Effects of chronic kidney disease on cognitive function and α-klotho expression in hippocampus

Alpha-klotho (α-KL) is not only related to the regulation of calcium-phosphorus metabolism, and fibrosis in chronic kidney disease (CKD), it is also involved in the regulation of many cognitive disorders. We conducted this study to investigate the effects of CKD on cognitive dysfunction and α-KL.

Doxorubicin was used to induce a CKD model, which was validated by weight, 24-hour urine protein quantification, serum creatinine (Cr), blood urea nitrogen (BUN), and kidney hematoxylin-eosin (HE) staining. The Morris water maze (MWM) paradigm was used to assess the effects of CKD on cognitive behavior. The expression of α-KL in the hippocampus was detected using real-time quantitative polymerase chain reaction, Western blot, and immunohistochemistry (IHC).

(I) In the CKD group, the weight of the rats increased slowly (P<0.001), 24-hour urine protein increased (P<0.05), and Cr (P=0.026) and BUN levels (P=0.003) increased; (II) HE staining showed that in the CKD group there were changes in the structure, fibrosis, and inflammatory infiltration of the renal tissues, and changes in the structure, cell necrosis, and neuronal degeneration of the hippocampus; (III) in the MWM experiment, the escape latency of the CKD group was prolonged compared to that of the control group (P=0.043, 0.023), and the number of crossing the platform was reduced (P=0.003); (IV) in the CKD group, the expressions of α-KL messenger ribonucleic acid (P=0.0005) and α-KL protein (P=0.0005) in the hippocampus were downregulated. The IHC results showed that the expression of α-KL protein in the hippocampal region III cornus ammonis (CA3) of the CKD group region was also downregulated, and the α-KL-positive cells (P=0.019) and mean optical density (P=0.015) were decreased.

The expression of α-KL appears to effect the cognitive function of CKD rats; thus, it may be a valuable target in the treatment of CKD with cognitive impairment.