Repeated cannabinoid administration increases indices of noradrenergic activity in rats

Pharmacol Biochem Behav. 2007 Jan;86(1):162-8. doi: 10.1016/j.pbb.2006.12.020. Epub 2007 Jan 9.


The present study examined the impact of repeated administration of a synthetic cannabinoid agonist, WIN 55,212-2 on the coeruleo-cortical pathway, a circuit implicated in anxiety. Male Sprague-Dawley rats received repeated systemic injections of WIN 55,212-2 (3.0 mg/kg). A separate group of rats received repeated WIN 55,212-2 injections followed by a period of abstinence. Control animals received vehicle injections. Ninety minutes following the last injection on day 8, anxiety-related behavior was assessed using the elevated plus maze. The abstinent group was tested after another 8 days. Following behavioral testing, brain tissue was extracted from the locus coeruleus (LC) and probed for tyrosine hydroxylase (TH) expression. In a separate group of animals, in vivo microdialysis was used to monitor extracellular norepinephrine efflux in the frontal cortex following repeated WIN 55,212-2 administration and following a period of abstinence. Repeated administration of WIN 55,212-2 evoked an anxiogenic-like response that was accompanied by an increase in TH protein expression in the LC. A similar neurochemical profile was observed using in vivo microdialysis where an augmented increase in cortical norepinephrine efflux was identified in response to a systemic injection of WIN 55,212-2 on day 8. Anxiety-like behavior, catecholamine synthesizing enzyme levels and NE efflux returned to control values after 8 days of abstinence. The present findings indicate that repeated administration of a synthetic cannabinoid receptor agonist induces transient anxiety-like behaviors that correlate with increases in catecholamine synthesizing enzyme expression in the LC and augmented norepinephrine efflux in response to a challenge injection of WIN 55,212-2.

MeSH terms

  • Animals
  • Anxiety / chemically induced
  • Anxiety / psychology
  • Behavior, Animal / drug effects
  • Benzoxazines / pharmacology
  • Blotting, Western
  • Cannabinoids / administration & dosage
  • Cannabinoids / pharmacology*
  • Chromatography, High Pressure Liquid
  • Extracellular Space / drug effects
  • Extracellular Space / metabolism
  • Male
  • Microdialysis
  • Morpholines / pharmacology
  • Naphthalenes / pharmacology
  • Norepinephrine / metabolism
  • Norepinephrine / physiology*
  • Prefrontal Cortex / drug effects
  • Prefrontal Cortex / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Cannabinoid, CB1 / agonists
  • Stimulation, Chemical
  • Tyrosine 3-Monooxygenase / metabolism


  • Benzoxazines
  • Cannabinoids
  • Morpholines
  • Naphthalenes
  • Receptor, Cannabinoid, CB1
  • (3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone
  • Tyrosine 3-Monooxygenase
  • Norepinephrine