Crude polysaccharide extracts were obtained from aqueous extracts of the microalgae Chlorella stigmatophora and Phaeodactylum tricornutum. The crude extracts were fractionated by ion-exchange chromatography on DEAE-cellulose columns. The molecular weights of the polysaccharides in each fraction were estimated by gel filtration on Sephacryl columns. The crude polysaccharide extracts of both microalgae showed anti-inflammatory activity in the carrageenan-induced paw edema test. In assays of effects on the delayed hyper-sensitivity response, and on phagocytic activity assayed in vivo and in vitro, the C. stigmatophora extract showed immunosuppressant effects, while the P. tricornutum extract showed immunostimulatory effects.

1 In this study, we investigated whether serotonin could regulate the in vitro activity of phagocytosis through 5-hydroxytryptamine or serotonin (5-HT 1A ) receptors. 2 Mouse peritoneal macrophages were cultured with serotonin and the activity of phagocytosis was assessed by the uptake of zymosan and latex particles added to the culture media. Specific binding of [ 3 H]8-OH-DPAT and immunohistochemistry using an affinity-purified anti-5-HT 1A -receptor antibody were assayed in the macrophages. In addition, we took advantage of the availability of pharmacological inhibitors of nuclear factor-kB (NF-kB) to explore its role in the regulation of the 5-HT 1A receptor. 3 Serotonin increased the in vitro activity of phagocytosis in a dose-dependent manner. The 5-HT 1A receptor agonist (7)-8-hydroxy-2-(di-n-propyl-amino)-tetralin (R(+)-8-OH-DPAT) reproduced these effects. Serotonin-or R(+)-8-OH-DPAT-induced increases in phagocytosis were blocked by the 5-HT 1A receptor antagonist WAY100635 and the NF-kB inhibitor pyrrolidinedithiocarbamate. Moreover, mouse peritoneal macrophages expressed specific binding sites for [3 H]8-OH-DPAT when cultivated in the presence of zymosan or latex beads. Immunohistochemistry confirmed the expression of the 5-HT 1A receptor protein in the macrophages. 4 These results show that serotonin can upregulate the activity of peritoneal macrophages through 5-HT 1A receptors.

Emotional stress can be viewed as a cause of adverse circumstances that induces a wide range of biochemical and behavioural changes. Oxidative stress is a critical route of damage in various psychological stress-induced disorders such as depression. Antidepressants are widely prescribed to treat these conditions; however, no animal study has investigated the effect of selective serotonin reuptake inhibitors (SSRIs) on the levels of intracellular reactive oxygen species in peripheral blood leucocytes of stressed mice. In this study, mice were immobilized for a period of 6 hr. Fluoxetine (5 mg ⁄ kg of bodyweight) was administered 30 min. before subjecting the animals to acute stress. The level of intracellular reactive oxygen species in leucocytes of the peripheral blood of stressed mice was investigated using a 2¢,7¢-dichlorofluorescein diacetate probe, and the antioxidant response of fluoxetine was evaluated by superoxide dismutase, diaphorase, catalase and reduced glutathione. Our results show that restraint stress significantly increases the generation of reactive oxygen species in the peripheral defence cells. Treatment with fluoxetine partially reverses the adverse effects of stress. The improvement in cellular oxidative status may be an important mechanism underlying the protective pharmacological effects of fluoxetine, which are clinically observed in the treatment of depressive disorders.

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Tobacco use is the leading risk factor for lung cancer, yet in addition to smoking habit, diet may also play a role in the disease's appearance. While there are reports to indicate that antioxidant vitamins and carotenoids may decrease the risk of lung cancer, results to date have been somewhat ambiguous. This review aimed to describe the results yielded by different studies, which have addressed antioxidant vitamin intake and lung cancer, and to indicate the mechanisms whereby these nutrients might be exercising their activity. Antioxidant vitamins were observed to have no clear protective effect, though there was some evidence pointing to a protective role for vitamins C and E. Vitamin A, in contrast, evinced no clear effect. Insofar as provitamin A carotenoids were concerned, lutein/zeaxanthin, lycopene and alpha-carotene displayed a certain protective trend, yet beta-carotene exhibited no protective effect whatsoever; and indeed, there was speculation as to whether it might even be pernicious in smokers. Beta-criptoxanthin, on the other hand, showed a more consistent protective effect. The study highlighted the need to conduct further research on smokers and non-smokers alike, and in particular, to investigate the effect, if any, on lung cancer of carotenoids or vitamins when ingested in differing dosages.