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?]
Catalogue details

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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    stirring of the alfalfa must be sufficient to ensure the complete destruc¬ tion of the carotene. If unheated instead of heated alfalfa be given, the nervous lesions do not appear. Similarly, if cabbage or carrots or any other source of carotene or vitamin A be added to the standard basal diet, the nervous system of the rabbit is protected. Pure carotene, in amounts of 1 to 3 mgm. daily, was sometimes added to the basal diet to prevent the nerve changes. In view of Stockman’s results [2] in which he has produced derangement of the nervous system by diets rich in cereals but containing very little available calcium, it is necessary to point out that in the present work there is no deficiency of available calcium in the diet. It may also be well to add that in each series of experiments a rabbit with a normal nervous system has been produced by adding a source of the protective factor to the same basal diet as that given to the affected animal. Behaviour of rabbits on the carotene-deficient diets.—The young rabbits grow and remain well on the basal diet for some months. The order of the appearance of signs of nerve defect varies, but slight stiff¬ ness of the legs, and especially of the hind legs, is generally the first abnormality noticed ; this may be seen after two to three months of the experimental diets. Xerophthalmia appears next, three to six months after the beginning of the experiment; a dull patch or band appears on the cornea, usually in the centre, running midway between and parallel to the eyelids, i.e. in that part most exposed [1(g)], At this stage examination will show that the pupillary reactions are sluggish. Head movements usually develop quickly after this, although in some cases they are noticed before the changes in the eyes. The animal moves its head in a curious and characteristic wav, as if it did not know its position in relation to the rest of the body; sometimes it is moved up and down and sometimes from side to side, and when at rest is often askew with ears awry. In the later stages of xerophthalmia some of the head movements may be due to ocular defects and obscured vision. The rabbit often moves about as if suffering from alcoholic intoxication. It may go round in circles, turn its head permanently towards one side, wobble from side to side, and in extreme cases even fall over either to the side or backwards, sometimes being unable to regain the normal position. When examined in the cage the early signs are not so obvious; the animal has a sleepy look, the eyes often being half closed; it sits quietly huddled in the corner of its cage. At no time is there any definite paralysis, but the animals appear