Studies on the etiology and pathogenesis of motor neuron diseases. II. Clinical and electrophysiologic features of pyramidal dysfunction in macaques fed Lathyrus sativus and IDPN.

A primate model of lathyrism has been produced in well-nourished male cynomolgus monkeys chronically fed a fortified diet composed of Lathyrus sativus (chickling or grass pea) and given daily per os an alcoholic extract of this legume. Animals given a diet of non-neurotoxic Cicer arietinum (chick pea) cross-matched with the nutritional properties of the experimental diet served as controls. Another group of animals received the same diet and oral doses of beta, beta'-iminodipropionitrile (IDPN), a reference compound that has been termed an "experimental neurolathyrogen." Monkeys fed Lathyrus developed clinical and electrophysiologic evidence of corticospinal deficits after 3 to 10 months of feeding. Animals administered IDPN showed clinical and/or electrophysiologic changes in the PNS and CNS motor and sensory pathways, and signs of cerebellar dysfunction. Since the two primate disorders are separable on clinical and electrophysiologic grounds, further use of the term "experimental neurolathyrogen" to describe the neurotoxic properties of IDPN seems inappropriate. These findings demonstrate the feasibility of developing a model of early human lathyrism in adequately nourished nonhuman primates.