The Effects of Induced Kynurenine Pathway on Immunocytochemical Changes in Rat Tissues Following Excessive L-Tryptophan Consumption
During the past decade it has been reported that diets containing excessive L-tryptophan have caused multisystemic manifestations in humans, known as Eosinophilia Myalgia Syndrome (EMS) (Duffy, 1992). Abnormal metabolism of tryptophan was also reported in clinical syndromes such as carcinoid syndrome (Cooper et al., 1991), scleroderma-like syndrome (Varge et al., 1990; Bruce et al., 1990; Smith et al., 1990), eosinophilic fasciitis (Freis et al., 1973), idiopathic scleroderma (Stenerg et al., 1980) and systemic sclerosis (Freis et al., 1973). Inflammatory responses were elicited in all these syndromes as leukocyte infiltration and fibroblast proliferation were constantly seen in histological sections from lung skin and muscle tissues. It is thus possible that excessive L-tryptophan intake is involved in stimulation of the immune system. However, the mechanism by which tryptophan or its metabolites are involved in these processes is not yet understood. Since it is impossible to precisely follow such effects in humans, it was the purpose of the present study to follow the effects of L- tryptophan and its metabolites in an animal model that demonstrates similar effects to those observed in human tissues.
KeywordsGastrocnemius Muscle Quinolinic Acid Carcinoid Syndrome Kynurenic Acid Kynurenine Pathway
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