WGA-HRP and choleragenoid-HRP as anterogradely transported tracers in vagal visceral afferents and binding of WGA and choleragenoid to nodose ganglion neurons in rodents

Abstract

The axonal and terminal labelling pattern in the brain stem resulting from the injection of horseradish peroxidase (HRP) conjugate of wheat germ agglutinin (WGA) or choleragenoid into the nodose ganglion of guinea pigs was examined. In addition, the binding profiles of WGA and choleragenoid in the nodose ganglion of guinea pig and rat were examined. The results show that WGA-HRP and choleragenoid-HRP (B-HRP) produce almost identical distribution of axonal and terminal labelling, the difference being some contralateral fibre labelling present only with B-HRP. However, WGA-HRP shows the strongest labelling at short survival times, whereas B-HRP requires longer postoperative survival times to reach maximum labelling intensity. All nodose ganglion neurons appear to bind WGA as well as choleragenoid although to a varying degree. The results of this and previous studies support the view that visceral sensory ganglion cells and the large light subpopulation fo somatic dorsal root ganglion cells both bind choleragenoid, whereas the small dark somatic cells show affinity for WGA but rarely for choleragenoid.