NGF and Alzheimer disease: For example, the prevention of C-fiber sprouting using intrathecal nerve growth factor (NGF) neutralizing antibody or trkA-IgG fusion protein in T4 spinal transected rats decreases CGRP-fiber density in association with reduced AD symptoms in experimental rats undergoing experimental colorectal distension (CRD; Christensen and Hulsebosch, 1997; Krenz et al., 1999; Marsh et al., 2002; Weaver et al., 2006).