Quantitative Electron Microscopic Investigation on Changes of Mitochondria in Long‐Term CPZ Administration in Rat Brain, Liver and Heart

Abstract: The effect of chronic administration of chlorpromazine (CPZ) on mitochondria (MT) in the rat brain (striatum), liver and heart was quantitatively examined with both the electron microscope and computer‐assisted PICTURE ANALYSIS OA‐1. The specimens were taken from six female rats, three controls and three experimentals to which 20 mg/kg body weight of CPZ was administered orally for 15 months from 5 weeks after birth. Thus the quantitative electron microscopic study was made on the mitochondrial sizes (cross‐sectional areas) and cristal densities and the following results were obtained: 1) The sizes of MT from the striatal nerve cells and axo‐dendritic spine postsynapses and liver parenchymal cells were larger in the CPZ‐administered rats than in the controls, whereas there were no statistically significant changes in the sizes of MT from the striatal axo‐dendritic spine presynapses and heart papillary muscle cells to which the influence of long‐term CPZ administration could be well expected. 2) In contrast, with the mitochondrial sizes, the cristal densities represented by the number of cristae per unit area (μ²) of MT have decreased in the striatal nerve cells and axo‐dendritic spine pre‐ and postsynapses, liver parenchymal cells and heart papillary muscle cells of the CPZ‐administered rats than in those of the controls. 3) From the above‐mentioned findings it was concluded that the changes of MT following a long‐term CPZ administration were the ubiquitous ones evolved not only in the brain cells but also in other somatic cells and that the enlargement of MT revealed by the quantity of organellar sizes was the compensatory change to the decrease of cristae suggesting the disintegration of the inner membrane system of the organelle.