Selective breeding for catalepsy changes the distribution of microsatellite D13Mit76 alleles linked to the 5-HT1A serotonin receptor gene in mice

Catalepsy (pronounced motor inhibition) is a natural defensive reaction against predator. Recently, the quantitative trait locus for catalepsy was mapped on mouse chromosome 13 near the 5-HT1A serotonin receptor gene. Here, the linkage between catalepsy and the 5-HT1A receptor gene was verified using breeding experiment. Selective breeding for high predisposition to catalepsy was started from backcross BC[CBA x (CBA x AKR)] generation between catalepsy-prone (CBA) and catalepsy-resistant (AKR) mouse strains. CBA and AKR strains also differed in the 5-HT1A receptor functional activity. A rapid increase of cataleptic percentage from 21.2% in the backcrosses to 71% in the third generation of selective breeding (S-3) was shown. The fragment of chromosome 13 including the 5-HT1A receptor gene was marked with D13Mit76 microsatellite. Breeding for catalepsy increased the concentration of CBA-derived and decreased the concentration of AKR-derived alleles of microsatellite D13Mit76 in the S-1 and S-2. All mice of the S-9 and S-12 were homozygous for CBA-derived allele of D13Mit76 marker. Mice of the S-12 showed CBA-like receptor activity. These findings indicate that selective breeding for behavior can involve selection of polymorphic variants of the 5-HT1A receptor gene.