CONICET | Buscador de Institutos y Recursos Humanos

In animal research, refinement refers to modifications of husbandry or experimental procedures to enhance animal well-being and minimize or eliminate pain and distress. In Chagas disease drug screening, it has been standardize a therapeutic scheme of 20 consecutive days of oral treatment in mice models. The aim of the study was to compare efficacy of orogastric gavage administration versus a refined method consisting in oral administration with disposable plastic tips. The protocol was approved by the Hospital?s Teaching and Ethics Committees. Five weeks-old male BALB/c mice were infected with 1,000 T. cruzi trypomastigotes (VD strain) by intraperitoneal (ip) route. At parasitaemia onset, 12 days post infection, treatment was started with benznidazole (BZ) at 100 mg/kg/day given with disposable tips coupled to an automatic pipette (n = 5) or with a K35 gavage (n = 5) in a final volume of 50 µL. After 20 consecutive days of treatment, an immunosuppression cycle with cyclophosphamide (CYP, 200 mg/ kg; ip) was initiated. At the end of the cycle, animals were euthanized and blood, skeletal muscle and heart were sampled for quantitative PCR (qt-PCR) diagnosis. No significant differences were found between mean required doses (± SD) to parasitaemia negativization (3.20±1.64 vs. 3.60±1.95, respectively; p= 0.586) or patent parasitaemia mean (expressed in days) (4.80±3.56 vs. 5.20±3.83; p = 0.9131) comparing both administration methods. At the end of the CYP cycle, parasitaemia did not rebound, and all blood samples were negative with qt-PCR and negative or below the quantification limit in skeletal o cardiac muscle, suggesting parasitological cure in both treatment groups.Oral BZ administration with disposable tips coupled with an automatic pipette did not influence its effectiveness in mice. Applying this refined method could contribute to improve animal welfare, reducing stress and risk of morbidity and mortality associated with traditional orogastic gavage administration methods, without interfering with therapeutical outcome.

enviar mensaje