Stress-induced peptide release from rat intermediate pituitary - An ultrastructural analysis

James A. Carr, Linda C. Saland, Ann Samora, Sima Desai, Salvador Benevidez

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11 Scopus citations


We tested the hypothesis that acute restraint stress results in ultrastructural evidence for enhanced release of alpha-melanocyte-stimulating hormone (α-MSH) and β-endorphin from the intermediate lobe (IL) of the rat pituitary. Measurements of plasma α-MSH-and β-endorphin-immunoreactivity (ir) were used to confirm ultrastructural findings. Plasma α-MSH-ir was elevated after 20 and 30 min of restraint while plasma β-endorphin-ir peaked 10 min after the onset of restraint. Ultrastructural analysis revealed a decrease in the content of secretory granules within IL cells of stressed rats. Analysis of Golgi-related immature secretory granules in IL cells indicated that new peptide synthesis was not enhanced after 30 min of restraint. These results confirm previous studies showing and elevation of plasma β-endorphin and α-MSH-ir during acute restraint. Furthermore, these results indicate that quantitative analysis at the ultrastructural level can be used to assess peptide release from IL secretory cells during stress.

Original languageEnglish
Pages (from-to)589-593
Number of pages5
JournalCell and Tissue Research
Issue number3
StatePublished - Sep 1990


  • Pituitary gland
  • Rat (Sprague-Dawley)
  • Secretory granules
  • Stress
  • pars intermedia
  • α-MSH
  • β-Endorphin


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