Inhibition of diet-restriction-induced behavioral deficits by tryptophan administration in rats

ABSTRACT

Diet has a great impact on brain health and function. It plays an important role to improve and control a number of psychiatric disorders such as depression, anxiety, hyperactivity and behavioral impulsivity. Anorexia Nervosa [AN] is one of the psychiatric disorder which is associated with diet. In AN, patients show extreme dieting, weight loss, hyperactivity, depression/anxiety, self-control and behavioral impulsivity. Previous studies showed that during diet restriction, tryptophan decreases serotonin [5-hydroxytryptamine; 5-HT] metabolism in the brain due to its less availability and contributes psychiatric problems associated with AN. The present study is designed to investigate the effects of tryptophan administration on 5-HT metabolism in diet-restricted rats. Tryptophan at a dose of 50 or 100mg/kg was given orally to respective freely fed [FF] or diet restricted [DR] animals daily for five weeks. Behavioral activities were also monitored weekly. The results show significant effect [p<0.05] on behavior in activity box, open field and in light/dark transition test by tryptophan administration in diet-restricted rats. This may be associated with the increased in serum tryptophan and brain 5-HT metabolism. Therefore, it is concluded that diet-restriction-induced behavioral changes might be reverted back with the administration of tryptophan and may be helpful to improve psychological problems in AN