RESUMO
Plant growth regulators [PGRs] especially gibberellic acids [GA3] are widely used in Egypt to increase plant size, production and to increase plant availability all the year. Little is known about the biochemical or physiological effects of GA3 in mammalian tissues. This study aimed to evaluate the histological, immunohistochemical and biochemical changes in the rat renal cortex with subacute and subchronic exposure to GA3 and to detect the possible mechanism of such toxicities. Fifty adult male albino rats were classified into control group [I], experimental group [IIa and IIb] received GA3 in a dose of 75ppm [part per million]. Seventy five parts per million of GA3 as drinking water for 2weeks in subgroup IIa [subacute exposure] and for 8 weeks in subgroup IIb [subchronic exposure]. Group III [recovery group]: Rats received GA3 for 8weeks and stopped for other 6weeks. Renal cortex was stained with H and E, Masson's trichrome, immunohistochemically for Bcl-2 protein and electron microscopic examination. Oxidative biomarker [MDA] was detected in kidney tissue and antioxidant enzymes were detected in erythrocyte pellets prepared from blood sample. GA3 administration in group [II], led to degeneration, necrosis, apoptosis of the epithelial cells lining some of the tubules of the renal cortex with subacute toxicity and in most of the tubules with subchronic toxicity, fibrosis is significantly apparent in the subchronic subgroup. Interstitial cellular infiltration and hemorhage were seen. Hyaline casts in the lumen of renal tubules were apparent in the subchronic subgroup. Area percentage of antiapoptotic protein Bcl-2 immunoreactivity was decreased in the subchronic subgroup. Picture of cystic glomerular atrophy, acute tubular necrosis, degenerated podocytes and thickened blood renal barrier became prominent in the subchronic subgroup. The histological changes were associated with biochemical markers of oxidative stress. These changes were reduced in the recovery group but not retained to normal and the picture of oxidative stress was still present. The findings implied that gibberellic acid [GA3] induced nephrotoxic effect associated with oxidative stress with some sort of self recovery after stoppage of exposure. So, gibberellic acid should be used cautionary. Also, producers and consumers should be in conscious on the probable toxic effects of these chemicals