Avaliação da influência da obesidade induzida pelo glutamato monossódico nos tecidos periodontais de ratas submetidas à periodontite experimental

Abstract

Periodontal disease is one of the most important diseases around the world. Its progress occurs due to a combination of factors which affect the sustainable tissues of teeth, and which leads to the development of periodontal pockets and to the reabsorption of the alveolar bone. This can also result in tooth loss. By considering obesity as one of the systemic diseases which pre-establishes a series of complications and as a risk factor to other chronic pathologies, several studies have suggested that this condition is also an important risk factor for the development of periodontal diseases. It is known that the periodontal disease is immune-inflammatory when there is an imbalance between the immune host responses and the causative agents, and that it may be intensified when associated to systemic factors and conditions. This study aims at evaluating the effect of obesity induced by monosodium glutamate (MSG) over the periodontal tissues of rats having induced periodontitis. In this study, 33 rats were divided, initially, into two groups which were submitted to intradermal injections in the cervical region using 1,25g/kg/day of saline solution (group CON), and 1,25g/kg/day of MSG solution (group B), in their first 5 days of life. At 70 days, the periodontal disease was induced with the placement of ligatures in first inferior premolars of both sides of animals. This served as a gingival irritation for 30 days, and provided the cumulus of bacterial plaque, and consequently, the development of periodontal disease. After this procedure, the animals were sub-divided into 4 groups: control group without ligatures (CON); control group with ligatures (CONLIG); obese without ligature (OB), and obese with ligature (OBLIG). At 100 days, the rats were weighed and measured related to the naso-anal length in order to determine the Lee index. Through the vaginal cytology, the female rats which were in proestrus in their estrous cycles were euthanized. After that, the perigonadal and retro perigonadal fats were collected and weighted. It was also collected blood from the right brain stem. The conditions of the estradiol and progesterone were determined by using specific kits. The left and right hemi mandibles were withdrawn and submitted to a radiographic and histological analysis, respectively. A sample of the gingival tissue was collected in order to dosage the cytokines. The data were analyzed and evaluated through the ANOVA and Tukey. Obesity was confirmed by Lee index and by retroperitoneal and perigonadal fat (p<0.05). At the radiographic analysis, it was verified the efficacy of the induction of periodontal diseases, showing the insertion loss in the groups submitted to the experimental periodontitis, with an alveolar bone loss smaller in the group OBLIG when compared to the group CONLIG (p<0.05). This was also proved by the histological analysis. By analyzing the gingival tissue, no differences between CONLIG and OBLIG groups were found. In the hormonal analysis, the concentrations of LH and FSH were reduced to the OB and OBLIG groups. According to the results, it is possible to suggest that the obesity model may have some protector effect over the alveolar bone loss in the cases of induction of periodontitis. Such condition also may interfere negatively in the plasmatic concentrations of some female sexual hormones