Glucocorticoid exposure causes disrupted glucoregulation, cardiac inflammation and elevated dipeptidyl peptidase-4 activity independent of glycogen synthase kinase-3 in female rats

Roflumilast counteracts high-dose dexamethasone-induced steatohepatitis, metabolic abnormalities and aortic injury via inhibiting TNF-α/NF-κB, NLRP3/IL-1β and ER stress sensors

INTRODUCTION

High-dose dexamethasone (DEX) is used for management of severe conditions. However, the multisystem adverse effects induced by glucocorticoids represent a hindering stone toward the effective clinical use of such agents. Various initiatives have been taken to ameliorate these complications with limited success.

AIM

The present study aims to explore the beneficial effects of roflumilast (ROF), a phosphodiesterase-4 (PDE-4) inhibitor, to combat DEX-induced steatohepatitis, metabolic abnormalities and aortic degeneration.

RESULTS

The application of ROF (2.5 and 5 mg/kg) has reverted the hepatic and aortic histopathological abnormalities as well as the rise in serum liver enzymes induced by DEX. Such palliative effect is probably attributed to PDE-4 inhibition (↑cAMP) that subsequently regulates multiple effectors. The chemotaxis of inflammatory cells (MCP-1) was inhibited by ROF treatments which was linked to inhibition of extracellular ROS production (MDA and NO) as well as restoration of cellular antioxidant defense (GSH). DEX challenge was associated with activation of the inflammatory pathways including TNF-α/NF-κB and NLRP3/IL-1β that were significantly dampened in the ROF groups. The oxidative stress as well as activation of inflammatory pathways exerted by DEX has contributed to the activation of endoplasmic reticulum stress (CHOP and PERK) posing more threats to the insulted cells, however, fortunately, ROF treatments showed inhibited activation of ER stress sensors and thereby abstaining the cells from inevitable damage. The metabolic abnormalities induced by DEX including elevated fasting insulin and heightened AUC of blood glucose level upon application of oral glucose tolerance test were significantly improved by ROF treatment.

CONCLUSION

The findings of our study depicted the hepatoprotective and metabolic regulating potentials of ROF in a rat model of DEX- induced steatohepatitis. Thereby, enhancing the overall efficacy and safety of DEX use in management of various disorders.

Depletion of hepatic glutathione and adenosine by glucocorticoid exposure in Wistar rats is pregnancy-independent

Liver diseases have gained increasing attention due to their substantial impact on health, independently as well as in association with cardio-metabolic disorders. Studies have suggested that glutathione and adenosine assist in providing protection against oxidative stress and inflammation while glucocorticoid (GC) therapy has been associated with chronic inflammatory disorders, even in pregnancy. The implications of Glucocorticoid exposure on maternal health and fetal growth is a concern, however, the possible role of glutathione and adenosine has not been thoroughly investigated. The study therefore hypothesize that exposure to glucocorticoids leads to depletion of hepatic glutathione and adenosine levels, contributing to oxidative stress and tissue injury. Additionally, we aim to investigate whether the effects of glucocorticoids on hepatic health are pregnancy dependent in female rats. Twelve Pregnant and twelve age-matched non-pregnant rats were used for this study; an exogenous administration of glucocorticoid (Dex: 0.2 mg/kg) or vehicle (po) was administered to six pregnant and six non-pregnant rats from gestational day 14 to 19 or for a period of 6 days respectively. Data obtained showed that GC exposure led to a decrease in hepatic glucose-6-phosphate dehydrogenase, glutathione peroxidase, GSH/GSSG ratio and adenosine content in both pregnant and non-pregnant rats. In addition, increased activities of adenosine deaminase and xanthine oxidase, along with increased production of uric acid and increased levels of lactate dehydrogenase, aspartate aminotransferase, alanine transferase, alkaline phosphatase and gamma-glutamyl transferase were observed. In summary, the study indicates that GC-induced liver damage is underlined by depleted hepatic adenosine and glutathione levels as well as elevated markers of tissue inflammation and/or injury. Furthermore, the findings suggest that the effects of GC exposure on hepatic health are pregnancy independent.

