Effect of Nigella sativa oil on paracetamol-induced renal cortical damage in rats: light and electron microscopic study

Background: Paracetamol or acetaminophen (N-acetyl-p-aminophenol; APAP) is a widely used analgesic and antipyretic drug. Unfortunately, it is now reported as the most common cause of toxic ingestion in the world. Nigella sativa oil (NSO) is an extract of N. sativa having antioxidant properties. Aim of the work: This study aimed to assess the possible role of NSO in ameliorating the toxic effect of APAP overdose on the rat renal cortical structure. Materials and methods: Thirty male albino rats were divided into three equal groups. Group I was the control group. Group II comprised rats treated with APAP (750 mg/kg/day) orally for 7 days. Group III received NSO (2 ml/kg/day orally) 30 min before oral administration of APAP at the same dose as that of group II for 7 days. Kidney specimens were processed for light and electron microscopic study of the renal cortex. Plasma renin activity and arterial blood pressure were estimated. Results: APAP-treated rats showed marked structural changes in the proximal convoluted tubules with dense nuclear staining, cytoplasmic vacuolization, increased peroxisomes, and partial loss of apical brush border and basal striations. Renal corpuscles revealed focal fusion of podocyte foot processes and irregular thickening of glomerular basement membranes. Juxtaglomerular cells contained few renin granules, reflecting an increase in renin exocytosis that coincided with increased plasma renin activity and increased arterial blood pressure. Concomitant administration of NSO with APAP revealed a noticeable amelioration of these histological and physiological changes. Conclusion: NSO exerted a protective effect against APAP-induced renal cortical damage.