Preconditioning with acute and chronic lithium administration reduces ischemia/reperfusion injury mediated by cyclooxygenase not nitric oxide synthase pathway in isolated rat heart

Beyond its Psychiatric Use: The Benefits of Low-dose Lithium Supplementation

Lithium is most well-known for its mood-stabilizing effects in the treatment of bipolar disorder. Due to its narrow therapeutic window (0.5-1.2 mM serum concentration), there is a stigma associated with lithium treatment and the adverse effects that can occur at therapeutic doses. However, several studies have indicated that doses of lithium under the predetermined therapeutic dose used in bipolar disorder treatment may have beneficial effects not only in the brain but across the body. Currently, literature shows that low-dose lithium (≤0.5 mM) may be beneficial for cardiovascular, musculoskeletal, metabolic, and cognitive function, as well as inflammatory and antioxidant processes of the aging body. There is also some evidence of low-dose lithium exerting a similar and sometimes synergistic effect on these systems. This review summarizes these findings with a focus on low-dose lithium's potential benefits on the aging process and age-related diseases of these systems, such as cardiovascular disease, osteoporosis, sarcopenia, obesity and type 2 diabetes, Alzheimer's disease, and the chronic low-grade inflammatory state known as inflammaging. Although lithium's actions have been widely studied in the brain, the study of the potential benefits of lithium, particularly at a low dose, is still relatively novel. Therefore, this review aims to provide possible mechanistic insights for future research in this field.

Induction of autophagy reduces ischemia/reperfusion injury in steatotic rat livers

BACKGROUND

Steatotic livers are particularly vulnerable to ischemia/reperfusion injury (IRI). One of the reasons is an underlying impairment of autophagy. Autophagy is regulated by glycogen synthase kinase 3b (GSK3b) and extracellular signal-regulated kinases (ERK1/2) pathways. Both of them are target proteins of a cell-protective drug, lithium chloride. Lithium chloride treatment reduces IRI in many organs including liver. Therefore, we aimed to investigate the effect of lithium chloride treatment on autophagy induction in steatotic rat livers. We also wanted to evaluate the related cell-protective effects on the enhanced hepatic IRI.

MATERIALS AND METHODS

After inducing hepatic steatosis, rats were injected with lithium chloride or normal saline for 3 d before being subjected to 70% selective warm ischemia for 60 min. After reperfusion, rats were observed for 30 min, 6, 24, and 48 h.

RESULTS

Lithium chloride appeared to protect hepatocytes from IRI via its ability to induce autophagy by modulation of both GSK3b and ERK1/2 pathways. Hepatic damage was significantly decreased in the treatment group as indicated by a reduced inflammatory response, less apoptosis, less necrosis, and lower liver enzyme levels.

CONCLUSIONS

Simultaneous modulation of GSK3b and ERK1/2 pathways might be an interesting strategy to reduce IRI in steatotic livers with an impairment of autophagy.

Chronic lithium treatment protects against liver ischemia/reperfusion injury in rats

Lithium has long been widely used in the treatment of bipolar mood disorders. Recent studies have demonstrated that lithium is able to decrease ischemia/reperfusion (I/R) injury in the brain, kidneys, and heart. Because lithium may act on a number of stress and survival pathways, it is of great interest to explore this compound also in the setting of liver I/R injury. In this study, we aimed to evaluate the effects of lithium in a model of liver I/R injury in rats. Chronic treatment with lithium (2 mmol/kg for 3 days before ischemia) decreased I/R injury, whereas acute treatment with a single dose of lithium (2 mmol/kg 1 hour before ischemia) did not confer any protection in a partial hepatic I/R model. Furthermore, rats subjected to chronic lithium treatment had a significantly better survival rate (60%) than saline-treated rats (27%) in a total hepatic I/R survival model. Chronic lithium treatment protected against liver I/R injury, as indicated by lower serum aminotransferase levels, fewer I/R-associated histopathological changes, lower hepatic inflammatory cytokine levels, less neutrophil infiltration, and lower hepatic high-mobility group box expression and serum levels. The mechanism of action of lithium appears to involve its ability to inhibit glycogen synthase kinase 3β activation, modulate mitogen-activated protein kinase activation, inhibit hepatic apoptosis, and induce autophagy. On the basis of these data, we conclude that lithium treatment may be a simple and applicable preconditioning intervention for protecting against liver I/R injury.

Lithium exacerbates hepatic ischemia/reperfusion injury by inhibiting GSK-3β/NF-κB-mediated protective signaling in mice

Lithium (an inhibitor of GSK-3β activity) has beneficial effects on ischemia/reperfusion (I/R) injury in the central nervous system, heart and kidney. However, the role of lithium in hepatic I/R injury is unknown. The aim of this study was to assess the effects of lithium on hepatic I/R injury in a mouse model of partial hepatic I/R. Previous studies showed that lithium chloride (LiCl) can phosphorylate residue Ser9, inhibit GSK-3β activity, and improve I/R injury in other organs. In the present study, mice were pretreated with either vehicle or LiCl, which had similar effects on GSK-3β activity. Surprisingly, treatment with LiCl significantly exacerbated hepatic I/R injury, which was determined by serological and histological analyses. Acute and chronic LiCl treatment caused serious damage in hepatic I/R injury, including increased apoptosis and oxidative stress. To gain insight into the mechanism involved in this damage, the activity of nuclear factor-κB (NF-κB) (GSK-3β can regulate the transcriptional complex of NF-κB) was analyzed, which revealed that LiCl treatment significantly down-regulated the activity of NF-κB. The NF-κB-mediated protective genes were then further evaluated, including anti-apoptotic genes (RAF2, cIAP 2, Bfl-1 and cFLIP) and the antioxidant gene MnSOD. The expression of these protective genes was obviously suppressed compared with the vehicle group. Taken together, these findings show that lithium exacerbates hepatic I/R injury by suppressing the expression of GSK-3β/NF-κB-mediated protective genes.

