Topographical distribution of lactate dehydrogenase activity in human clear eye lenses and in lenses with different types of senile cataract: a histochemical investigation

Abstract

In growing clear human and bovine lenses, independent of age, the more peripherally located cortical fibers bearing cell nuclei exhibit strong enzyme-histochemical reactions. More centrally located lens areas lacking cell nuclei increase in volume in an age-dependent manner. These lens regions do not exhibit enzyme activities detectable by our histochemical technique. Therefore the lens areas free of histochemical reaction product become larger with increasing age, whereas the peripherally located lens fibers apparently do not change their enzyme activities with age. Thus, homogenates of total lenses show age-dependent reductions of enzyme activities, although enzyme activities remain at a physiological level in cortical lens fibers with recognizable cell nuclei. In lenses with immature supranuclear cortical and (particularly) in lenses with black nuclear cataracts, cortical fibers still can exhibit high enzyme activities. Unexpectedly, also ruptured and broken fibers in immature deep supranuclear cortical cataracts show strong enzyme activities. In contrast, in lenses with (incipient) subcapsular cortical cataracts only the most superficially located lens fibers exhibit some enzyme activity.

Vitreoretinal influences on lens function and cataract

“…Once the nuclei and other membrane-bound organelles are lost from the fibre cells, their ability to synthesize proteins, carry out oxidative metabolism and synthesize new membranes ceases. It has been reported that activity of lactic dehydrogenase (LDH), the last enzyme in the glycolytic pathway, ceases soon after organelle degradation [3]. If this is correct, glycolytic metabolism also ceases soon after organelle degradation, since LDH is required to produce the NAD þ required by 'upstream' steps in glycolysis.…”

Cortical and Subcapsular Cataracts: Significance of Physical Forces

“…Histochemical enzyme activities (mainly lactate dehydrogenase) in both clear lenses and cortical cataracts have only been shown to be high in lens epithelial cells and cell nuclei containing cortical lens fibers [3]. In contrast, a loss of lactate dehydrogenase activity has already been detected histochemically in all cortical fibers in the early stages of subcapsular cataracts [3].…”

“…In contrast, a loss of lactate dehydrogenase activity has already been detected histochemically in all cortical fibers in the early stages of subcapsular cataracts [3]. Regional distribution of adenine, guanidine and uridine (ATP, ADP, GTP and UTP) [4], and the content of glutathione [5], has been shown to be high in cortices of clear lenses and of cortical cataracts.…”

“…Regional distribution of adenine, guanidine and uridine (ATP, ADP, GTP and UTP) [4], and the content of glutathione [5], has been shown to be high in cortices of clear lenses and of cortical cataracts. These values were significantly less in cortices of subcapsular cataracts [3,4,5]. Human subcapsular cataracts but not cortical cataracts have also been found to be associated with activity loss in glutathione synthesis enzymes [6].…”