BIRTH DATES AND SURVIVAL AFTER AXOTOMY OF NEUROCHEMICALLY DEFINED SUBSETS OF TRIGEMINAL GANGLION-CELLS

Trigeminal (V) ganglion cells with different neurochemical phenotypes or different birth dates are affected differently by neonatal axonal t ransection. The aim of the present study was to determine if V ganglio n cell birth date and neurochemical phenotype were correlated and if t hese two variables could be related to responses to neonatal axonal tr ansection. Immunocytochemistry, histochemistry, and [H-3]thymidine lab elling were used to determine the birth dates of V ganglion cells reco gnized by antibodies directed against neurofilament protein (NF), calc itonin gene-related peptide (CGRP), and substance P (SP) and those tha t bound the lectin Bandierea simplicifolia-I (BS-I). All V ganglion ce lls were born between embryonic days (E-) 9.5 and 14.5. All ganglion c ells were born between E-9.5 and E-14.5. In a normalized population (p ercentages normalized to equal 100%), over 90% of NF-positive V gangli on cells were born between E-10.5 and E-12.5. The majority of CGRP-pos itive and SP-positive ganglion cells (> 90%) were generated from E-13. 5 to E-14.5 and E-12.5 through E-14.5, respectively. Almost 85% of BS- I-positive ganglion cells were generated on E-12.5 through E-14.5. Pre vious results and additional data from this study indicated that NF- a nd BS-I-positive ganglion cells are proportionally more likely to be l ost after neonatal axotomy and that SP-positive cells are more likely to remain. The percentage of CGRP-positive cells in the V ganglion was not significantly altered by neonatal infraorbital nerve transection. Overall, these findings do not indicate a strong relationship between cell birth date and the probability of survival after neonatal axonal damage for all V ganglion cell phenotypes. (C) 1995 Wiley-Liss, Inc.