Comparative histological, histochemical and ultrastructural study on the effect of ochratoxin A and ochratoxin B on the liver of rat

ABSTRACT

The present work was designed to investigate the possible histological, histochemical and ultrastructural changes in the rat liver under the effects of each of ochratoxin A and ochratoxin B. Sixty male albino rats were divided into three groups, each of 20 animals. The first group served as control. The animals of the second group were orally given 1/100 LD50 of ochratoxin A /3 times/week for one or two months and the animals of the third group were orally given 1/100 LD50 of ochratoxin B /3 times/week for one or two months. In rats given doses of ochratoxin A equivalent to 1/100 LD 50/3 times per week for one month, foci of coagulative necrosis appeared in the liver. Vacuoles of different sizes were shown in some liver cells. Apoptotic bodies were frequent. In rats subjected to the same treatment for two months the liver manifested hepatoma. Some liver cell nuclei showed bizarre shapes. Electron micrographs of liver cells of these rats revealed the increased accumulation of glycogen particles. The mitochondria displayed marked increase in size. A number of mitochondria were U- or ring shaped; the latters are often referred to as doughnut mitochondria. Besides, autophagic vacuoles were frequent in the cytoplasm of the liver cells. In rats given oral doses of ochratoxin B in doses equivalent to 1/100 LD50/ 3 times/ week for one month, some hepatocytes were vacuolated and showed mitotic activity. In rats subjected to the same treatment for two months, the liver tissue showed coagulative necrosis. Many liver cell nuclei were pyknotic. The electron micrographs of liver ultrathin sections of such rats revealed that many mitochondria were enlarged in size and the peroxisomes increased in number. Besides, there were deterioration of liver cell cytoplasm and distortion of microvilli of the bile canaliculi. In animals given ochratoxin A or ochratoxin B [1/100 LD50/3 times/week for one or two months] the histochemical study showed that glycogen in the liver cells appeared more densely aggregated if compared with the untreated material. The present study shows that exposure to ochratoxin A or ochratoxin B is undoubtedly harmful to the liver, and this fact raises the alarm about reflections of ochratoxicosis on the body metabolism. Also, the present study shows that ochratoxin A is more hepatotoxic agent than ochratoxin B, and that hepatoma, mitochondrial transformation are among the most important diagnostic criteria of ochratoxicosis A besides the frequency of the apoptotic bodies in the early stages of poisoning