Exposure to perinatal morphine promotes developmental changes in rat striatum

Alfredo Gorio, Maria Luisa Malosio, Letizia Vergani, A. M D Giulio

Research output: Contribution to journalArticlepeer-review


This study shows that perinatal exposure to morphine promotes developmental changes (up to 8 months of life) in the striatum by up-regulating concentrations of substance P and met-enkephalin with changes of prometenkephalin A mRNA expression at the day of birth only. Dopamine metabolism (up to 60 days) is also increased as suggested by the reduced concentrations of dopamine and increased content of 3,4-dihydroxyphenylacetic acid. Tyrosine hydroxylase mRNA expression is selectively reduced only in the substantia nigra by perinatal morphine. Serotonin content is reduced only during the early postnatal days and is unaffected thereafter. Supplementation of naltrexone to morphine-exposed rats prevents monoaminergic and neuropeptidergic changes in the striatum, which directly implicates opioid receptors in the developmental changes caused by morphine. The data suggest that perinatal morphine may inhibit met-enkephalin release, causing accumulation of the peptide without corresponding changes in specific mRNA. Dopamine release may also be increased as indicated by a higher metabolism and consequent reduction of tyrosine hydroxylase mRNA expression in the substantia nigra.

Original languageEnglish
Pages (from-to)471-479
Number of pages9
JournalInternational Journal of Developmental Neuroscience
Issue number4
Publication statusPublished - Jul 1996


  • Dopamine
  • Met-enkephalin
  • Morphine
  • Opioid receptor
  • Serotonin
  • Substance P
  • Tyrosine hydroxylase

ASJC Scopus subject areas

  • Developmental Biology
  • Developmental Neuroscience


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