Effect of diazepam on the immune response of rats exposed to acute and chronic swim stress

Role of Elsholtzia communis in counteracting stress by modulating expression of hspa14, C/EBP homologous protein, nuclear factor (erythroid-derived 2)-like-2 factor, Caspase-3, and brain-derived neurotrophic factor in rat hippocampus

OBJECTIVE:

Elsholtzia communis (Collett and Hemsl.) Diels has been widely distributed and is reported for many therapeutic effects. The present study aims to investigate the antistress activity of the leaf extract and its possible molecular mechanism.

MATERIALS AND METHODS:

Hydroethanolic extract of leaves of E. communis (100 and 200 mg/kg, p.o.) were administered for 7 days to stress-induced male Wistar rats. The experimental animals were divided into five groups (n = 6). The mRNA/protein profile of few stress responsive chaperones (hspa14), endoplasmic reticulum stress markers (C/EBP homologous protein [CHOP]), antioxidant regulating genes (nuclear factor (erythroid-derived 2)-like-2 factor [Nrf2]), apoptotic factors (Caspase-3) in rat hippocampus were studied by polymerase chain reaction and immunoblotting.

RESULTS:

The stress-related genes such as hspa14, CHOP, antioxidant gene Nrf2, apoptotic gene Caspase-3 which were overexpressed in the stress control group were significantly suppressed following administration of the extract at both the doses and the standard drug Ginseng. Likewise, brain-derived neurotrophic factor which is closely related with stress, was downregulated in the stress control group, was found to be upregulated following treatment with the extract and the standard drug Ginseng.

CONCLUSION:

Our findings clearly indicate that E. communis was able to counteract stress. Hence, it has the potential to develop as adaptogen and also as a replacement/substitute of the popularly used drug, Ginseng or Ashwagandha, which is on the verge of extinction or becoming endemic due to overuse.

The effect of creatine supplementation on myocardial function, mitochondrial respiration and susceptibility to ischaemia/reperfusion injury in sedentary and exercised rats

AIM

To investigate the effects of dietary creatine supplementation alone and in combination with exercise on basal cardiac function, susceptibility to ischaemia/reperfusion injury and mitochondrial oxidative function. There has been an increase in the use of creatine supplementation among sports enthusiasts, and by clinicians as a therapeutic agent in muscular and neurological diseases. The effects of creatine have been studied extensively in skeletal muscle, but not in the myocardium.

METHODS

Male Wistar rats were swim-trained for 8 weeks, 5 days per week. Hearts were excised and either freeze-clamped for biochemical analysis or perfused on the isolated heart perfusion system to assess function and ischaemia/reperfusion tolerance. Mechanical function was documented in working heart and retrograde mode. The left coronary artery was ligated and infarct size determined. Mitochondrial oxidative capacity was quantified.

RESULTS

Aortic output recovery of hearts from the sedentary controls (CSed) was significantly higher than those from creatine-supplemented sedentary (CrSed), creatine-supplemented exercised (CrEx) as well as control exercised (CEx) groups. Ischaemic contracture of hearts from CrEx was significantly higher than that of CSed. There were no differences in infarct size and mitochondrial oxygen consumption.

CONCLUSION

This study suggests that creatine supplementation has no effects on basal cardiac function but reduces myocardial tolerance to ischaemia in hearts from exercise-trained animals, by increasing the ischaemic contracture and decreasing reperfusion aortic output. Exercise training alone also significantly decreased aortic output recovery. However, the exact mechanisms for these adverse myocardial effects are unknown and need further investigation.

