Differential expression of cell adhesion molecules on trigeminal cutaneous and muscle afferents

Previous work from our laboratory (Woodbury and Scott, 1995) suggested that embryonic cutaneous and muscle afferents might express different surface cell adhesion molecules (CAMs) on their growth cones. To examine this possibility directly we measured the relative levels of expression of various adhesion molecules on growth cones of neurons from the dorsomedial portion of the trigeminal ganglion (DM-TG), which are largely cutaneous, and from the trigeminal mesencephalic nucleus (TMN), which are exclusively muscle afferents. Axonin-1,L1, BEN, and N-cadherin were expressed more abundantly on DM-TG growth cones, whereas N-CAM was more abundant on TMN neurons. Expression of polysialated N-CAM was similar on the two populations, addition of NGF and NT-3 appeared to increase expression of polysialated N-CAM on TMN neurons. Although the levels of L1 and axonin-1, both of which bind L1, were markedly different on TMN and DM-TG neurons, these differences were not sufficient to cause dramatic differences in the growth rates of TMN and DM-TG neurons on L1.