Seminal vesicles aldose reductase

ALDOSE REDUCTASE I e The enzyme is present in I iver, kidney, retina, lens, nerve I tissue, seminal vesicles, and. ovaries. 

Fructose synthesis from glucose in the polyol pathway occurs in seminal vesicles and other tissues. Aldose reductase converts glucose to the sugar alcohol sorbitol (a polyol), which is then oxidized to fructose. In the lens of the eye, elevated levels of sorbitol in diabetes mellitus may contribute to cataract formation. 

In these coupled reactions, the overall transformation of glucose to fructose is accompanied by a transfer of hydrogen from NADPH to NAD. Studies on the activity of aldose reductase and sorbitol dehydrogenase as well as the presence of sorbitol in seminal vesicles of several species and rat coagulating gland are consistent with the operation of the sorbitol pathway as a major determinant of seminal fructose biosynthesis (248, 252-260). Nonphosphorylative conversion of glucose to sorbitol has also been demonstrated in placenta (258, 261, 262), smooth muscle of the aorta (263), the lens of the eye (264, 265), erythrocytes (266) and hepatoma-derived (HTC) cells in culture (267), and possibly normal liver cells (267, 268). 

Sorbitol is secreted by boar seminal vesicle which produces rather little fructose and exhibits considerable aldose reductase but feeble sorbitol dehydrogenase activity (257). Considerable amounts of glucose and sorbitol (but not fructose) are present in seminal plasma of the stallion and jackass in which species these seminal sugars probably originate from the vesicular glands (5, 270). 

---