Acute stress suppresses pro-inflammatory cytokines TNF-alpha and IL-1 beta independent of a catecholamine-driven increase in IL-10 production

Interleukin (IL)-10 is an anti-inflammatory cytokine that can down-regulate various aspects of the immune response. In this study we demonstrate that exposure to a psychophysiological stressor (swim stress) increases IL-10 production in female rats in response to an in vivo challenge with bacterial lipopolysaccharide (LPS). This increase in LPS-induced IL-10 was associated with suppression of the pro-inflammatory cytokines IL-1beta and TNF-alpha, indicating that overall, swim stress promotes an immunosuppressive cytokine phenotype. Despite the well-documented ability of IL-10 to suppress pro-inflammatory cytokine production, neutralisation of IL-10 failed to block the stress-induced suppression of IL-1beta and TNF-alpha. These data indicate that the suppressive effect of swim stress on these pro-inflammatory cytokines occurs independently of increased IL-10 production. To determine if swim stress-induced immunosuppression was mediated by increased sympathetic nervous system activity, and subsequent beta-adrenoceptor activation, we assessed the ability of the beta-adrenoceptor antagonist nadolol to block stressor-induced changes in cytokine production. Whilst pre-treatment with nadolol completely blocked the stress-induced increase in IL-10, it failed to alter the suppression of TNF-alpha or IL-1beta. Similarly, pre-treatment with the glucocorticoid receptor antagonist mifepristone also failed to attenuate the suppressive effect of swim stress on IL-1beta and TNF-alpha production. These data indicate that neither increased glucocorticoid secretion, nor catecholamine-induced beta-adrenoceptor activation, mediates the suppressive effect of swim stress on pro-inflammatory cytokine production. Taken together, these data demonstrate a role for beta-adrenoceptor activation in the ability of acute swim stress to increase LPS-induced IL-10 production, and also highlight a mechanistic dissociation between the ability of swim stress to increase IL-10 and suppress pro-inflammatory cytokine production.

Environmental enrichment in mice decreases anxiety, attenuates stress responses and enhances natural killer cell activity

The importance of environment in the regulation of brain, behaviour and physiology has long been recognized in biological, social and medical sciences. Animals maintained under enriched conditions have clearly been shown to have better learning abilities than those maintained under standard conditions. However, the effects of environmental enrichment (EE) on immunity and emotionality have been less documented and remain questionable. Therefore, we investigated the effect of EE on natural killer (NK) cell activity, psychological stress responses and behavioural parameters. Male C3H mice were housed either in enriched or standard conditions for 6 weeks. Behaviour was then examined by the grip-strength test, staircase and elevated plus maze, and corticosterone levels and NK cell activity were measured. Furthermore, animals exposed to the stress paradigm, achieved by electric shock with reminders, were tested for freezing time in each reminder. Corticosterone levels were also measured. The EE mice showed decreased anxiety-like behaviour and higher activity compared to standard mice, as revealed by a greater percentage of time spent in the open arms of the elevated plus maze, and a higher rate of climbing the staircase. A shorter freezing time in the stress paradigm and no corticosterone level reactivity were measured in EE mice. In addition, NK cell activity in spleens of EE mice was higher than that demonstrated in those of standard mice. Thus, EE has a beneficial effect on anxiety-like behaviour, stress response and NK cell activity. The effect on NK cell activity is promising, due to the role of NK cells in host resistance.

Antifatigue and antistress effect of the hot-water fraction from mycelia of Cordyceps sinensis

This study was conducted to investigate the chemical component of the hot water (HW) fraction of mycelia of Cordyceps sinensis and its antifatigue and antistress effect against a stimulus in vivo using rats and mice. The growth of mycelia reached a maximum level of 31.6 g/l after 120 h of incubation. The main chemical composition of the HW fraction of mycelia of C. sinensis was found to be carbohydrate (78.9%) with 5% moisture. The swimming endurance capacity of mice orally administered with the HW fraction (150 and 300 mg/kg/d, respectively) was significantly prolonged from 75 to 90 min with a lessening of fatigue. When the HW fraction (150 mg/kg/d) was given to rats for 8 d including a 48 h stress period, the weight changes of the adrenal gland, spleen, thymus, and thyroid, which is an index of stress, were suppressed. The HW fraction also significantly inhibited the increase in total cholesterol and the decrease in alkaline phosphatase levels as biochemical parameters of immobilization stress in rats.

