Thyroidal modulation of androgenic expression in mice submandibular gland

We investigated the influence of testes and thyroid gland on the maintenance of biochemical parameters and of [3H]R1881 binding sites of adult mice submandibular gland (SMG). Castration (Cx) performed at beginning of puberty prevented sex-dependent SMG development without interfering with maximal androgen binding capacity. Thyroidectomy (Tx) had strong effects on SMG, mainly by lowering the number of androgen binding sites. All alterations could be fully reverted after treatment with testosterone (5 mg/animal, single dose) or with thyroxine (T4, 250 micrograms/animal per day during 5 days). The effects of Cx on SMG could be reverted by therapy with testosterone, T4, or with both hormones (testosterone + T4) in a non-synergistic fashion. It is shown the importance of thyroidal activity on the physiological maintenance of androgen receptors in the murine SMG; the role played by thyroid gland seems to be essential for the full expression of the androgen-dependent SMG activity in adult mice.