X-ray induced cataract in rabbit lens

Abstract

Experimental cataracts were obtained by X-irradiation of one eye of 2-month-old rabbits with 1800 rad. In the cataractous lens high molecular weight (HM-)crystallin is already found in great amounts in the lens cortex, whereas in the unirradiated lens this is true only for the nucleus. In the cataractous cortex and nucleus the subunit structures of α-crystallin, HM-crystallin and US fraction (urea-soluble part of the albumoid) are very complex. Their compositions are similar to those of the corresponding preparations from the nucleus of the normal lens. They are composed of α- and β-crystallin polypeptide chains. In the case of US fraction of the cataractous lens also trace amounts of γ-crystallin were observed. On the other hand, relatively simple polypeptide chain compositions were found in the normal lens cortex. Electron microscopic studies of HM-crystallin from the cataractous lens cortex and nucleus revealed a wide size distribution of irregularly shaped giant aggregates. The same feature was observed for HM-crystallin of the normal nucleus, whereas only relatively small aggregates were seen in HM-crystallin of the normal cortex. The ultrastructure of the normal lens fibres exhibits an electron-dense appearance without any significant demonstrable organelles. On the other hand, the cataractous lens showed pathological changes, as demonstrated by a distinct granular content of the fibres. Indications for an interpretation of X-ray induced cataract in terms of an accelerated aging process are discussed.