The influence of septal lesions on sodium and water retention induced by Walker 256 tumor

In the course of studies on the effects of septal area lesions on neuroimmunomodulation and Walker 256 tumor development, it was observed that tumor-induced sodium and water retention was less marked in lesioned than in non-lesioned rats. In the present study possible mechanisms involved in this phenomenon were investigated. The experiments were performed in septal-lesioned (LW; N = 15) and sham-operated (SW; N = 7) 8-week-old male Wistar rats, which received multifocal simultaneous subcutaneous (sc) inoculations of Walker 256 tumor cells about 30 days after the stereotaxic surgery. Control groups (no tumor, sham-operated food-restricted (SFR), N = 7) and lesioned food-restricted (LFR, N = 10) were subjected to a feeding pattern similar to that observed in tumor-bearing animals. Multifocal inoculation of Walker 256 tumor rapidly induces anorexia, which is paradoxically accompanied by an increase in body weight, as a result of renal Na+ and fluid retention. These effects of the tumor were also seen in LW rats, although the rise in fractional sodium balance during the early clinical period was significantly smaller than in SW rats (day 4: SW = 47.6 = 6.4 percent and LW = 13.8 = 5.2 percent; day 5: SW = 57.5 = 3.5 percent and LW = 25.7 = 4.8 percent; day 6: SW = 54.4 = 3.8 percent and LW = 32.1 = 4.4 percent; P<0.05), suggesting a temporary reduction in tumor-induced sodium retention. In contrast, urine output was significantly reduced in SW rats and increased in LW rats (LW up to -0.85 and SW up to 4.5 ml/100 g body weight), with no change in osmolar excretion. These temporary changes in the tumor's effects on LW rats may reflect a "reversal" of the secondary central antidiuretic response induced by the tumor (from antidiuretic to diuretic)

A sobrevida de ratos com tumor de Walker submetidos previamente à imunogenicidade das células tumorais / Survival in rats with Walker's tumor submitted previously to the tumoral cells immunogenicity

A inoculaçao de 37.10 5 células do tumor de Walker, por via intramuscular, na coxa do rato confirmou uma evoluçao rápida do mesmo, ao exibir um crescimento expansivo da massa tumoral no local do inóculo, culminando com a morte do animal. Todavia, quando da inoculaçao em ratos expostos previamente à "imunogenicidade destas células", observou-se uma evoluçao mais lenta e uma maior sobrevida, sugerindo modulaçao na imunidade destes animais. O contato prévio com as células tumorais ou ainda a fraca imunogenicidae destas células, provavelmente, possa ter sido suficiente e responsável pelo retardo no desenvolvimento do tumor e pela maior sobrevida dos animais

Alteraçäo da resposta inflamatória e imunológica em animais portadores de tumor experimental / Alteration on inflammatory and immunological response in animal carriers of experimental tumor

Os autores estudaram em camundongos portadores de tumor de Walker as alteraçöes de resposta a agente inflamatório e as modificaçöes de reaçöes imunológicas, assim como o período no qual se tornam evidentes. Usaram como agente inflamatório a carragenina e como parâmetro imunológico o teste de hipersensibilidade ao BCG. As conclusöes foram que os animais portadores de tumor apresentam diminuiçäo na capacidade de resposta inflamatória inespecífica à carragenina e ao CBG, assim como no teste de hipersensibilidade tardia ao BCG