Altered KLOTHO and NF-κB-TNF-α Signaling Are Correlated with Nephrectomy-Induced Cognitive Impairment in Rats

PLoS One. 2015 May 11;10(5):e0125271. doi: 10.1371/journal.pone.0125271. eCollection 2015.

Abstract

Renal insufficiency can have a negative impact on cognitive function. Neuroinflammation and changes in klotho levels associate with chronic kidney disease (CKD) and may play a role in the development of cognitive impairment (CI). The present study evaluates the correlation of cognitive deficits with neuroinflammation and soluble KLOTHO in the cerebral spinal fluid (CSF) and brain tissue of nephrectomized rats (Nx), with 5/6 renal mass ablation. Nx and sham Munich Wistar rats were tested over 4 months for locomotor activity, as well as inhibitory avoidance or novel object recognition, which started 30 days after the surgery. EMSA for Nuclear factor-κB and MILLIPLEXMAP or ELISA kit were used to evaluate cytokines, glucocorticoid and KLOTHO levels. Nx animals that showed a loss in aversive-related memory and attention were included in the CI group (Nx-CI) (n=14) and compared to animals with intact learning (Nx-M n=12 and Sham n=20 groups). CSF and tissue samples were collected 24 hours after the last behavioral test. The results show that the Nx-groups have increased NF-κB binding activity and tumor necrosis factor-alpha (TNF-α) levels in the hippocampus and frontal cortex, with these changes more pronounced in the Nx-CI group frontal cortex. In addition, the Nx-CI group showed significantly increased CSF glucocorticoid levels and TNF-α /IL-10 ratio compared to the Sham group. Klotho levels were decreased in Nx-CI frontal cortex but not in hippocampus, when compared to Nx-M and Sham groups. Overall, these results suggest that neuroinflammation mediated by frontal cortex NF-κB, TNF-α and KLOTHO signaling may contribute to Nx-induced CI in rats.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Attention
  • Brain / metabolism
  • Cognition Disorders / etiology
  • Cognition Disorders / metabolism*
  • Glucuronidase / cerebrospinal fluid
  • Glucuronidase / genetics
  • Glucuronidase / metabolism*
  • Interleukin-10 / genetics
  • Interleukin-10 / metabolism
  • Klotho Proteins
  • Male
  • Memory
  • NF-kappa B / genetics
  • NF-kappa B / metabolism*
  • Nephrectomy / adverse effects
  • Rats
  • Rats, Wistar
  • Signal Transduction*
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / metabolism*

Substances

  • NF-kappa B
  • Tumor Necrosis Factor-alpha
  • Interleukin-10
  • Glucuronidase
  • Klotho Proteins

Grants and funding

EMK and AEB are supported by postdoc fellowships from Fundação de Amparo à Pesquisa do Estado de São Paulo- FAPESP and R.A. from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); ARV and SD are Ph.D student research fellowship from FAPESP and CAPES respectively, and LSL is supported by grants from Universidade de São Paulo and Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq. This research was supported by grants from FAPESP (2011/50596-1), CNPq and partially funded by the University of São Paulo (Grant#2011.1.9333.1.3, NAPNA). CS, RZ, CDM, TAV and HSB, are research fellows of CNPq. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.