Homeostasis of ocular surface epithelium in the rat is regulated by opioid growth factor

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Abstract

Endogenous opioid peptides serve as growth factors in developing, renewing, and neoplastic cells and tissues. This study examined the hypothesis that opioids serve to modulate the homeostatic renewal of ocular surface epithelium in the rat. DNA synthesis in the epithelium of the central (CC) and peripheral (PC) cornea, limbus (LM), and conjunctiva (CN) was investigated using adult male rats. Animals received an injection of opioid growth factor (OGF), [Met3]-enkephalin, OGF and naloxone (NAL), NAL alone, naltrexone (NTX), or an equivalent volume of sterile water (CO) and sacrificed 4 h later (i.e. 16:00 h). [3H]thymidine was administered 1 h before sacrifice. With the exception of NTX (20 mg/kg), all compounds were given at 10 mg/kg. Examination of 5 time points over an 18-h period revealed no variation in DNA synthesis within a region of ocular surface basal epithelium (BE). OGF depressed DNA synthesis of the BE by 25, 48, and 50% in the PC, LM, and CN, respectively; little labeling was recorded in the BE of the CC. Exposure to OGF-NAL or NAL alone did not alter DNA synthesis of the BE. Complete blockade of OGF-ζ receptor interaction by administration of the potent opioid antagonist. NTX, increased the number of epithelial cells in the PC, LM, and CN undergoing DNA synthesis by 30 to 72%. The effects of OGF and NTX on DNA synthesis of BE also were observed in an organ culture setting. Utilizing immunocytochemistry, OGF and its receptor ζ were associated with both the basal and the suprabasal cells of the ocular surface epithelium. These results indicate that an endogenous opioid peptide, OGF, and its receptor are present and govern homeostatic cellular renewal processes in ocular surface epithelium. OGF regulates DNA synthesis in a direct manner, and does so by a tonic, inhibitory, and receptor-mediated mechanism.

Original languageEnglish (US)
Pages (from-to)92-102
Number of pages11
JournalBrain research
Volume759
Issue number1
DOIs
StatePublished - Jun 6 1997

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Opioid Analgesics
Intercellular Signaling Peptides and Proteins
Homeostasis
Epithelium
Naltrexone
Naloxone
DNA
Conjunctiva
Opioid Peptides
Limbus Corneae
Narcotic Antagonists
Enkephalins
Organ Culture Techniques
Carbon Monoxide
Thymidine
Epithelial Cells
Immunohistochemistry
Injections
Water
methionine-enkephalin receptor

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

Cite this

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title = "Homeostasis of ocular surface epithelium in the rat is regulated by opioid growth factor",
abstract = "Endogenous opioid peptides serve as growth factors in developing, renewing, and neoplastic cells and tissues. This study examined the hypothesis that opioids serve to modulate the homeostatic renewal of ocular surface epithelium in the rat. DNA synthesis in the epithelium of the central (CC) and peripheral (PC) cornea, limbus (LM), and conjunctiva (CN) was investigated using adult male rats. Animals received an injection of opioid growth factor (OGF), [Met3]-enkephalin, OGF and naloxone (NAL), NAL alone, naltrexone (NTX), or an equivalent volume of sterile water (CO) and sacrificed 4 h later (i.e. 16:00 h). [3H]thymidine was administered 1 h before sacrifice. With the exception of NTX (20 mg/kg), all compounds were given at 10 mg/kg. Examination of 5 time points over an 18-h period revealed no variation in DNA synthesis within a region of ocular surface basal epithelium (BE). OGF depressed DNA synthesis of the BE by 25, 48, and 50{\%} in the PC, LM, and CN, respectively; little labeling was recorded in the BE of the CC. Exposure to OGF-NAL or NAL alone did not alter DNA synthesis of the BE. Complete blockade of OGF-ζ receptor interaction by administration of the potent opioid antagonist. NTX, increased the number of epithelial cells in the PC, LM, and CN undergoing DNA synthesis by 30 to 72{\%}. The effects of OGF and NTX on DNA synthesis of BE also were observed in an organ culture setting. Utilizing immunocytochemistry, OGF and its receptor ζ were associated with both the basal and the suprabasal cells of the ocular surface epithelium. These results indicate that an endogenous opioid peptide, OGF, and its receptor are present and govern homeostatic cellular renewal processes in ocular surface epithelium. OGF regulates DNA synthesis in a direct manner, and does so by a tonic, inhibitory, and receptor-mediated mechanism.",
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Homeostasis of ocular surface epithelium in the rat is regulated by opioid growth factor. / Zagon, Ian; Sassani, Joseph; Kane, Edward R.; McLaughlin, Patricia.

In: Brain research, Vol. 759, No. 1, 06.06.1997, p. 92-102.

Research output: Contribution to journalArticle

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