Combinative effects of hexachlorobenzene and crowding on rat adrenal cell mitochondria.

The effects of social stress (crowding) on hexachlorobenzene (HCB) toxicity in male rats was evaluated by a morphometrical analysis of adrenal cortex mitochondria. The social stress was produced by transferring singly-housed rats from cages of ample size (1000 cm2 floor space) into small cages (100 cm2 floor space) each containing four rats. Differences in cage design as well as size may have contributed to the overall stress experienced by the rats. The food of the treated rats was supplemented with 250 ppm HCB. Structural changes in mitochondrial volume, surface area, or cristae area were not significant in HCB-treated or in crowded animals when compared with those of the controls. However, increases in mitochondrial volume and diameter were significant in those animals simultaneously challenged by HCB and crowding. The results strongly suggest that even a relatively mild social stress may adversely affect the ability of an animal to resist the effects of some exogenous chemicals.