Effect of diazepam treatment and its withdrawal on pro/antioxidative processes in rat brain

Exploratory studies were undertaken to ascertain the role of pro/antioxidative processes during a 3 weeks administration of low sub-toxic dose of diazepam and its withdrawal. Rats were administered 3 mg/kg diazepam for 21 consecutive days and the changes observed in different regions of rat brain at the sub-cellular level. Mitochondria from cerebrum showed a 27% lowering of TBARS whereas those from cerebellum and brain stem showed 48 and 24% enhanced MDA levels respectively. No significant alteration in the SOD isozymes was observed after the dose schedule. The mitochondrial glutathione reductase (GR) activity showed a decrease in all the regions with maximum decrease (36%) recorded in brain stem while post mitochondrial fraction showed significant lowering in cerebrum (37%). Total -SH content increased in all the three regions with maximum enhancement recorded in cerebellum while the free thiol content also showed significant changes (p < 0.001) in cerebellum and brain stem. One week after the withdrawal of the drug MDA levels decreased by 38% in cerebrum and 53% each in mitochondrial fractions of cerebellum and brain stem. Regional heterogeneity in response was also observed in the post mitochondrial fractions. Mn-SOD showed lowered activity in cerebellum (22%) and in brain stem (15%). The mitochondrial GR activity decreased in all the regions being highest in cerebrum with no significant change in post mitochondrial fractions. The total and free -SH content in the withdrawn animals increased by 46% in cerebellum with no change in the other two regions. The results indicate towards lower oxidative phenomenon during 3 weeks treatment with diazepam while abrupt withdrawal causes lowering of antioxidant defenses which showed regional heterogeneity. A decrease in peroxidative decomposition of polyunsaturated fatty acids of membranes was observed on withdrawal, which could be due to stabilisation of membranes after long-term binding of diazepam.

Phagocytosis--the mighty weapon of the silent warriors

Professional phagocytes, comprising polymorphonuclear neutrophils and monocyte/macrophage cells, play an important role in the host defense. Any defect in their function exposes the organism to microbial intruders terminating in fatal diseases. The functional responses of the phagocytes to bacterial and fungal infections include chemotaxis, actin assembly, migration, adhesion, aggregation, phagocytosis, degranulation, and reactive oxygen species production. Superoxide generation by phagocytic NADPH oxidase is an imperative step toward bacterial killing. Phagocytes participate in inflammatory reactions and exert tumoricidal activity. They are supported by serum factors such as immunoglobulins, cytokines, complement, the acute phase reactant C-reactive protein, production of antibacterial proteins, and others. In addition to their principal task to eliminate bacteria, they are engaged in removing damaged, senescent, and apoptotic cells. Engulfed cell debris, large particles such as latex beads, fat, and oil droplets, are examples of phagocytic activity illustrated in the present review with transmission and scanning electron microscope micrographs. Numerous factors, such as diseases and stressful conditions, affect the engulfing activity of the professional phagocytes. Our experience regarding the impaired phagocytic capacity of cells in patients with diabetes and chronic renal failure is discussed. The results obtained in our laboratory from experiments detecting the effect of strenuous physical exercise, hypothermia, fasting, and abdominal photon irradiation on the phagocytic capacity of human polymorphonuclear neutrophils and rat peritoneal macrophages are hereby summarized and the reports on those subjects in the recent literature are reviewed. A variety of assays are applied for quantifying phagocytosis. Flow cytometry based on incubation of phagocytic cells with fluorescent conjugated particles and measuring the amount of fluorescence as an indicator of the engulfing capacity of the cells is a useful method. A direct visualization of the ingested particles using light or electron microscopy is a valuable tool for estimation of phagocytic function. In our hands, the use of semithin sections of embedded phagocytes following their incubation with latex particles provided satisfactory results for measuring the total number of phagocytic cells, as well as the internalizing capacity of each individual cell. Microbiological assays, the nitroblue tetrazolium test, quantitation of antibody- and antigen-mediated phagocytosis, as well as methods reviewed in detail in other reports are additional applications for determination of this intricate process.