RESUMEN
O uso de animais isogênicos apresenta grandes vantagens experimentais, como uniformidade fenotípica e genotípica (reduzindo o número de animais em experimentos) e histocompatibilidade, permitindo, assim, o acúmulo de informações e a repetibilidade dos experimentos. A linhagem isogênica de Rattus norvegicus Fischer 344 existe há 90 anos, entretanto pouco se sabe sobre as razões de seu baixo índice reprodutivo. O presente estudo demonstrou que ratos Fischer F344 são fotorresponsivos quanto à reprodução, tendo seus índices de prenhezes acrescidos com o aumento do fotoperíodo. Os melhores índices são obtidos quando os machos são submetidos a 14 horas de luz e fêmeas a 16 horas de luz, indicando dimorfismo sexual na fotorresponsividade.
The use of isogenic animals presents great experimental advantages, as phenotypic and genotypic uniformity (reducing the number of experimental animals) and histocompatibility, thus allowing, the accumulation of information, and the repeatability of the experiments. The isogenic strain of Rattus norvegicus Fischer 344 has existed for 90 years, however the reasons of its low reproductive index are not knew. The present study has demonstrated that Fischer F344 rats are photoresponsive regarding reproduction, having improved its pregnancy index with the increase of the photoperiod. The best indexes were achieved when the males had been submitted to 14 hours of light and females to 16 hours of light, indicating sexual dimorphism in photoresponsivity.
RESUMEN
Neste trabalho avaliou-se histologicamente o reparo em feridas cutâneas no dorso de ratos hiperreativos (Fischer-344) e hiporreativos (Lewis). Quarenta ratos adultos foram selecionados, sendo 20 da linhagem Fischer (Grupo F) e outros 20 da linhagem Lewis (grupo L). Os animais foram anestesiados e uma ferida com área de 1 cm² foi feita no dorso de cada animal até atingir o tecido subcutâneo, preservando-se o músculo. Após 7 e 14 dias de realizadas as feridas, dez ratos de cada grupo foram selecionados aleatoriamente e submetidos à eutanásia. Os tecidos da região da ferida foram removidos e fixados em formalina para o processamento histológico laboratorial. Para análise histológica, um examinador cego aos grupos observou todos os cortes, identificando e analisando a região central e as bordas da ferida. No sétimo dia, o Grupo F apresentou discreta proliferação de epitélio junto às bordas da ferida. No tecido conjuntivo subjacente mais distante da ferida, observaram-se poucos fibroblastos e elevada quantidade de macrófagos e linfócitos. O grupo L apresentou alta proliferação epitelial e moderada quantidade de fibroblastos próximos a macrófagos e linfócitos. Aos 14 dias, o Grupo F apresentou discreta proliferação de epitélio. No tecido conjuntivo, foi observado poucos fibroblastos e moderado número de linfócitos e macrófagos. No grupo L, o epitélio recobria totalmente a ferida. No tecido conjuntivo, raros linfócitos e macrófagos foram observados. Concluindo, ratos do Grupo L (hiporreativos) apresentam um melhor reparo de feridas cutâneas em dorso que os ratos do Grupo F (hiperreativos).
Asunto(s)
Animales , Ratas , Tejido Conectivo , Cicatrización de Heridas , Ratas Endogámicas LewRESUMEN
@#Objective To establish animal model of prolactinoma with Fischer 344 (F344) rats.MethodsFemale F344 rats were injected with estradiol benzoate-treated and 0.9% sodium chloride respectively. After 50 days of treatment, MRI scan was performed and animal's living status was observed, and pituitary weight, serum prolactin level, pathological and PRL immunohistochemistry changes were also detected.ResultsAll estradiol benzoate-treated rats formed the prolactinoma after treatment for 50 days and the growth of body weight was retarded obviously. Pituitary weight and serum PRL increased significantly in estradiol benzoate-treated animals compared with those treated with 0.9% sodium chloride. Pituitary adenomas were found in MRI scan and HE stain was positive. The forming rate of tumor was 100%.ConclusionThe animal model of pituitary adenoma established with F344 rat has more characters such as having a short tumor forming period, easy and stable, and coincided with features of prolactinoma.
RESUMEN
In previous studies, acute exercise might induce inflammatory cytokines from immunological cells, but it was not clear that tumor necrosis factor (TNF) -α in the liver was induced by acute exercise. In this study, we first measured the changes from acute exercise in plasma TNF-α, lipopolysaccharide (LPS), interferon (IFN) -γ and prostaglandin (PG) E2 ; from and investigated the effect of acute exercise on TNF-α expression in the liver. Then we examined the response of TNF-α to PGE2 in isolated Kupffer cells. Female Fischer 344 rats were run on a treadmill at 21 m/min for 60 min on a 15% grade. Although the portal venous plasma endotoxin concentration in the exercised group was higher than that in the resting group, plasma TNF-α was not detected in either group. In addition, plasma IFN-γ, which accelerates TNF-α production, was not detected. TNF-α mRNA expression in the liver didn't change significantly. On the other hand, plasma PGE2, which is an inhibitor of TNF-α production, markedly increased immediately after the exercise. In addition, PGE2 inhibited TNF-α production by LPS-stimulated Kupffer cells in in vitro. These results sug gest that LPS-induced TNF-α expression in rat liver is inhibited by an increase of PGE2 during acute exercise.
RESUMEN
The muscle fiber-capillary barrier consists of the capillary endothelium and the interstitium. Thinning of the barrier is physiologically significant for gas exchange in skeletal muscle because it shortens the diffusion distance of gases. The purpose of the present study was to examine the effect of endurance training on the ultrastructure of the muscle fiber-capillary barrier in soleus muscle of growing rats. Seventeen male Fischer 344 rats, aged 5 weeks, were assigned to either an exercisetrained group (ET, n=5), a paired-weight sedentary group (PWS, n=6), or a sedentary group (S, n=6), and matched as closely as possible with regard to body mass and Vo<SUB>2max</SUB>. The ET group performed a treadmill running program for 5 days/week for 10 weeks. The ET and S rats were freely fed rat chow and water. The PWS rats had their food intake restricted so that their mean body mass would be the same as that of the ET rats. After the training period, the diffusion distance in the ET group was significantly shorter than that in the PWS and S groups. There were no differ-ences in the thicknesses of the capillary endothelium among the three groups, but the interstitium was significantly thinner in the ET group than in the PWS and S groups. The degree of decrease in the interstitium thicknesses in the ET group was almost equal to that of the diffusion distance. Therefore it was identified that endurance training shortens the diffusion distance, which depends on thinning of the interstitium. These results suggest that morphological adaptation to endurance training partly contributes to the improvement of gas exchange in the muscle and aerobic work capacity.