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Neurolathyrism and L-ascorbic acid
Kamaluddin Ahmad and Khursheed Jahan
Institute of Nutrition and Food Science, University of Dacca,
Dacca, Bangladesh
Neurolathyrism is a disease that has crippled many thousands in the Indian subcontinent and elsewhere during the past several centuries ( 1). It struck poor people who used the seeds of Lathyrus sativus as the principal item in their diet continuously for a period of at least two to three months. The disease appeared to affect humans almost exclusively. No experimental animal model was available to facilitate biomedical research on the subject until recently, when we produced the condition in guinea pigs (2). When guinea pigs having a subacute deficiency of L-ascorbic acid were fed for four to five weeks on a diet of cooked L. sativus seeds supplemented with minerals and the usual vitamins except for L-ascorbic acid, they developed typical symptoms of neurolathyrism, affecting the hind limbs.
The same condition also appeared within two to three hours following intraperitoneal administration of an extract of L. sativus (3) in guinea pigs previously made deficient in ascorbic acid by omitting it from a normal diet that did not include any L. sativus seeds. We further found that L-ascorbic acid not only protected the animals from the neurotoxic effect of L. sativus, but also had a curative effect on those that had earlier become paralysed by the toxicity of the seeds.
We subsequently produced the same symptoms of neurolathyrism in monkeys made deficient in ascorbic acid by feeding them cooked L. sativus seeds or by administering extracts of L sativus intraperitoneally. Thus, a subacute deficiency of L-ascorbic acid that was not severe enough to produce scorbutic symptoms was found to be a precondition for the appearance of neurolathyrism attributed to L. sativus seeds. This also explained the failure to produce experimental neurolathyrism in laboratory animals that do not require any dietary supply of L-ascorbic acid or that were provided this vitamin in the experimental diet before we suspected that its deficiency could be a predisposing factor.
Finally, a neurotoxin, ß-N-oxalyl L -a, ß-diamino propionic acid (ODAP), isolated from L. sativus seeds (4), was administered intraperitoneally in two-day-old chicks. It produced neurological symptoms such as retraction of the head and paralysis of the legs, indicating damage to the central nervous system.
REFERENCES
1. S. L.N. Rao, K. Malathi, and P.S. Sarma, World Review of Nutrition and Dietetics, 10: 214 (Karger, Basel, New York, 19691.
2. K. Ahmad and K. Jahan, The Third Asian Congress of Nutrition, Jakarta, Indonesia, 6-10 Oct. 1980, p. 190.
3. V, Nagarajan and C. Gopalan, "Production of Neurolathyrism in Chicks by Injection of Lathyrus sativus Concentrates," Current Sci, 32: 116(1963h).
4. S.L.N Rao, P.R. Adiga, and P.S. Sarma, "Isolation and
Characterisation of ß-N-oxalyl L a,
ß-diamino Propionic Acid, a Neurotoxin from Seeds of Lathyrus
sativus," Biochem., 3: 432
(1964).