Skip to main page content
U.S. flag

An official website of the United States government

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Mar 15;35(6):825-841.
doi: 10.1089/neu.2017.5329. Epub 2018 Jan 11.

Protective Effects of Estradiol and Dihydrotestosterone following Spinal Cord Injury

Dale R Sengelaub  1 , Qi Han  2 , Nai-Kui Liu  2 , Melissa A Maczuga  1 , Violetta Szalavari  1 , Stephanie A Valencia  1 , Xiao-Ming Xu  3
Affiliations

Protective Effects of Estradiol and Dihydrotestosterone following Spinal Cord Injury

Dale R Sengelaub et al. J Neurotrauma. .

Abstract

Spinal cord injury (SCI) results in lesions that destroy tissue and disrupt spinal tracts, producing deficits in locomotor and autonomic function. We previously demonstrated that motoneurons and the muscles they innervate show pronounced atrophy after SCI, and these changes are prevented by treatment with testosterone. Here, we assessed whether the testosterone active metabolites estradiol and dihydrotestosterone have similar protective effects after SCI. Young adult female rats received either sham or T9 spinal cord contusion injuries and were treated with estradiol, dihydrotestosterone, both, or nothing via Silastic capsules. Basso-Beattie-Bresnahan locomotor testing was performed weekly and voiding behavior was assessed at 3 weeks post-injury. Four weeks after SCI, lesion volume and tissue sparing, quadriceps muscle fiber cross-sectional area, and motoneuron dendritic morphology were assessed. Spontaneous locomotor behavior improved after SCI, but hormone treatments had no effect. Voiding behavior was disrupted after SCI, but was significantly improved by treatment with either estradiol or dihydrotestosterone; combined treatment was maximally effective. Treatment with estradiol reduced lesion volume, but dihydrotestosterone alone and estradiol combined with dihydrotestosterone were ineffective. SCI-induced decreases in motoneuron dendritic length were attenuated by all hormone treatments. SCI-induced reductions in muscle fiber cross-sectional areas were prevented by treatment with either dihydrotestosterone or estradiol combined with dihydrotestosterone, but estradiol treatment was ineffective. These findings suggest that deficits in micturition and regressive changes in motoneuron and muscle morphology seen after SCI are ameliorated by treatment with estradiol or dihydrotestosterone, further supporting a role for steroid hormones as neurotherapeutic agents in the injured nervous system.

Keywords: dendrites; morphology; neuroprotection; steroids.

PubMed Disclaimer

Conflict of interest statement

No competing financial interests exist.

