Glycine levels in the degenerated human spinal cord

Distribution of glycine, GABA, aspartate and glutamate in the rat spinal cord

Glycine, GABA, aspartate and glutamate are putative neurotransmitters in the mammalian spinal cord. The distribution of these amino acids was determined in the rat spinal cord. Transversely, the highest levels of glycine, aspartate and glutamate were in the intermediate and ventral gray; whereas, the highest levels of GABA were in the dorsal gray. Longitudinally, the highest levels of GABA and aspartate were in the thoracic and lumbar segments; whereas, the highest levels of glycine and glutamate were in the cervical and thoracic segments, respectively. In general, the distribution of these amino acids is similar to that reported for the cat, dog and human.

Pilot study of threonine supplementation in human spasticity

Threonine supplementation (500 mg/day) was given to 6 patients with genetic spasticity syndromes for a period of 12 months, followed by a 4-month observation period without medication. All 6 patients showed partial improvement of spasticity, intensity of knee jerks and muscle spasms without changes in true pyramidal tract signs. The improvement in motor performance, objectively measured, averaged 29% (19% in upper limbs and 42% in lower limbs). The range of overall improvement was 19--35% (7--30% for upper limbs; 25--67% for lower limbs). No toxic clinical or biochemical side effects were encountered. Thus threonine, a precursor of glycine, produced the same effect on spasticity than that previously observed with glycine. It is concluded that threonine supplementation is feasible and safe and that it deserves a controlled trial in well defined (preferably genetic) cases of spasticity.