Neutrophil gelatinase-associated lipocalin in a triphasic rat model of adenine-induced kidney injury

The aim of this study is to investigate whether NGAL, given its advantages over traditional biomarkers, can be used to describe the dynamic characteristics of the renal tubulointerstitial insult caused by adenine. Subsequently, it will be possible to assess NGAL as a biomarker of any acute kidney injury, on top of chronic interstitial disease, if NGAL levels are stable through the chronic phase of our adenine model. Study group rats were fed an adenine diet, and control group rats were fed a regular diet only. Blood and urine samples for urea, creatinine and NGAL were drawn from each rat at the beginning of the study and after 1, 3, 4, 5, 6, 7 and 8 weeks. Kidney slices from these rats were stained with Hematoxylin-eosin (HE) and β-actin stainings. Serum urea, creatinine and NGAL levels and urinary NGAL/creatinine ratio in the study group were higher than baseline and than in the control group; these differences were statistically significant in some of the intervals. Tubulointerstitial changes and adenine crystals were evident in the study group rats. In the rats fed adenine, serum urea, creatinine and NGAL levels and urinary NGAL/creatinine ratio followed a triphasic pattern of kidney injury: an acute phase while on the adenine diet, a partial recovery phase after switching to the regular diet and a chronic kidney disease phase after stabilization of renal function. NGAL can serve a biomarker for acute kidney injury and possibly for chronic kidney disease in the tubulointerstitial rat model.