Generation of double KOs.
We crossed Bax KO females on a C57BL/6 background (Jackson Laboratory, Bar Harbor, Maine, United States) to NT-3 heterozygote males on a 129 Sv background to generate double heterozygote animals. Progeny was genotyped with PCR, and animals heterozygous for both genes were bred to obtain the double KOs. Primers used for the Bax locus were R661, GTT GAC CAG AGT GGC GTA GG; R662, CCG CTT CCA TTG CTC AGC GG; and R663, GAG CTG ATC AGA ACC ATC ATG. Primers used for the NT-3 locus were NT3A, CGT GGT GAG GTT CTA TTG GCT AC; NT3B, CAG AGC ACC CTG CCC AAA GCA GAG; NT3R, CCT TGA CAA TAC TGA ATG CC; and NEOF, GGG AAC TTC CTG ACT AGG. WT, Bax KO, and NT-3 KO littermates were used as controls. A total of 11 Bax/NT-3 double KO mice were analyzed, of these nine were P0 pups. The p75 colony on a 129 S1 background was received from Jackson Laboratory. We used tail DNA to genotype animals using the primers IMR0013, CTT GGG TGG AGA GGC TAT TC; IMR0014, AGG TGA GAT GAC AGG AGA TC (generic neo primers); IMR0710, TGT TAC GTT CTC TGA CGT GGT GAG; and IMR0711, TCA GCC CAG GGT GTG CAC TC (p75 locus). For embryonic experiments, day of plug positivity was considered E0. All of the protocols used in this study were approved by the Louisiana State University Health Sciences Center Institutional Animal Care and Use Committee and conformed to the National Institutes of Health guidelines for use of experimental animals.