Background: Naphthalene (NA) is a common environmental contaminant and is abundant in tobacco smoke. Rosemary (Rosmarinus officinalis) is a herb commonly used as a spice and flavoring agents in food processing and is useful in the treatment of many diseases. Aim of the work: To study the nephrotoxicity of NA and to evaluate the possible protective role of rosemary extract in adult male albino rat.
Materials and Methods: 25 animals were divided into three groups: Group I (Control group), Group II (NA treated group) received NA at a dose of 200 mg/kg/day dissolved in 5 ml/kg corn oil orally by gastric tube, Group III (protected group) received rosemary extract (10 ml/kg/day) followed after 60 min by NA at the same previous dose orally by gastric tube. The experiment lasted 30 days. The following parameters were studied: Biochemical assessment of renal function, histological, immunohistochemical, morphometric studies and statistical analysis of the results.
Results: NA treatment resulted in a highly significant increase in the mean values of serum urea and creatinine. NA induced histological changes in the form of glomerular congestion. Some glomeruli demonstrated marked mesangial expansion and hence that Bowman’s spaces were almost completely obliterated. Shrinkage of renal glomeruli with widening of Bowman’s spaces could also be seen. Focal tubular dilatation with appearance of casts inside the tubules was observed. Congested peritubular blood vessels and interstitial hemorrhage were also seen. The medullary region demonstrated vascular congestion and fibrosis. Focal cellular infiltration was presented in the interstitium. The renal cortex of NA treated rats showed a noticeable down regulation in alkaline phosphatase positive immunoreactive cells in some proximal convoluted tubules. NA induced up regulation of positive immunoreaction for inducible nitric oxide synthase in the proximal and distal convoluted tubules as well as in the collecting tubules. All previous results were significantly reversed in the protected group compared with NA treated group.
Conclusions: It is concluded that NA has a harmful effect on rat kidney. Rosemary extract had a protective role against renal injury induced by NA and this effect may be attributed to its antioxidant and anti-inflammatory activity.
Keywords: Naphthalene, tobacco smoke, rosemary, iNOS, alkaline phosphatase