Thyroid hormone deiodinases response in brain of spontaneausly hypertensive rats after hypotensive effects induced by mandibular extension

Abstract

Purpose: The deiodinases activate or inactivate the thyroid hormones (TH) in virtually all tissues in both physiological and pathological conditions. The three deiodinases, DIO1, DIO2, and DIO3, have different catalytic functions and regulate TH tissue distribution. The aim of the present study was to evaluate the modulation of gene expression of the deiodinases and TH transporters and protein levels of DIO1 in parietal and frontal areas of cerebral cortex of spontaneously hypertensive rats (SHRs), after two successive mandibular extensions (ME).

Methods: ME was performed on anesthetized rats by a dilatator appropriately designed and real-time PCR and western blotting techniques were employed for gene expression and protein level study.

Results: Mean blood pressure (MBP) significantly decreased in 2ME-treated rats when compared to sham-operated rats (p < 0.001) and this decrease lasted for the entire observation period. In gene expression analysis, in 2ME-treated rats we did not observe any significant variation of DIO1 and DIO3 with respect to the sham-operated rats. Differently, DIO2 gene expression significantly increased in frontal area of 2ME-treated rats, with respect to sham-operated rats (p < 0.01). Furthermore, in parietal area, protein levels of DIO1 in 2ME-treated rats were significantly higher than in sham-operated rats (p < 0.01). Moreover MCT8 and OATP1C1 both resulted significantly higher (p < 0.05 and p < 0.001) in sham frontal cortex.

Conclusion: In summary, our data on SHRs, while confirming the hypotensive effect of two MEs, show that the treatment also solicits the three deiodinases production in the cerebral cortex.

Keywords: Cerebral cortex; Deiodinases; Gene expression; Protein levels; Spontaneously hypertensive rats (SHR); TH-transporters.