Figure 1.

Schematic overview of the neural control of salivary gland function. Acinar cells (below) are prompted to produce saliva by neurotransmitters (above) that bind specifically to surface receptors. The parasympathetic arm releases acetylcholine and neuropeptides (i.e. vasoactive intestinal peptide, VIP) that bind to muscarinic (M1 and M3) and peptidergic receptors, respectively. The sympathetic neurotransmitter norepinephrine binds to α1- and β1-adrenergic receptors. Fluid secretion is mainly the result of muscarinic and α1-adrenergic activation, whereas protein production derives mainly from the stimulation of peptidergic and β1-adrenergic receptors.