Indomethacin-induced gut damage in a surrogate insect model,Galleria mellonella

Abstract

13Indomethacin is a non-steroidal anti-inflammatory drug that causes gastric ulceration 14 and increased 'leakiness' in rat models, and is used routinely as an assay to screen 15 novel compounds for repair and restitution properties. We set out to establish 16 conditions for indomethacin-induced gut damage in wax-moth (Galleria mellonella) 17 larvae with a view to reducing the need for rodents in such experimentation. We 18 administered indomethacin (1 -7.5 µg/larva) to G. mellonella via intrahaemocoelic 19 injection and gavage (force-feeding) and monitored larval survival and development, 20 blood cell (haemocyte) numbers, and changes in gut permeability. Increased levels 21 of gut leakiness were observed within the first 4 to 24-hours by tracking fluorescent 22 microspheres in the faeces and haemolymph (blood equivalent). Additionally, we 23 recorded varying levels of tissue damage in histological sections of the insect 24 midgut, including epithelial sloughing and cell necrosis. Degeneration of the midgut 25 was accompanied by significant increases in detoxification-associated activities 26(superoxide dismutase and glutathione-S-transferase). Herein, we present the first 27 evidence that G. mellonella larvae force-fed indomethacin display broad symptoms 28 of gastric damage similar to rodent models. 29 30 Keywords: gastrointestinal damage; histopathology; rodent models; innate 31 immunity; gavage; gut leakiness 32 33 34 From mouth to rectum, the digestive system of lepidopteran larvae (like G. 54 mellonella) consists of three distinct regions: the foregut (stomatodaeum), midgut 55 (mesenteron) and hindgut (proctodaeum) (Engel and Moran, 2013; Linser and 56