Effect of alpha-tryptophan on conditioning and behavior in rats with experimental pathology of the thyroid gland

Effects of L-tryptophan on learning and behavior were studied in male rats with a deficit or excess of thyroid hormones. Learning was assessed in active avoidance paradigm, and behavior was estimated in the "open-field" test. It was found that L-tryptophan restored the capability of thyreoidectomized rats for acquisition and reproduction of the active avoidance reaction and increased the exploratory behavior of these rats in the open-field. In triiodothyronine treated rats, L-tryptophan eliminated a light stimulatory effects of thyroid hormones on the processes of formations and retention of the active avoidance reaction, increased the exploratory activity, but decreased grooming in the open-field.