Thyroidal modulation of androgenic expression in mice submandibular gland

Area of Science:

• Endocrinology
• Molecular Biology
• Mouse Models

Background:

• The submandibular gland (SMG) exhibits sex-dependent development and function.
• Androgen receptors play a key role in regulating SMG activity.
• The influence of endocrine glands on SMG maintenance requires further elucidation.

Purpose of the Study:

• To investigate the roles of the testes and thyroid gland in maintaining biochemical parameters and androgen binding sites in the adult mouse SMG.
• To determine the effects of castration and thyroidectomy on SMG androgen receptor levels.
• To assess the reversibility of these effects using hormone replacement therapy.

Main Methods:

• Adult mice underwent castration (Cx) or thyroidectomy (Tx).
• Hormone replacement therapy with testosterone and/or thyroxine (T4) was administered.
• Biochemical parameters and [3H]R1881 binding sites (androgen receptor capacity) in the SMG were analyzed.

Main Results:

• Castration prevented sex-dependent SMG development but did not affect maximal androgen binding capacity.
• Thyroidectomy significantly reduced the number of androgen binding sites in the SMG.
• Hormone replacement with testosterone or T4 fully reverted the alterations caused by Cx and Tx.
• Combined testosterone and T4 treatment showed non-synergistic effects in reverting Cx-induced changes.

Conclusions:

• Thyroidal activity is vital for the physiological maintenance of androgen receptors in the murine SMG.
• The thyroid gland plays an essential role in the full expression of androgen-dependent SMG activity in adult mice.
• Both testicular and thyroid hormones are critical for maintaining SMG homeostasis, with the thyroid having a specific role in androgen receptor regulation.