Avaliação dos efeitos inflamatórios produzidos pelo nitrogênio líquido em língua de rato

Abstract

Cryotherapy is the intentional destruction of a tissue by means of applying extremely low temperatures. It is a versatile method that has been used in the treatment of innumerable benign and malignant lesions, either in the soft or hard tissues. The aim of this research was to assess the inflammatory effects produced by cryosurgery when applied to rat tongues. Liquid nitrogen was applied at 1 cm from the tip of the tongue by means of a closed probe 1mm in diameter. Seventy-five male Wistar rats (300-400 g) were divided into three groups of twenty-five animals. Group A received 1 application lasting 1 minute; group B two applications of 1 minute with a 5-minute interval between the applications, and group C, three applications with a 5-minute interval. The groups were subdivided into five subgroups of five animals each. Each subgroup was sacrificed on pre-established times, counted as from the day of the application: 6 hours, 24 hours, 72 hours, 7 days and 14 days. Two animals served as control group, in which no therapy was instituted. After the above-mentioned periods, the rats were sacrificed; the tongues were removed, processed and stained with hematoxylin and eosin (HE). The histological parameters considered were: inflammatory infiltrate, hemorrhage, vasodilatation, edema, ulceration, reepithelization, muscle tissue features and necrosis. Scores were established (0, 1, 2 and 3) so that each sample received a value. The study demonstrated greater inflammatory effects with repetition of the cycles. The cryotherapy may to produce a inflammation degree able to cause tissue destruction.