Ageing and compositional changes of rat lens.

In order to elucidate chemical changes in the lenses of aged animals, carbohydrate and fatty acid compositions were studied in 36 healthy male and female Fischer 344 rats from 3 weeks to 32 months of age. Senile cataract was observed on six lenses of 12 rats aged 28-32 months. The carbohydrate content increased rapidly within 7 months of age and remained constant until 29 months. But the myoinositol content showed a maximum at 7 months of age and afterwards a decreasing trend was observed. In cataractous lenses, the myoinositol content decreased rapidly; sorbitol and fructose showed similar changes although the rates were much lower than that of myoinositol. Lens fatty acids increased steadily during the life span and the ratio of unsaturated to saturated fatty acids was maintained in a narrow range (1.20-1.30). However, the value was significantly altered in cataractous lenses. An age-dependent change was found with nervonic acid, which increased markedly from 1.8% of fatty acids at 3 weeks of age to 6.8% at 29 months. In cataractous lenses, the predominant changes noticed were a rapid decrease of arachidonic acid and a high content of nervonic acid.