| Abstrakt: |
Labelled steroid hormones,3H-hydrocortisone and14C-testosterone, being injected in the gray matter of the L 5− L 6 spinal cord segments were shown to be transported via ventral and dorsal root fibers (antero- and retrograde directions, respectively) of old (25 to 28 months) rats with a lower velocity than in adult young (6 to 11 months) animals. The averaged maximum velocities of axon transport (AT) through the ventral and dorsal roots were: for3H-hydrocortisone, 756±63 and 738±46 mm per day, and for14H-testosterone, 624±54 and 608±80 mm per day, respectively. Therefore, in old rats the AT velocities for3H-hydrocortisone and14C-testosterone were about four and seven-eight times lower than those in adult rats. In the course of anterograde, AT through the ventral roots in old rats the inclusion of3H-hydrocortisone is sharply suppressed (by more than an order of magnitude), as compared with than in adult animals. The doses of non-labelled steroid hormones within a 10−7 – 10−6 range, injected into the lumbar spinal segments, resulted in hyperpolarization of muscle fibers of the mm. gastrocnemius and deltoideus, but this phenomenon developed in old rats much later than in adult rats. It is obvious that AT of steroid hormones can be considered one of the mechanisms of their effects on the tissue of an organism, and this mechanism undergoes extremely intensive modifications with aging. [ABSTRACT FROM AUTHOR] |
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