Dietary-Induced Changes in Lipid and Fatty Acid Composition Can Modify Chronaxie Values in the Rat Sciatic Nerve

Abstract

The present investigation aimed at clarifying the possible correlations among dietary lipids, peripheral fatty acid composition of nerve lipids and an index of the nervous tissue excitability, the chronaxie. The experiments were performed on female albino rats fed diets containing olive oil (OO) and fish oil (FO) along two generations. Total lipids fatty acid composition of the sciatic nerves from the two groups differed in the proportions of 18:1(n-9), 20:1(n-9), 22–1, 20:5(n-3) and 22:6(n-3). Also the lipid class composition showed significant differences among FO and OO specimens (free cholesterol more concentrated in the OO lipids; triacylglycerols more concentrated in the FO ones). The sciatic nerve isolated from FO rats showed a significant decrease in the chronaxie values if compared to the OO specimens. These results could follow from dietary-induced changes in the perineural permeability and/or possible modifications in the cable properties of the peripheral nerve fibers related to the myelin sheath composition.

The effects of general anaesthesia on nerve‐motor response characteristics (rheobase and chronaxie) to peripheral nerve stimulation

“…The same result has been reported in the literature, and many explanations for the wide range of chronaxie values have been suggested . First, there are a number of disease states that are known to affect nerve excitability ; second, evidence from animal models suggests that dietary changes can alter chronaxie values ; and third, as I used surface electrodes in this study, the distance from the stimulating electrode to the nerve cannot be standardised and will, therefore, affect the measured chronaxie and rheobase values . Another source of variability is temperature: general anaesthesia is known to induce hypothermia , and temperature affects both conduction velocity and compound action potential .…”

Contrasting effects of treatment with ?-3 and ?-6 essential fatty acids on peripheral nerve function and capillarization in streptozotocin-diabetic ratsn

“…The mechanisms underlying hyper-excitability and RHCF are poorly understood but are accompanied by a degree of axonal depolarisation that reduces excitation thresholds [42] and may depend on changes in membrane-bound calcium levels that modulate axonal excitability [43]. The reasons why GLA and fish oil changed hyper-excitability in opposite directions are unclear, but these effects probably do not result from direct changes in membrane properties as both treatments would be expected to produce similar reductions in membrane fluidity [44,45]. Thus, these actions may depend on products of eicosanoid metabolism, which can acutely alter nerve function [46].…”