Inhibition of nitric oxide synthase aggravates brain injury in diabetic rats with traumatic brain injury.

Studies have shown that hyperglycemia aggravates brain damage by affecting vascular endothelial function. However, the precise mechanism remains unclear. Male Sprague-Dawley rat models of diabetes were established by a high-fat diet combined with an intraperitoneal injection of streptozotocin. Rat models of traumatic brain injury were established using the fluid percussion method. Compared with traumatic brain injury rats without diabetic, diabetic rats with traumatic brain injury exhibited more severe brain injury, manifested as increased brain water content and blood-brain barrier permeability, the upregulation of heme oxygenase-1, myeloperoxidase, and Bax, the downregulation of occludin, zona-occludens 1, and Bcl-2 in the penumbra, and reduced modified neurological severity scores. The intraperitoneal injection of a nitric oxide synthase inhibitor N(5)-(1-iminoethyl)-L-ornithine (10 mg/kg) 15 minutes before brain injury aggravated the injury. These findings suggested that nitric oxide synthase plays an important role in the maintenance of cerebral microcirculation, including anti-inflammatory, anti-oxidative stress, and anti-apoptotic activities in diabetic rats with traumatic brain injury. The experimental protocols were approved by the Institutional Animal Care Committee of Harbin Medical University, China (approval No. ky2017-126) on March 6, 2017.

Identification of HLA-DQB1*03:222 by cloning and sequencing in a Chinese individual.

HLA-DQB1*03:222 differs from HLA-DQB1*03:03:02:01 by a single nucleotide change in exon 3.

Effects of a high concentration of hydrogen on neurological function after traumatic brain injury in diabetic rats.

Reactive oxygen species, inflammation, and apoptosis are major contributors to secondary injuries that follow traumatic brain injury (TBI) in diabetic patients. Hydrogen (H2) can selectively neutralize reactive oxygen species and downregulate inflammatory and apoptotic factors. Therefore, we investigated the effects of inhaled high and low concentrations of hydrogen on neurological function after TBI in diabetic rats and the potential mechanism. We found that the inhalation of high concentrations of H2 significantly improved outcomes following TBI in diabetic rats. The inhalation of 42% H2 for one hour per day for 48 h significantly reduced brain edema, decreased the extravasation of sodium fluorescein, and reduced oxidative stress markers (p < 0.05). In addition, the inhalation of a high concentration of H2 (42% for one hour per day for 7 days) improved neurological deficits (p < 0.05) and reduced the expression of apoptotic protein markers (p < 0.05). However, the inhalation of 3% H2 did not yield significant effects. These results showed that the inhalation of 42% H2 can alleviate nerve damage and improve neurological function after TBI in diabetic rats. Therefore, the inhalation of a high concentration of H2 may be associated with the treatment of traumatic brain injuries.

Recent advances in the neuroprotective effects of medical gases.

Central nervous system injuries are a leading cause of death and disability worldwide. Although the exact pathophysiological mechanisms of various brain injuries vary, central nervous system injuries often result in an inflammatory response, and subsequently lead to brain damage. This suggests that neuroprotection may be necessany in the treatment of multiple disease models. The use of medical gases as neuroprotective agents has gained great attention in the medical field. Medical gases include common gases, such as oxygen, hydrogen and carbon dioxide; hydrogen sulphide and nitric oxide that have been considered toxic; volatile anesthetic gases, such as isoflurane and sevoflurane; and inert gases like helium, argon, and xenon. The neuroprotection from these medical gases has been investigated in experimental animal models of various types of brain injuries, such as traumatic brain injury, stroke, subarachnoid hemorrhage, cerebral ischemic/reperfusion injury, and neurodegenerative diseases. Nevertheless, the transition into the clinical practice is still lagging. This delay could be attributed to the contradictory paradigms and the conflicting results that have been obtained from experimental models, as well as the presence of inconsistent reports regarding their safety. In this review, we summarize the potential mechanisms underlying the neuroprotective effects of medical gases and discuss possible candidates that could improve the outcomes of brain injury.

Therapeutic hypercapnia reduces blood-brain barrier damage possibly via protein kinase Cε in rats with lateral fluid percussion injury.

BACKGROUND: This study investigated whether therapeutic hypercapnia (TH) ameliorated blood-brain barrier (BBB) damage and improved the neurologic outcome in a rat model of lateral fluid percussion injury (FPI), and explored the possible underlying mechanism. METHODS: Rats underwent lateral FPI and received inhalation of 30%O2-70%N2 or 30%O2-N2 plus CO2 to maintain arterial blood CO2 tension (PaCO2) between 80 and 100 mmHg for 3 h. To further explore the possible mechanisms for the protective effects of TH, a PKC inhibitor staurosporine or PKCαß inhibitor GÖ6976 was administered via intracerebral ventricular injection. RESULTS: TH significantly improved neurological function 24 h, 48 h, 7 d, and 14 d after FPI. The wet/dry ratio, computed tomography values, Evans blue content, and histological lesion volume were significantly reduced by TH. Moreover, numbers of survived neurons and the expression of tight junction proteins (ZO-1, occludin, and claudin-5) were significantly elevated after TH treatment at 48-h post-FPI. TH significantly increased the expression of protein kinase Cε (PKCε) at 48-h post-FPI, but did not significantly change the expression of PKCα and PKCßII. PKC inhibitor staurosporine (but not the selective PKCαß inhibitor-GÖ6976) inhibited the protective effect of TH. CONCLUSIONS: Therapeutic hypercapnia is a promising candidate that should be further evaluated for clinical treatment. It not only protects the traumatic penumbra from secondary injury and improves histological structure but also maintains the integrity of BBB and reduces neurologic deficits after trauma in a rat model of FPI.

Adrenomedullin Reduces Secondary Injury and Improves Outcome in Rats with Fluid Percussion Brain Injury.

OBJECTIVE: Traumatic brain injury (TBI) is a devastating neurologic injury and remains a major cause of death in the world. Secondary injury after TBI is associated with long-term disability in patients with TBI. This study evaluated adrenomedullin (AM) on secondary injury and neurologic functional outcome in rats after TBI. METHODS: Forty-eight Sprague Dawley rats were randomly assigned into 3 groups: sham, TBI, and TBI with AM groups. TBI was induced by fluid percussion injury, and AM was intravenously injected. Neurologic function was examined at 2, 3, and 7 days after TBI. Enzyme-linked immunosorbent assay was used to test tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-8 levels in the brain. Brain edema and blood-brain barrier (BBB) permeability in brain tissue were tested. Western blot was used to examine the expression of aquaporin-4, phosphorylated myosin light-chain, and cleaved caspase-3. Terminal deoxynucleotidyl transferase dUTP nick end labeling was used to test the apoptosis. RESULTS: Compared with the sham group, TNF-α, IL-1ß, and IL-6 levels, brain edema, BBB permeability, neurologic examination scores, terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells, and expression of aquaporin-4, phosphorylated myosin light-chain, and cleaved caspase-3 significantly increased in the TBI group. AM treatment significantly inhibited TBI-induced effects. CONCLUSIONS: AM can improve neurologic function and ameliorate brain injury in rats with TBI. AM exerts its neuroprotective effect via its anti-inflammatory and antiapoptotic effect.