Testosterone-induced acceleration of recovery from facial paralysis following crush axotomy of the facial nerve in male hamsters

Kathleen A. Kujawa, Nancy B. Kinderman, Kathryn J. Jones

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Abstract

In this study, the effects of testosterone propionate (TP) on recovery from facial paralysis following crush axotomy of the facial nerve in male hamsters were examined. In the first experiment, TP (5 mg/ml sesame oil; 0.1 ml) was injected subcutaneously and on alternate days in one-half of the animals subjected to crush axotomies of the facial nerve, with the second half receiving vehicle alone. An accelerative effect of TP on recovery from facial paralysis was observed near the end of the first and beginning of the second week after crush axotomy. When the dosage and frequency were doubled in the next experiment, a greater accelerative effect of TP on recovery from facial paralysis was observed. In the last experiment, castrated animals were used in order to eliminate the endogenous source of the hormone and two different modes of hormone administration, TP implants vs TP injections, were compared. The results of that experiment indicate that continuous exposure to the hormone, in the form of subcutaneous implants of 100% crystalline TP, had the most pronounced effect on acceleration of recovery from facial paralysis. In addition, no differences in the responses of the castrated, axotomized animals and the normal, axotomized animals were found. This suggests that the presence of endogenous hormone contributes little to the acceleration of functional recovery observed with TP. Finally, the time course of the accelerative effect of TP suggests that the hormone is acting primarily at the level of the facial neuron, which contains androgen receptors, and perhaps secondarily at the level of the facial muscles, which are also known to contain androgen receptors.

Original languageEnglish (US)
Pages (from-to)80-85
Number of pages6
JournalExperimental Neurology
Volume105
Issue number1
DOIs
StatePublished - Jul 1989

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ASJC Scopus subject areas

  • Neurology
  • Developmental Neuroscience

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