Role of tryptophan metabolites in inhibition of spinal deformity of chum salmon fry caused by tryptophan deficiency.

5-hydroxy-L-tryptopha (5-HTP) and kynurenine were supplemented to the tryptophan deficient diet to confirm if these substances can prevent occurrence of spinal deformity such as scoliosis caused by tryptophan deficiency. None of the fish showed scoliosis in the group fed the tryptophan deficient diet with 5-HTP (130mg/100g diet) for 4 weeks. However, scoliosis was recognized in 62% of the fish fed the tryptophan deficient diet with DL-kynurenine (240mg/100g diet). On the other hand, the administration (290mg/100g diet) of DL-p-chlorophenyl-alanine (PCPA) to the diet with sufficient quantity of tryptophan resulted in a high incidence (64%) of spine-deformed fish, and the 5-HT content in the brain of PCPA treated group were significantly lower than that of the control group. These findings indicated that the occurrence of spinal deformity is related to the depletion of 5-HT in the body or the brain.