Neurochemistry of the spinal cord in British Saddleback piglets affected with congenital tremor, type A-IV, a second form of hereditary cerebrospinal hypomyelinogenesis.

Abstract

AbstractCongenital tremor, type A‐IV is an inherited abnormality of British Saddleback piglets characterized by the presence of poorly myelinated axons throughout the CNS. This is reflected by a general lowering of the spinal cord lipid content to about half control values. In particular, cerebroside and plasmalogen levels are markedly reduced.Changes in the fatty acid composition of total lipid extracts and two isolated cerebroside fractions suggest that there is a metabolic defect in which fatty acid chain elongation, desaturation and hydroxylation are sub‐optimal.Cholesterol esters accumulate, make up about 30 per cent of total sterols and contain more than 90 per cent of C16 and C18 fatty acids. These may have arisen through the breakdown of cerebrosides containing abnormal proportions of these acids. Slightly increased levels of acid hydrolase activity appear to confirm that abnormal or immature myelin is disposed of by enhanced macrophagic activity.Differences between this and type A‐III, the sex‐linked inherited form of cerebrospinal hypomyelinogenesis are discussed and comparisons made with two forms of murine leuko‐dystrophy.