Heloísa Helena Paro de Oliveira

Effect of fish oil supplementation for two generations on changes of lymphocyte function induced by Walker 256 cancer cachexia in rats.

Fish oil supplementation has been shown to improve the cachectic state of tumor-bearing animals and humans. Our previous study showed that fish oil supplementation (1 g per kg body weight per day) for 2 generations had anticancer and anticachetic effects in Walker 256 tumor-bearing rats as demonstrated by reduced tumor growth and body weight loss and increased food intake and survival. In this study, the effect of fish oil supplementation for 2 generations on membrane integrity, proliferation capacity, and CD4/CD8 ratio of lymphocytes isolated from mesenteric lymph nodes, spleen, and thymus of Walker 256 tumor-bearing animals was investigated. We also determined fish oil effect on plasma concentration and ex vivo production of cytokines [tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-4 (IL-4), IL-6, and IL-10]. Lymphocytes from thymus of tumor-bearing rats presented lower viability, but this change was abolished by fish oil supplementation. Tumor growth increased proliferation of lymphocytes from all lymphoid organs, and fish oil supplementation abolished this effect. Ex vivo production of TNF-α and IL-6 was reduced in supplemented animals, but IL-4 and IL-10 secretion was stimulated in both nontumor and tumor-bearing rats. IL-10 and IFN-γ plasma levels was also decreased in supplemented animals. These results suggest that the anticachetic effects of fish oil supplementation for a long period of time (2 generations) in Walker 256 tumor-bearing rats may be associated to a decrease in lymphocyte function as demonstrated by reduced viability, proliferation capacity, and cytokine production.

Antitumor and anti-cachectic effects of shark liver oil and fish oil: comparison between independent or associative chronic supplementation in Walker 256 tumor-bearing rats

BackgroundShark liver oil (SLOil) and fish oil (FOil), which are respectively rich in alkylglycerols (AKGs) and n-3 polyunsaturated fatty acids (PUFAs), are able to reduce the growth of some tumors and the burden of cachexia. It is known that FOil is able to reduce proliferation rate and increase apoptotic cells and lipid peroxidation of tumor cells efficiently. However, there are few reports revealing the influence of SLOil on these parameters. In the current study, effects of FOil chronic supplementation on tumor growth and cachexia were taken as reference to compare the results obtained with SLOil supplementation. Also, we evaluated if the association of SLOil and FOil was able to promote additive effects.MethodsWeanling male Wistar rats were divided into 4 groups: fed regular chow (C), supplemented (1 g/kg body weight) with SLOil (CSLO), FOil (CFO) and both (CSLO + FO). After 8 weeks half of each group was inoculated with Walker 256 cells originating new groups (W, WSLO, WFO and WSLO + FO). Biochemical parameters of cachexia, tumor weight, hydroperoxide content, proliferation rate and percentage of apoptotic tumor cells were analysed. Fatty acids and AKG composition of tumor and oils were obtained by high performance liquid chromatography and gas chromatography – mass spectrometry, respectively. Statistical analysis was performed by unpaired t-test and one-way ANOVA followed by a post hoc Tukey test.ResultsFourteen days after inoculation, SLOil was able to restore cachexia parameters to control levels, similarly to FOil. WSLO rats presented significantly lower tumor weight (40%), greater tumor cell apoptosis (~3-fold), decreased tumor cell proliferation (35%), and higher tumor content of lipid hydroperoxides (40%) than observed in W rats, but FOil showed more potent effects. Supplementation with SLOil + FOil did not promote additive effects. Additionally, chromatographic results suggested a potential incorporation competition between the n-3 fatty acids and the AKGs in the tumor cells’ membranes.ConclusionsSLOil is another marine source of lipids with similar FOil anti-cachectic capacity. Furthermore, despite being less potent than FOil, SLOil presented significant in vivo antitumor effects. These results suggest that the chronic supplementation with SLOil may be adjuvant of the anti-cancer therapy.

Mixtures of benzo(a)pyrene, dichlorodiphenyltrichloroethane and tributyltin are more toxic to neotropical fish Rhamdia quelen than isolated exposures

