The use of indomethacin to demonstrate an enterotoxic activity in extracts of entamoeba histolytica trophozoites

• Main Author: Udezulu, Ifeanyi Afam
• Format: Others
• Published: DigitalCommons@Robert W. Woodruff Library, Atlanta University Center 1982
• Subjects: Biology
• Online Access: http://digitalcommons.auctr.edu/dissertations/1494; http://digitalcommons.auctr.edu/cgi/viewcontent.cgi?article=3074&context=dissertations

Axenically cultured Entamoeba histolytica trophozoites of the pathogenic strain HM-1 were harvested in phosphate buffered saline (PBS). The cells were disrupted with ultrasonic energy, centrifuged, and the supernatant fluid tested for enterotoxic activity in the i[n vivo rabbit ileum loop .and-the rat proximal colon loop. This HM-1 extract, equivalent to 106 trophozoites/ml, had no effect on intestinal absorption in either animal model, but secretion resulted in both preparations when indomethacin (0.1 mg/kg) was administered subcutaneously to reduce cytoprotection. In the rat colon a lower dose of indomethacin was ineffective in allowing the ameba preparation to cause frank secretion, while higher doses, 1 and 10 mg/kg, directly inhibited this secretory response. In the absence of indomethacin, a preparation equivalent to 107 trophozoites/ml reduced colonic absorption without producing secretion, while a preparation of 107 trophozoites/ml of the non-pathogenic E_. histolytica-like Laredo strain was ineffective even in the presence of 0.1 mg/kg indomethacin. The HM-1 enterotoxic activity was heat labile. Prior exposure of the loop lumen to fetuin (100 wg/ml) blocked the secretory response to subsequent enterotoxin exposure in indotnethacin-treated animals. Fetuin inhibition of secretion could not be reversed by inoculating the loop with fresh trophozoite extract at hourly intervals for 4 hours.