Hyperglycemia Aggravates Blood-Brain Barrier Disruption Following Diffuse Axonal Injury by Increasing the Levels of Inflammatory Mediators through the PPARγ/Caveolin-1/TLR4 Pathway

Cerebral Glucose Metabolism following TBI: Changes in Plasma Glucose, Glucose Transport and Alternative Pathways of Glycolysis-A Translational Narrative Review

Traumatic brain injury (TBI) is a major public health concern with significant consequences across various domains. Following the primary event, secondary injuries compound the outcome after TBI, with disrupted glucose metabolism emerging as a relevant factor. This narrative review summarises the existing literature on post-TBI alterations in glucose metabolism. After TBI, the brain undergoes dynamic changes in brain glucose transport, including alterations in glucose transporters and kinetics, and disruptions in the blood-brain barrier (BBB). In addition, cerebral glucose metabolism transitions from a phase of hyperglycolysis to hypometabolism, with upregulation of alternative pathways of glycolysis. Future research should further explore optimal, and possibly personalised, glycaemic control targets in TBI patients, with GLP-1 analogues as promising therapeutic candidates. Furthermore, a more fundamental understanding of alterations in the activation of various pathways, such as the polyol and lactate pathway, could hold the key to improving outcomes following TBI.

From diabetic hyperglycemia to cerebrovascular Damage: A narrative review

Diabetes mellitus is a globally significant disease that can lead to systemic complications, particularly vascular damage, including cardiovascular and cerebrovascular diseases of relevance. The physiological changes resulting from the imbalance in blood glucose levels play a crucial role in initiating vascular endothelial damage. Elevated glucose levels can also penetrate the central nervous system, triggering diabetic encephalopathy characterized by oxidative damage to brain components and activation of alternative and neurotoxic pathways. This brain damage increases the risk of ischemic stroke, a leading cause of mortality worldwide and a major cause of disability among surviving patients. The aim of this review is to highlight important pathways related to hyperglycemic damage that extend to the brain and result in vascular dysfunction, ultimately leading to the occurrence of a stroke. Understanding how diabetes mellitus contributes to the development of ischemic stroke and its impact on patient outcomes is crucial for implementing therapeutic strategies that reduce the incidence of diabetes mellitus and its complications, ultimately decreasing morbidity and mortality associated with the disease.

Hyperglycemia disrupted the integrity of the blood-brain barrier following diffuse axonal injury through the sEH/NF-κB pathway

OBJECTIVES

We aimed to investigate the role of soluble epoxide hydrolase for hyperglycemia induced-disruption of blood-brain barrier (BBB) integrity after diffuse axonal injury (DAI).

METHODS

Rat DAI hyperglycemia model was established by a lateral head rotation device and intraperitoneal injection of 50% glucose. Glial fibrillary acidic protein, ionized calcium-binding adapter molecule-1, β-amyloid precursor protein, neurofilament light chain, and neurofilament heavy chain was detected by immunohistochemistry. Cell apoptosis was examined by terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) assay. The permeability of blood-brain barrier (BBB) was assessed by expression of tight junction proteins, leakage of Evans blue and brain water content. The soluble epoxide hydrolase (sEH) pathway was inhibited by 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU) and the nuclear transcription factor kappa B (NF-κB) pathway was inhibited by pyrrolidine dithiocarbamate and activated by phorbol-12-myristate-13-acetate in vivo and/or vitro, respectively. The inflammatory factors were detected by enzyme-linked immunosorbent assay.

RESULTS

Hyperglycemia could exacerbate axonal injury, aggravate cell apoptosis and glial activation, worsen the loss of BBB integrity, increase the release of inflammatory factors, and upregulate the expression of sEH and NF-κB. Inhibition of sEH could reverse all these damages and protect BBB integrity by upregulating the expression of tight junction proteins and downregulating the levels of inflammatory factors in vivo and vitro, while the agonist of NF-κB pathway abrogated the protective effects of TPPU on BBB integrity in vitro.

CONCLUSIONS

sEH was involved in mediating axonal injury induced by hyperglycemia after DAI by disrupting BBB integrity through inducing inflammation via the NF-κB pathway.

Case report: Fatal insulin overdose in a dog with type 1 diabetes mellitus-characteristics and successful management

Administering more than 10 times the therapeutic dose of insulin is extremely rare in diabetic dogs and is life threatening with hypoglycemia and seizures if not accompanied by appropriate treatment. A 15-year-old, castrated male miniature poodle dog managed for diabetes presented with depression, disorientation, ataxia, and cluster seizures. The dog had been administered 11.1 U/kg of neutral protamine hegadorn (NPH) insulin (10 times the prescribed dose) 3 h before the onset of symptoms. Blood analysis revealed hypoglycemia, with a circulating glucose level of <50 mg/dL. To treat the hypoglycemia-induced seizures, dextrose was repeatedly administered intravenously. Repeated generalized seizures were treated with anticonvulsants and intermittent mannitol. Since refractory hypoglycemia persisted 24 h after the insulin overdose, it was decided to proceed with glucagon treatment (15-30 ng/kg/min titrated to the blood glucose level after a loading dose of 50 ng/kg intravenous bolus infusion). After 37 h of glucagon treatment, blood glucose levels stabilized. After entering a hyperglycemic state, NPH insulin was administered to manage insulin-dependent diabetes mellitus. This is the first case documented of successful treatment with glucagon, anticonvulsants and intermittent mannitol for refractory hypoglycemia and seizure caused by fatal insulin overdose. Thus, it has great clinical value in veterinary medicine.