I just want to highlight a single phrase from this paper:
Until recently, rT3 was regarded as an inactive hormone, ...
I have long suspected that rT3 (reverse T3) might have some activity of importance. Although this paper concerns male rats - it does claim to identify an action.
PLoS One. 2013; 8(10): e77176.
Published online 2013 Oct 10. doi: 10.1371/journal.pone.0077176
Rapid Responses to Reverse T3 Hormone in Immature Rat Sertoli Cells: Calcium Uptake and Exocytosis Mediated by Integrin
Ana Paula Zanatta,1 Leila Zanatta,2 Renata Gonçalves,1 Ariane Zamoner,1 and Fátima Regina Mena Barreto Silva1,*
Toshi Shioda, Editor
1Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis-Santa Catarina, Brazil
2Universidade Comunitária da Região de Chapecó, Chapecó, Santa Catarina, Brazil
Massachusetts General Hospital, United States of America
* E-mail: email@example.com
Competing Interests: The authors have declared that no competing interests exist.
Conceived and designed the experiments: APZ LZ RG AZ FRMBS. Performed the experiments: APZ LZ RG. Analyzed the data: APZ LZ RG AZ FRMBS. Contributed reagents/materials/analysis tools: AZ FRMBS. Wrote the manuscript: APZ LZ FRMBS.
There is increasing experimental evidence of the nongenomic action of thyroid hormones mediated by receptors located in the plasma membrane or inside cells. The aim of this work was to characterize the reverse T3 (rT3) action on calcium uptake and its involvement in immature rat Sertoli cell secretion. The results presented herein show that very low concentrations of rT3 are able to increase calcium uptake after 1 min of exposure. The implication of T-type voltage-dependent calcium channels and chloride channels in the effect of rT3 was evidenced using flunarizine and 9-anthracene, respectively. Also, the rT3-induced calcium uptake was blocked in the presence of the RGD peptide (an inhibitor of integrin-ligand interactions). Therefore, our findings suggest that calcium uptake stimulated by rT3 may be mediated by integrin αvβ3. In addition, it was demonstrated that calcium uptake stimulated by rT3 is PKC and ERK-dependent. Furthermore, the outcomes indicate that rT3 also stimulates cellular secretion since the cells manifested a loss of fluorescence after 4 min incubation, indicating an exocytic quinacrine release that seems to be mediated by the integrin receptor. These findings indicate that rT3 modulates the calcium entry and cellular secretion, which might play a role in the regulation of a plethora of intracellular processes involved in male reproductive physiology.
Full paper freely available here: