Effects of Inhalation Anesthetics and Neurotransmitters on the Rat Submandibular Gland

Abstract

The mechanism for salivary secretion is complicated because it is controlled not only by the autonomic nervous system but also by the high-level central nervous system, including emotions.
We assessed the effects of inhaled anesthetics (nitrous oxide, halothane, and enflurane) on salivary secretion in the rat submandibular gland under total spinal block (TSB) in order to eliminate the effect of the high-level central nervous system. At the same time we analyzed the effects of the neurotransmitters adrenalin and vasoactive intestinal polypeptide (VIP) in order to clarify the mechanism of salivary secretion. The distribution of VIP-positive fibers was also examined immunohistologically.
The following results were obtained.
1. Under TSB, nitrous oxide had no influence on salivary secretion.
2. Under TSB, halothane and enflurane inhibited secretion.
3. Adrenalin (3μg/kg) inhibited secretion and glandular blood flow. However, it had no effect under TSB.
4. Atropine would not block salivary secretion following administration of VIP (100μg/kg).
5. VIP-positive fibers were observed immunohistologically around the secretory ducts and acini.