Pulmonary Hypertension in Obese Mice Is Accompanied by a Reduction in PPAR-γ Expression in Pulmonary Artery.

Obesity and insulin resistance (IR) are well-studied risk factors for systemic cardiovascular disease, but their impact on pulmonary hypertension (PH) is not well clarified. This study aims to investigate if diet-induced obesity induces PH and if peroxisome-proliferator-activated receptor (PPAR-γ) and/or endoplasmic reticulum (ER) stress are involved in this process. Mice were maintained on a high-fat diet (HFD) for 4 months, and IR and PH were confirmed. In a separate group, after 4 months of HFD, mice were treated with pioglitazone (PIO) or 4-phenylbutyric acid for the last month. The results demonstrated that HFD for at least 4 months is able to increase pulmonary artery pressure, which is maintained, and this animal model can be used to investigate the link between IR and PH, without changes in ER stress in the pulmonary artery. There was also a reduction in circulating adiponectin and in perivascular adiponectin expression in the pulmonary artery, associated with a reduction in PPAR-γ expression. Treatment with PIO improved IR and PH and reversed the lower expression of adiponectin and PPAR-γ in the pulmonary artery, highlighting this drug as potential benefit for this poorly recognized complication of obesity.

Fluoxetine effect on kidney water reabsorption.

BACKGROUND: The pathogenesis of hyponatraemia caused by fluoxetine(Fx) use in the treatment of depression is not well understood. It has been attributed to a SIADH, although ADH-enhanced plasma level has not yet been demonstrated in all the cases reported in humans. This experiment aimed at investigating the effect of fluoxetine on the kidney and more specifically in the inner medullary collecting duct (IMCD). METHODS: (1) In vivo study: (a) 10 rats were injected daily i.p. with 10 mg/kg fluoxetine doses. After 10 days, rats were sacrificed and blood and kidneys were collected. (b) Immunoblotting studies for AQP2 protein expression in the IMCD from injected rats and in IMCD tubules suspension from 10 normal rats incubated with 10(-7) M fluoxetine. (2) In vitro microperfusion study: The osmotic water permeability (P(f), mum/s) was determined in normal rats IMCD (n = 6), isolated and perfused by the standard methods. RESULTS: In vivo study: (a) Injected rats with fluoxetine lost about 12% body weight; Na(+) plasma level decreased from 139.3 +/- 0.78 mEq/l to 134.9 +/- 0.5 mEq/l (p < 0.01) and K(+) and ADH plasma levels remained unchanged. (b) Immunoblotting densitometric analysis of the assays showed an increase in AQP2 protein abundance of about 40%, both in IMCDs from injected rats [control period (cont) 99.6 +/- 5.2 versus Fx 145.6 +/- 16.9, p < 0.05] and in tubule suspension incubated with fluoxetine (cont 100.0 +/- 3.5 versus 143.0 +/- 2.0, p < 0.01). In vitro microperfusion study fluoxetine increased P(f) in the IMCD in the absence of ADH from the cont 7.24 +/- 2.07 to Fx 15.77 +/- 3.25 (p < 0.01). CONCLUSION: After fluoxetine use, the weight and plasma Na(+) level decreased, and the K(+) and ADH plasma levels remained unchanged, whereas the AQP2 protein abundance and water absorption in the IMCD increased, leading us to conclude that the direct effect of fluoxetine in the IMCD could explain at least in part, the hyponatraemia found sometime after this drug use in humans.