Hypothyroidism and pituitary contents of immunoactive met-enkephalin and β-endorphin in male rats of different ages

Abstract

A comparison of the effect of PTU-induced hypothyroidism on the contents of immunoactive met-enkephalin and β-endorphin in the pituitaries from rats aged 2 1/2 , 12, and 18 months was made. In all ages, there was significant reduction of IR-met-enkephalin content in the anterior lobe and IR-β-endorphin content in the neuro-intermediate lobe after PTU treatment. There was a significant age-related decrease in IR-β-endorphin content in the anterior lobe. Rats of all three ages responsed to PTU treatment with an increase in serum TSH level and a drastic reduction in serum T3 and T4 levels. The results indicate that there was no age-related difference in the change of pituitary opioid peptide contents in response to hypothyroidism.