The peptidergic innervation of the rat parotid gland: Effects of section of the auriculo-temporal nerve and/or of otic ganglionectomy

The origin/pathways of peptidergic nerves contributing to the parotid gland contents of vasoactive intestinal peptide (VIP), substance P and calcitonin gene-related peptide (CGRP) were investigated by performing surgery on one side of the rat. Comparisons (based on total amount of peptide) were made between the gland on the operated side and the contralateral gland 7 days postoperatively. Otic ganglionectomy showed that almost all of the parotid gland contents of VIP (98%) and substance P (98%) were due to the otic connection, while this was true for only a minor portion (32%) of the CGRP-gland content. Section of the auriculo-temporal nerve showed that almost all of the VIP- and substance P-containing nerve fibres reached the parotid gland via this nerve, as judged by a reduction in the VIP-content by 88% and in the substance P-content by 93%, while the CGRP-content was only reduced by 37%. Section of the auriculo-temporal nerve combined with otic ganglionectomy did not reduce the gland contents of CGRP and substance P further than just otic ganglionectomy. Thus, the auriculo-temporal nerve is not likely to innervate the parotid gland with CGRP- and/or substance P-containing nerve fibres from the trigeminal ganglion.