Effect of testosterone on the mucosal defence against intestinal helminths in Indian soft-furred rats, Millardia meltada with reference to goblet and mast cell responses

Effects of testosterone on the mucosal defence mechanisms against intestinal helminths were examined in Millardia meltada. When female M. meltada were treated with testosterone at the pharmacological dose, Nippostrongy-lus brasiliensis infection persisted for over seven weeks with prominent biphasic pattern of faecal egg production, whereas almost complete expulsion was observed by two weeks in untreated controls. In spite of a biphasic pattern of faecal egg production, the worm burden of testosterone-treated animals remained constant up to three weeks and then slowly decreased by seven weeks. To see whether or not this delayed expulsion in testosterone treated animals was due to altered cellular responses of the intestinal mucosa, goblet and mast cell responses were examined histologically. At two weeks post-infection, goblet cell responses at the infected site were significantly lower in testosterone-treated animals than in controls. In contrast mast cell hyperplasia was comparable between testosterone-treated and control animals. When Strongyloides venezuelensis, in which expulsion is dependent on mucosal mast cells, were infected concurrently with N. brasiliensis, testosterone-treated animals could expel S. venezuelensis worms by Day 18, but failed to expel N. brasiliensis. Histologically, mast cell hyperplasia was associated with expulsion ofS. venezuelensis, while goblet cell responses were suppressed. From these results, testosterone seems to suppress proliferation/function of goblet cells but does not affect mast cells ofM. meltada.