Effect of the neuropeptides vasoactive intestinal peptide, peptide histidine methionine and substance P on human major salivary gland secretion.
OBJECTIVE
The parasympathetic transmitters vasoactive intestinal peptide (VIP) and substance P (SP) are secretagogues in salivary glands of animals. Currently, we hypothesise that in human salivary glands, these neuropeptides and the VIP-related peptide histidine methionine (PHM) also exert secretory actions, reflected morphologically by exocytosis of acinar protein/glycoprotein-storing granules.


METHODS
Submandibular and parotid gland tissues, exposed in vitro to VIP and PHM, and SP, respectively, were examined by light and transmission electron microscopy. For comparison, the response to in vitro stimulation of isoproterenol, phenylephrine and carbachol was examined. Moreover, the peptidergic innervation of the glands was examined by immunohistochemistry.


RESULTS
Vasoactive intestinal peptide- and PHM-immunoreactive nerves were in close proximity to acini and ducts in the two glands, while these elements lacked a SP-positive innervation. While no morphological changes occurred in response to SP (parotid glands), VIP and PHM administration (submandibular glands) caused conspicuous acinar degranulation accompanied by luminal space broadening. In the two glands, both α1 - and β-adrenergic receptor stimulation and muscarinic receptor stimulation caused similar changes as to VIP/PHM, although to varying extent.


CONCLUSIONS
Vasoactive intestinal peptide and PHM, but not SP, are likely transmitters in the parasympathetic control of salivary (protein) secretion in humans.
Section of Cytomorphology, Department of Biomedicals Sciences, University of Cagliari, Cagliari, Italy.
M
M
Del Fiacco
M
M
Quartu
J
J
Ekström
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T
Melis
M
M
Boi
M
M
Isola
F
F
Loy
M P
MP
Serra
D000328:Adult; D000368:Aged; D002217:Carbachol / Q000494:pharmacology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009479:Neuropeptides / Q000494:pharmacology*; D010451:Peptide PHI / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology; D012463:Saliva / Q000378:metabolism; D012469:Salivary Glands / Q000166:cytology / Q000187:drug effects* / Q000294:innervation / Q000378:metabolism*; D013373:Substance P / Q000494:pharmacology*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
D009479:Neuropeptides; D010451:Peptide PHI; D010656:Phenylephrine; D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D002217:Carbachol; D007545:Isoproterenol
human parotid gland; human submandibular gland; immunohistochemistry; in vitro stimulation; light and electron microscopy; neuropeptides