Ultrastructural changes of rat liver cells induced by copper sulfate
Since the first conclusive proof that copper is an essential nutrient was reported by Hart, et al. in 1928, many studies pertinent to the biochemical and physiological roles of copper have been re-ported (Bush, et at., 1965: Scheinberg and Sternieb, 1967: Dowdy, 1969), and some catalytic fun-tions of this mineral in the body have been well established. But in 1912, Wilson described a familial nervous discase associated with cirrhosis of the liver and later increased copper contents in talc liver of those patients wish derangement of copper metabolism was reported. Many efforts to clarify the nature of the derangement and pathogenesis have been made. However the pathogenesis of Wilson's disease is not known.
Previous studios on the effects of experimental copper intoxication on the liver have drawn attention to a number of changes, including hepatocellular necrosis and regenerative activity, early cirrhosis, Kupffer cell mobilization and
hepatocellular pigment formation (Hall & Butt, 1928; Herkl, 1930; Mallory & Parker, 1931; Howell, 1959: Wolff, 1960: Vogel & Evans, 1961: Bal & Halder, 1961: McNary, 1963; Barka, et at., 1964), but most attempts to produce equivalent hepatic dysfunction and cirrhosis have not been successful in spite of deposition of large amounts of copper in the liver_ So the mechanic of the destuctive effect of copper on the hepatie cells is net clear yet.
The purpose of this paper is to describe ultrastructural changes in the liver cells of copper into-xicated rats and to elucidate the role of copper in heapatic damage, and compare the pathology to that found in Wilson's disease.
Material and Methode
Adult albino rats weighing around 200gm were used regardless of sex. The animals were divided into throe groups and treated as follows:
Group Ⅰ: Normal control 9 rats
Group Ⅱ: 0.05% CuSO4 treated 27 rats
Group Ⅲ: 0.5% CuSO4 treated 27 rats
Normal control rats acre given 0.3cc of distilled water, intraperitoneally, and in the experim-ental groups, copper sulfate were given intraperitoneally every day in a dose of 0.3cc after cupric sulfate crystal (U.S.P.) were dissolved in distilled water. At intervals of 6, 12, and 24 hours after the first injection and then at 5 day intervals until the 30 th day, one control rat and three rats from each experimental group were killed by exangiunation from the carotid artery. The liver and other organs were examined grossly and specimens for light and electron microscopic examination were obtained immediately from the liver.
Specimens for the light microscopic examinations were fixed in 10% neutral formalin and embe-dded in paraffin. Sections 6 μ thick were made and stained with hematoxylin and eosin for overall histolegic change and sodium diethyldithiocarbamate was used (Howell, 1969) for the histochemical demonstration of copper and roticulin stain for reticulin fiber. One part of the specimen also was fixed in absolute alcohol and embedded in paraffin. Six μ thick sections were made and stained with periodic acid Schiff to detect changes of glycogen concent.
Specimens for the electron microscopic examinations were cut in 1mm**3 size and fixed in 1% osmic acid in veronal buffer at pH 7.4, followed by dehydration in graded alcohol. They were embedded in EPon 812 and cut into 400 to 700 A thickness with the glass knife. After staining with uranyl acetate and lead hydroxide, observation was mads with Hitachi HU 11-E model electron microscope.
Results and Discussion.
In the liver of control rats, no stainable copper was found with sodium dietblydithiocarbamatereaction, but in experimental groups, stainable copper was apparent after five subsequent in jections and in group Ⅲ, the amount was graduallyl·actually increased and maintained at a high level until the 30th day.
The intracellular distribution of copper was mainly peribiliary in location without peri-nuclcar capping. But throughout the whole experimental period, neither hepatic cell necrosis nor cirrhosis were noted and glyoogen content was not changed. The
intralobular reticulin fiber frame-work wag also intact.
The most significant ultastructural changes were found in Iysosomes and pinocytotic vesicls.
The pinocytotic versicles were increased in number from 12 hours after copper injection and at 24th hour these vesicles were found in enlarged Iysosomes through phagocytic process. And then the size and density of the Iysosomes began to increase and to be irregular in shape. On the 5th day, large amounts of highly dense Iysosomes were located with histochemically demonstrated copper, and these changes were also found in the liver of rats killed at 10, 16, 20, 26, and 30 days. In addition to these Iysosomal changes, several other organelles showed some alterations such as dilatation of rough endoplasmic reticulum, increased smooth
endoplasmic reticulum, dilatation of Golgi complex and swelling of mitochondria which took plate in the early period and reached a maximum degree at 24th hours after injection and then recovered. No necrotic changes were noted.
In summary, hepatic cell damage was not induced with administration of copper, even with a large dose. Lysosome seemed to haute an important role in excretion of excessively deposited copper in the hepatic cell and in preventing cytotoxic effects of talc copper.