Hepatic and biochemical repercussions of a polyunsaturated fat-rich hypercaloric and hyperlipidic diet in Wistar rats / Repercussões hepáticas e bioquímicas da dieta hipercalórica e hiperlipídica rica em gordura poliinsaturada em ratos Wistar

CONTEXT: Non-alcoholic fatty liver disease is characterized by lipid deposits in the hepatocytes and has been associated with obesity, dyslipidemia and type-2 diabetes. It is considered a hepatic manifestation of the metabolic syndrome, of which the main component is insulin resistance leading to hyperinsulinemia and increased production of inflammatory cytokines. Saturated fat promotes hypertriglyceridemia and hyperinsulinemia, reduces levels of high-density cholesterol and increases levels of low-density cholesterol, while polyunsaturated fat is associated with hypolipidemic, antiinflammatory and imunoregulating action. OBJECTIVE: To evaluate the hepatic and biochemical repercussions of a polyunsaturated fat-rich diet in Wistar rats. METHODS: Twenty-two rats were distributed equally in two groups: GI - standard diet (Biobase Bio-tec Ratos e Camundongos®) providing 3.000 kcal/kg and GII - hypercaloric and hyperlipidic diet providing 4.250 kcal/kg (ω-6:ω-3 = 3:1). The animals were euthanized after 23 weeks of experiment. The weight, biochemical parameters and hepatohistological changes were registered. RESULTS: Findings were submitted to variance analysis with the level of statistical significance at 5 percent. The average weight did not differ significantly between the groups at baseline (P = 0.711), but was greater in Group II by the end of the experiment (P = 0.000). The levels of triglycerides (P = 0.039), total cholesterol (P = 0.015) and HDL (P = 0.005) were higher in Group I than in Group II. Macrovesicular steatosis was significantly more common in Group II than in Group I (P = 0.03). CONCLUSION: Hypercaloric and hyperlipidic diet rich in polyunsaturated fat promotes weight gain and favors the development of hepatic steatosis while reducing serum levels of triglycerides, total cholesterol and HDL.

CONTEXTO: A doença hepática gordurosa não-alcoólica caracteriza-se por depósito de lipídios nos hepatócitos. Desperta grande interesse por sua associação com obesidade, dislipidemias e diabetes mellitus tipo 2. É considerada a manifestação hepática da síndrome metabólica, cujo principal componente é a resistência à insulina, com consequente hiperinsulinemia e produção aumentada de citocinas inflamatórias. Dietas ricas em gorduras saturadas promovem hipertrigliceridemia, diminuição do colesterol de alta densidade, aumento do colesterol de baixa densidade e hiperinsulinemia, enquanto dietas ricas em gordura poliinsaturada podem apresentar efeitos hipolipidêmicos, antiinflamatórios e imunorreguladores. OBJETIVO: Investigar as repercussões hepáticas e bioquímicas da dieta rica em gordura poliinsaturada em ratos Wistar. MÉTODOS: Os animais (22) foram distribuidos nos grupos GI-dieta padrao (Biobase Bio-tec Ratos e Camundongos®) com 3000 kcal/kg e GII-dieta hipercalorica e hiperlipidica, com 4250 kcal/kg, relação ω-6: ω-3 = 3:1. Foram mortos apos 23 semanas de administração das dietas. Avaliaram-se peso, exames bioquimicos e alteracoes histológicas do fígado. RESULTADOS: Foram utilizados testes de análise de variância com nível de significância de 5 por cento (P<0,05). Não houve diferença significante na média de peso entre os grupos (P = 0,711) no início, entretanto GII apresentou maior média que GI ao final do experimento (P = 0,000). GI mostrou níveis significantemente mais elevados de triglicerídeos (P = 0,03), colesterol total (P = 0,039) e HDL (P = 0,015) do que GII. O GII apresentou maior média de esteatose macrovesicular do que GI (P = 0,005). CONCLUSÃO: A dieta hipercalórica e hiperlipídica, rica em gordura poliinsaturada, promove esteatose hepática e incremento de peso, contudo reduz os níveis séricos de triglicerídeos, colesterol total e HDL.

Experimental model of human corpus cavernosum smooth muscle relaxation

PURPOSE: To describe a technique for en bloc harvesting of the corpus cavernosum, cavernous artery and urethra from transplant organ donors and contraction-relaxation experiments with corpus cavernosum smooth muscle. MATERIALS AND METHODS: The corpus cavernosum was dissected to the point of attachment with the crus penis. A 3 cm segment (corpus cavernosum and urethra) was isolated and placed in ice-cold sterile transportation buffer. Under magnification, the cavernous artery was dissected. Thus, 2 cm fragments of cavernous artery and corpus cavernosum were obtained. Strips measuring 3 x 3 x 8 mm3 were then mounted vertically in an isolated organ bath device. Contractions were measured isometrically with a Narco-Biosystems force displacement transducer (model F-60, Narco-Biosystems, Houston, TX, USA) and recorded on a 4-channel Narco-Biosystems desk model polygraph. RESULTS: Phenylephrine (1µM) was used to induce tonic contractions in the corpus cavernosum (3 - 5 g tension) and cavernous artery (0.5 - 1g tension) until reaching a plateau. After precontraction, smooth muscle relaxants were used to produce relaxation-response curves (10-12M to 10-4 M). Sodium nitroprusside was used as a relaxation control. CONCLUSION: The harvesting technique and the smooth muscle contraction-relaxation model described in this study were shown to be useful instruments in the search for new drugs for the treatment of human erectile dysfunction.