Strain differences and the role of AT(1) receptor expression in anxiety.

This study investigated strain specific differences to the anxiolytic response to losartan focusing on genetic variation that may influence such responses. This included: AT(1) receptor sequence variation, angiotensin II receptor associated protein (ATRAP) and receptor expression between strains. Sequencing of exon 3 of AT(1a)R revealed no differences between BKW mice (n=6) and C57 and DBA(2) strains (n=3). Comparisons of AT(1) expression do show significant differences, whereby BKW mice showed the highest levels of expression and DBA(2) mice intermediate levels when compared to the C57 strain. Sequencing of sections of the Angiotensin receptor associated protein (ATRAP) identified a non-synonymous point mutation- (T/C) transversion (position 109-161) (SNP id = rs13467517) resulting in a Valine → Alanine (V157A) amino acid change in the BKW and DBA(2) strains. Our results indicate that the previously reported strain dependent effects are not due to variation in AT(1a) receptor sequence. Differences in AT(1)gene expression levels between strains, which mirror their anxiety phenotype, are observed. This is coupled with a non-synonymous single nucleotide polymorphism in ATRAP, a negative regulator of AT(1) signalling.