Biological, systemic and reproductive evaluation in Wistar rats feed on genetically modified soybean resistant to the glyphosate.

A esp??cie vegetal geneticamente modificada mais cultivada no Brasil ?? a soja [Glycine max (L.) Merr.] resistente ao herbicida sist??mico p??s-emergente glifosato, com 12,3 milh??es de hectares cultivados. Essa soja foi obtida pela introdu????o do gene correspondente ?? enzima 5-enolpiruvilchiquimato-3-fosfato sintase (EPSPS, E.C 2.5.1.19, CP4), enzima da via de chiquimato, resistente ao glifosato, mantendo ativa a via biossint??tica de amino??cidos arom??ticos. A modifica????o gen??tica fez com que par??metros preconizados pela legisla????o brasileira fossem revistos e o limite m??ximo permitido de glifosato nos gr??os que era de 0,2 mg/kg aumentasse para 10 mg/kg. Embora o Brasil cultive h?? mais de dez anos a soja resistente ao glifosato e seja o terceiro maior produtor mundial dessa leguminosa, com 50% da produ????o nacional com gen??tipos transg??nicos, poucos estudos t??m sido conduzidos no pa??s com o intuito de avaliar, em ensaios biol??gicos, o impacto dessa tecnologia sobre o meio ambiente, a qualidade e a seguran??a do alimento. Sendo assim, o presente trabalho objetivou estudar a influ??ncia do consumo de gr??os de soja geneticamente modificada resistente ao glifosato (GMRR) isog??nica ?? convencional e n??o isog??nica, tratada com este herbicida, sobre a qualidade nutricional, poss??veis efeitos ?? exposi????o cr??nica, bem como efeitos sobre a fertilidade e o desenvolvimento de ratos Wistar e a possibilidade deste, desregular o sistema end??crino. A qualidade nutricional foi avaliada atrav??s do valor prot??ico mediante ??ndices biol??gicos, em 30 machos rec??m desmamados, distribu??dos em cinco grupos, alimentados por 28 dias com ra????o contendo 10% de prote??na de soja GMRR n??o isog??nica, soja GMRR da isog??nica, soja convencional, leite (case??na) ou por 10 dias com ra????o aproteica. O ganho de massa corporal e o consumo alimentar das dietas n??o diferiu entre os tratamentos. Esse mesmo comportamento foi observado no que concerne ??s vari??veis de crescimento e ??ndices de balan??o nitrogenado. Na exposi????o cr??nica de 40 machos e 39 f??meas distribu??dos em 4 grupos que consumiram dietas contendo sojas GMRR (isog??nica e n??o isog??nica), soja convencional e grupo padr??o sem soja, 6 sinais de toxicidade sist??mica nos machos foram evidenciados na neutrofilia, linfopenia do grupo que consumiu soja convencional em rela????o ao grupo padr??o, e na hiperplasia linf??ide dos pulm??es nos animais que consumiram soja GMRR e convencional; sinais de toxicidade reprodutiva foram observados atrav??s do aumento da massa relativa dos test??culos e epid??dimos e redu????o da concentra????o esperm??tica. Nas f??meas, os efeitos no sistema reprodutivo foram evidenciados atrav??s dos ??ndices de fertilidade, e desmame. Estes resultados indicam que a qualidade prot??ica da soja modificada geneticamente ?? preservada, por??m h?? uma associa????o de fatores que desencadeiam em uma prov??vel desregula????o end??crina. Outros estudos s??o necess??rios para elucidar o mecanismo de intera????o que provoca efeitos de toxicidade em machos e f??meas alimentados com soja convencional e GMRR que apresentam n??veis detect??veis de glifosato.The most cultivated genetically modified plant in Brazil is the soybean [Glycine max (L.) Merr.] resistant to the systemic herbicide glyphosate. There are 12.3 millions of cultivated hectares. This soybean was obtained through the introduction of the gene that codes for the 5-enolpyruyilshikimic-acid3-phosphate synthase enzyme, (EPSPS, E.C 2.5.1.19, CP4), of the shikimic pathway, resistant to glyphosate that keeps active the aromatic amino acids biosynthetic pathway. To the soybean genetical modification the parameters in law were reviewed and the maximum glyphosate limit permitted in beans that was 0.2 mg/kg was increased to 10 mg/kg to GMRR soybean. Although Brazil is the 3rd biggest worldwide producer, cultivates the GMRR soybean for more than ten years, and represents 50% of the overall production of soybean in Brazil, just a few studies have been conducted in the country to evaluate in biological assays, the impact of this technology on the food quality and safety. Thus, the present work seeks for to evaluate the influence of the genetic modification of the soybean on the nutritional quality, on the possible effects of chronical exposition, as well as the effects on the fertility and the development of Wistar rats and the on the endocrine system. The nutritional quality was evaluated through the protein value, in 30 male rats, just weaned, distributed in five groups, fed along 28 days with the following diets, 10% protein ration GMRR soybean no isogenic, GMRR soybean isogenic, conventional soybean, milk (casein) or for 10 days with a non-protein diet. The weight gain and the food intake of diets did not present statistical relevance. The same behavior was observed in the variables of growth and the nitrogen balance study. In the chronical exposition of 40 male and 39 female rats distributed in four groups that consumed genetically modified soybean no isogenic and isogenic, conventional soybean and the standard group without soybean it signs of systemic toxicity on males have been evident in the neutrophilia, lymphocytopenia in the group conventional soybean compared with the standard group, lymphoid hyperplasia of the lungs in the groups without soybean; the signs of reproductive toxicity through of 8 the increase on relative weight of the tests and epididymis and also through the decrease of the sperm concentration. On the females the effect on the reproductive system became evident through the fertility pregnancy and weaning index. These results point out that the protein quality of the genetically modified soybean is preserved, but there is an association of factors that trigger a probable endocrine disruption. Studies are necessary to elucidate the mechanism of interaction that cause toxicity on males and females fed with conventional soybean and genetically modified soybean that presented detectable glyphosate levels