Effect of cyhalothrin on Ehrlich tumor growth and macrophage activity in mice

Cyhalothrin, a pyrethroid insecticide, induces stress-like symptoms, increases c-fos immunoreactivity in the paraventricular nucleus of the hypothalamus, and decreases innate immune responses in laboratory animals. Macrophages are key elements in cellular immune responses and operate at the tumor-host interface. This study investigated the relationship among cyhalothrin effects on Ehrlich tumor growth, serum corticosterone levels and peritoneal macrophage activity in mice. Three experiments were done with 10 experimental (single gavage administration of 3.0 mg/kg cyhalothrin daily for 7 days) and 10 control (single gavage administration of 1.0 mL/kg vehicle of cyhalothrin preparation daily for 7 days) isogenic BALB/c mice in each experiment. Cyhalothrin i) increased Ehrlich ascitic tumor growth after ip administration of 5.0 x 106 tumor cells, i.e., ascitic fluid volume (control = 1.97 ± 0.39 mL and experimental = 2.71 ± 0.92 mL; P < 0.05), concentration of tumor cells/mL in the ascitic fluid (control = 111.95 ± 16.73 x 106 and experimental = 144.60 ± 33.18 x 106; P < 0.05), and total number of tumor cells in the ascitic fluid (control = 226.91 ± 43.22 x 106 and experimental = 349.40 ± 106.38 x 106; P < 0.05); ii) increased serum corticosterone levels (control = 200.0 ± 48.3 ng/mL and experimental = 420.0 ± 75.5 ng/mL; P < 0.05), and iii) decreased the intensity of macrophage phagocytosis (control = 132.3 ± 19.7 and experimental = 116.2 ± 4.6; P < 0.05) and oxidative burst (control = 173.7 ± 40.8 and experimental= 99.58 ± 41.7; P < 0.05) in vitro in the presence of Staphylococcus aureus. These data provide evidence that cyhalothrin simultaneously alters host resistance to Ehrlich tumor growth, hypothalamic-pituitary-adrenocortical (HPA) axis function, and peritoneal macrophage activity. The results are discussed in terms of data suggesting a link between stress, HPA axis activation and resistance to tumor growth.

Caffeine inhibits the development of Ehrlich ascites carcinoma cells in female mice.

Long-term administration of caffeine at a dose of 20 mg /kg/day p.o. suppressed the viability, oxygen consumption and [3H]-thymidine incorporation of Ehrlich ascites carcinoma (EAC) cells. Though no significant change in the levels of plasma and adrenal corticosterone as well as both total and reduced adrenal ascorbic acid were observed following long-term caffeine consumption, pretreatment of caffeine and continuation of its treatment in the course of development of EAC cells restored the EAC Cell-induced changes in both corticosterone and ascorbic acid levels to control values. These results, thus, suggest that caffeine may suppress the growth of EAC cells by modulating the adrenal ascorbate level as well as corticosterone status.

Evoluçäo do carcinoma mamário: novos parâmetros imunopatológicos de avaliaçäo; estudo experimental em camundongos (MuMT), II. Alteraçöes hematológicas / Course of mammary carcinoma: new immunopathologic parameters of evaluation; experimental study in mice (MuMT), II. Hematological changes

Foram comparados perfis hematológicos do sangue periférico de camundongos normais com os de camundongos inoculados, intraperitonialmente, com carcinomas de Ehrlich (MuMT). Esses animais foram sacrificados em grupos de dez, diariamente, até o 20§ dia de experimentaçäo. durante esse período de observaçäo constatou-se uma queda gradual do número de hemácias e uma inversäo dos porcentuais dos polimorfonucleares com os linfócitos, os primeiros aumentando progressivamente enquanto que os segundos decresciam da mesma forma. Os monícitos e eosinófilos aumentaram, em termos porcentuais nos primeiros dias e em seguida na metade do período de observaçäo, decresceram progressivamente até 50% dos valores iniciais. As plaquetas aumentaram ligeiramente até o 2§ dia de observaçäo e decresceram gradualmente chegando no vigésimo dia a 25% do percentual inicial

Alteraçöes da hemostasia em alguns tumores experimentais / Hemostatic changes in some experimental tumors

As alteraçöes hemostásicas em animais portadores de tumores de Ehrlich, Krebs e do carcinoma Walker-256 foram avaliadas pelo tempo de protrombina de Quick e pelo tempo de tromboplastina parcial ativada. Nos animais portadores da forma sólida desses tumores, o tempo de protombina foi sempre igual aos dos grupos-controles. Nos animais portadores das formas ascíticas, o tempo de protombina esteve aumentado, enquanto o tempo de tromboplastina parcial esteve normal nos tumores de Krebs e Ehrlich e aumentado no tumor de Walker-256