Gender differences in learned helplessness behavior are influenced by genetic background

Learned helplessness behavior was examined in female and male C57BL/6J (B6) , 129/J (129) and (B6 x 129)F1 mice, common genetic backgrounds for the gen eration of knockout models, as well as in mice of a mixed genetic backgroun d (outbred mice). Both genotype and gender differences were observed in lea rned helplessness. Outbred males showed increased shuttle escape latencies following 60, 120, or 360 inescapable shocks compared to nonshocked control s, but outbred females showed no increase in escape latencies following ine scapable shock pretreatment. B6 females showed increased escape latencies f ollowing 60, 120, or 360 inescapable shocks, whereas B6 males showed increa sed latencies only after 360 shocks. Female and male 129 and B6129F1 mice d id not show an increase in escape latencies following inescapable shock, bu t this was most likely due to poor escape performance in nonshocked control mice. Differences in escape performance could not be explained by differen ces in pain thresholds between genotypes. These results support the idea th at genetic background and gender are important to consider when using the l earned helplessness model in genetically manipulated mice. (C) 2000 Elsevie r Science.