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  • 1
    Online Resource
    Online Resource
    American Physiological Society ; 2012
    In:  American Journal of Physiology-Renal Physiology Vol. 302, No. 11 ( 2012-06-01), p. F1430-F1439
    In: American Journal of Physiology-Renal Physiology, American Physiological Society, Vol. 302, No. 11 ( 2012-06-01), p. F1430-F1439
    Abstract: Bilateral ureteral obstruction (BUO) in rats is associated with increased cyclooxygenase type 2 (COX-2) expression, and selective COX-2 inhibition prevents downregulation of aquaporins (AQPs) in response to BUO. It was hypothesized that a murine model would display similar changes in renal COX-2 and AQPs upon BUO and that targeted disruption of COX-2 protects against BUO-induced suppression of collecting duct AQPs. COX-2 −/− and wild-type littermates (C57BL/6) were employed to determine COX-1, -2, AQP2, and AQP3 protein abundances and localization after BUO. In a separate series, sham and BUO wild-type mice were treated with a selective COX-2 inhibitor, parecoxib. The COX-2 protein level increased in wild-type mice in response to BUO and was not detectable in COX-2 −/− . COX-1 protein abundance was increased in sham-operated and BUO mice. Total AQP2 and -3 mRNA and protein levels decreased significantly after BUO in the cortex+outer medulla (C+OM) and inner medulla (IM). The decrease in C+OM AQP2 and -3 levels was attenuated/prevented in COX-2 −/− mice, whereas there was no change in the IM. In parallel, inhibition of COX-2 by parecoxib rescued C+OM AQP3 and IM AQP2 protein level in wild-type mice subjected to BUO. In summary, 1) In C57BL/6 mice, ureteral obstruction increases renal COX-2 expression in interstitial cells and lowers AQP2/-3 abundance and 2) inhibition of COX-2 activity by targeted disruption or pharmacological blockade attenuates obstruction-induced AQP downregulation. In conclusion, COX-2-derived prostaglandins contribute to downregulation of transcellular water transporters in the collecting duct and likely to postobstruction diureses in the mouse.
    Type of Medium: Online Resource
    ISSN: 1931-857X , 1522-1466
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2012
    detail.hit.zdb_id: 1477287-5
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  • 2
    Online Resource
    Online Resource
    American Physiological Society ; 2015
    In:  American Journal of Physiology-Renal Physiology Vol. 309, No. 12 ( 2015-12-15), p. F1035-F1048
    In: American Journal of Physiology-Renal Physiology, American Physiological Society, Vol. 309, No. 12 ( 2015-12-15), p. F1035-F1048
    Abstract: Renal oxidative stress is increased in response to ureteral obstruction. In vitro, cyclooxygenase (COX)-2 activity contributes to protection against oxidants. In the present study, we tested the hypothesis that COX-2 activity counters oxidative stress and apoptosis in an in vivo model of obstructive nephropathy. Renal oxidative stress markers, antioxidant enzymes, and markers of tubular injury, tubular dilation, and apoptosis were investigated in COX-2 knockout (COX-2 −/− ) and wild-type (WT) mice subjected to 3 or 7 days of unilateral ureteral obstruction (UUO). In a separate series, WT sham-operated and UUO mice were treated with a selective COX-2 inhibitor, parecoxib. COX-2 increased in response to UUO; the oxidative stress markers 4-hydroxynonenal and nitrotyrosine protein residues increased in kidney tissue with no genotype difference after UUO, whereas the antioxidant enzymes heme oxygenase-1 and SOD2 displayed higher levels in COX-2 −/− mice. Tubular injury was aggravated by COX-2 deletion, as measured by tubular dilatation, an increase in kidney injury molecule-1, cortical caspase-3 content, and apoptosis index. In conclusion, COX-2 is necessary to protect against tubular injury and apoptosis after UUO but not necessary to protect against oxidative stress. COX-2 is not likely to directly regulate antioxidant enzymes heme oxygenase-1 and SOD in the kidney.
    Type of Medium: Online Resource
    ISSN: 1931-857X , 1522-1466
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2015
    detail.hit.zdb_id: 1477287-5
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  • 3
    Online Resource
    Online Resource
    American Physiological Society ; 2015
    In:  American Journal of Physiology-Regulatory, Integrative and Comparative Physiology Vol. 308, No. 11 ( 2015-06-01), p. R973-R982
    In: American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 308, No. 11 ( 2015-06-01), p. R973-R982
    Abstract: To characterize mechanisms responsible for fat accumulation we used a selectively bred obesity-prone (OP) and obesity-resistant (OR) rat model where the rats were fed a Western diet for 76 days. Body composition was assessed by magnetic resonance imaging scans, and as expected, the OP rats developed a higher degree of fat accumulation compared with OR rats. Indirect calorimetry showed that the OP rats had higher respiratory exchange ratio (RER) compared with OR rats, indicating an impaired ability to oxidize fat. The OP rats had lower expression of carnitine palmitoyltransferase 1b in intra-abdominal fat, and higher expression of stearoyl-CoA desaturase 1 in subcutaneous fat compared with OR rats, which could explain the higher fat accumulation and RER values. Basal metabolic parameters were also examined in juvenile OP and OR rats before and during the introduction of the Western diet. Juvenile OP rats likewise had higher RER values, indicating that this trait may be a primary and contributing factor to their obese phenotype. When the adult obese rats were exposed to the orexigenic and adipogenic hormone ghrelin, we observed increased RER values in both OP and OR rats, while OR rats were more sensitive to the orexigenic effects of ghrelin as well as ghrelin-induced attenuation of activity and energy expenditure. Thus increased fat accumulation characterizing obesity may be caused by impaired oxidative capacity due to decreased carnitine palmitoyltransferase 1b levels in the white adipose tissue, whereas ghrelin sensitivity did not seem to be a contributing factor.
    Type of Medium: Online Resource
    ISSN: 0363-6119 , 1522-1490
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2015
    detail.hit.zdb_id: 603839-6
    detail.hit.zdb_id: 1477297-8
    SSG: 12
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