Role of nitric oxide on zymosan-induced inhibition of crop emptying in chicks

• Published in: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Vol. 261; p. 111057
• Main Authors: Takahashi, Maki, Khan, Md Sakirul Islam, Makino, Ryosuke, Cline, Mark A., Tachibana, Tetsuya
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2021
• Subjects: Animal Feed - analysis; Animals; Chick; Chickens; Crop emptying; Crop, Avian - drug effects; Crop, Avian - metabolism; Digestion - drug effects; Gastrointestinal Motility - drug effects; Gastrointestinal Tract - drug effects; Gastrointestinal Tract - metabolism; Inducible nitric oxide synthase; Male; Nitric oxide; Nitric Oxide - metabolism; Zymosan; Zymosan - pharmacology; Zymosan; Crop emptying; Chick; Inducible nitric oxide synthase; Nitric oxide
• ISSN: 1095-6433; 1531-4332
• DOI: 10.1016/j.cbpa.2021.111057

Zymosan, a component of yeast cell walls, reduces feed passage through the digestive tract in chicks (Gallus gallus), although the mechanism mediating this effect is poorly understood. Nitric oxide (NO) is associated with a variety of biological actions including effects on the immune system. In addition, it has been suggested that NO is involved in relaxation of the digestive tract and affects feed passage in mammals. It is therefore possible that NO might be related to zymosan-induced reduction of feed passage in chicks. However, the role of NO on the effect of zymosan feed passage has not been clarified yet. Thus, the purpose of the present study was to investigate whether NO is associated with zymosan-induced alteration of feed passage in chicks. Intraperitoneal (IP) injection of zymosan significantly increased plasma nitrate and nitrite (NOx) concentrations at 6 h after injection. Zymosan-induced elevation of plasma NOx concentration was abolished by co-injection of S-methylisothiourea (SMT), a selective inhibitor for inducible NO synthase (iNOS), indicating that zymosan facilitated the induction of iNOS. Furthermore, because zymosan increased iNOS mRNA expression in the digestive tract, NO is likely associated with the effect of zymosan on the digestive tract. IP injection of NO donors significantly decreased crop emptying rate, suggesting that NO functions as an inhibitor of crop emptying. This result implied that zymosan stimulates NO production by the induction of iNOS in the digestive tract and thereby inhibits crop emptying rate. However, the co-injection of SMT did not attenuate the inhibitory effect of zymosan on crop emptying. The present study provides evidence that some changes in the digestive tract caused by zymosan are mediated by iNOS-induced NO in chicks, but NO does not mediate the effect of zymosan on feed passage through the crop. [Display omitted] •Intraperitoneal injection of zymosan induced the NO production in chicks.•Zymosan-induced NO production was abolished by a specific iNOS inhibitor.•Zymosan increased the iNOS mRNA expression in the digestive tract.•NO would be related to feed passage because NO donor reduced crop emptying.•However, NO was not involved in zymosan-induced retardation of crop emptying.