HMGB1 suppression confers neuroprotection against stroke in diabetic rats

Neuroprotective Potential of Glycyrrhizic Acid in Ischemic Stroke: Mechanisms and Therapeutic Prospects

Background/Objectives: Ischemic stroke is a leading cause of disability and mortality worldwide, with current therapies limited in addressing its complex pathophysiological mechanisms, such as inflammation, oxidative stress, apoptosis, and impaired autophagy. Glycyrrhizic acid (GA), a bioactive compound from licorice (Glycyrrhiza glabra L.), has demonstrated neuroprotective properties in preclinical studies. This review consolidates current evidence on GA's pharmacological mechanisms and assesses its potential as a therapeutic agent for ischemic stroke. Methods: This review examines findings from recent preclinical studies and reviews on GA's neuroprotective effects, focusing on its modulation of inflammation, oxidative stress, apoptosis, and autophagy. Studies were identified from major scientific databases, including PubMed, Web of Science, and Embase, covering research from January 2000 to August 2024. Results: GA has demonstrated significant neuroprotective effects through the modulation of key pathways, including HMGB1/TLR4/NF-κB and Keap1/Nrf2, thereby reducing neuroinflammation, oxidative stress, and apoptosis. Additionally, GA promotes autophagy and modulates immune responses, suggesting it could serve as an adjunct therapy to enhance the efficacy and safety of existing treatments, such as thrombolysis. Conclusions: Current findings underscore GA's potential as a multi-targeted neuroprotective agent in ischemic stroke, highlighting its anti-inflammatory, antioxidant, and anti-apoptotic properties. However, while preclinical data are promising, further clinical trials are necessary to validate GA's therapeutic potential in humans. This review provides a comprehensive overview of GA's mechanisms of action, proposing directions for future research to explore its role in ischemic stroke management.

Ischemic stroke and diabetes: a TLR4-mediated neuroinflammatory perspective

Ischemic stroke is the major contributor to morbidity and mortality in people with diabetes mellitus. In ischemic stroke patients, neuroinflammation is now understood to be one of the main underlying mechanisms for cerebral damage and recovery delay. It has been well-established that toll-like receptor 4 (TLR4) signaling pathway plays a key role in neuroinflammation. Emerging research over the last decade has revealed that, compared to ischemic stroke without diabetes mellitus, ischemic stroke with diabetes mellitus significantly upregulates TLR4-mediated neuroinflammation, increasing the risk of cerebral and neuronal damage as well as neurofunctional recovery delay. This review aims to discuss how ischemic stroke with diabetes mellitus amplifies TLR4-mediated neuroinflammation and its consequences. Additionally covered in this review is the potential application of TLR4 antagonists in the management of diabetic ischemic stroke.

Green tea and its active compound epigallocathechin-3-gallate (EGCG) inhibit neuronal apoptosis in a middle cerebral artery occlusion (MCAO) model

OBJECTIVES

To determine the effect of green tea with the active ingredient epigallocathechin-3-gallate (EGCG) on the inhibition of apoptosis in the middle cerebral artery occlusion (MCAO) model.

METHODS

Four month old male Rattus norvegicus rats with a body weight of 200-275 g was used for the MCAO model and divided into five groups, and the treatment was carried out for 7 days. Before being sacrificed, the subject had 1 cc of blood drawn for high mobility group box 1 (HMGB-1) examination using enzyme-linked immunosorbent assay (ELISA), and after being sacrificed, the brain tissue specimen was taken to examine caspase-3 and B-cell lymphoma 3 (BCL-3) using immunohistochemistry methods.

RESULTS

There was no significant difference in HMGB-1 results for the treatment group compared to the control group (P1: 384.20 ± 231.72 [p = 0.553]; P2: 379.11 ± 268.4 [p = 0.526]; P3: 284, 87 ± 276.19 [p = 0.140]; P4: 435.32 ± 279.95 [p = 0.912]). There is a significant increase in BCL-2 expression between the treatment group compared to the control group (P1: 2.58 ± 0.51 [p = 0.04]; P2: 3.36 ± 0.50 [p<0.001]; P3: 4.00 ± 0.42 [p<0.001]; P4: 3.60 ± 0.52 [p<0.001]). There was a significant difference in caspase-3 expression compared to the control group in the P3 group (P1: 4.33 ± 0.49 [p = 0.652]; P2: 4.09 ± 0.30 [p = 0.136]; P3: 3.58 ± 0.51 [p = 0.01]; P4: 3.89 ± 0.42 [p = 0.063]). There is no correlation between HMGB-1 and caspase-3 (r = -0.063; p = 0.613) or BCL-2 (r = -0.106; p = 0.396). There is significant negative correlation between caspase-3 and BCL-2 (r = -0.459; p = 0.000).

CONCLUSIONS

Green tea with the active ingredient EGCG can inhibit neuronal cell death through the apoptotic pathway and not through the activation of HMGB-1.