Opposite modulation of opiate withdrawal behaviors on microinfusion of a protein kinase A inhibitor versus activator into the locus coeruleus or periaqueductal gray

Laurie J. Punch, David W. Self, Eric J. Nestler, Jane R. Taylor

Research output: Contribution to journalArticle

112 Scopus citations

Abstract

Chronic opiate administration upregulates the cAMP pathway in the locus coeruleus (LC). This adaptation is thought to increase the electrical excitability of LC neurons and contribute to the dramatic increase in LC firing induced by opioid receptor antagonists in opiate-dependent animals. The goal of the present study was to evaluate directly a role of the cAMP pathway in opiate withdrawal behaviors by studying, in vivo, whether withdrawal is influenced by intra-LC infusion of compounds known to activate or inhibit protein kinase A (PKA). Infusions into amygdala or periaqueductal gray (PAG) were studied for comparison. In one series of experiments the effect of intra-LC, intra-amygdala, or intra-PAG infusions of the PKA inhibitor Rp-cAMPS on naloxone-precipitated withdrawal from morphine was examined. Intra-LC infusions of Rp-cAMPS significantly attenuated several prominent behavioral signs of morphine withdrawal. Intra-PAG infusions of Rp- cAMPS also significantly attenuated opiate withdrawal behaviors, although different behaviors were affected. In contrast, intra-amygdala infusions of Rp-cAMPS were without significant effect. In a second series of experiments the effect of intra-LC or intra-PAG infusions of the PKA activator Sp-cAMPS on behavior in nondependent drug-naive animals was determined. Sp-cAMPS infusions into either brain region induced a quasi-withdrawal syndrome, but the observed behaviors differed between the two groups. Analysis of the phosphorylation state of tyrosine hydroxylase, a well characterized substrate for PKA, confirmed the ability of Rp-cAMPS and Sp-cAMPS to inhibit and activate, respectively, PKA activity in vivo. Together, these data provide direct evidence for involvement of the cAMP-PKA system in the LC, as well as in the PAG, in opiate withdrawal and withdrawal-related behaviors.

Original languageEnglish
Pages (from-to)8520-8527
Number of pages8
JournalJournal of Neuroscience
Volume17
Issue number21
StatePublished - Nov 6 1997
Externally publishedYes

Keywords

  • Amygdala
  • Morphine
  • Opiate dependence
  • Periaqueductal gray
  • Protein phosphorylation
  • cAMP

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