Impact of chronic lithium treatment on brain oxidative stress and anxiety-like behaviors in rats: Dose-dependent effects.

Lithium (Li) is a mood-stabilizing drug. Although one of the potential mechanisms underlying the neuroprotective effects of lithium is related to its antioxidative effect, its mechanisms of action are not fully understood. Herein we aimed to investigate the impact of varied dosages of long-term lithium therapy on oxidative stress parameters in the brains of healthy rats, and on anxiety-like behaviors, and whether any changes in behavior can be attributed to modifications in oxidative stress levels within the brain. Thirty-two adult Wistar albino male rats were randomly assigned to four treatment groups. While the control (C) group was fed with a standard diet, low Li (1.4 g/kg/diet), moderate Li (1.8 g/kg/diet), and high Li (2.2 g/kg/diet) groups were fed with lithium bicarbonate (Li2CO3) for 30 days. Malondialdehyde increased, while superoxide dismutase and catalase levels decreased in the brains of the high Li group animals. In addition, anxiety-like behaviors of animals increased in the high Li group considering fewer entries to and less time spent in the open arms of the elevated plus maze test. Our findings underscore the potential adverse effects of prolonged lithium treatment, especially at doses approaching the upper therapeutic range. The induction of toxicity, manifested through heightened oxidative stress, appears to be a key mechanism contributing to the observed increase in anxiety-like behaviors. Consequently, caution is warranted when considering extended lithium therapy at higher doses, emphasizing the need for further research to delineate the precise mechanisms underlying these effects and to inform safer therapeutic practices.

The effects of environmental enrichment and transport stress on the weights of lymphoid organs, cell-mediated immune response, heterophil functions and antibody production in laying hens.

The effects of environmental enrichment and transport stress on the immune system were investigated in laying hens. A total of 48 1-day-old chickens were used, half of the chickens were reared in conventional cages (RCC) and the rest in enriched cages (REC). Transport stress was applied in the 17th week. Liver weight decreased, spleen and bursa of Fabricius weights, white blood cell count, CD4+ and CD8+ cell proportions increased due to the transport. Environmental enrichment significantly increased antibody production and tended to increase monocyte percentage and CD8+ cell proportion. The effect of transport on, heterophil (H) and lymphocyte (L) percentages was not significant in RCC chickens. While heterophil percentage and H:L ratio increased, lymphocyte percentage decreased in REC chickens subjected to transport. Transport stress increased heterophil functions both in REC and RCC chickens, but the increase was higher in REC hens than in RCC hens. In conclusion, although environmental enrichment did not neutralize the effect of transport on lymphoid organs, it activated the non-specific immune system, cellular and the humoral branches of the specific immune system by increasing heterophil functions, CD8+ cells and antibody production, respectively. Therefore, environmental enrichment suggested for improving animal welfare may also be beneficial to improve the immune system of birds exposed to stress.

The effect of furnished cages on the immune response of laying hens under social stress.

The aim of the study was to examine the effects of cage furnishing and social stress on some lymphoid organ weight and innate, cell-mediated, and humoral immune responses in laying hens. Sixty-four chickens were used. The chickens were divided into 2 groups; one of the groups was reared in furnished cages (RFC) and the other was reared in conventional cages (RCC). In wk 17, social stress was applied. Heterophil and lymphocyte percentages; liver, spleen, thymus, and bursa of Fabricius weights; phagocytic activity; oxidative burst and chemotaxic activity of heterophil; CD4+ and CD8+ cell proportions; and antibody production were measured. The effect of rearing methods was significant on heterophil, lymphocyte percentage, heterophil/lymphocyte (H/L) ratio, and antibody production. Heterophil percentage and H/L ratio were lower (P=0.001, P=0.001, respectively), and antibody production was higher (P=0.003) in RFC hens compared to RCC hens. The main effect of social stress was also significant on heterophil, lymphocyte percentages, and H/L ratio. Heterophil percentage was higher (P=0.049); H/L ratio tended to be higher (P=0.068); and lymphocyte percentage tended to be lower (P=0.072) due to stress. In addition, thymus and bursa of Fabricius weights tended to be lower (P=0.073 and P=0.074, respectively) in stressed hens. There were significant interactions between rearing methods and social stress on oxidative burst, chemotaxic activity, and CD4+ and CD8+ proportion (P=0.001, P=0.004, P=0.054, and P=0.001, respectively). These parameters were significantly higher in RFC hens, when they were exposed to stress. On the other hand, they did not differ in RCC or unstressed RFC hens. These results indicated that cage furnishing positively affected heterophil functions, CD4+ and CD8+ cell proportions, and antibody production. Therefore, we suggest that cage furnishing, which is recommended for improving the welfare of animals, is also beneficial for improving the immune response of hens under the stress condition.