title: Entamoeba histolytica: apoptosis induced in vitro by nitric oxide species.
abstract: Apoptosis has been described in some parasites like Leishmania, Trypanosoma, and Trichomonas. This phenomenon has not been observed yet in Entamoeba histolytica. This work analyzed the in vitro effect of sodium nitroprusside, sodium nitrite and sodium nitrate (NOs) on E. histolytica apoptosis. Parasites incubated for 1h with NOs revealed apoptosis 6h later (95% viability), demonstrated by YOPRO-1, TUNEL, DNA fragmentation and low ATP levels. The caspase inhibitor Z-VAD-FMK inhibited total intracellular cysteine protease activity (CPA) but had no effect on apoptosis. When treated with NOs some amebic functions like complement resistance and hemolytic activity decreased but CPA and erythrophagocytosis remained unchanged. After treatment in vitro with NOs, parasite death was almost complete at 24h; but when injected into hamster livers they disappeared in less than 6h. These results show that apoptosis is induced in vitro by NOs in E. histolytica and renders them incapable of surviving in hamster's livers.
authors.affiliation: Departamento de Medicina, Experimental, Facultad de Medicina;Universidad Nacional Autónoma de México, México DF, Mexico.
authors.forename: Espiridión
authors.initials: E
authors.lastname: Ramos
authors.forename: Alfonso
authors.initials: A
authors.lastname: Olivos-García
authors.forename: Mario
authors.initials: M
authors.lastname: Nequiz
authors.forename: Emma
authors.initials: E
authors.lastname: Saavedra
authors.forename: Eusebio
authors.initials: E
authors.lastname: Tello
authors.forename: Andrés
authors.initials: A
authors.lastname: Saralegui
authors.forename: Irmgard
authors.initials: I
authors.lastname: Montfort
authors.forename: Ruy
authors.initials: R
authors.lastname: Pérez Tamayo
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D006224:Cricetinae; D053938:DNA Fragmentation; D004748:Entamoeba histolytica / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D020287:In Situ Nick-End Labeling; D008101:Liver Abscess, Amebic / Q000469:parasitology; D008297:Male; D008647:Mesocricetus; D018613:Microscopy, Confocal; D009566:Nitrates / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D012977:Sodium Nitrite / Q000494:pharmacology
chemical_list: D009566:Nitrates; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D009569:Nitric Oxide; C031618:sodium nitrate; D012977:Sodium Nitrite