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CHANGES IN MET‐ENKEPHALIN AND β‐ENDORPHIN CONTENTS IN THE HYPOTHALAMUS AND THE PITUITARY IN DIABETIC RATS: EFFECTS OF INSULIN THERAPY
Author(s) -
Tang Fai
Publication year - 1989
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1989.tb01530.x
Subject(s) - medicine , endocrinology , hypothalamus , insulin , met enkephalin , enkephalin , endorphins , chemistry , alloxan , pituitary gland , diabetes mellitus , opioid , hormone , receptor
SUMMARY 1. Immunoreactive (IR)‐met‐enkephalin and β‐endorphin contents in the hypothalamrus and the pituitary were measured in alloxan‐diabetic rats with or without insulin treatment. 2. Both IR‐met‐enkephalin and IR‐β‐endorphin in the pituitary were substantially reduced in alloxan‐diabetic rats 1 month after treatment. 3. Hypothalamic IR‐β‐endorphin content was also significantly lower. 4. Gel‐filtration chromatography showed that the peaks co‐eluting with met‐enkephalin precursor, met‐enkephalin and β‐endorphin were lower in the pituitaries from the diabetic rats, whereas the peaks co‐eluting with β‐endorphin precursor and β‐lipotropin were not. 5. In another experiment, the IR‐β‐endorphin contents of the neuro‐intermediate lobe and hypothalamus, but not the anterior lobe were significantly lowered in diabetic rats, whereas IR‐met‐enkephalin contents were significantly reduced in both the anterior and neuro‐intermediate lobe. 6. All these changes were reversed by insulin treatment. 7. As a decrease in general protein synthesis could not explain the recorded changes, these results suggest a possible direct role of insulin in regulating the opioid peptide content of the hypothalamus and pituitary.