The impact of oxytocin on thiol/disulphide and malonyldialdehyde/glutathione homeostasis in stressed rats

We aimed to investigate the impact of oxytocin on serum thiol/disulphide and malonylyldialdehyde (MDA)/glutathione balance under acute stress (AS) and chronic stress (CS) exposure in rats. Animals were allocated into control (C), AS and CS groups, then the groups subdivided as intranasal oxytocin or saline applied groups, randomly. Animals in the AS or CS groups were exposed to combined cold-immobilisation stress. Salivary corticosterone levels and elevated plus maze (EPM) scores were used to assess stress response. MDA, glutathione, thiol-disulphide levels were measured in the serum samples. Oxytocin treatment attenuated stress response regardless of the stress duration verified by lower corticosterone level and favorable profile in EPM parameters measured. Furthermore, oxytocin modulated oxidant profile suggesting lowered oxidant stress with decreased serum MDA/glutathione and disulfide/native thiol ratios. Oxytocin improves the response of organism to stress via both its anxiolytic and antioxidant effects. That’s why it can be considered as a protective measure to employ methods to increase endogenous oxytocin and/or to apply exogenous oxytocin to prevent stress-induced increase in oxidant stress, which plays a pivotal role in the pathogenesis of various stress-related diseases.

Anxiolytic-like effect of Bifidobacterium adolescentis IM38 in mice with or without immobilisation stress

To better understand the role of gut microbiota in the anxiety, we isolated bifidobacteria and lactobacilli from the human faecal microbiota, investigated their inhibitory effects on the expression of interleukin (IL)-6 and tumour necrosis factor (TNF)-α in lipopolysaccharide-stimulated macrophages, and examined the anxiolytic-like effect of Bifidobacterium adolescentis IM38 in mice treated with or without immobilisation stress using the elevated plus maze (EPM) task. Oral administration of IM38 at a dose of 1×109 cfu/mouse showed a significant anxiolytic-like effect both in mice exposed to immobilisation stress and in control mice using the EPM test (P<0.05). Moreover, IM38 treatment significantly increased the amount of time spent on open arms and open arm entries. The anxiolytic-like effect of IM38 was comparable to that of buspirone (1 mg/kg). Moreover, this anxiolytic-like effect was blocked by treatment with flumazenil (3 mg/kg, i.p.), a benzodiazepine receptor antagonist, but was not affected by treatment with bicuculine or WAY-100635. IM38 treatment also reduced the blood levels of corticosterone and IL-6 in mice with or without immobilisation stress, whereas this effect was abolished by treatment with flumazenil. IM38 treatment also reduced the blood TNF-α level in mice subjected to immobilisation stress but not in normal control mice. Treatment with flumazenil also significantly increased TNF-α and IL-6 levels in immobilisation stress-free mice treated with IM38. These findings suggest that IM38 may attenuate anxiety through modulation of the benzodiazepine site on the GABAA receptor and modulate stress-related cytokine expression.

Impact of thymoquinone supplementation on immobilisation stress-induced changes in reproductive characteristics of male mice

The aim of the current study was to investigate changes in the reproductive parameters during stress and the impact of thymoquinone during the period. The effects of stress were measured through immobilisation stress on mice. Group I was administered normal saline daily via intraperitoneal injection while Groups II and III were subjected to 2 and 6 hours of immobilisation stress respectively. Groups IV and V were subjected to stress for 2 and 6 hours respectively followed by intraperitoneal injection of 10 mg/kg thymoquinone which was continued on alternate days. The level of significance was set at p<0.05 and statistical analysis showed significant difference in testicular weight of mice in groups II and III compared to the controls but no significant difference was obtained for sperm count between all groups. Sperm motility, however, was significantly different among the groups under stress for 2 and 6 hours and that of 6 hours with the treatment of thymoquinone when compared to the controls. The histology of the testes also indicated a few alterations in comparison to the controls in the germinal epithelium and spermatogenic pattern in groups III and V.

Serum lipid peroxidation markers are correlated with those in brain samples in different stress models

ObjectiveStress can stimulate increased production of oxygen radicals. We investigated the correlations between serum levels of lipid peroxidation markers and those in brain samples in different stress models.MethodsAnimals (n= 96) were divided equally into eight groups: a control group and groups treated with vitamin E (Vit E); exposed to immobilisation stress; exposed to immobilisation stress and treated with Vit E; exposed to cold stress; exposed to cold stress and treated with Vit E; exposed to both immobilisation and cold stress; and a final group exposed to both immobilisation and cold stress and treated with Vit E. Thiobarbituric acid-reactive substance (TBARS) in brain samples and levels of TBARS, corticosterone, conjugated dienes (CD), lipids, and paraoxonase-1 (PON1) activity in serum were analysed.ResultsSerum corticosterone (p< 0.001), CD (p< 0.05), lipid (p< 0.05) levels, and brain TBARS (p< 0.05) levels were significantly higher in all stress groups than in controls, and the elevated levels were reversed in the Vit E-treated stress groups (p< 0.05). Serum PON1 activity was not different among the groups (p> 0.05). Serum TBARS levels increased significantly in all stress groups (p< 0.05), but this elevation was only reversed in the group exposed to both immobilisation and cold stress and treated with Vit E (p< 0.001).ConclusionThese results suggest that serum levels of lipid peroxidation markers can be determined readily and may be useful as indicators to evaluate the effects of oxidative stress in the brain.