Intact
lenses from New Zealand white rabbits were incubated in tissue
culture media containing either 5 mM
glucose or 5 mM
glucose plus 30 mM
galactose. The standard media did not contain
taurine.
Lenses were also cultured in a third medium containing 30 mM
galactose plus 0.2 mM
taurine. The frequency of
cataract formation was evaluated as a function of the
culture media. One lens (1/10), in media containing 5 mM
glucose, developed a lenticular opacification during a 72-h incubation.
Lenses (12/15) incubated in 30 mM
galactose, without
taurine, developed
cataracts; fewer
lenses (2/13) exposed to 30 mM
galactose plus 0.2 mM
taurine developed
cataracts (p < 0.005).
Galactose cataracts have been associated with lens
edema attributed to the osmotic stress of tissue
polyol (
galactitol) accumulation. The water content of the noncataractous and cataractous
lenses in this experiment did not differ. Lens
edema, therefore, was not thought to be important in
cataract pathogenesis.
Taurine, an organic osmolyte was lower (5.1 +/- 1.5 mumol/
g protein) in cataractous
lenses than in control
lenses (10.0 +/- 1.0 mumol/
g protein).
Malondialdehyde, an
indicator of lipid peroxidation, was higher (36.6 +/- 5.0 mumol/
g protein) in lens-containing opacifications than in noncataractous
lenses (10.1 +/- 1.9 mumol/gm
protein) (p < 0.01). The levels of
malondialdehyde suggest that lipid peroxidation was increased in the process of
sugar cataractogenesis. The
malondialdehyde content of all the
lenses correlated inversely (r = -0.53, p < 0.01) with the coincident lens
taurine levels.
Taurine appears to protect the lens against the development of
sugar cataracts; its inverse relationship with lens
malondialdehyde suggests this is an
antioxidant effect.