Ontogenetic development of the pro-enkephalin B (= pro-dynorphin) opioid peptide system in the rat pituitary.
The postnatal development of several pro-enkephalin-B-derived opioid peptides - dynorphin 1-17, dynorphin 1-8, dynorphin B, alpha-neo-endorphin and beta-neo-endorphin - was examined in rat pituitary lobes. The concentrations of pro-enkephalin-B-derived peptides from the anterior pituitary were between 4- and 12-fold and those from the neurointermediate pituitary between 17- and 122-fold lower in newborn as compared to adult rats. Similarly, the concentrations of vasopressin in the neurointermediate pituitary increased 50-fold between birth and adulthood; those of oxytocin, however, increased more than 540-fold over this period. The molecular weight pattern of dynorphin 1-17, dynorphin 1-8, dynorphin B, alpha- and beta-neo-endorphin-immunoreactive peptides in the anterior and neurointermediate pituitary did not differ between 3-day-old pups and adult rats. In the neurointermediate pituitary, the major immunoreactive components had the same chromatographic properties as synthetic dynorphin 1-17, dynorphin 1-8, dynorphin B, alpha- and beta-neo-endorphin, respectively, on gel filtration and high-performance liquid chromatography (HPLC). This indicates that neonatal rats were already capable of processing the precursor pro-enkephalin B into these various opioid peptides. In newborn rats, however, the amount of dynorphin 1-8 in the neurointermediate pituitary was three times lower than that of its putative intermediate precursor peptide dynorphin 1-17. Similarly, the amount of beta-neo-endorphin was almost four times lower than that of its putative precursor alpha-neo-endorphin. In contrast, in the neurointermediate pituitary of adult rats, dynorphin 1-17 and dynorphin 1-8, in addition to a alpha- and beta-neo-endorphin, occurred in equimolar amounts.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation; D002851:Chromatography, High Pressure Liquid; D004399:Dynorphins / Q000031:analogs & derivatives / Q000378:metabolism; D004723:Endorphins / Q000378:metabolism; D004743:Enkephalin, Leucine / Q000378:metabolism; D004745:Enkephalins / Q000378:metabolism*; D005260:Female; D008297:Male; D008970:Molecular Weight; D010121:Oxytocin / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000166:cytology*; D010904:Pituitary Gland, Posterior / Q000166:cytology*; D011247:Pregnancy; D011498:Protein Precursors / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014667:Vasopressins / Q000378:metabolism
D004723:Endorphins; D004745:Enkephalins; D010446:Peptide Fragments; D010455:Peptides; D011498:Protein Precursors; D014667:Vasopressins; D010121:Oxytocin; D004743:Enkephalin, Leucine; C025681:alpha-neoendorphin; D004399:Dynorphins; C026770:dynorphin (1-8); C036200:rimorphin; C033660:preproenkephalin