Increase of annexin 1 immunoreactivity in spinal cord of newborn opossum (Monodelphis domestica) at the time when regeneration after injury stops being possible.

Abstract

Annexins constitute a family of proteins that associate reversibly with cell membranes in a calcium dependent manner. We have studied the distribution of annexin 1, which is known to mediate anti-inflammatory actions of glucocorticoids, and which is upregulated after spinal cord injury, in newborn and adult South American opossum (Monodelphis domestica) spinal cord. We show the increase in the annexin 1 immunoreactivity in spinal cords of neonatal opossums over the critical period when regeneration after injury ceases to be possible. We further show the restricted and specific sites at which it is detected in adult opossum cerebellum and hippocampus. Since the procedures used in immunochemistry of annexin in CNS have in the past yielded conflicting results, different procedures were tested and shown to be reliable. As a control, annexin 1 distribution was surveyed in kidney.