Abstract
The intensity of axon transport (AT) of3H-hydrocortisone via fibers of the ventral (anterograde AT) and dorsal (retrograde AT) roots was shown to depend on the concentration of labelled hormone injected into the gray matter of theL 5-L6 spinal segments. The concentration dependence of anterograde flow (axons of motoneurons) was manifested both in the velocity and amount of transported hormone, while only velocity was modified in retrograde AT (in central processes of dorsal root ganglion neurons). In old rats, a concentration-dependent increase in the amount of labelled hormone was observed only within rather narrow range of activity of injected3H-hydrocortisone (from 0.036 to 0.108 MBq/μl). An increase in the activity of labelled hormone to 0.14–0.18 MBq/μl suppressed its uptake into the ventral root fibers. At the same time, modifications of the AT velocity showed direct dependence on the concentration within the entire studied range of3H-hydrocortisone activity. similar modification of the velocity were observed in the dorsal roots of old rats. It is supposed that an increase in the intracellular concentration of a glucocorticoid activates the mechanisms of hormone removal from the motoneurons, and these mechanisms become sharply weaked in old age.
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Tanin, S.A. Regulation of axon transport of hydrocortisone via spinal root fibers and its modification in old rats. Neurophysiology 30, 246–249 (1998). https://doi.org/10.1007/BF02462829
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DOI: https://doi.org/10.1007/BF02462829