Renal structural changes and apelin receptor expression in spontaneously hypertensive rats: implications for hypertension-induced kidney injury.

Background: Arterial hypertension is a primary risk factor for kidney disease. Recent advances have implied a potential link between the apelin system and renal homeostasis.

Materials and methods: We used 6- and 12-month-old spontaneously hypertensive rats and age-matched normotensive controls to assess the changes in the renal expression of the apelin receptor by immunohistochemical method. The study also evaluated correlations between the renal apelin receptor's expression and renal injury indicators.

Results: The histological analysis showed elevated glomerular sclerosis and tubulointerstitial damage indices in both groups of hypertensive rats compared to age-matched controls. Older rats within each group exhibited higher scores than younger ones. The immunohistochemical analysis revealed varying apelin receptor expression patterns, with tubular expression intensifying both with hypertension severity and age. Glomerular expression was notably higher in older hypertensive rats compared to normotensive controls. We reported significant positive correlations between glomerular apelin receptor expression and glomerular sclerosis index in older hypertensive animals. Similarly, a positive correlation between tubular apelin receptor expression and tubulointerstitial damage index was discovered in hypertensive rats, suggesting hypertension-related changes in apelin receptor expression and renal damage.

Conclusions: Our study found kidney changes and varying apelin receptor correlations in hypertensive rat kidneys, suggesting complex roles needing research.