Pain originating from the hip may be referred to the groin and anterior thigh. We investigated sensory dorsal root ganglion
neurons innervating the hip and the inguinal skin in rats using retrograde neurotransport and immunohistochemistry. A retrograde
neurotracer Fluoro-Gold™ was injected into the left hip or inguinal skin of rats. Seven days later, we harvested bilateral
dorsal root ganglions and counted the number of Fluoro-Gold™-labeled neurons positive for calcitonin gene-related peptide,
a marker of nerve growth factor-dependent neurons, or isolectin B4, a marker of glial cell line-derived neurotrophic factor-dependent
neurons. In the hip group, Fluoro-Gold™-labeled neurons were distributed throughout the left dorsal root ganglions from T13
to L5, primarily at L1, L2, L3, and L4, and the percentage of calcitonin gene-related peptide-positive neurons was higher
than that of isolectin B4-binding neurons. In the inguinal skin group, Fluoro-Gold™-labeled neurons were distributed throughout
the left dorsal root ganglions from T13 to L3, primarily at L1, L2, and L3, and the percentage of isolectin B4-binding neurons
was higher than that of calcitonin gene-related peptide-positive neurons. These data suggest the sensory innervation pattern
and characteristics of the sensory nerve of the rat hip are different from those of inguinal skin.
Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest,
patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
Each author certifies that his or her institution has approved the animal protocol for this investigation and that all investigations
were conducted in conformity with ethical principles of research.