Elucidation and Characteristics of Non-opioid  -Endorphin Receptors in Rat Adrenal Cortex

• Published in: Biochemistry (Moscow) Vol. 69; no. 8; pp. 870 - 875
• Main Authors: Navolotskaya, E. V., Kovalitskaya, Yu. A., Zolotarev, Yu. A., Kudryashova, N. Yu, Goncharenko, E. N., Kolobov, A. A., Kampe-Nemm, E. A., Malkova, N. V., Yurovsky, V. V., Lipkin, V. M.
• Format: Journal Article
• Language: English
• Published: New York Springer Nature B.V 01-08-2004
• Subjects: Adrenal glands; Tritium
• ISSN: 0006-2979; 1608-3040
• DOI: 10.1023/B:BIRY.0000040218.03078.9f

β-Endorphin-like decapeptide immunorphin (SLTCLVKGFY), a selective agonist of non-opioid β-endorphin receptor, was labeled with tritium to specific activity of 24 Ci/mmol. It was used for the detection and characterization of nonopioid β-endorphin receptors on rat adrenal cortex membranes (K^sub d1^ = 39.6 ± 2.0 nM, B^sub max1^ = 40.7 ± 2.3 pmol/mg protein; K^sub d2^ = 0.25 ± 0.01 μM, B^sub max2^ = 187.8 ± 9.4 pmol/mg protein). β-Endorphin was found to inhibit the [^sup 3^H]immunorphin specific binding to membranes (K^sub i^ = 70.0 ± 9.2 nM); naloxone, [Met^sup 5^]enkephalin, and α- and γ-endorphins tested in parallel were inactive. Immunorphin at concentrations of 10^sup -9^-10^sup -6^ M was found to inhibit the adenylate cyclase activity in adrenocortical membranes, while intramuscular injection of immunorphin at doses of 10-100 μg/kg was found to reduce the secretion of 11-oxycorticosteroids from the adrenals to the bloodstream.[PUBLICATION ABSTRACT]