Dados do Trabalho

Título

Parasitemia of mice orally and intraperitoneally inoculated with Trypanosoma cruzi I (Colombian strain), treated with an association of benznidazole with ICM-20a and immunosuppressed

Objetivo(s)

Our objective was to evaluate the parasitemia of mice orally (OR) or intraperitoneally (IP) inoculated with Trypanosoma cruzi, treated with the association of benznidazole (BZ) and ICM-20a, and immunosuppressed with cyclophosphamide (Cy)

Material e Métodos

Balb/c mice were inoculated via OR or IP routes with 2x106 metacyclic trypomastigotes derived from a culture of the Colombian strain (DTU TcI), considered resistant to BZ. The following groups were evaluated:1) OR infected and untreated (NT); 2) IP infected and NT; 3) OR infected and treated with BZ 100 mg/kg/day; 4) OR infected and treated with ICM-20a; 5) IP infected and treated with ICM-20a; 6) OR infected and treated with ICM-20a+BZ 5 mg/kg/day; 7) IP infected and treated with ICM-20a+BZ 5 mg. Fresh blood examination was performed from the 3rd day after inoculation (dpi) to obtain the mean of the following parameters: pre-patent period (PPP), patent period (PP), maximum parasitemia peak (Pmax) and day of maximum parasitemia (Dpmax). The substances were administered by gavage for 20 consecutive days, starting at the 5th dpi, and one week after the end of the etiological treatments, the animals were immunosuppressed with Cy 50 mg/kg/day for 3 weeks

Resultados e Conclusão

The PPP was 14.9 and 8.3 days (p=0.001), the PP of 9.3 and 21.3 days (p=0.01), the Pmax of 5,805 blood trypomastigotes (BT)/0.1 mL of blood and 9,288 BT/0.1 mL of blood (p=0.008) and the Dpmax occurred around 19 dpi and 14.7 dpi (p=0.001), respectively for the animals in the OR-NT and IP-NT groups. OR animals treated with BZ 100 mg and with the association ICM-20a+BZ 5 mg showed complete suppression of parasitemia and significant reduction (p<0.0001) of the parameters derived from the curve. On the other hand, IP animals treated with ICM-20a+BZ 5 mg showed patent parasitemia for at least one day during treatment. The infection reactivation rates, the return of patent parasitemia after immunosuppression, in ascending order were: 20% (OR+BZ 100 mg) = 20% (OR+ICM-20a/BZ 5 mg) < 50% (OR+ ICM-20a) < 70% (IP+ICM-20a/BZ 5 mg) < 100% (IP+ICM-20a). Animals inoculated by the OR route showed lower and later parasitemia than IP animals, suggesting that the severity of the OR infection depends on the T. cruzi strain/DTU. The association (ICM-20a+BZ 5 mg) promoted total suppression of parasitemia and a lower reactivation rate (20%) in OR infection, similar to BZ 100 mg, confirming its synergistic effect in vivo

Palavras-chave

Chagas disease, mice, drug association, oral infection, parasitemia