The effect of beta-aminoproprionitrile on the lingual artery and aorta of the rat: a light microscopic study.

The effects of chronic toxicity of beta-aminoproprionitrile (BAPN) on the lingual artery and aorta of the rat were compared. Thirty-two three week old weanling male white Wistar rats were given 1 g/kg/day (for five days weekly) of a 40% saturated solution of BAPN fumarate by intragastric tube. The animals were divided into four groups of eight animals each and sacrificed after one, three, six and nine weeks respectively. For each group, four controls were used. Cross-sections of the lingual artery and aorta stained with hematoxylin-erythrosin-safranin, alcian blue, Masson's trichrome and Verhoeff's iron hematoxylin were studied. BAPN had no effect on the lingual artery. Early changes were seen in the aorta at six weeks. Characteristic lesions were found at nine weeks involving the elastic tissue, myocytes and ground substance. The elastic lamellae were thinner, lost their normal orientation, and became swollen and finally fragmented. The myocytes of the media changed orientation and migrated into the intima. The proteoglycans increased and fibrosis supervened at the end stage. Failure to induce lesions in the lingual artery may be explained by early structural maturation and a low metabolic turnover rate in muscular arteries, decreased exposure to or greater protection from mechanical stress.