Autonomic control of submandibular chromogranin A secretion in the anaesthetized rat

Region-specific radioimmunoassay (RIA) developed with anti-rat chromogranin A (CgA) (359-389) serum was used for estimating levels of CgA-like immunor eactivity (CgA-like IR) in saliva and plasma of rats. Under pentobarbitone anaesthesia, the sympathetic and parasympathetic nerves innervating the sub mandibular gland were stimulated in both efferent and afferrent direction. The stimulation of the nerves caused elevation of CgA-like IR level in the plasma from the resting level (0.97 +/- 0.34 nM) to 1.23 +/- 0.42 nM, the l evel in the saliva from non-collectable level to 631 +/- 359 nM, and saliva ry flow rate from non-collectable rate to 10.7+/-2.6 mu L min(-1) gl. The i ntramural injection of acetylcholine (total 0.2 mt of 0.1 mM solution) into the submandibular gland induced a distinct increase in flow rate of the sa liva from non-collectable level to 16 +/- 5.5 mu L min(-1) g(-1), which con tained 5,964 +/- 2,065 nM CgA-like IR. CgA-like IR was immunohistochemicall y ascertained in duct cells but not in neural elements and acinar cells in rat submandibular gland. These results are compatible with a novel view tha t the source of salivary CgA-like IR is the duct cells, which release highl y concentrated CgA-like IR into saliva in response to activation of the aff erent autonomic axis of the stress system, and provide experimental bases f or a view that CgA-like IR may be a sensitive and substantial index for psy chosomatic stress response.