vasoactive-intestinal-peptide and Sialorrhea

The parasympathetic transmitter vasoactive intestinal peptide (VIP) increases salivary gland blood flow and evokes protein secretion and, in some species, such as rats, a small fluid secretion. It interacts synergistically with muscarinics for protein and fluid output. Human salivary acini are supplied with VIP-containing nerves. We hypothesise that VIP and clozapine, acting together, evoke a volume of saliva greater than the sum of those induced by each drug given separately. It was further considered whether, in the current test situation, circulatory events influenced the magnitude of the secretory response.. Saliva from parotid glands deprived of their autonomic innervation, and saliva and blood from innervated submandibular glands were collected in adrenoceptor antagonist-pretreated pentobarbitone-anaesthetised rats. Initially, the individual and then the combined effects of intravenous doses of VIP and clozapine were established.. The submandibular volume response to the combination was 2-3 times higher, while blood pressure and glandular blood flow did not differ from those to VIP alone. The synergism occurred independent of nerves as shown in denervated parotid glands.. From the current preclinical data, we speculate that VIP of parasympathetic origin, by its synergistic interaction with clozapine, may contribute to the clozapine (muscarinic M1-receptor)-induced sialorrhoea in schizophrenics.

Topics: Animals; Antipsychotic Agents; Clozapine; Female; Parasympathetic Nervous System; Parotid Gland; Rats; Rats, Sprague-Dawley; Sialorrhea; Submandibular Gland; Vasoactive Intestinal Peptide

To determine the mechanism of inhibitory effect of botulinum toxin type A (BTX-A) on parotid gland secretion.. Female Wistar rats (n = 18) were randomly divided into saline injection group (n = 6) and BTX-A injection group ( n = 12), respectively. 0.1 ml of saline was injected into left parotid gland and 2.5 U of BTX-A injected into right parotid gland. Rats were sacrificed at day 7, 12 and 35 post-injections respectively for morphology and vasoactive intestinal polypeptide (VIP) immunoreactivity of parotid gland.. Following BTX-A injection, some atrophic cells and reduction of number of VIP-immunoreactive (VIP-IR) fibers were found in gland and tube at day 7 (P < 0.05); at day 12, there was more obvious reduction of VIP-IR fibers around tube and vessels and atrophy of cells in BTX-A injection gland than saline injection gland (P < 0.001); at day 35, the glandular cells and VIP-IR fibers were similar to saline injection group.. BTX-A is effective for temporary elimination of hyperfunctioning sialorrhea via inhibition of VIP release which plays a key role in modulation of parotid glands secretion.

Topics: Animals; Botulinum Toxins, Type A; Female; Parotid Gland; Rats; Rats, Wistar; Sialorrhea; Vasoactive Intestinal Peptide