In situ hybridization reveals specific increases in Gαs and Gαo mRNA in discrete brain regions of morphine-tolerant rats

Daniela Parolaro, Tiziana Rubino, Enzo Gori, Paola Massi, Caterina Bendotti, Gabriela Patrini, Cristiana Marcozzi, Marco Parenti

Research output: Contribution to journalArticlepeer-review


In situ hybridization histochemistry has been used to detect the basal distribution of mRNA encoding the α subunit of Gs, Go and Gi2 proteins throughout the rat brain. Based on these data we investigated the effect of chronic morphine on the content of these G protein α subunits mRNA. We observed an increase in the expression of αs and αo messages of chronically morphine-treated animals, while no changes were seen in αi2 mRNA. Specifically a 30% increase in expression for αs was seen only in the paraventricular nucleus of hypothalamus and a 20% elevation for αo was detected in the claustrum and endopiriform nucleus. Immunoblotting analysis was used to correlate the changes in αs and αo messages with equivalent changes in protein levels. Chronic morphine significantly increased αs amounts in the hypothalamus (70%), and produced a minor elevation (30%) in Gαo levels in the olfactory area. Our results indicate that in discrete brain regions altered G protein expression is part of the adaptive changes underlying opiate tolerance.

Original languageEnglish
Pages (from-to)211-222
Number of pages12
JournalEuropean Journal of Pharmacology: Molecular Pharmacology
Issue number3
Publication statusPublished - Feb 15 1993


  • Brain regions
  • G protein expression
  • Immunoblot analysis
  • In situ hybridization histochemistry
  • Morphine tolerance

ASJC Scopus subject areas

  • Pharmacology

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