This mouse model expresses a severe anxiety phenotype in the elevated plus maze and open field tests which is highly consistent with the generally observed anxiolytic effects of 5-HT1A receptors. 5HT1A receptor knockout mouse are also characterized by increased avoidance of novel objects and reduced exploratory activity.

Heisler et al, 1998: Anxious like behavior of 5-HT1A knockout mice. +/+= WT mice, +/- = heterozygous 5-HT1A receptor knockout mice, -/-= homozygous 5-HT1A knockout mice. Open field test: (A) time; (B) distance and (C) number of entrances into the center of an open field arena during 30 min test. Here again, a clear inverse relationship is demonstrated between level of 5-HT1A gene expression and levels of anxiety as demonstrated in the three parameters measured.

References:

Gordon JA, Hen R (2004) Genetic approaches to the study of anxiety. Annu Rev Neurosci 27:193-222

Heisler LK, Chu HM, Brennan TJ, Danao JA, Bajwa P, Parsons LH, Tecott LH (1998) Elevated anxiety and antidepressant-like responses in serotonin 5-ht1a receptor mutant mice. Proc Natl Acad Sci U S A 95(25):15049-15054