Histological and immunohistochemical study of the effect ofmonosodium l-glutamate on the jejunal mucosa of adult albinorat and the possible role of propolis

IntroductionMonosodium l-glutamate (MSG) is used as a flavor-enhancing agent in many kindsof food products. It has been considered to induce a variety of side effects.Propolis is a bee product that has a broad spectrum of biological activitiesincluding antioxidative, antimicrobial, and anti-inflammatory effects.Aim of the workThis work aimed to study the effect of MSG on the jejunal mucosa of adult albinorat and to evaluate the possible role of propolis as a protective agent.Materials and methodsAdult male albino rats (n=40) were randomly divided into four equal groups:control group, propolis-treated group (100 mg/kg body weight), MSG-treatedgroup (15 mg/kg body weight), and a group treated with both propolis and MSG.The animals were treated orally once daily for 6 weeks. Specimens from the jejunumwere processed for light and electron microscopy. Immunohistochemical study wascarried out to detect the inducible isoform of nitric oxide synthase in the epithelialcells covering the villi and lining the crypts. The results were analyzed statistically.ResultsSpecimens from MSG-treated animals showed distortion and focal loss of thevilli, disorganization and shedding of the enterocytes, cytoplasmic vacuolation, andnuclear irregularity. The lamina propria showed congested dilated blood capillariesand infiltration with inflammatory cells. Ultrastructurally, focal loss of microvilli,widening of the intercellular spaces, and swollen mitochondria with disrupted cristaewere observed in some enterocytes. Immunohistochemical study showed a highlysignificant increase in the immunoreaction in the cytoplasm of epithelial cells. Incontrast, minimal changes were observed in rats treated concomitantly with bothpropolis and MSG, with a nonsignificant increase in the immunoreaction.ConclusionMSG induced structural changes in rat jejunal mucosa that could be ameliorated byconcomitant treatment with propolis.