Age-dependent effect of PPARγ agonist pioglitazone on kidney signaling in borderline hypertensive rats.

The peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear receptor and nutrition factor which takes part in the cellular signaling by several agonists such as pioglitazone. PPARγ can serve as potential target in treatments of metabolic syndrome diseases and/or hypertension. In the present study we investigated the effects of pioglitazone, a PPARγ agonist, on hypertension development in young and adult borderline hypertensive rats (BHR). In renal signaling we observed connections between PPARγ and Nrf2, antioxidant in adult animals and differences between young and adult BHR in Nrf2-activated detoxificant outputs (NQO1, HO-1) and NO-synthases. Blood pressure in animals had been detected by cuff plethysmography, cell signaling in the kidney was studied by gene expression determination using qPCR, and nitric oxide synthase (NOS) activity was measured by radioactive detection. Pioglitazone treatment in adult BHR caused no detectable changes in antioxidant and detoxificant responses. The main effects were observed in blood pressure improvement, endothelial NOS expression and NOS activities in both young and adult BHR.

Effects of PPAR γ Agonist Pioglitazone on Redox-Sensitive Cellular Signaling in Young Spontaneously Hypertensive Rats.

PPAR γ receptor plays an important role in oxidative stress response. Its agonists can influence vascular contractility in experimental hypertension. Our study was focused on the effects of a PPAR γ agonist pioglitazone (PIO) on blood pressure regulation, vasoactivity of vessels, and redox-sensitive signaling at the central (brainstem, BS) and peripheral (left ventricle, LV) levels in young prehypertensive rats. 5-week-old SHR were treated either with PIO (10 mg/kg/day, 2 weeks) or with saline using gastric gavage. Administration of PIO significantly slowed down blood pressure increase and improved lipid profile and aortic relaxation after insulin stimulation. A significant increase in PPAR γ expression was found only in BS, not in LV. PIO treatment did not influence NOS changes, but had tissue-dependent effect on SOD regulation and increased SOD activity, observed in LV. The treatment with PIO differentially affected also the levels of other intracellular signaling components: Akt kinase increased in the the BS, while ß -catenin level was down-regulated in the BS and up-regulated in the LV. We found that the lowering of blood pressure in young SHR can be connected with insulin sensitivity of vessels and that ß -catenin and SOD levels are important agents mediating PIO effects in the BS and LV.