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Plasma inorganic phosphate incorporation into inorganic and organic acid-soluble phosphate fractions of the rat sciatic nerve increases markedly during Wallerian degeneration. Administration of cycloheximide and actinomycin D remains without effect on this specific increase which appears thus independent of cytoplasmic protein neosynthesis.

The subcutaneous injection of acrylamide (30 mg kg-1 day-1) in adult male rats induces a severe impairment of the general state of health and a progressive polyneuropathy at the cumulative dose of 180 mg/kg. At the cumulative dose of 400 mg acrylamide does not interfere with the incorporation of plasma inorganic phosphate into the inorganic and organic acid-soluble phosphate fractions of either the gastrocnemius muscle or the sciatic nerve Schwann cells. Nor does it modify the characteristic metabolic response of these fractions to Wallerian degeneration and neurogenic muscle atrophy.

Inorganic phosphate exchanges between plasma and sciatic nerve have been measured in the rabbit using a 32PO4 tracer technique. Inorganic phosphate is taken up at the rate of 0.13 microng per hour and per 100 mg fresh weight. Incorporation of plasma radiophosphate is markedly increased into the inorganic and organic acid soluble phosphate fractions of the distal part of the sectioned sciatic nerve. This increase is already signficant within one hour after surgical division, spreading at least 3 cm distally within 6 hours. This high level of incorporation persists until the 29th day of degeneration. These results favour the hypothesis that the axonal continuity maintains the metabolic activity of the Schwann cells at an inframaximal level. We confirm the rapid decrease in total phospholipid concentration in the nerve undergoing Wallerian degeneration as well as the marked increase in their specific activity. We show however that this increase in specific activity is due partly to the increased specific activities of the precursors (organic acid soluble phosphates), partly to the disappearance of a metabolically insert pool (myelin phospholipids). The Schwann cells of the nerve undergoing Wallerian degeneration do not have a more active phospholipid metabolism than their normal counterparts.

The excised sciatic nerve of the trembler mouse synthesizes minute amounts of C20 and C22 saturated fatty acids as compared to the normal PNS. No lignoceric acid synthesis is observed. The microsomal fraction contains however an elongase able to synthesize with nearly normal levels the saturated very long chain fatty acids.