Androgen receptor mRNA regulation in adult male and female hamster facial motoneurons: Effects of axotomy and exogenous androgens

Troy D. Larkowski, Susan M. Drengler, Lisa Tanzer, Kathryn J. Jones

Research output: Contribution to journalArticle

12 Scopus citations


Testosterone propionate (TP) administration at the time of facial nerve injury in the adult hamster augments the regenerative properties of the injured facial motoneurons (FMN), with the androgen receptor (AR) playing a key role in mediating the actions of TP on facial nerve regeneration. The purpose of the present study was to determine the effects of axotomy on AR mRNA expression in FMN. This was accomplished using in situ hybridization in conjunction with a (35)S-labeled AR riboprobe. Gonadally intact adult male and gonadectomized (gdx) adult female hamsters were subjected to a right facial nerve axotomy, with the left side serving as internal, unoperated control. Half the animals were subcutaneously implanted with a 10-mm TP Silastic capsule, and the other half were sham-implanted. An additional group of nonaxotomized, gonadally intact males was also included. Postaxotomy survival times were 1, 4, and 7 days. At 1 postoperative day 1, there were no effects of axotomy on AR mRNA levels. By postoperative days 4 and 7, axotomy caused a significant decrease in AR mRNA levels in FMN of gonadally intact males, relative to either the contralateral control FMN of the same animals or FMN from the group of gonadally intact males that were not subjected to facial nerve axotomy. There were no significant differences between AR mRNA levels in contralateral control FMN and FMN from the gonadally intact group of nonaxotomized males. TP administration at the time of axotomy had no effect on AR mRNA levels in either the axotomized or contrala(teral control FMN of gonadally intact males, relative to the nonaxotomized, gonadally intact male group. Corroborating our previous work, AR mRNA levels were reduced in the contralateral control FMN of gdx females, relative to the nonaxotomized, gonadally intact male group, with axotomy having no additional effects. The data are discussed in a mechanistic framework suggesting how TP acts to augment facial nerve regeneration. (C) 2000 John Wiley and Sons, Inc.

Original languageEnglish (US)
Pages (from-to)207-214
Number of pages8
JournalJournal of Neurobiology
Issue number4
StatePublished - Dec 12 2000



  • Axon injury
  • Gonadal steroids
  • Motor neurons
  • Nerve regeneration
  • Steroid receptor

ASJC Scopus subject areas

  • Neuroscience(all)
  • Cellular and Molecular Neuroscience

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