Figures

<b>FIG. 1.</b>
FIG. 1.
Spinal cord injury (SCI) reduced locomotor performance in all groups, with improvement plateauing at 3 weeks post-injury. Treatment with hormones had no effect on locomotor performance. SCI, n = 5; SCI+estradiol (SCI+E), n = 7; SCI+dihydrotestosterone (SCI+DHT), n = 8; SCI+ estradiol and dihydrotestosterone (SCI+E+DHT), n = 6. The dashed line represents a perfect Basso-Beattie-Bresnahan (BBB) score of 21.
<b>FIG. 2.</b>
FIG. 2.
(A) Following spinal cord injury (SCI), void frequency decreased in untreated animals. Treatment with either estradiol (SCI+E) or dihydrotestosterone (SCI+D) improved voiding frequency; treatment with both hormones (SCI+E+D) improved voiding frequency to normal levels. (B) Following SCI, untreated animals had the highest volume per void. Treatment with either estradiol or dihydrotestosterone reduced void volume with the greatest decrease in animals treated with both hormones. Bar heights represent means ± standard error of the mean. *indicates significantly different from normal; †indicates significantly different from untreated SCI; # indicates significantly different from SCI + E and SCI+D; ††indicates significantly different from SCI+E. Normal (naïve), n = 8; SCI, n = 5; SCI+E, n = 7; SCI+DHT, n = 7; SCI+E+DHT, n = 5. (C) Representative smoothed metabolic cage traces illustrating micturition patterns. Normal (naive) animals typically have short latencies and small void volumes. Three weeks post-injury, untreated SCI animals have long latencies and high void volumes resulting in a step-like pattern. Animals that received either estradiol (SCI+E) or dihydrotestosterone (SCI+D) have a smoother pattern; treatment with both hormones (SCI+E+D) resulted in a micturition pattern that closely approximated the normal pattern.
<b>FIG. 3.</b>
FIG. 3.
Histological and stereological analysis of spinal cord spared tissue and lesion volume after contusive spinal cord injury (SCI) with or without hormone treatment. (A) Representative sections through the lesion epicenter of an untreated animal (SCI) and an estradiol-treated animal (SCI+E) stained with cresyl violet and eosin, showing large centrally located cystic cavities with rims of spared tissue surrounding the cavity. Scale bar = 500 μm. (B) Stereo Investigator drawings from the same sections showing the lesion area (including regions of cavitation and fibrosis), residual white matter (WM), and spared gray matter (GM). (C) Lesion volume was reduced in SCI animals treated with estradiol. Bar heights represent means ± standard error of the mean. *indicates significantly different from untreated SCI; SCI, n = 11; SCI+estradiol (SCI+E), n = 7; SCI+dihydrotestosterone (SCI+DHT), n = 8; SCI+ estradiol and dihydrotestosterone (SCI+E+DHT), n = 6.
<b>FIG. 4.</b>
FIG. 4.
Percent total volumes of lesion and spared white and gray matters across groups. Bar heights represent means ± standard error of the mean. Spinal cord injury (SCI; white bars), n = 11; SCI+estradiol (SCI+E, light gray bars), n = 7; SCI+dihydrotestosterone (SCI+DHT, medium gray bars), n = 8; SCI+ estradiol and dihydrotestosterone (SCI+E+DHT, dark gray bars), n = 6.
<b>FIG. 5.</b>
FIG. 5.
Darkfield digital micrographs and matching computer-generated composites of transverse hemisections through the lumbar spinal cords of a sham animal (A, F), an injured animal given a blank implant (spinal cord injury [SCI]; B, G), an estradiol-treated injured animal (SCI+E; C, H), a dihydrotestosterone-treated injured animal (SCI+D; D, I), and an injured animal treated with both hormones (SCI+E+D; E, J), after BHRP injection into the left vastus lateralis muscle. Computer-generated composites of BHRP-labeled somata and processes were drawn at 480 μm intervals through the entire rostrocaudal extent of the quadriceps motor pool; these composites were selected because they are representative of their respective group average dendritic lengths. Scale bar = 500 μm.
<b>FIG. 6.</b>
FIG. 6.
Dendritic lengths of quadriceps motoneurons of sham animals (n = 7) and injured animals that were either untreated (spinal cord injury [SCI]), n = 11, or treated with estradiol (SCI+E), n = 6; SCI+dihydrotestosterone (SCI+DHT), n = 6; or estradiol and dihydrotestosterone combined (SCI+E+DHT), n = 6. Following contusion injury, surviving quadriceps motoneurons lost over 50% of their dendritic length. Treatment with hormones attenuated this dendritic atrophy. Bar heights represent means ± standard error of the mean. *indicates significantly different from sham animals, †indicates significantly different from untreated SCI.
<b>FIG. 7.</b>
FIG. 7.
(A) Drawing of spinal gray matter divided into radial sectors for measure of quadriceps motoneuron dendritic distribution and maximal radial extent. (B) Quadriceps motoneuron dendritic arbors display a non-uniform distribution, with the majority of the arbor located between 300° and 120°. Following contusion injury, surviving quadriceps motoneurons in untreated animals (spinal cord injury [SCI]) had reduced dendritic lengths throughout the radial distribution, especially ventromedially (60%, 300° to 360°). Treatment with hormones attenuated these reductions. *indicates significantly different from sham animals, †indicates significantly different from untreated SCI. (C) Following contusion injury, dendritic extent measures of surviving quadriceps motoneurons did not differ across groups, demonstrating a comparable degree of dendritic labeling. For graphic purposes, measures of dendritic length and extent have been collapsed into six bins of 60° each. Bar heights represent means ± standard error of the mean. Sham animals (n = 7); untreated SCI (white bars), n = 11; SCI+estradiol (SCI+E, light gray bars), n = 6; SCI+dihydrotestosterone (SCI+DHT, medium gray bars), n = 6; SCI+ estradiol and dihydrotestosterone (SCI+E+DHT, dark gray bars), n = 6.
<b>FIG. 8.</b>
FIG. 8.
Digital micrographs of cross-sections through vastus lateralis muscles fibers from a sham animal (A), and injured animals that were either untreated (B), or treated with estradiol (C), dihydrotestosterone (D), or estradiol and dihydrotestosterone (E). Scale bar = 100 μm. (F) Following contusion injury, muscle fiber size in untreated animals was reduced 25%, and by 26% in animals treated with estradiol. Treatment with dihydrotestosterone, either alone or in combination with estradiol, attenuated reductions in fiber area. Bar heights represent means ± standard error of the mean. *indicates significantly different from sham animals, †indicates significantly different from untreated spinal cord injury (SCI). Sham animals (n = 7); untreated (SCI), n = 11, SCI+estradiol (SCI+E), n = 7; SCI+dihydrotestosterone (SCI+DHT), n = 8; SCI+ estradiol and dihydrotestosterone (SCI+E+DHT), n = 6.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. National SCI Statistical Center. Available at: www.nscisc.uab.edu Accessed December1, 2017
    1. Liu X.Z., Xu X.M., Hu R., Du C., McDonald J.W., Dong H.X., Wu Y.J., Fan G.S., Jacquin M.F., Hsu C.Y., and Choi D.W. (1997). Neuronal and glial apoptosis after traumatic spinal cord injury. J. Neurosci. 17, 5395–5406 - PMC - PubMed
    1. Liu D., Thangnipon W., and McAdoo D.J. (1991). Excitatory amino acids rise to toxic levels upon impact injury to the rat spinal cord. Brain Res. 547, 344–348 - PubMed
    1. Diaz-Ruiz A., Ibarra A., Perez-Severiano F., Guizar-Sahagun G., Grijalva I., and Rios C. (2002). Constitutive and inducible nitric oxide synthase activities after spinal cord contusion in rats. Neurosci. Lett. 319, 129–132 - PubMed
    1. Wang C.X., Olshowka J.A., and Wrathall J.R. (1997). Increase of interleukin-1beta mRNA and protein in the spinal cord following experimental traumatic injury in the rat. Brain Res. 759, 190–196 - PubMed

Publication types

LinkOut - more resources