LOCALIZATION OF EXTRANEURONAL DOPAMINE‐β‐HYDROXYLASE IN RAT SALIVARY GLAND BY IMMUNOFLUORESCENCE HISTOCHEMISTRY

Abstract— Superior cervical ganglionectomy results in a complete noradrenergic neuronal denervation of the rat sublingual‐submaxillary salivary gland. Dopamine‐β‐hydroxylase activity in the serous submaxillary gland falls approximately 90% after noradrenergic denervation; but in the mucinproducing sublingual gland dopamine‐β‐hydroxylase activity is reduced by only 33%. Dopamine‐β‐hydroxylase immunofluorescence in the submaxillary gland is distributed with noradrenergic neurons and is eliminated by superior cervical ganglionectomy. In the sublingual gland dopamine‐β‐hydroxylase immunofluorescence is localized within mucinous acini and small ducts, and the disposition and intensity of staining materials is not affected by noradrenergic denervation for up to 30 days. DBH protein in the sublingual gland had little physiologic activity in vivo. Low levels of authentic dopamine‐β‐hydroxylase activity were detected in saliva. Thus, dopamine‐β‐hydroxylase protein is present in the sublingual gland in an extraneuronal location and appears to be a secretory product of the gland.