Loss of BDNF or its receptors in three mouse models has unpredictable consequences for anxiety and fear acquisition

Fear memory is increased in BDNF and p75^NTR deficient mice but impaired in TrkB heterozygotes. (A–C) All genotypes display normal acquisition of short-term fear memory (1-h test) (n = 5–13 of each genotype). (D) TrkB^+/− mice are severely impaired in long-term fear memory (24-h test) (+/−, n = 6; +/+, n = 10) (P = 0.008). (E,F) Twenty-four hours post shock, Bdnf^+/− and Ngfr^−/− mice have increased fear memory compared to wild-type controls: (E) +/−, n = 7 and +/+, n = 9 (P = 0.05); (F) p75^NTR KO, n = 6 and wild-type, n = 13 (P = 0.02).