Effects of oregano aqueous extract on defence ability of pig gut

Different studies in the last years have focused on use of natural compounds from herbs and spices as an alternative to synthetic additives in order to avoid the growing problem of antibiotic resistance. Among officinal plants Origanum vulgare L., belonging to Lamiaceae family, has been shown to possess antioxidant, antibacterial, antifungal, anti-inflammatory, antitumor, antiparasitic, antiviral, anti-hyperglycemic, anti-cholinesterase, diaphoretic, carminative, antispasmodic and analgesic activities, which are mainly attributed to its components carvacrol, limonene, gamma-caryophyllene, rhocymenene, camphor, linalol, alpha-pinene and thymol. Among oregano properties, the antioxidant and the antibacterial ones are of special interest. Oregano is also able to induce a higher glycoconjugate production. Secretion glycoconjugates cover the intestinal mucosae creating a continuous gel layer, which performs various functions: lubrication, barrier for certain low molecular weight solutes, proteolytic degradation and a barrier for microorganisms and parasites. On the basis of above considerations, this work is aimed to evaluate the effects of oregano aqueous extract (OAE) dietary supplementation on pig gut complex carbohydrates, detected by conventional histochemistry, and oxidative stress, using as target molecule Bcl-2 Associate X protein (BAX). Glycohistochemical and immunohistochemical treatments were carried out on four gut tracts: duodenum, ileum, caecum and colon. Glycohistochemistry was performed by staining with Periodic acid-Schiff (PAS), Alcian blue (AB) pH 2.5, AB-PAS, AB pH 1, AB pH 0.5, low iron diamine, high iron diamine. Adjacent serial sections were pre-treated with Sialidase V before staining with AB pH 2.5 preceded or not by saponification with 1% KOH in 70% ethanol to remove the acetyl groups. Positive histochemical responses were found at goblet cell level in all examined gut tracts; duodenal glands were also reactive. The data analysis evidenced significant differences to the histochemical treatment reactivity between control and oregano supplemented groups. BAX immunostaining decreased in oregano supplemented group. Our results showed that oregano aqueous extract supplementation improves the production of the glycoconjugates able to enhance the protection of the pig intestinal mucosae; in addition, it reduced BAX immunostaining, suggesting an enhanced antioxidant action in oregano supplemented group. Finding from this experiment could be useful for carrying out studies aimed to reduce antibiotic use and prevent antimicrobial resistance, enhancing endogenous defence ability.