Chronic lithium treatment protects the rat kidney against ischemia/reperfusion injury: the role of nitric oxide and cyclooxygenase pathways

Ischemia/reperfusion injury is a major problem in renal transplantation. Several evidences represent lithium preconditioning effect against ischemia/reperfusion injury in various tissues. In this study our aim was to investigate the protective effect of chronic lithium administration on renal ischemia/reperfusion injury in rats. Ischemia/reperfusion injury was induced by clamping left renal pedicle for 60 min, 2 weeks after right nephrectomy. Lithium-treated animals received lithium-chloride in drinking water for 30days. In order to investigate the role of nitric oxide (NO) and cyclooxygenase (COX) pathways in renoprotective effect of lithium, N(ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME, NO synthase inhibitor) and indomethacin (COX inhibitor) were used, respectively. Serum creatinine, blood urea nitrogen and renal histology were assessed 24h after inducing ischemia/reperfusion injury. Dimercaptosuccinic acid scan was also performed 48 h following operation. Chronic lithium treatment in ischemia/reperfusion injury groups significantly decreased creatinine (1.09±0.16 mg/dl), blood urea nitrogen (59.0±13.38 mg/dl), histological damage (7.83%±4.02%) and improved cortical function compared with non-lithium treated animals (4.45±0.44, 176.66±12.24 mg/dl and 83.5%±3.5%, respectively) (P<0.001). Either L-NAME or indomethacin administration partially reversed the protective effect of lithium, while simultaneous blockade of NO and COX pathways completely abolished lithium renoprotective effect. Our results indicate that lithium ameliorates renal ischemia/reperfusion injury through NO and/or COX pathways. We propose that lithium pre-treatment as a simple and practical intervention to boost the renal viability and function after ischemia/reperfusion injury may be promising in the setting of transplantation.

Involvement of GSK-3β in attenuation of the cardioprotective effect of ischemic preconditioning in diabetic rat heart

Ischemic preconditioning (IPC) produces cardioprotection by phosphorylation of glycogen synthase kinase-3β (GSK-3β) that inhibits the opening of mitochondrial permeability transition pore (MPTP). The activity of glycogen GSK-3β is elevated during diabetes mellitus (DM). This study investigated the role of GSK-3β in attenuation of cardioprotective effect of IPC in diabetic rat. DM was induced by single administration of streptozotocin (STZ, 50 mg/kg, i.p.). Isolated perfused heart was subjected to 30 min of ischemia followed by 120 min of reperfusion. Myocardial infarct size was estimated by triphenyltetrazolium chloride (TTC) staining and lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) was analyzed in coronary effluent. IPC significantly decreased myocardial infarct size and release of LDH and CK-MB from normal rat heart. The cardioprotective effect of IPC was significantly attenuated in diabetic rat. Four episodes of preconditioning by either of GSK-3β inhibitors, lithium chloride (LiCl, 20 mM), indirubin-3 monooxime (1 μM), and SB216763 (3 μM) significantly reduced the LDH and CK-MB release and decreased infarct size in diabetic rat heart. Perfusion of atractyloside, an opener of MPTP, significantly attenuated, the cardioprotective effect of IPC in normal rat heart, and of GSK-3β inhibitor induced preconditioning in the DM rat heart. Our results suggest that preconditioning with GSK-3β inhibitors in diabetic rat heart may provide a more consistent cardioprotection, as compared to IPC. Also, the mechanism of diabetes mellitus-induced attenuation of cardioprotective effect of IPC involves activation of GSK-3β, due to impaired protective upstream signaling pathways and opening of MPTP during reperfusion.

The ischemic metabolite lysophosphatidylcholine increases rat coronary arterial tone by endothelium-dependent mechanisms

Lysophosphatidylcholine (LPC), a hydrolysis product of phospholipid degradation, accumulates in the ischemic myocardium. Using isolated hearts or rat coronary septal arteries, we tested the impact of LPC in modulating basal function or the responses to vasoactive agents. Sustained perfusion of hearts with LPC augmented coronary perfusion pressure (CPP) and reduced left ventricular developed pressure (LVDP). By mechanisms that have yet to be identified, these effects on CPP and LVDP were exaggerated when LPC was removed from the perfusate. Although LPC (or its washout) had no direct effect on vascular tone in the isolated coronary artery, it selectively potentiated the receptor-coupled vasoconstrictor response to U-46619, a thromboxane A(2) mimetic. Interestingly, when LPC was washed out, the potentiation to U-46619 was even more pronounced. Both the immediate and residual effects of LPC were endothelium-dependent. EDHF was likely the sole mediator responsible for the direct effects of LPC on U-46619-vasoconstriction, whereas the augmented vasoconstrictor responses following LPC washout may in part be related to an increase in ET-1, and a striking reduction in the bioavailability of NO. Our data suggest that in addition to reducing the accumulation of LPC to prevent ischemia-reperfusion (I/R) damage, efforts targeting an improved endothelium-dependent regulation of vascular tone could be an attractive approach to limit the cardiac damage induced by I/R.