Further studies on neomycin and experimental hypertension

Acute glucocorticoid (corticosterone) hypertension in the rate is significantly attenuated by neomycin administration (Honour 1981), as is ACTH-induced hypertension is the same species (Honour & Kent 1981) presumably by altering gut bacterial steroid metabolism. The effect on blood pressure of oral neomycin administration was therefore examined in hypertension resulting from administration of a variety of glucocorticoid hormones. Neomycin significantly attenuated the elevation of blood pressure following ACTH or corticosterone, as previously shown, or prednisolone 1 mg/day; it did not affect blood pressure in rats given dexamethasone 0.2 mg/day, or cortisol 4 mg twice daily. Since the differential effect of neomycin on hypertension parallels neither pressor nor glucocorticoid activity of the administered steroids we propose that it reflects different patterns of enterohepatic handling and metabolism.