NTRK1 and type 1 diabetes mellitus: While previous investigations in STZ-induced type 1 diabetic rodent models exhibit reduced IENFD (Christianson et al., 2003a; Kennedy and Zochodne, 2005; Ozaki et al., 2018), high fat fed mice show no change in IENFD (Obrosova et al., 2007; Guilford et al., 2011; Xu et al., 2014) or increased TrkA nerve fiber density (Groover et al., 2013; Zhang et al., 2018).