Antidepressant-like action of intracerebral 6-fluoronorepinephrine, a selective full α-adrenoceptor agonist

Int J Neuropsychopharmacol. 2011 Apr;14(3):319-31. doi: 10.1017/S1461145710000507. Epub 2010 May 12.

Abstract

The present study examined the ability of 6-fluoronorepinephrine (6FNE), a full selective α-adrenoceptor agonist, to produce antidepressant-like effects in mice. The drug, administered in the 4th ventricle, produced marked anti-immobility effects at mid-dose range in the acute forced swim, tail suspension and repeated open-space forced swim tests with minimal effect on open-field motor activity and also reversed anhedonia following lipopolysaccharide administration. Its antidepressant effects were equal to or greater than that of an established systemic antidepressant, desmethylimipramine, given subacutely. Experiments with α-adrenoceptor antagonists indicated that the drug acts primarily via the α2-receptor in contrast to endogenous catecholamines which appear to control depressive behaviour primarily via the α1-receptor. Antidepressant activity declined at higher doses signifying a possible pro-depressant effect of one of the α-adrenoceptor subtypes. Compared to the selective α2-agonist, dexmedetomidine, 6FNE showed equivalent antidepressant action in the tail suspension test but appeared to have a greater efficacy or speed of action in the repeated open-space forced swim test which produces a more sustained depression. Studies of regional brain Fos expression induced during the antidepressant tests showed that 6FNE tended to inhibit neural activity in two stress-responsive regions (locus coeruleus and paraventricular hypothalamus) but to enhance activity in two areas involved in motivated behaviour (nucleus accumbens shell and lateral septal nucleus) producing a neural pattern consistent with antidepressant action. It is concluded that 6FNE elicits a rapid and effective antidepressant and anti-stress response that may compare favourably with available antidepressants.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adrenergic alpha-2 Receptor Agonists / administration & dosage
  • Adrenergic alpha-2 Receptor Agonists / pharmacology*
  • Animals
  • Antidepressive Agents / administration & dosage
  • Antidepressive Agents / pharmacology*
  • Behavior, Animal / drug effects
  • Brain / drug effects
  • Depression / drug therapy*
  • Desipramine / pharmacology*
  • Hindlimb Suspension
  • Injections, Intraventricular
  • Male
  • Mice
  • Motor Activity / drug effects
  • Norepinephrine / administration & dosage
  • Norepinephrine / analogs & derivatives*
  • Norepinephrine / pharmacology
  • Pleasure / drug effects
  • Random Allocation
  • Swimming

Substances

  • Adrenergic alpha-2 Receptor Agonists
  • Antidepressive Agents
  • 6-fluoronorepinephrine
  • Desipramine
  • Norepinephrine