Figure 1 Structure of thioctyl-y-linolenic acid (GLAaaTA). The molecule is a l ,2,3-propanediol diester with one molecule of GLA and one molecule of TA joined to the propanediol backbone by ester linkages.

(p < 0.05 and 0.01 respectively) (Fig. 2B). GLA TA also increased NGF levels (Fig. 2B) and both motor and sensuous nerve conduction velocities (Fig. 2A), so that these values were not significantly different from those of control rats. The potential dependence of the neuropeptide changes on NGF levels was examined by regression analyses. For the dependence of SP on NGF, r2 was 0.257 (p < 0.005), but the levels of NPY were less closely related to those of NGF, where r was 0.145 and the regression was barely significant (p < 0.05).

NPY in the sciatic nerve may derive from mixed fiber populations— some must be in sympathetic postganglionic fibers (88,89), but there may also be some in somatic sensory fibers. However, the level of expression in somatic afferents is low unless they are damaged, when it increases (90); after axo-tomy, this increased expression may be reduced by either NT-3 or NGF (91,92). Expression of NPY by the sympathetic phenotype is clearly stimulated by NGF (93), and NGF-responsive elements have been identified on the NPY promoter (94). Thus, the findings reported here might be most easily explained by the proposition that the NPY deficit in sciatic nerves of diabetic rats is also derived from reduced NGF neurotrophic support. However, our previous study showed that treatment of diabetic rats with NGF, although normalizing the SP levels in sciatic nerve, did not affect the NPY deficit (20). Thus, there may be control of NPY expression in these fibers by another neuro-trophin, and the NGF response elements become functional only when other influences are removed. This might explain the NGF effects on NPY in vitro (93,95) and increases in NPY after axotomy in vivo (90,96). Thus, the evolution of the decrease in NPY expression in our diabetic rats cannot be explained as yet, though the deficit clearly responds to treatment with the GLAaaTA conjugate and, in our previous study, also responded to TA (20).

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Peripheral Neuropathy Natural Treatment Options

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