immunoreactivity, however, was declined in the gastrocnemius muscle as well as its tendon in 2 hour ischemic group. The CGRP immunoreactivity in the dorsal root ganglia was significantly decreased, particularly in large A cell, compared to the control group. The SP immunoreactivity in the dorsal root ganglia, on the other hand, was markedly increased. In conclusion, these results suggest that the ischemia may evoke the alteration of neurotransmitter expressions as well as the muscle degeneration, and that the changes of neuropeptide distribution induced by ischemia show the difference from the kind of neuropeptides.