THE EFFECTS OF VARIOUS LEVELS OF SWEET PEAS (LATHYRUS ODORATUS) IN THE DIET, WITH AND WITHOUT DIETARY SUPPLEMENTS, ON THE GROWTH OF THE MANDIBULAR RAMUS AND ARTICULATION IN YOUNG RATS

¹ Department of Pathology, Georgetown University, Schools of Medicine and Dentistry, Washington, D. C.

Experiments on rats indicated that systemic treatment with beta-aminopropionitrile from sweet peas produces a metabolic defect which causes the mandible and skeleton to respond with new bone formation in regions of mechanical topical stress.

Experiments on rats showed that moderate doses of beta-aminopropionitrile in sweet peas, which in themselves elicited lesions characteristic of skeletal lathyrism, produced very minor lesions with no morbid changes when fed in combination with dietary supplementation of proteins and other substances (amino acids).

Most important among these alterations were: thickening and proliferation of the periosteum, subperiosteal new bone formation at muscle insertion sites on the ramus and angular process of the mandible and on the roof of the mandibular articulation, ectopic bone formation in temporalis muscle, presence of basophilic bone globules (positive to periodic acid-Schiff stain) in newly formed lathyrismic bone, and osteoporosis with dilatation of the blood vessel channels in solid bone.

Certain basophilic granules and globules were described in the intercellular substance of newly formed bone of mandibles of rats fed nonsupplemented sweet pea diets. These globules appeared to be very specific for experimental lathyrism.

The osteoporosis of the ramus became accentuated with continued protein deprivation and led to severe breakdown of bone tissue in the nonsupplemented groups where one may assume an increased rate of resorption took place.

Dietary supplementation with proteins and amino acids greatly diminished the development of bone lathyrism that is normally produced by aminopropionitrile (Lathyrus odoratus) in the rat. The amino acids, L-cysteine-HCl and L-glutamine, gave protection against onset and severity of skeletal lesions in the ramus and mandibular articulation in rats fed sweet peas.

Glutamine had a growth stimulating effect, in addition to delaying the onset and severity of changes in the ramus and mandibular articulation.

The protein supplements, casein and gelatin in high levels, delayed the onset and reduced the severity of lesions of the ramus and mandibular articulation. Casein exerted a greater protective action than gelatin. The protein and amino acid supplements restored the ability of the lathyrismic rat to diminish osteoporosis and osteoclastic activity, to stimulate normal apposition of bone, and to prevent new bone formation at sites of muscle insertions.

The lack of development of exostoses, therefore, may be used as an early and reliable indicator of the success of supplemental feedings of proteins and amino acids to lathyrismic diets.

The finding of a protective agent was deemed of considerable biologic importance since a possible relationship exists between experimental lathyrism and a number of human diseases of unknown etiology.