The 5-HT(1A) receptor knockout mouse and anxiety

Behav Pharmacol. 2001 Nov;12(6-7):439-50. doi: 10.1097/00008877-200111000-00004.

Abstract

The 5-HT(1A) receptor has been implicated in the modulation of anxiety processes, mainly via pharmacological experiments. The recent production, in three independent research groups, of 5-HT(1A) receptor knockout (R KO) mice in three different genetic backgrounds (C57BL/6J, 129/Sv, Swiss-Webster) led to the intriguing finding that all mice, independent from the genetic background strain from which the null mutants were made, showed an "anxious" phenotype compared to corresponding wild-type mice. The present paper reviews the behavioral findings in these three KO lines and focuses on new findings in the 129/Sv-KO mice. These mice were more anxious or stress-prone only under specific conditions (high stress) and not as broadly as suggested from the initial studies. The 5-HT(1A) R KO made in the Swiss-Webster background displays disturbances in the GABA(A)-benzodiazepine (BZ) receptor system in the brain, including downregulation of GABA(A) alpha1 and alpha2 subunits in the amygdala. In contrast, the GABA(A)-BZ receptor system seems to function normally in the 5-HT(1A) R KO in the 129/Sv background suggesting that changes in the GABA(A)-BZ receptor system may not be a prerequisite for anxiety but rather could have a modifying effect on this phenotype. It can be concluded that the constitutive absence of the 5-HT(1A) receptor gene and receptor leads to a more "anxious" mouse, dependent on the stress level but independent from the strain. Depending on the genetic background, this null mutation may be associated with changes in GABA(A)-ergic neurotransmission. It is as yet unclear which mechanisms are involved in this intriguing differentiation.

Publication types

  • Review

MeSH terms

  • Animals
  • Anxiety / genetics*
  • Anxiety / physiopathology
  • Arousal / genetics*
  • Arousal / physiology
  • Genotype
  • Hippocampus / physiopathology
  • Humans
  • Mice
  • Mice, Knockout
  • Nerve Net / physiopathology
  • Receptors, Serotonin / genetics*
  • Receptors, Serotonin, 5-HT1
  • Social Environment

Substances

  • Receptors, Serotonin
  • Receptors, Serotonin, 5-HT1