Capsaicin Induces Cystatin S-like Substances in Submandibular Saliva of the Rat

Abstract

Irritating dietary substances such as tannin and papain have been reported to alter the morphology of salivary glands and their secretions. Such alterations can be one line of protection from toxic or irritating substances in food. We investigated the effects of dietary capsaicin (a pungent ingredient of hot red pepper) on the rat submandibular gland and its secretions. Several groups of animals were offered either control diets or diets containing capsaicin (from 0.0001 to 0.1%) for seven days. Higher concentrations suppressed food consumption for two days, after which only the highest concentration continued to reduce intake. The relative weight of the salivary glands in capsaicin-diet groups increased in a dose-dependent fashion, and new proteins appeared in the submandibular saliva. Chromatographic and electrophoretic properties of these proteins were identical or similar to those of isoproterenol-induced proteins. After affinity chromatography of the new protein fraction on a Cm-papain Sepharose 4B column, SDS-electrophoresis of the eluate revealed three major bands (15,500, 16,500, and 28,000 kDa). Hydrolysis of N-benzoyl-D,L-arginine-p-nitroanilide by papain (a cysteine protease) decreased in the presence of the new protein fraction, suggesting that these proteins have cystatin-like activity (inhibition of cysteine protease). Denervation of the glossopharyngeal nerve suppressed induction of these proteins. The results suggest that dietary capsaicin induces cystatin S-like substances in submandibular saliva by stimulating the reflex arc involving the glossopharyngeal nerve. These proteins likely facilitate ingestion of diets containing the irritating substance.

First identification of tannin‐binding proteins in saliva of Papio hamadryas using MS/MS mass spectrometry

“…A new and very interesting finding is the presence of cystatins in the precipitated fractions after tannic acid addition to the saliva of hamadryas baboons. The induction of cystatin SA was earlier shown in rat submandibular saliva and was suggested to be one line of protection of oral mucosa from toxic or irritating phytochemicals, such as capsaicin [Katsukawa & Ninomiya, 1999; Katsukawa et al, 2002]. However, our study is the first to demonstrate an interaction of cystatin SA with tannins in a primate species.…”

Induction of Salivary Proteins Modifies Measures of Both Orosensory and Postingestive Feedback during Exposure to a Tannic Acid Diet

“…Cystatin SN, a closely related protein to cystatin S, has been linked to the sensitivity to the bitter taste of caffeine in humans [23]. It has also been demonstrated that oral capsaicin [17] and quinine [18] stimulate the production of salivary cystatin S-like proteins suggesting that this class of proteins is generally responsive to aversive oral stimuli, but to our knowledge, this is the first suggestion that this protein is related to meal size.…”

“…The protein content of saliva is altered under a variety of circumstances including diet composition [13], [14], disease [15], [16], exposure to compounds like capsaicin [17] or bitter taste stimuli [18]–[21]. Likewise, there is evidence that some of these proteins modulate bitter taste acceptance.…”

Evaluation of 2-week repeated oral dose toxicity of 100 nm zinc oxide nanoparticles in rats

“…Of all adverse clinical signs observed, salivation and abdominal distension probably resulted from irritation of the oral mucosa and gastrointestinal track by ZnO AE100(+) . Salivation is often observed in gavage studies and may have been a reaction to the taste or mucosal irritation of the test article [ 17 18 19 20 ]. Fur loss and weakness were indications of stress and/or malnutrition induced by ZnO AE100(+) , which is supported by the decreases in body weight and feed consumption.…”