Sexual Dimorphism in Balance and Coordination in p75NTR(exonIII) Knock-Out Mice.

The p75 neurotrophin receptor (p75NTR) is implicated in various biological functions during development and adulthood. Several animal models have been developed to identify the roles of p75NTR in vivo and in vitro. P75NTR(ExonIII) knock-out mice are widely used to study the neurotrophin receptor and its signaling pathways. Similar to other models of p75NTR knock-out (p75NTR(Exon IV) KO) or conditional knock-out (p75NTR(fl/fl)) mice, p75NTR(ExonIII) knock-out mice present severe abnormalities in walking, gait, balance and strength. The present study identifies a sexual dimorphism in the p75NTR(ExonIII) knock-out strain regarding balance and coordination. Using Kondziela's inverted grid test, we observed that p75NTR(ExonIII) knock-out males performed poorly at the task, whereas p75NTR(ExonIII) knock-out females did not exhibit any defects. We also observed that female p75NTR(ExonIII) knock-out mice performed significantly better than male p75NTR(ExonIII) knock-out mice at the beam balance test. There were no differences in strength, skin innervation, or the number of ulcers on the toes between p75NTR(ExonIII) knock-out males and females. The literature regarding the role of p75NTR in behavior is controversial; our results suggest that studies investigating the role of p75NTR in vivo using p75NTR knock-out mice should systematically report data from males and females.