Elsevier

Neuroscience

Volume 92, Issue 4, June 1999, Pages 1399-1404
Neuroscience

Peculiarities of axonal transport of steroid hormones (hydrocortisone, testosterone) in spinal root fibres of adult and old rats

https://doi.org/10.1016/S0306-4522(99)00085-8Get rights and content

Abstract

The labelled steroid hormones [3H]hydrocortisone and [14C]testosterone, being injected into the gray matter of the rat spinal cord L5–L6 segments, were shown to be transported at a high velocity along the ventral (anterograde) and dorsal (retrograde) root fibres. The maximum velocity of axonal transport along the ventral and dorsal roots in adult rats was, on average, 3006±101 and 3028±48 mm/day for [3H]hydrocortisone and 4594±186 and 5185±485 mm/day for [14C]testosterone, respectively. In old rats, axonal transport of steroid hormones was markedly slower. Its maximum velocity along the ventral and dorsal roots averaged to 756±64 and 738±48 mm/day for [3H]hydrocortisone and 624±54 and 608±80 mm/day for [14C]testosterone, respectively. In old rats the amount of labelled hydrocortisone incorporated into the ventral root fibres was sharply reduced (by more than an order of the value) as compared to that in adult animals. At the same time, the intensity of the labelled testosterone incorporation into the ventral root fibres did not demonstrate any significant age-related difference. The injection of low doses of steroid hormones (from less than one microgram to a few micrograms) into the lumbar spinal cord resulted in a significant hyperpolarization several hours later first of the gastrocnemius and then of deltoideus muscle fibres. In old rats, such a hyperpolarization occurred much later.

It is suggested that axonal transport of steroid hormones is one of the mechanisms responsible for the effects of hormones on the tissues, which undergoes considerable changes with ageing.

Section snippets

Experimental procedures

The experiments were performed on male Wistar rats aged six to 11 and 25–28 months kept at 22–26°C. The animals were anaesthetized with sodium pentobarbital (30 mg/kg, i.p.). Axonal transport was studied in the L5–L6 ventral (anterograde flow) and dorsal (retrograde flow) spinal roots using the technique described elsewhere.8 Benzene-ethanol solution of [3H]hydrocortisone and benzene solution of [14C]testosterone were injected into the gray matter of L5–L6 segments in a dose of 7–8 μl. It

Results

Studying the distribution of labelled hydrocortisone in the spinal roots of adult rats showed that this hormone becomes involved rather quickly in both the anterograde (motoneuronal axons) and retrograde (central processes of the spinal ganglia neurons) AT.

Ten minutes after the hormone administration into the spinal cord, an elevated frequency of disintegrations, significantly exceeding their background level, was noted in the root fragments located 21–24 mm away from the spinal cord, whereas 15 

Discussion

The results of our experiments indicated that steroid hormones ([3H]hydrocortisone and [14C]testosterone) become involved in AT and are transported with very high velocity along the fibres of the ventral and dorsal spinal roots in adult rats. The calculated maximum velocities of anterograde and retrograde transports of [3H]hydrocortisone were practically equal to each other and amounted to about 3000 mm/day. The velocities of anterograde and retrograde transports of [14C]testosterone were 1.5

References (29)

  • Frolkis V. V. (1992) Invertors—a regulators of plasmic membrane controlled by genome Dokl. Acad. Sci. Russia 324,...
  • B.M. Giovanelli et al.

    Propriospinal fibers interconnecting the spinal enlargements in cat

    Brain Res.

    (1969)
  • J. Goemaere-Vanneste et al.

    Ageing in the peripheral nervous system: a qualitative and quantitative study of fibers regeneration

    Neurosci. Lett.

    (1985)
  • S. Gonzales et al.

    Glucocorticoid receptors and enzyme introduction in the spinal cord of rats: effects of acute transection

    J. Neurochem.

    (1990)
  • View full text