Blood and spleen natural killer cell cytotoxicity after exposure to open field stress in rats: the effect of spontaneous locomotor activity

Changes in blood CD4+T and CD8+T lymphocytes in stressed rats pretreated chronically with desipramine are more pronounced after chronic open field stress challenge

The present study examines the influence of a chronic (14 consecutive days) desipramine (10mg/kg i.p.) pretreatment by itself vs. after chronic (7 consecutive day) open-field (OF) on immune system alterations in response to acute (30 min) OF in Wistar rats (n=60). Opposing to the effect of desipramine injected alone, the combined pretreatment after chronic OF challenge exerts suppressive effects on peripheral blood T/B, CD4(+)T-helper/inducer and CD8(+)T-cytotoxic/suppressor but not NK cell number, decreased interferon-γ/interleukin-10 ratio and thymus weight in the stressed rats. It suggests that chronic stress exposure is important for the immunomodulatory effects of pretreatment with antidepressants.

Effects of chronic desipramine pretreatment on open field-induced suppression of blood natural killer cell activity and cytokine response depend on the rat's behavioral characteristics

Effects of 14 consecutive day exposure to desipramine (10mg/kg i.p.), by itself or following chronic open field (OF) exposure, on subsequent neuroimmunological effects of acute (30 min) OF stress and the involvement of individual differences in response to novelty or social position in the anti-depressive responsiveness were investigated. Chronic desipramine pretreatment did not protect against OF stress-induced suppression of blood anti-tumor natural killer cell activity but increased plasma interleukin-10 and decreased interferon-γ and corticosterone concentration. These effects were particularly dangerous for the animals with increased responsivity to stress (desipramine alone) or with low behavioral activity (desipramine after chronic stress).

Immuno-enhancement effects of Shenqi Fuzheng Injection on cyclophosphamide-induced immunosuppression in Balb/c mice

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Codonopsis and Radix Astragali, of which Shenqi Fuzheng Injection (SFI) is composed, are commonly used in traditional Chinese medicine to improve immune function against chronic diseases.

AIM OF THE STUDY

The present study was thus designed to systematically elucidate the in vivo immuno-enhancement effects of SFI in immunosuppressed mice induced by cyclophosphamide (Cy) treatment.

MATERIALS AND METHODS

Balb/c mice were injected intraperitoneally (i.p.) once daily with low-dose (2.5 g raw materials/kg), intermediate-dose (5 g raw materials/kg), high-dose (10 g raw materials/kg) of SFI for 10 consecutive days, respectively, accompanied by i.p. injection of Cy (80 mg/kg) on Days 4-6.

RESULTS

Compared with vehicle group, low-, intermediate- and high-dose SFI treatment accelerated recovery dose-dependently of spleen index, peripheral white blood cell and bone marrow cell counts, enhanced T cell and B cell proliferation responses, as well as splenic nature killer cell activity and peritoneal macrophage phagocytosis, and restored the level of interleukin-2 in the serum. Furthermore, SFI treatment promoted recovery of the amount of peripheral white blood cells on Day 6, rather than recombinant human Granulocyte Colony-Stimulating Factor (rhG-CSF) did.

CONCLUSIONS

These results demonstrate, for the first time, that chronic treatment with SFI results in accelerating recovery of immunosuppression in Cy-treated mice, which is competent in taking into consideration for both precautions and remedy. Our findings provide experimental evidences for further researches and clinical application in cancer patients undergoing chemotherapy.

Basal anxiety-like behavior predicts differences in dendritic morphology in the medial prefrontal cortex in two strains of rats

Basal differences in the brain may account for why some individuals are more vulnerable to stress than others. Although trait anxiety behavior varies greatly in human populations, most animal models of anxiety disorders tend to focus on the development of anxiety after a stressful experience. In this study, adult male Sprague-Dawley and Lewis rats were grouped according to baseline anxiety-like behavior in the open field, measured by time spent and distance traveled in the center. Individuals that fell one standard deviation above and below the mean, approximately the top and bottom 15%, were selected for the Low and High Anxiety groups. Pyramidal neurons from layer II/III of the prelimbic region of the medial prefrontal cortex were iontophoretically loaded with Lucifer yellow dye and reconstructed. In both strains, animals in the High Anxiety group had smaller apical dendrites than those in the Low Anxiety group. No difference was found in basal dendrites. Sholl analysis revealed a strain difference in the distribution of dendritic material between anxiety groups. These results illustrate significant variability in dendritic morphology in the prefrontal cortex of healthy adult male rats prior to experimental manipulation that correlates with baseline levels of anxiety-like behavior.

Airway cytokine responses to acute and repeated stress in a murine model of allergic asthma

Although stress is known to exacerbate asthma, the underlying mechanisms are unclear. Using a murine model of allergic asthma, Th1 (interleukin [IL]-2 and gamma-interferon [IFN-γ]) and Th2 (IL-4 and IL-5) airway cytokine responses and Th1:Th2 cytokine ratios to acute and repeated stress were examined in bronchoalveolar lavage fluid (BALF). Asthmatic mice showed significantly higher IL-4 level and Th2 predominance, compared with healthy mice. To acute stress, asthmatic mice significantly increased IL-4 but decreased IFN-γ levels favoring Th2 predominance, whereas healthy mice significantly decreased IL-4 level favoring Th1 predominance in BALF. To repeated stress, asthmatic mice significantly decreased IFN-γ, IL-4 and IL-5 levels overall favoring Th1 predominance, whereas healthy mice basically maintained the same response profile shown to acute stress. These findings suggest that a significant shift toward Th2 predominance in asthmatic mice under acute stress may be a mechanism underlying exacerbation of asthma.

The immunosuppressive effects of 10mg/kg cyclophosphamide in Wistar rats

The purpose of this study is to identify the immunosuppressive effects of cyclophosphamide (a known immunosuppressant) in male Wistar rats which were administered orally for 30 days repeatedly, and to find a proper dose of cyclophosphamide at which the immunosuppressive effects is identified. The dose of cyclophosphamide is 2, 5, 10mg/kg bw, respectively. The results showed that 10mg/kg cyclophosphamide treatment induced decreases in body weight, body weight gain, relative weight of spleen and thymus, antibody plaque-forming cells, delayed-type hypersensitivity reaction, natural killer cell activity, lipopolysaccharide-induced B-cell proliferation, and Concanavalin A-induced T-cell proliferation. The histopathology observation on spleen and thymus revealed as decreased cellularity. But, no significant clinical symptoms of toxicities and stress were observed and no rats died. These results indicated that the immunosuppressive effects of 10mg/kg cyclophosphamide dosed for 30 days orally were identified in male Wistar rats. Based on the results, it is considered that the dose of 10mg/kg of cyclophosphamide orally for 30 days in male Wistar rats could be used as the dose of positive control group for chemicals immunotoxicity assessment tests. This study also proved that the testing procedures and the experimental techniques established in our laboratory for immunotoxicity tests in male Wistar rats are reliable and feasible.