THE INFLUENCE OF NERVES ON THE SECRETION OF IMMUNOGLOBULIN-A INTO SUBMANDIBULAR SALIVA IN RATS

1. The influence of sympathetic and parasympathetic nerve stimulations on salivary secretion of immunoglobulin A (IgA) was studied in the su bmandibular glands of anaesthetized rats by stimulating the nerve supp lies with bipolar electrodes. 2. Although the flow of saliva from symp athetically stimulated glands was only 23% of that from parasympatheti cally stimulated glands the output of IgA was over 2-fold greater. Thi s difference was attributable to influences of the nerves on IgA secre tion through the epithelial cell polymeric immunoglobulin receptor-med iated pathway, as Western blotting with specific antibodies to IgA and secretory component revealed that secretory IgA (SIgA) dominated in a ll saliva samples. 3. Study of saliva secreted in sequential periods o f nerve stimulation or following rest pauses suggested that SIgA secre tion occurred in the absence of stimulation but this was upregulated 2 .6- and 6-fold by parasympathetic and sympathetic nerve stimulations, respectively, compared with the calculated unstimulated rate. 4. The I gA content of extensively stimulated glands was 77% of levels in unsti mulated contralateral control glands despite a secretion into saliva e quivalent to almost 90% of the glandular IgA content. The IgA may be s ynthesized and secreted by glandular plasma cells at a rate which exce eds demand and/or such synthesis may be upregulated by nerve impulses. 5. The results indicate that salivary secretion of SIgA is upregulate d by nerve impulses and that sympathetic nerves induce a greater effec t than parasympathetic nerves.