EFFECTS OF IMMOBILIZATION AND FOOD DEPRIVATION ON RAT BRAIN TRYPTOPHAN METABOLISM

TLDR

Withdrawal of food or immobilization alters rat brain tryptophan metabolism. Food withdrawal and immobilization increased brain tryptophan and 5‑hydroxyindoleacetic acid levels, with larger effects from food withdrawal; 5‑hydroxytryptamine changes were modest, plasma tryptophan remained unchanged, and adrenalectomy did not eliminate the brain indole changes, highlighting altered serotonin regulation.

Abstract

Abstract— Withdrawal of food or immobilization both led to changes in rat brain tryptophan metabolism. Brain tryptophan and 5‐hydroxyindolylacetic acid concentrations both increased while changes in 5‐hydroxytryptamine were much smaller. Changes were greater upon withdrawal of food. The brain tryptophan change did not appear merely to reflect an overall increase of brain amino acid concentrations, brain tyrosine concentration being only slightly increased by food withdrawal and significantly decreased upon immobilization. Plasma tryptophan did not increase. The changes in brain indole metabolism were not abolished by adrenalectomy. Results are discussed in relation to the regulation of brain serotonin metabolism.