Opioid growth factor and organ development in rat and human embryos.
In addition to neurotransmission, the native opioid peptide, [Met5]enkephalin, is a tonically active inhibitory growth molecule that is termed opioid growth factor (OGF). OGF interacts with the zeta (zeta) opioid receptor to influence cell proliferation and tissue organization. We now identify OGF and the zeta receptor in embryonic derivatives including ectoderm, mesoderm, and endoderm of the rat on gestation day 20. Messenger RNA for preproenkephalin (PPE), the precursor of OGF, was detected in the developing cells, suggesting an autocrine production of this peptide. Acute exposure of the pregnant female to OGF resulted in a decrease in DNA synthesis in cells of organs representing all three germ layers, and did so in a receptor-mediated fashion. The influence of OGF was direct, as evidenced in organ culture studies. Blockade of endogenous opioid interaction using naltrexone (NTX) produced an increase in DNA synthesis, indicating the constitutive and functional nature of opioid activity on growth during prenatal life. Human fetal cells contained OGF and the zeta receptor. These data support the hypothesis that endogenous opioid modulation of organ development is a fundamental principle of mammalian embryogenesis, and that OGF has a profound influence on ontogeny. Irregularities in the role of opioids as growth regulators in relationship to the more than 500,000 newborns suffering from birth defects each year in the US needs to be examined.
Zagon
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IS
Department of Neuroscience and Anatomy, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey 17033, USA. isz1@psu.edu
Wu
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Y
McLaughlin
P J
PJ
D000818:Animals; D001921:Brain / Q000196:embryology; D001923:Brain Chemistry / Q000502:physiology; D004247:DNA / Q000096:biosynthesis; D004475:Ectoderm / Q000737:chemistry / Q000502:physiology; D005314:Embryonic and Fetal Development / Q000502:physiology*; D004707:Endoderm / Q000737:chemistry / Q000502:physiology; D004744:Enkephalin, Methionine / Q000032:analysis / Q000494:pharmacology*; D004745:Enkephalins / Q000235:genetics; D005260:Female; D005333:Fetus / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D006321:Heart / Q000196:embryology; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007422:Intestines / Q000737:chemistry / Q000196:embryology; D008297:Male; D008648:Mesoderm / Q000737:chemistry / Q000502:physiology; D009132:Muscles / Q000737:chemistry / Q000196:embryology; D009206:Myocardium / Q000737:chemistry; D009271:Naltrexone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D011247:Pregnancy; D011498:Protein Precursors / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000032:analysis / Q000235:genetics*; D012272:Ribs / Q000737:chemistry / Q000196:embryology; D012867:Skin / Q000737:chemistry / Q000196:embryology; D014059:Tongue / Q000737:chemistry / Q000196:embryology
D004745:Enkephalins; D009292:Narcotic Antagonists; D011498:Protein Precursors; D012333:RNA, Messenger; D011957:Receptors, Opioid; C029992:proenkephalin; C062922:zeta receptor; D004744:Enkephalin, Methionine; D009271:Naltrexone; D004247:DNA