Eletrofisiologia da visão em modelo experimental de ratos com diabetes e hipotireoidismo

Abstract

Diabetes mellitus is a worldwide public health problem because of its potential morbidity and mortality. This pathology is characterized as a metabolic disorder with chronic hyperglycemia, results from an absolute or relative deficiency in the secretion and/or insulin action. Associated to this case, problems with the thyroid are often found in patients with diabetes, especially with advancing age. Furthermore, there is a body of knowledge describing that both diabetes and hypothyroidism cause visual loss, however, there are not many publications on the physiology involving both pathologies in conjunction with the visual complications. Therefore, this work aimed to investigate issues relevant to a more detailed understanding of the framework for the evolution of retinal impairment in animal models simultaneously affected by two diseases: diabetes and hypothyroidism. For this, 50 male Wistar rats (Rattus norvegicus) were used, two-months-old, weighing between 80 to 120 grams, divided into four groups: a control group without procedures; a group with hypothyroidism opting for a bilateral experimental model of thyroidectomy; a group with diabetes, with application of 200 mg/kg to 2% Aloxana; and two groups with both pathologies, adopting both experimental procedures by changing the sequence of the pathologies in question. In the studied groups, it was used the electroretinogram (ERG), a non-invasive method widely used in academia to evaluate the visual changes, in different periods of 30, 45 and 60 days. We found a decrease in the average amplitude of the wave-a of the animals in the groups with diabetes and with both pathologies in all the realized registrations, the ones that showed the highest statistical differences were in relation to the registration of maximum estocópica, as well as difference in oscillatory potential of both groups with both pathologies. These results support the hypothesis that both concomitant pathologies (diabetes and hypothyroidism) significantly diminish the ERG responses.