Production of fructose and fructose-3-phosphate in maturing rat lenses.
OBJECTIVE
A large increase in glycation of crystallins between 1 and 8 months has been demonstrated in lenses obtained from aging rats. The objective of this study was to investigate if an age-associated increase in the levels of any of the phosphorylated and nonphosphorylated sugars in the aging rat lenses could be correlated with this increase.


METHODS
Lenses were obtained from Sprague-Dawley rats ranging in age from 2 to 20 months. Trichloroacetic extracts of these tissues were analyzed by using 31P-NMR for sugar phosphates and high-pressure liquid chromatography equipped with an electrochemical detector for sugars and polyols.


RESULTS
Although no elevation in the lenticular glucose levels was observed, an age-associated increase in the concentrations of polyol pathway-associated metabolites--sorbitol, fructose, sorbitol-3-phosphate, and fructose-3-phosphate--was detected. In contrast, no significant changes were observed in glycolytic or pentose shunt metabolites.


CONCLUSIONS
Aging lenses accumulate increased concentrations of fructose and fructose-3-phosphate. Because fructose-3-phosphate is a potent glycating agent and a potential in vivo source of 3-deoxyglucosone, its accumulation in the lens, along with fructose, may be a contributing factor in the age-associated increase of nonenzymatic glycation in rat lenses.
Lal
S
S
Department of NMR and Medical Spectroscopy, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
Szwergold
B S
BS
Taylor
A H
AH
Randall
W C
WC
Kappler
F
F
Brown
T R
TR
D000375:Aging; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005632:Fructose / Q000032:analysis / Q000096:biosynthesis*; D005636:Fructosephosphates / Q000032:analysis / Q000096:biosynthesis*; D007908:Lens, Crystalline / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D010710:Phosphates / Q000032:analysis; D010759:Phosphorus Isotopes; D051381:Rats; D017207:Rats, Sprague-Dawley
D005636:Fructosephosphates; D010710:Phosphates; D010759:Phosphorus Isotopes; C062519:fructose 3-phosphate; D005632:Fructose