Lesions of the central and peripheral nervous systems produced in young rabbits by vitamin A deficiency and a high cereal intake / by Edward Mellanby.

  • Edward Mellanby
Date:
[1935?]
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Licence: In copyright

Credit: Lesions of the central and peripheral nervous systems produced in young rabbits by vitamin A deficiency and a high cereal intake / by Edward Mellanby. Source: Wellcome Collection.

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    and very sluggish as compared with the response of the same muscle in a normal animal. Sherrington calls this type of reaction “ transneuronal degeneration.” So far, then, the evidence of traumatic degeneration indicates that spinal motor nerve-cells may be either normal or abnormal when the conducting fibres are degenerated, that the nerve-fibres may appear normal when their corresponding cells show chromolysis and that, in the case of some afferent nerve units, the cells may escape chromolysis when the conducting fibres are degenerating. It is evident that these results of trauma offer no aid to the solution of the problem as to whether the primary lesion in experiments described in this paper is in the nerve¬ cell or its conducting fibre. At one period of the work, when the demyelination changes in nerve- fibres seemed to be the outstanding effect of vitamin-A deficiency, H. N. Green [19], working in my laboratory, endeavoured to find out whether vitamin A had some special relationship to fat metabolism. If this had been established, it might have afforded some support for the view that the nerve-fibre, and especially its myelin covering, wTas primarily involved in vitamin A deficiency. However, there was no evidence of any specific relationship between vitamin A and fat metabolism. There is, as indicated above, a good deal of specificity in the nerve cells and fibres affected, the afferent system being on the whole much more liable to change than the motor system. This might be regarded as evidence that the nerve-cell lesion is primary because it seems more likely that specificity of reaction would be shown by nerve-cells than nerve-fibres. It may be possible to settle this question in the adult animal, for early observations indicate abnormality of the cell without any obvious change in its conducting fibres. Thus in one adult animal the ganglion cells of the retina are degenerating and show chromolysis while there is no obvious myelin degeneration in the optic nerve. In their biochemical aspect these experiments have a particular interest, especially in view of earlier and contemporary work showing the close interaction between specific chemical substances and the nervous system. I refer particularly to the recent work by Dale and his colleagues [20 and 21] on acetyl choline in relation to nerve-endings and nerve-cell activity, and to the earlier investigations which established the close relationship between adrenaline and most sympathetic nerve-endings (Elliott [22]). It would appear indeed that a new stage of biochemical knowledge regarding nervous tissue is opening up, and that the time is not far distant when there will be much more information available about