Differential regulation of behavioral tolerance to WIN55,212-2 by GASP1

Lene Martini, Dawn Thompson, Viktor Kharazia, Jennifer L Whistler

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


Cannabinoid agonists have shown some promise clinically as analgesics, in particular for cancer pain, in which they have the additional benefit of decreasing nausea. However, as for most other drugs, the long-term use of cannabinoids is limited by the development of tolerance. Several molecular mechanisms have been proposed to explain drug tolerance, including receptor downregulation. The cannabinoid 1 (CB1) receptors can be downregulated in vitro through an interaction with the G-protein-coupled receptor-associated sorting protein1, GASP1, that targets CB1 receptors for degradation after their agonist-mediated endocytosis. To investigate whether GASP1-mediated postendocytic sorting of the CB1 receptor contributes to tolerance to cannabinoid drugs in vivo, we generated a mouse with a disruption of GASP1. In wild-type mice, repeated administration of the cannabinoid agonist WIN55,212-2 promoted downregulation of CB1 receptor levels and concomitant tolerance to the effects of drug on antinociception, motor incoordination, and locomotor hypoactivity. In contrast, GASP1 knockout mice did not develop tolerance to any of these effects and showed no significant receptor downregulation. Taken together, this study provides evidence that GASP1 regulates CB1 receptor downregulation in vivo, and that postendocytic receptor trafficking has a key role in the development of tolerance to WIN55,212-2.

Original languageEnglish
Pages (from-to)1363-73
Number of pages11
Issue number6
Publication statusPublished - May 2010


  • Analgesics
  • Animals
  • Benzoxazines
  • Cannabinoids
  • Carrier Proteins
  • Down-Regulation
  • Drug Tolerance
  • Endocytosis
  • Male
  • Mice
  • Mice, Knockout
  • Morpholines
  • Motor Activity
  • Naphthalenes
  • Pain
  • Protein Transport
  • Receptor, Cannabinoid, CB1


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