The effects of benzo(a)pyrene (BaP), dichlorodiphenyltrichloroethane (DDT) and tributyltin (TBT) association were investigated through a multi-biomarker approach. Ten Rhamdia quelen fish per group were exposed through intraperitoneal injections either to BaP (0.3; 3 or 30 mg kg(-1)), DDT or TBT (0.03; 0.3 or 3 mg kg(-1)) or BaP/DDT, BaP/TBT, DDT/TBT or BaP/DDT/TBT on their lowest doses. The experiments were divided in acute (one dose, 5-day) and sub-chronic (3 doses, 15-day). Control groups received an equal volume of PBS or canola oil (1 ml kg(-1)). The three tested contaminants altered AChE activity in brain and muscle in similar ways; the mixtures antagonized the increase evoked by the contaminants alone. BaP and TBT increased GSH content and mixtures reduced it. GPx activity was increased by DDT and TBT in the 15-day experiment and reduced by the mixtures. BaP increased GST activity in sub-chronic experiment while TBT reduced it in the acute experiment. BaP/TBT increased GST activity compared to all groups; the other mixtures reduced it compared to BaP or DDT in the 5-day experiment. BaP, DDT and TBT increased δ-ALAd activity mainly in acute exposure; the mixtures also increased δ-ALAd compared to DDT or TBT in 5 and 15-day. BaP, TBT and BaP/DDT decreased LPO in the acute experiment. In the sub-chronic experiment DDT/TBT increased LPO when compared to TBT. None of the contaminants alone altered PCO, but all mixtures increased it compared to one or another contaminant. Contaminants isolated had a more acute effect in ALT plasma level; their lowest dose, which had no effect alone, in combination has led to an increase of this enzyme, especially after 15 days. DDT increased AST in the acute and sub-chronic experiments, while TBT did the same in the latter. DDT/TBT decreased AST opposing the effect of the contaminants alone in the 5-day experiment. Hepatic lesions index could be explained by a more acute effect of the contaminants alone or combined and by activation of cell defenses after the sub-chronic exposure. TBT increased melanomacrophages counting in the 5-day experiment and the mixtures increased it in the 5 and 15-day experiments. Overall, the majority of the biomarkers pointed to a more toxic effect when these contaminants were combined, leading to unexpected toxicities compared to individual exposure scenarios. These findings are relevant considering environmental exposure conditions, since organisms are often exposed to different combinations of contaminants.

Bax/Bcl-2 Protein Expression Ratio and Leukocyte Function Are Related to Reduction of Walker-256 Tumor Growth After β-Hydroxy-β-Methylbutyrate (HMB) Administration in Wistar Rats

This study investigated the mechanisms by which β-hydroxy-β-methylbutyrate (HMB) administration in rats reduces Walker-256 tumor growth. Male Wistar rats were supplemented with HMB (76 mg/kg/day) (HW), or a placebo (W), during 8 wk by gavage. At the 6th wk, rats were inoculated with a suspension of Walker 256 tumor cells (3 × 107/mL). Fifteen days after inoculation, the HW group showed higher glycemia (109.4 ± 5.53 vs. 89.87 ± 7.02 mg/dL, P < 0.05) and lower spleen (1.35 ± 0.05 vs. 1.65 ± 0.12 g, P < 0.05) and tumor weights (9.64 ± 1.07 vs. 13.55 ± 1.19 g, P < 0.05) compared to the W group. Tumor cells extracted from the HMB-treated rats displayed a 36.9% decrement in rates of proliferation ex vivo and a significant increase in the Bax/Bcl-2 protein expression ratio in comparison to those extracted from the placebo-treated rats (P < 0.05). Both phagocytic capacity and H2O2 production rates were higher in polymorphnuclear cells that were obtained from the blood of the HW rats in comparison to those from the W rats (P < 0.05). Reduction of necrotic regions and an intense infiltration of leukocytes and activated granulocytes in HW were evident by transmission electron microscopy. Our findings suggest that HMB supplementation decreases tumor burden by modifying the inner environment of tumor cells and by interfering with blood leukocyte function.

Complex metabolic interactions between benzo(a)pyrene and tributyltin in presence of dichlorodiphenyltrichloroethane in South American catfish Rhamdia quelen

In an attempt to explore complex metabolic interactions between toxicants present in polluted freshwater, hepatic metabolism of benzo(a)pyrene (BaP) and tributyltin (TBT) in fish was investigated when these compounds were administrated alone, mixed together and along with dichlorodiphenyltrichloroethane (DDT). Ten Rhamdia quelen per group were treated with a single intra-peritoneal (IP) dose (5-day experiment) or three successive doses (15-day experiment) either containing BaP (0.3; 3 or 30mgkg(-1)) or TBT (0.03; 0.3 or 3mgkg(-1)) or a combination of BaP+TBT, BaP+DDT, TBT+DDT and BaP+TBT+DDT under their respective lower doses, with DDT dose kept at 0.03mgkg(-1). Tetrahydroxy-benzo(a)pyrene (BaP-tetrol-I), and dibutyltin (DBT) and monobutyltin (MBT) were analyzed to assess BaP and TBT hepatic metabolism, respectively. A significant difference in BaP-tetrol-I concentration was observed in liver and bile between the lowest and the highest doses of BaP in both 5 and 15-day experiments. In the 15-day experiment, the presence of TBT with BaP reduced the amount of BaP-tetrol-I in bile compared to the BaP alone. The time of exposure and the number of doses affected BaP-tetrol-I concentration in the bile of fish exposed to BaP 0.3mgkg(-1) and BaP+DDT. TBT and its metabolites concentrations showed a dose-dependent increase in the liver in both experiments and in the bile in the 5-day experiment. TBT at its lowest dose was completely metabolized into DBT and MBT in the liver in the 15-day experiment. No TBT metabolites were detected in the bile of fish exposed to the mixtures in the 5-day experiment, except for a small MBT amount found in BaP+TBT+DDT. This study strengthens the hypothesis of a metabolic interaction between BaP and TBT in fish and suggests DDT as an important third player when present in the mixture.