HISTOCHEMICAL STUDY ON OXIDATIVE ENZYME ACTIVITY IN THE BRAIN, PARTICULARLY OF ASTROCYTES, IN SPONTANEOUSLY HYPERTENSIVE RATS

Hanakita J., Hazama F., Amano S., Yamada E. & Handa H. (1980)
Neuropathology and Applied Neurobiology 6, 471–482
Histochemical study on oxidative enzyme activity in the brain, particularly of astrocytes, in spontaneously hypertensive rats
In order to obtain indirect information concerning brain oedema or increased vascular permeability under hypertensive conditions, the enzyme responses of astrocytes in the brains of spontaneously hypertensive rats were histo-chemically investigated. Reactions for oxidative enzymes, such as NADH₂-, NADPH2-tetrazolium reductases and succinate dehydrogenase were performed on SHR brains of various ages. In the hypertensive rats, proliferation, hypertrophy and increased enzyme activity were observed in astrocytes, particularly in the white matter. This activation of astrocytes appeared at 12 13 weeks-of-age and increased with advancing age. These findings suggest that increased vascular permeability of the materials in the smaller molecules begins in the early stage of the development of hypertension before the breakdown of the blood-brain barrier. Many degenerating astrocytes, showing clasmatodendritic changes, were observed in severely oedematous regions or around cystic foci in the white matter. The changes in astrocytic function seem to be related to the development of the parenchymal changes, particularly of the white matter in the chronic hypertensive state.