DISTRIBUTION OF VASOACTIVE-INTESTINAL-PEPTIDE (VIP) AND ITS BINDING-SITES IN LABIAL SALIVARY-GLANDS IN SJOGRENS-SYNDROME AND IN NORMAL CONTROLS

Objective. Tissue distribution of vasoactive intestinal peptide (VIP)- containing nerves and their target cells were studied in labial saliva ry glands in patients with Sjogren's syndrome and in healthy controls. Methods. Immunoperoxidase staining was used to demonstrate VIP-contai ning nerve fibers, and receptor autoradiography with I-125-Bolton Hunt er (BH)-VIP was used to demonstrate VIP positive binding sites. Result s. VIP-containing nerves were seen around salivary acini, salivary duc ts, blood vessels and deep parenchyma, but were absent from large infl ammatory cell foci inpatients with Sjogren's syndrome. Receptor autora diography with I-125-BH-VIP disclosed VIP binding sites on mucous acin ar cells and blood vessels, whereas salivary ducts contained no VIP re ceptors. VIP binding sites were also absent from the centers of large inflammatory cell foci/acinar atrophy. Conclusion. The topology of VIP and its receptor suggests that VIP may act on the vascular and secret ory components of the salivary glands. However, VIP causes only a slig ht increase.in non-adrenergic, non-cholinergic salivary secretion. It is therefore more likely that this extensive tissue distribution of VI P and its receptors reflects its recently suggested trophic effects on salivary gland tissue. This is further supported by the observation t hat VIP-IR nerves/VIP binding sites were absent in areas of focal lymp hocytoid infiltrates/acinar atrophy in patients with Sjogren's syndrom e.