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Opioid antagonist modulation of DNA synthesis in mouse tongue epithelium is circadian dependent

I S Zagon1, Y Wu, P J McLaughlin

  • 1Department of Neuroscience and Anatomy, Pennsylvania State University, College of Medicine, Hershey 17033.

Pharmacology, Biochemistry, and Behavior
|July 1, 1994
PubMed

Insights

Endogenous opioids act as growth factors. Blocking opioid receptors with naltrexone (NTX) stimulated epithelial cell renewal in mouse tongues, indicating a role in circadian-dependent cellular renewal.

Area of Science:

  • Cell Biology
  • Endocrinology
  • Physiology

Background:

  • Endogenous opioids are known for neuromodulation.
  • Emerging evidence suggests opioid peptides may also function as growth factors.
  • Their role in epithelial renewal remains largely unexplored.

Purpose of the Study:

  • To investigate the involvement of opioid peptides in epithelial renewal.
  • To determine if disrupting opioid-receptor interactions affects cell proliferation.

Main Methods:

  • Systemic injections of naltrexone (NTX), an opioid antagonist, were administered to mice.
  • The number of basal epithelial cells undergoing DNA synthesis was quantified.
  • Experiments were conducted at different times of day (0700 h and 1700 h).

Main Results:

  • Naltrexone administration significantly increased DNA synthesis in tongue epithelial cells (43-150% above control).
  • This stimulatory effect was observed on the tip, dorsal, and ventral tongue surfaces.
  • The effect was transient, lasting up to 8 hours post-injection, and showed circadian rhythm dependency (present at 1700 h, absent at 0700 h).

Conclusions:

  • This study provides the first evidence that endogenous opioids regulate cellular renewal processes.
  • Opioid peptide involvement in epithelial renewal is dependent on the circadian rhythm.
  • Targeting opioid pathways may offer novel strategies for promoting tissue regeneration.

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