Avaliação dos efeitos do praziquantel sobre o Schistosoma mansoni adulto recuperado de camundongos com desnutrição proteica

Abstract

Protein malnutrition and schistosomiasis affect millions of people, representing a public health challenge. Praziquantel is the main therapy to control schistosomiasis. To evaluate the possible effects of a low-protein diet and praziquantel on adult Schistosoma mansoni, male Swiss Webster mice (21 days old), fed a low-protein diet (8% protein) or standard diet (22% protein), were infected with approximately 100 cercariae (BH strain) in the fourth week of the diet. In the eighth week of infection (12 weeks of diet), treatment with praziquantel (100 mg/kg, single dose) was administered, dividing the groups as follows: infected and standard diet (IDP); infected, treated, and standard diet (ITDP); infected and low-protein diet (IDH); infected, treated and low-protein diet (ITDH). One week after treatment, the animals were euthanized, and the helminths and small intestines were collected. The morphology and morphometry of the reproductive system of adult helminths and the tegument of males were examined using bright-field, confocal, and scanning electron microscopy. The stages of egg maturation were assessed through qualitative intestinal oogram. The oogram results showed an alteration in the egg maturation profile, where the praziquantel-treated groups (ITDP and ITDH) exhibited fewer mature eggs and more dead eggs compared to the untreated groups (IDP and IDH). Concerning the diet, the low-protein group (ITDH) presented more dead eggs compared to the normoproteic group (ITDP). In helminths, the treated groups (ITDP and ITDH) showed a reduction in the number of males, females, and the total number of specimens compared to the untreated groups (IDP and IDH). In the morphology and morphometry of males, a lower percentage of germ cells was observed in the ITDP and IDH groups compared to IDP, and ITDH compared to IDH. The ITDH group also showed an increase compared to ITDP. There was a reduction in the height of tubercles in both ITDP and IDH groups compared to IDP, and a decrease in width in the IDH group compared to IDP. In females, the vitelline glands showed a higher percentage of yolk in the ITDP and IDH groups compared to IDP. The seminal receptacle of both ITDP and IDH groups showed a reduction in the percentage of spermatozoa inside compared to IDP. Confocal analysis of the reproductive system of helminths revealed empty spaces due to the lower quantity of spermatozoa (ITDP, IDH, and ITDH) and the presence of immature germ cells in both the seminal vesicle (IDH and ITDH) and the testicular lobes (ITDP), as well as empty spaces inside the testicular lobes (IDH and ITDH). In the IDH and ITDH groups, there were morphological alterations in both the testicular lobes and the germ cells inside, in males. In females, the ITDP, IDH, and ITDH groups showed a scarcity of cells and the presence of immature cells in the vitelline glands and oocytes arranged disorganized within the ovary, showing scarcity and many immature cells. Scanning electron microscopy of the tegument in males showed loss of intertubercular grooves, contraction, and severe desquamation of the tegument, and erosive lesions on the tubercles, with spine loss in both treated groups. The stress imposed on the parasite, whether due to low protein or the action of praziquantel, resulted in significant morphological changes, with the low-protein diet not compromising the drug’s effectiveness.