REN and thyroid gland disorder: In order to obtain a more comprehensive view of the response of the renin-angiotensin system in the hypothalamus-pituitary-adrenal axis of animals with thyroid disorders, the pattern of behavior of these activities correlating intra-tissue and inter-tissues was analyzed fluorometrically in hypothalamus, anterior- and posterior-pituitary, adrenal gland, and plasma of euthyroid, hypothyroid, and hyperthyroid rats, using arylamide derivatives as substrates.