Age-dependent muscarinic stimulation of β-endorphin secretion from rat neurointermediate lobe in vitro

Zsuzsanna Ács, István Barna, James I. Koenig, Gábor B. Makara

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1 Citation (Scopus)


The effect of acetylcholine on the neurointermediate lobe β-endorphin secretion was studied in the neonatal and in the adult rat in vitro. Acetylcholine stimulated β-endorphin secretion from the 2-day- and 5-day- old neurointermediate lobe, the effect was dose dependent and more pronounced in the presence of the cholinesterase inhibitor eserine. The 10-day-, the 21- day-old end the adult rat neurointermediate lobes did not respond to acetylcholine, even in the presence of eserine. Basal β-endorphin secretion was elevated by the D2 receptor antagonist sulpiride, but acetylcholine was without effect in the 10-day-old and in the adult neurointermediate lobe even after dopamine receptor blockade. The β-endorphin stimulatory response to acetylcholine was diminished by the M1 muscarinic receptor antagonist pirenzepine and blocked by the M3 > M1 antagonist 4-diamino-phenyl- piperidine (4-DAMP). The selective M2 antagonist methoctramine and nicotine had no effect. These data indicate that the neurointermediate lobe β- endorphin secretion is under special muscarinic cholinergic regulation for a relatively short time after birth. The disappearance of this stimulatory cholinergic effect in later life might be due to changes in the intracellular secretory machinery in the IL and/or to the uncoupling of the cholinergic receptors from the intracellular signal transduction system(s) responsible for the stimulated secretion in the rat melanotrope cells.

Original languageEnglish
Pages (from-to)719-725
Number of pages7
JournalBrain Research Bulletin
Issue number6
Publication statusPublished - Jan 1 1997


  • Acetylcholine
  • Muscarinic receptor
  • Neonatal
  • Pituitary
  • β-Endorphin secretion

ASJC Scopus subject areas

  • Neuroscience(all)

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