Exosomes from Adipose-Derived Mesenchymal Stem Cells Protect Against Cyclophosphamide-Induced Cardiotoxicity in Rats

A certain dosage of cyclophosphamide (CYP) in clinical applications contributes to severe cardiotoxicity. Herein, this study explored the impact of adipose-derived mesenchymal stem cell (AdMSC)-exosomes (Exos) on CYP-induced cardiotoxicity.AdMSCs and AdMSCs-Exos were isolated and identified. CYP was utilized for developing a cardiotoxicity rat model, after which blood was collected and then the serum contents of cardiac injury-related indexes (creatine kinase-MB, lactate dehydrogenase, aspartate aminotransferase, and alkaline phosphatase) were detected with enzyme-linked immunosorbent assay kits. Oxidative stress (OS)-related indicators were measured with the corresponding kits. Myocardial pathological changes and collagen fibrosis were tested with hematoxylin-eosin and Masson staining, and apoptosis-related and autophagy-related proteins in rat cardiac tissues with immunohistochemistry and Western blot assays, respectively.AdMSCs and AdMSCs-Exos were successfully isolated. AdMSCs-Exos could target rat hearts. AdMSCs-Exos improved cardiac function and diminished the content of the cardiac injury-related indexes in CYP rats. In addition, AdMSCs-Exos reduced CYP-induced cardiac fibrosis, OS, apoptosis, and autophagy in rats.AdMSCs-Exos alleviated CYP-induced cardiotoxicity in rats via the repression of OS, apoptosis, and autophagy.

Insulin resistance and depressed cardiac G6PD activity induced by glucocorticoid exposure during pregnancy are attenuated by maternal estrogen-progestin therapy

This study aimed to investigate the effects of maternal combined oral contraceptive (COC) on dams that were exposed to late gestational glucocorticoids (GC). Twenty-four pregnant female rats were randomly allotted into 4 groups of 6 dams each. Dams received COC (combination of 1.0 μg ethinylestradiol and 5.0 μg levonorgestrel p.o.) between 3rd and 11^th week after delivery with or without prior exposure to GC (dexamethasone; 0.2 mg/kg p.o.) that was administered between gestational days 14-19. Data showed that late-gestational GC exposure led to insulin resistance (IR), increased cardiac adenosine deaminase (ADA), xanthine oxidase (XO), lactate, lactate dehydrogenase (LDH), and disrupted cardiac glucose-6-phosphate dehydrogenase (G6PD)-dependent antioxidant defenses. On the other hand, maternal COC treatment in dams not exposed to gestational GC led to IR, increased cardiac XO, LDH and defective cardiac G6PD-dependent antioxidant defenses. However, maternal COC with prior gestational GC exposure led to attenuated IR, cardiac ADA, UA, LDH, and improved cardiac G6PD-dependent antioxidant defenses but worsened cardiac triglyceride (TG) accumulation when compared with dam with gestational GC exposure without maternal COC. Taken together, the findings of this study provide evidence that maternal COC treatment improves late gestational GC-programmed effects. This is however accompanied with enhanced cardiac TG accumulation.

Dexamethasone increases renal free fatty acids and xanthine oxidase activity in female rats: could there be any gestational impact?

Dexamethasone (DEX) is used for various conditions in female and even during pregnancy. We tested the hypothesis that DEX exposure in female rats would lead to renal free fatty acid (FFA) accumulation with elevated xanthine oxidase (XO) activity that would be aggravated by pregnancy. Twenty-four female rats (n = 6/group) were randomly assigned to non-pregnant (NPR), DEX-exposed non-pregnant (NPR + DEX), pregnant (PRE) and DEX-exposed pregnant (PRE + DEX), respectively. NPR and PRE rats received vehicle (po) while NPR + DEX and PRE + DEX groups received DEX (0.2 mg/kg; po), between gestational days 14 and 19. Data showed that DEX exposure caused increased plasma creatinine, urea, renal FFA accumulation, lipid peroxidation, aminotranferases, depressed glutathione, increased activity of XO, and elevated uric acid in both pregnant and non-pregnant rats. The findings of this study indicate that DEX exposure would cause renal FFA accumulation and glutathione depletion that are accompanied by increased activity of XO/uric acid independently of gestation. The study also implies that DEX-induced renal damage could be worsened by gestation.