Short- and Long-Term Effects of Dietary Supplementation with Fish Oil on Inflammatory Pain in Rats.

INTRODUCTION: Dietary supplementation with fish oil is promising as a complementary therapy for inflammatory pain. However, further studies are needed to support its therapeutic potential. For example, the antinociceptive effect of fish oil is widely suggested to be dependent on decreased prostaglandin E2 (PGE2) synthesis, but no previous study has investigated if it affects PGE2-induced nociceptive response. Similarly, beneficial long-term effects on inflammatory response are related to early exposure to fish oil, however, whether these effects include decreased inflammatory pain throughout life is not known. OBJECTIVE: The aim of this study was to investigate the short- and long-term effects of fish oil on inflammatory pain. METHODS: Dietary fish oil supplementation was performed through two protocols: in adult rats, during 20 days, or in dams, during pregnancy and lactation, with tests performed in adult offspring. The hyperalgesic response induced by carrageenan and its final mediators PGE2 and norepinephrine was used to model inflammatory pain. RESULTS: The findings demonstrated for the first time that dietary fish oil (1) decreases the hyperalgesia induced by carrageenan; (2) but not that induced by its final mediator PGE2 and norepinephrine; (3) increase omega-3 polyunsaturated fatty acids in peripheral neural tissue; and (4) attenuates inflammatory pain in individuals exposed to fish oil during pre-natal life and lactation. CONCLUSION: Together, these findings support that fish oil decreases inflammatory pain either when consumed during adult life or during prenatal development. Future studies should confirm the therapeutic potential of fish oil in humans, which is essential for the development of public policies to encourage a fish oil richer diet.

0.1T magnetic resonance image in the study of experimental hydrocephalus in rats. Accuracy of the method in the measurements of the ventricular size.

PURPOSE: To investigate the accuracy of 1.0T Magnetic Resonance Imaging (MRI) to measure the ventricular size in experimental hydrocephalus in pup rats. METHODS: Wistar rats were subjected to hydrocephalus by intracisternal injection of 20% kaolin (n=13). Ten rats remained uninjected to be used as controls. At the endpoint of experiment animals were submitted to MRI of brain and killed. The ventricular size was assessed using three measures: ventricular ratio (VR), the cortical thickness (Cx) and the ventricles area (VA), performed on photographs of anatomical sections and MRI. RESULTS: The images obtained through MR present enough quality to show the lateral ventricular cavities but not to demonstrate the difference between the cortex and the white matter, as well as the details of the deep structures of the brain. There were no statistically differences between the measures on anatomical sections and MRI of VR and Cx (p=0.9946 and p=0.5992, respectively). There was difference between VA measured on anatomical sections and MRI (p<0.0001). CONCLUSION: The parameters obtained through 1.0T MRI were sufficient in quality to individualize the ventricular cavities and the cerebral cortex, and to calculate the ventricular ratio in hydrocephalus rats when compared to their respective anatomic slice.

0.1T magnetic resonance image in the study of experimental hydrocephalus in rats. Accuracy of the method in the measurements of the ventricular size / Imagem de ressonância magnética de 1,0T no estudo da hidrocefalia experimental em ratos. Avaliação do método de medição do tamanho ventricular

PURPOSE: To investigate the accuracy of 1.0T Magnetic Resonance Imaging (MRI) to measure the ventricular size in experimental hydrocephalus in pup rats. METHODS: Wistar rats were subjected to hydrocephalus by intracisternal injection of 20% kaolin (n=13). Ten rats remained uninjected to be used as controls. At the endpoint of experiment animals were submitted to MRI of brain and killed. The ventricular size was assessed using three measures: ventricular ratio (VR), the cortical thickness (Cx) and the ventricles area (VA), performed on photographs of anatomical sections and MRI. RESULTS: The images obtained through MR present enough quality to show the lateral ventricular cavities but not to demonstrate the difference between the cortex and the white matter, as well as the details of the deep structures of the brain. There were no statistically differences between the measures on anatomical sections and MRI of VR and Cx (p=0.9946 and p=0.5992, respectively). There was difference between VA measured on anatomical sections and MRI (p<0.0001). CONCLUSION: The parameters obtained through 1.0T MRI were sufficient in quality to individualize the ventricular cavities and the cerebral cortex, and to calculate the ventricular ratio in hydrocephalus rats when compared to their respective anatomic slice.

OBJETIVO: Investigar a fidelidade das Imagens de Ressonância Magnética de 1,0T no estudo do tamanho ventricular na hidrocefalia experimental em ratos jovens. MÉTODOS: Ratos Wistar foram submetidos à hidrocefalia através da injeção intracisternal de caulim 20%. Dez animais permaneceram sem injeção para uso como controles. Ao final do experimento, os animais foram submetidos à Ressonância magnética de encéfalo e sacrificados. O tamanho ventricular foi avaliado por três medidas: razão ventricular (VR), espessura cortical (Cx) e área ventricular (VA), tomadas em fotografias das secções anatômicas e nas imagens de ressonância magnética (RM). RESULTADOS: As imagens por RM apresentaram qualidade suficiente para individualizar os ventriculos laterais, mas a distinção entre córtex e substância branca, bem como detalhamento das estruturas profundas do encéfalo não foram possíveis. Quando comparadas as medidas em seções anatômicas e RM, não houve diferença estatística entre as médias de razão ventricular e espessura cortical (p=0,9946 e p=0,5992, respectivamente). Houve diferença da área ventricular comparando-se as secções anatômicas e ressonância magnética (p<0,0001). CONCLUSÃO: Os parâmetros obtidos através de imagens da ressonância magnética de 1,0T foram suficientes para individualizar as cavidades ventriculares e o córtex cerebral, e para calcular o tamanho ventricular em ratos hidrocefálicos quando comparados aos seus respectivos cortes anatômicos.