Regulation of axon transport of hydrocortisone via spinal root fibers and its modification in old rats
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.
KeywordsDorsal Root Ganglion Neuron Axon Transport Ventral Root Spinal Root Root Fiber
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- 1.H. Selye,Stress und Altern, Angelsachsen-Verlag, Bremen (1962).Google Scholar
- 2.M. A. Krasil'nikov, “On a probable role of glucocorticoid hormones in aging of an organism,”Vestn. Akad. Med. Nauk SSSR, No. 3, 56–59 (1990).Google Scholar
- 4.O. Mehis, B. Tonshoff, G. Kovacs, et al., “Interaction between glucocorticoids and growth hormone,”Acta Pediat., Suppl. 388. 77–82 (1993).Google Scholar
- 6.V. V. Frol'kis and S. A. Tanin, “Axon transport of steroid hormones along fibers of the spinal roots in rats,”Neirofiziologiya/Neurophysiology,29, No. 2, 98–104 (1997).Google Scholar
- 9.V. G. Shalyapina, D. A. Zhukov, I. A. Gorina, and V. V. Rakitskaya, “Transport mechanisms in the effects of corticosteroid hormones,” in:Physiology of Hormone Reception [in Russian], Nauka, Leningrad (1986), pp. 34–69.Google Scholar
- 10.M. J. Meaney, V. Vian, D. H. Aitken, and S. Bhatnagar, “Stress-induced occupancy and translocation of hippocampal glucocorticoid receptors,”Brain Res.,445, No. 1, 198–203 (1998).Google Scholar
- 11.V. V. Frol'kis and S. A. Tanin, “Peculiarities of axon transport of steroid hormones along fibers of the spinal roots in old rats,”Neirofiziologiya/Neurophysiology,30, No. 3, 182–188 (1998).Google Scholar
- 12.V. V. Frol'kis, S. A. Tanin, V. I. Martsinko, and O. K. Kul'chitskii, “Velocity of axoplasmic transport via the ventral spinal roots in old age and its dependence on the level of energetic metabolism,”Neirofiziologiya/Neurophysiology,26, No. 2, 189–194 (1994).Google Scholar
- 16.T. S. Bogdanova and T. T. Podvigina, “Corticosteroids and energy exchange in the brain,” in:The Hypophyseal-Adrenal System and the Brain [in Russian], Nauka, Leningrad (1990).Google Scholar
- 17.N. A. Emel'yanov and I. A. Gerasimova,Corticosteroids and Metabolism in the Brain [in Russian], Nauka, Leningrad (1990).Google Scholar
- 19.Aging of the Brain [in Russian], Nauka, Leningrad (1991).Google Scholar
- 20.F. I. Grishko, “Ontogenesis-related specificities of the tissue metabolism in the muscles, nerves, and spinal cord,” in:Mechanisms of Aging [in Russian], Gosmedizdat, Kiev (1963), pp. 299–304.Google Scholar