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Assessing Cellular Stress and Inflammation in Discrete Oxytocin-secreting Brain Nuclei in the Neonatal Rat Before and After First Colostrum Feeding
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Effects of neonatal stress and morphine on kappa opioid receptor signaling

Thuy N Vien1, Christine A Gleason, Sarah L Hays

  • 1Department of Pediatrics, University of Washington, Seattle, WA 98195-6320, USA. sjuul@u.washington.edu

Neonatology
|May 30, 2009
PubMed

Insights

Neonatal stress activates the kappa opioid receptor (KOR) system in mice, particularly when combined with morphine. This stress response involves the dynorphin system and can lead to inflammation in the brain.

Area of Science:

  • Neuroscience
  • Neonatal Research
  • Pharmacology

Background:

  • Critically ill neonates face significant stressors, often managed with opioids.
  • Long-term effects of neonatal stress and opioid exposure remain unclear.
  • The role of the kappa opioid system in neonatal stress is largely unknown.

Purpose of the Study:

  • To map kappa opioid receptor (KOR) distribution in the neonatal mouse brain.
  • To investigate how neonatal morphine, stress, or combined exposure alters KOR signaling.

Main Methods:

  • Utilized wild-type and prodynorphin (Pdyn) knockout mouse models.
  • Administered saline, morphine, or stress (with saline/morphine) from postnatal days 5-9.
  • Examined brain tissue using KOR-P, GFAP, and GAD immunolabeling.

Main Results:

  • Neonatal stress increased KOR-P in wild-type mice but not Pdyn(-/-) mice.
  • Combined stress and morphine significantly elevated KOR-P (38-500%) and caused gliosis.
  • Pdyn(-/-) mice showed increased gliosis even without KOR-P signaling.

Conclusions:

  • Neonatal stress activates KOR through the dynorphin system.
  • Co-exposure to stress and morphine exacerbates KOR activation and induces hippocampal gliosis.
  • Endogenous dynorphin may mitigate stress-induced inflammatory responses.
Abstract

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