+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Effects of chronic treatment of rats with dopamine receptor drugs on the post-translational processing of Beta-endorphin in the neurointermediate lobe of the pituitary gland



Effects of chronic treatment of rats with dopamine receptor drugs on the post-translational processing of Beta-endorphin in the neurointermediate lobe of the pituitary gland



Journal of Neuroendocrinology 2(4): 531-537



Abstract To investigate whether chronic changes in the activity of proopiomelanocortin cells in the neurointermediate lobe (NIL) of the pituitary gland are associated with changes in the enzymatic processing of beta-endorphin (betaE), the effects of treatment of rats with the dopamine receptor antagonist haloperidol or the dopamine receptor agonist bromocriptine (2.5 mg.kg(-1) sc, once daily for 21 days) were studied on the content of betaE-related peptides in the NIL and on the release of these peptides from NILs in an in vitro superfusion system. Treatment with haloperidol increased, and with bromocriptine decreased the tissue content and the release of N(alpha)-acetyl-, beta-, gamma- and alpha-endorphin-immunoreactivity (AcE-, betaE-, gammaE, and alphaE-IR). The endorphin-IR was further characterized using reversed-phase high-performance liquid chromatography and specific radioimmunoassay systems, and the following peptides were identified: des-tyrosine alpha-endorphin (DTalphaE), alphaE, AcalphaE, gammaE, AcgammaE, betaE-(1-31), AcbetaE-(1-31), AcbetaE-(1-27), AcbetaE-(1-26) and betaE-(1-26)/betaE-(1-27) (the latter peptides were not separated with the high-performance liquid chromatography system used). Analysis of NIL superfusates indicated that all peptides found in the tissue were released in vitro. In addition, an as yet unidentified acetylated IR-endorphin component was found which was not observed in extracts of NIL tissue, and therefore was probably formed during release. Following haloperidol treatment, the levels of all betaE-related peptides detected were increased in the tissues as well as superfusates, the increase in AcbetaE-(1-27) being most and that in betaE-(1-26)/betaE-(1-27) least pronounced. Following bromocriptine treatment, the concentrations of all peptides in tissues and superfusates were decreased as compared to vehicle controls. The acetylated endorphins, in particular AcbetaE-(1-27), were most affected and betaE-(1-26)/betaE-(1-27) least affected. The results indicate that chronic modulation of the synthesizing and secretory activity of proopiomelanocortin cells in the NIL is parallelled by changes in the enzymatic processing of betaE.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 052859703

Download citation: RISBibTeXText

PMID: 19215385

DOI: 10.1111/j.1365-2826.1990.tb00444.x


Related references

Biosynthesis and release of beta-endorphin-, N-acetyl beta-endorphin-, beta-endorphin-(1-27)-, and N-acetyl beta-endorphin-(1-27)-like peptides by rat pituitary neurointermediate lobe: beta-endorphin is not further processed by anterior lobe. Journal of Neuroscience 1(6): 585-595, 1981

Effects of chronic treatment with haloperidol and bromocriptine on the processing of beta-endorphin to gamma- and alpha-endorphin in discrete regions of the rat pituitary gland and brain. Neuropharmacology 29(1): 61-68, 1990

Cyproheptadine and desmethylcyproheptadine directly inhibit the release of adrenocorticotrophin and beta-lipotrophin/beta-endorphin activity from the neurointermediate lobe of the rat pituitary gland. Journal of Endocrinology 96(3): 395-400, 1983

Dopaminergic agents differentially alter beta-endorphin processing patterns in the rat pituitary neurointermediate lobe. Neuroscience Letters 59(1): 141-146, 1985

Stimulation of beta-endorphin and beta-lipotropin release from the anterior but not the neurointermediate pituitary lobe in the rat after acute administration of serotonin-acting drugs. Life Sciences 31(25): 2809-2818, 1982

Involvement of calcium ion on the release mechanism of beta endorphin like immunoreactivity from dispersed cells of the neurointermediate lobe of the rat pituitary gland. Acta Obstetrica et Gynaecologica Japonica (Japanese Edition) 36(11): 2362, 1984

Involvement of calcium in the release of immunoreactive beta-endorphin-like peptide from dispersed cells of the neurointermediate lobe of the rat pituitary gland. Japanese Journal of Pharmacology 37(3): 259-267, 1985

Effects of chronic ethanol treatment on the in vitro biosynthesis of pro-opiomelanocortin and its posttranslational processing to beta-endorphin in the intermediate lobe of the rat pituitary. Journal of Neurochemistry 43(3): 607-613, 1984

The effects of dopamine on the release of immunoreactive beta-endorphin-like peptide from the dispersed cells of the rat neurointermediate lobe. Nihon Naibunpi Gakkai Zasshi 61(7): 744-752, 1985

Binding of [125I]-N-(p-aminophenethyl)spiroperidol to the D-2 dopamine receptor in the neurointermediate lobe of the rat pituitary gland: a thermodynamic study. Molecular Pharmacology 33(2): 163-169, 1988

Effect of chronic morphine treatment on beta-endorphin biosynthesis by the rat neurointermediate lobe. European Journal of Pharmacology 72(4): 313-321, 1981

Chronic ethanol treatment alters the biosynthesis of beta-endorphin by the rat neurointermediate lobe. Canadian Journal of Physiology and Pharmacology 61(9): 967-976, 1983

Isoproterenol-stimulated release of beta-endorphin and related peptides from the rat pituitary neurointermediate lobe in vitro: evidence for preferential release of certain molecular forms of beta-endorphin. Neuropeptides 17(2): 63-74, 1990

Identification of Na-acetyl-a-endorphin and Na-acetyl-c-endorphin isolated from the neurointermediate lobe of the rat pituitary gland. The Journal of Biological Chemistry 260: 63-9, 1985

Stress, dopaminergic blockade and median eminence-neurointermediate lobe catecholamine depletion: effects on hypothalamic, pituitary and plasma immunoreactive beta-endorphin. Clinical and Experimental Pharmacology and Physiology 11(3): 221-229, 1984