ACTH-immunoreactive boutons form synaptic contacts in the hypothalamic arcuate nucleus of rat: evidence for local opiocortin connections

Brain Res. 1983 Mar 14;263(1):142-6. doi: 10.1016/0006-8993(83)91211-8.


ACTH-like immunoreactive structures were localized in rat hypothalamic arcuate nucleus using the unlabeled antibody, peroxidase-antiperoxidase method. At the ultrastructural level, immunoreactive presynaptic nerve terminals were observed forming symmetrical synaptic contacts with unlabeled dendrites and with ACTH-like immunoreactive perikarya. The results obtained are consistent with the hypothesis that ACTH in the brain acts as a synaptic regulator or transmitter, contributing not only to long projection pathways but also to a local circuit in the arcuate nucleus where ACTH cell bodies are localized.

MeSH terms

  • Adrenocorticotropic Hormone / metabolism*
  • Animals
  • Arcuate Nucleus of Hypothalamus / anatomy & histology*
  • Dendrites / ultrastructure
  • Endorphins / metabolism*
  • Male
  • Melanocyte-Stimulating Hormones / metabolism*
  • Microscopy, Electron
  • Neural Pathways / anatomy & histology
  • Neurons / metabolism
  • Rats
  • Rats, Inbred Strains
  • Synapses / ultrastructure*
  • Synaptic Vesicles / ultrastructure
  • beta-Endorphin
  • beta-Lipotropin / metabolism*


  • Endorphins
  • beta-Endorphin
  • Adrenocorticotropic Hormone
  • Melanocyte-Stimulating Hormones
  • beta-Lipotropin