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Placental dysfunction leads to foetal damage, which jeopardises the exchange between the maternal and foetal systems. We evaluated the effects of tumour growth on the activity of antioxidant enzymes and oxidative stress in placental tissue and cell culture from tumour-bearing pregnant rats compared to non-tumour-bearing pregnant rats that were ascitic fluid injected. Ascitic fluid is obtained from Walker tumour-bearing rats and contains a cytokine called Walker factor (WF), which is a molecule similar to proteolysis-inducing factor (PIF), and induces changes in protein metabolism and oxidative stress. Pregnant Wistar rats were distributed into control (C), tumour-bearing (W) and ascitic fluid injected (A) groups and were sacrificed on days 16, 19 and 21 of pregnancy to analyse the profile of enzyme activities (glutathione-S-transferase (GST), catalase (CAT), alkaline phosphatase (AP)) and malondialdehyde (MDA) content in placental tissue. Meanwhile, placenta samples from all groups were obtained on day 21, placed in primary culture and treated with WF for 72 h. The presence of tumour or ascitic fluid reduced the protein content of the placental tissue. On day 16 there was a significant reduction in AP activity in W rats, and on day 19, CAT activity and MDA content significantly increased. These results indicate that the presence of cancer decreased antioxidant enzyme capacity in the placenta, increasing the amount of oxidation in these cells, which may contribute to irreversible placental damage and compromisefoetal development. WF treatment induces similar changes in placental cells in primary culture, resulting in less cell viability and increased oxidative stress. These results indicate that WF, provided by the tumour or inoculation of ascitic fluid, has negative effects on placental homeostasis, which impairs foetal health., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The placenta provides all energy and nutrient requirements for healthy fetal development. The placenta in rats is capable of storing glycogen, although the placenta cells must therefore mobilize stored glycogen to its own glucose supply. Moreover, maternal glucose and/or placental lactate furnished the fetal growth. Adult female Wistar rats were divided into three groups: Control-C, tumour bearing-W; injected ascitic fluid-A. The rats were sacrificed on the 16th, 19th or 21st day of gestation, analysing the placenta and fetus weights and placental tissue samples was aliquoted for biochemical assays of glycogen and protein content and alkaline phosphatase activity. Placental sections were morphometrically analysed and glycogen positive cells were counted. The placental and fetal weight were significantly reduced in both W and A rats from 16th up to 21st day of gestation, which showed high levels of fetal reabsorption sites. Significant reduction in labyrinth zone at day 21 in both tumour bearing and ascitic fluid injected groups was shown, suggesting less substrate exchange at the maternal/fetal surface. The alkaline phosphatase activity as well total protein content were found to be reduced in W and A group. The total placental glycogen and glycogen cells decreased during tumour bearing and ascitic fluid injection, suggesting reduction in its own stored energy. Ascitic fluid injected group, representing an indirect tumour effect, presented similar reduction changes in the placenta to the tumour-bearing group. In conclusion, the tumour growth and, especially, ascitic fluid injection promoted irreversible placental tissue damage altering homeostasis and compromising fetal development.

Cancer cachexia induces host protein wastage but the mechanisms are poorly understood. Branched-chain amino acids play a regulatory role in the modulation of both protein synthesis and degradation in host tissues. Leucine, an important amino acid in skeletal muscle, is higher oxidized in tumor-bearing animals. A leucine-supplemented diet was used to analyze the effects of Walker 256 tumor growth on body composition in young weanling Wistar rats divided into two main dietary groups: normal diet (N, 18% protein) and leucine-rich diet (L, 15% protein plus 3% leucine), which were further subdivided into control (N or L) or tumor-bearing (W or LW) subgroups. After 12 days, the animals were sacrificed and their carcass analyzed. The tumor-bearing groups showed a decrease in body weight and fat content. Lean carcass mass was lower in the W and LW groups (W = 19.9 0.6, LW = 23.1 1.0 g vs N = 29.4 1.3, L = 28.1 1.9 g, P < 0.05). Tumor weight was similar in both tumor-bearing groups fed either diet. Western blot analysis showed that myosin protein content in gastrocnemius muscle was reduced in tumor-bearing animals (W = 0.234 0.033 vs LW = 0.598 0.036, N = 0.623 0.062, L = 0.697 0.065 arbitrary intensity, P < 0.05). Despite accelerated tumor growth, LW animals exhibited a smaller reduction in lean carcass mass and muscle myosin maintenance, suggesting that excess leucine in the diet could counteract, at least in part, the high host protein wasting in weanling tumor-bearing rats.