Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1984560 | The International Journal of Biochemistry & Cell Biology | 2010 | 6 Pages |
Although the biological effects of thyroid hormones are mediated by nuclear receptors (genomic mechanisms), interactions with receptors associated with the plasma membrane (non-genomic mechanisms) of target cells are not clear. In this study we investigated the rapid stimulatory effect of thyroxine (T4) on 45Ca2+ uptake as well as ionic currents and intracellular messengers involved in the stimulatory action of T4 in amino acid accumulation in immature rat testes. Results indicated that 10−9 M or 10−6 M T4 was able to increase immediately 45Ca2+ uptake after 60 s of hormone exposure. These results indicate for the first time that voltage-dependent Ca2+ channels and ATP-dependent K+ channels can be seen as a set-point in the stimulatory effect of T4 on amino acid accumulation. Apamin-sensitive small-conductance Ca2+-activated K+ channels (SKCa) and chloride channels were shown to be partially involved in this mechanism. The amino acid accumulation triggered by the PKC pathway suggests a functional link between different ion channel activities and the stimulatory effect of T4 on amino acid accumulation. In conclusion, we show in this study a rapid and stimulatory effect of T4 on calcium uptake and on amino acid accumulation, both events initiated at the plasma membrane, which strongly characterizes a non-genomic effect of T4 in immature rat testes.