Cement Dust Exposure Alters Secretory Functions, Biochemical Profile and Morphology of Gastrointestinal Tissues in Rats

Abstract

Asides direct gastrointestinal exposure, inhalation route is another major xenobiotic exposure pathway to the gastrointestinal tract via mucociliary escalator. This triphasic study assesses the effect of cement dust inhalation exposure on gastrointestinal tissues and secretion. Seventy-two male, 16-week old Wistar rats were randomized into 3 different phases of 24 animals. Each phase comprised of three groups of 8 animals. Group 1 (control) were sham-operated with clean ambient air, group 2 (14-day exposed) were exposed to cement dust for 14 days, and group 3 (28-day exposed) were exposed to cement dust for 28 days. Biochemical indices including superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), sulfhydryl group, carbonyl group, Na+-K+ ATPase pump activity, Nitric oxide (NO) were investigated spectrophotometrically in gastric and hepatic tissues while histopathology was studied using standard procedure. There were significant increases in the levels of MDA, NO and carbonyl-an observation that contrasts with the level of CAT, SOD and sulfhydryl; no significant difference in Na+-K+-ATPase pump was observed in the exposed groups compared with control. Histopathological alterations in salivary glandular and gastric tissues includes edema, inflammatory cell infiltration and vascular congestion. There were significant alterations in basal salivary, gastric and biliary secretions; increased stimulated salivary and gastric secretions via cholinergic stimulation. Histopathological and spectrophotometric analyses revealed that exposure to cement dust significantly alters gastrointestinal secretions and predisposes the gastrointestinal tract to an array of deleterious effects via protein oxidation, antioxidant depletion and tissue peroxidation.