Effects of escins Ia, Ib, IIa, and IIb from horse chestnuts on gastric emptying in mice

Abstract

Inhibitory effects of the saponin fraction and its principal constituents, escins Ia, Ib, IIa, and IIb, from horse chestnuts on gastric emptying were investigated in mice loaded with a non-nutrient or nutrient meal. The saponin fraction and escins Ia–IIb inhibited gastric emptying of a 1.5% carboxymethyl cellulose sodium salt (CMC-Na) meal by 11.1–54.2% (12.5–200 mg/kg). Escins Ia–IIb (50 mg/kg) also inhibited gastric emptying of a 40% glucose meal by 21.1–23.5% except for escin Ia, a milk meal by 18.4–33.1%, and a 30% ethanol meal by 13.5–15.9%. The effects of escins Ia–IIb on gastric emptying of the CMC-Na meal were attenuated by pretreatment with streptozotocin (100 mg/kg, i.v.), capsaicin (75 mg/kg in total, s.c.), or insulin (1 U/kg, s.c.). The effect of insulin was reduced by glucose (2 g/kg, i.v.) which can directly nourish the brain, but not by fructose (2 g/kg, i.v.) which cannot be utilized by the brain. The effects of escins Ia–IIb (50 mg/kg) were overridden in 60% ethanol-loaded mice, in which the central nervous system was suppressed by ethanol. These results suggest that capsaicin-sensitive sensory nerves and central nervous system partly participate in the effects of escins Ia–IIb.