Androgen Receptor Levels in Cranial Nerve Nuclei and Tongue Muscles in Rats

The Journal of Neuroscience, 1986 · DOI: · Published: May 1, 1986

Simple Explanation

This study demonstrates the presence of androgen receptors in specific brain stem nuclei (hypoglossal, facial, and cochlear) and tongue muscles of adult rats. These receptors bind to androgens with high affinity and limited capacity, similar to receptors found in brain regions associated with reproductive function. The presence of these receptors suggests that androgens may play a broader role in regulating neuron physiology beyond just reproductive behaviors, potentially influencing nerve regeneration.

Study Duration

Not specified

Participants

Sprague-Dawley rats (200-220 gm)

Evidence Level

Not specified

Key Findings

1
Hypoglossal nuclei have higher levels of androgen receptors (8.9 fmol/mg protein) than facial (4.8 fmol/mg protein) or cochlear nuclei (4.0 fmol/mg protein).
2
Treatment with testosterone propionate (TP) led to a significant decrease in androgen receptor binding in the cytosol of hypoglossal and facial nuclei and tongue muscles.
3
A highly significant increase in cell nuclear R1881 binding was observed in hypoglossal nuclei of TP-treated rats, contrasting with the absence of nuclear binding in vehicle-injected controls.

Research Summary

This study demonstrates the presence of androgen receptors in hypoglossal, facial, and cochlear nuclei, and tongue muscles of adult rats, using in vitro binding assays with a synthetic ligand, R1881. The androgen binding sites exhibit high affinity, limited capacity, and steroid specificity, resembling those found in forebrain limbic regions and limb muscles. The findings suggest that androgen receptors in neurons and muscles could mediate androgenic effects on nerve regeneration, and that motor neurons may be extensively regulated by steroid hormones.

Practical Implications

Nerve Regeneration

Androgens, interacting with specific intracellular receptors, may enhance axotomy-induced protein synthetic activity of neurons, influencing nerve regeneration.

Muscle Function

Androgen receptors in tongue muscles suggest a role for androgens in the skeletal muscles of the cranial area.

Auditory Function

The presence of androgen receptors in the cochlear nuclei may indicate a role in communicatory functions and social interactions in rodents.

Study Limitations

1
The target site of androgen action (neurons vs. muscles) remains unclear.
2
Whether denervation affects androgen receptor levels in tongue muscles is unknown.
3
The study questions the interpretation of nuclear translocation based on recent literature.

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