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
C G SweepV M Wiegant

Abstract

The intermediate lobe of the pituitary gland synthesizes the multifactorial precursor molecule pro-opiomelanocortin (POMC), from which, through a process of post-translational enzymatic processing, beta-endorphin-(1-31) (beta E) and a variety of N alpha-acetylated and C-terminally shortened forms of this peptide are generated. Using an in vitro superfusion system, the release of these endorphins from intact rat neurointermediate lobes (NILs) was investigated under basal and isoproterenol (ISO) stimulated conditions. Superfusion of NILs with the beta-adrenergic agonist ISO (30 min pulse) resulted in a rapid, sustained and concentration-dependent stimulation of the release of beta E-like immunoreactivity (beta E-IR) over basal as determined with an antiserum directed against the C-terminus of the beta E- (1-31) sequence (10(-6) M: + 145%; 10(-7) M: + 73%; 10(-8) m: + 41%). The release of N(alpha)-acetylated-endorphin-like immunoreactivity (AcE-IR) was stimulated to a similar extent. These effects of ISO were antagonized by the competitive alpha-adrenoceptor antagonist propranolol in a concentration-dependent manner, indicating the involvement of alpha-adrenoceptors. The beta-related peptides released from the NILs under basal and...Continue Reading

References

Jul 1, 1977·Proceedings of the National Academy of Sciences of the United States of America·R E MainsN Ling
Jul 1, 1978·Proceedings of the National Academy of Sciences of the United States of America·N G SeidahM Chretien

Related Concepts

Acetylation
Metazoa
Beta-Endorphin
High Pressure Liquid Chromatography Procedure
Novodrin
Infundibular Stem
August Rats
Rats, Laboratory

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