Identification of fructose in mammalian nerve

Goji fruit (Lycium barbarum) protects sciatic nerve function against crush injury in a model of diabetic stress

Excess fructose consumption causes changes in functioning of the central and peripheral nervous systems, which increase the vulnerability of peripheral nerves to traumatic injury. The aim of this study was to evaluate the electrophysiological parameters of responses of motoneurons of the spinal cord at high-frequency stimulation of the distal part of the injured sciatic nerve in a model of diabetic stress under action of Lycium barbarum (LB). Male albino rats were given with drinking water with 50% concentration of dietary fructose for 6 weeks. Starting on the 7th week a crush injury of the left sciatic nerve was carried out. Some of the animals received fructose post-injury for 3 weeks and some of the animals received fructose+dry LB fruits for 3 weeks. In the fructose+crush+LВ group a relatively proportional division of tetanic and posttetanic potentiation and depression in responses of ipsilateral and contralateral motoneurons was observed, which would suggest the modulatory role of LB in short-term synaptic plasticity formation. Generally, LB fruit is able to modulate central nervous system reorganization, amplifying positive adaptive changes that improve functional recovery and promote selective target reinnervation in high fructose-diet rats with sciatic nerve crush-injury.

Aldose reductase in the etiology of diabetic complications. 3. Neuropathy

Aldose reductase has been shown to be present in both autonomic and somatic nerves. Activation of this enzyme and the polyol pathway has been demonstrated in diabetic animal models to cause a range of biochemical, functional, and structural consequences that include the accumulation of sorbitol and fructose; axoglial dysjunction; paranodal demyelination; abnormalities in axonal transport, blood flow, and vascular permeability; and resistance to ischemic transmission of action potentials. These data provide an insight into the range of processes that if activated may either singly or in combination result in altered patterns of nerve function and structural alterations in diabetic neuropathy. In animal models of diabetes, it has been shown that inhibition of aldose reductase can modify these diabetes-induced changes. It is hoped that the results of large-scale controlled trials will provide clinical evidence to support these data.

Aldose metabolism in developing human fetal brain and liver

Aldose reductase, sorbitol dehydrogenase, and glucose-6-phosphate dehydrogenase enzyme activities were studied in human foetal brain and liver at different periods of gestation. Aldose reductase activity in liver disappears after 16 weeks of gestation whereas sorbitol dehydrogenase keeps on increasing in liver as well as in brain. In utero, some glucose metabolism may be mediated through an active sorbitol pathway in human fetuses.

Polyol accumulation in galactosemic and diabetic rats: control by an aldose reductase inhibitor

An orally active inhibitor of aldose reductase, 1,3-dioxo-1H-benz[de]-isoquinoline-2(3H)acetic acid (AY-22,284), prevented cataractous changes in cultured lenses exposed to high concentrations of galactose. When given orally, AY-22,284 markedly decreased the accumulation of polyols in the lenses and sciatic nerves of galactosemic rats and rats with streptozotocin-induced diabetes. In addition, treatment of galactosemic rats with AY-22,284 effectively suppressed the formation of cataracts.

Sorbitol pathway: presence in nerve and cord with substrate accumulation in diabetes

Glucose, sorbitol, fructose, and inositol are present in peripheral nerve and spinal cord. Marked elevation of these substances occurs in these tissues in mildly diabetic animals. These alterations provide biochemical mechanisms which could be significant in the etiology of diabetic neuropathy.