Intravenous administration of Honokiol provides neuroprotection and improves functional recovery after traumatic brain injury through cell cycle inhibition.

Recently, increasing evidence has shown that cell cycle activation is a key factor of neuronal death and neurological dysfunction after traumatic brain injury (TBI). This study aims to investigate the effects of Honokiol, a cell cycle inhibitor, on attenuating the neuronal damage and facilitating functional recovery after TBI in rats, in an attempt to unveil its underlying molecular mechanisms in TBI. This study suggested that delayed intravenous administration of Honokiol could effectively ameliorate TBI-induced sensorimotor and cognitive dysfunctions. Meanwhile, Honokiol treatment could also reduce the lesion volume and increase the neuronal survival in the cortex and hippocampus. The neuronal degeneration and apoptosis in the cortex and hippocampus were further significantly attenuated by Honokiol treatment. In addition, the expression of cell cycle-related proteins, including cyclin D1, CDK4, pRb and E2F1, was significantly increased and endogenous cell cycle inhibitor p27 was markedly decreased at different time points after TBI. And these changes were significantly reversed by post-injury Honokiol treatment. Furthermore, the expression of some of the key cell cycle proteins such as cyclin D1 and E2F1 and the associated apoptosis in neurons were both remarkably attenuated by Honokiol treatment. These results show that delayed intravenous administration of Honokiol could effectively improve the functional recovery and attenuate the neuronal cell death, which is probably, at least in part, attributed to its role as a cell cycle inhibitior. This might give clues to developing attractive therapies for future clinical trials.

Hydrogen gas ameliorates oxidative stress in early brain injury after subarachnoid hemorrhage in rats.

OBJECTIVE: Hydrogen gas has been demonstrated to neutralize free radicals and reduce oxidative stress recently. Our objective was to determine the therapeutic effect of H2 inhalation and its antioxidative activity on early brain injury after subarachnoid hemorrhage. DESIGN: Controlled in vivo laboratory study. SETTING: Animal research laboratory. SUBJECTS: One hundred thirty-seven adult male Sprague-Dawley rats weighing 280-350 g. INTERVENTIONS: Subarachnoid hemorrhage was induced by endovascular perforation method in rats. Subarachnoid hemorrhage rats were treated with 2.9% hydrogen gas inhaled for 2 hrs after perforation. At 24 and 72 hrs, mortality, body weight, neurologic deficits, and brain water content were assessed. Blood-brain barrier permeability and apoptosis were also measured at 24 hrs. To investigate the antioxidative activity of hydrogen gas, the expression of malondialdehyde, nitrotyrosine, and 8-hydroxyguanosine, which are oxidative markers of lipid, protein, and DNA damage, respectively, were measured at 24 hrs. MEASUREMENTS AND MAIN RESULTS: Hydrogen gas significantly alleviated brain edema and blood-brain barrier disruption, reduced apoptosis, and improved neurologic function at 24 hrs but not 72 hrs after subarachnoid hemorrhage. These effects were associated with the amelioration of oxidative injury of lipid, protein, and DNA. CONCLUSIONS: Hydrogen gas could exert its neuroprotective effect against early brain injury after subarachnoid hemorrhage by its antioxidative activity.

[Correlation analysis of increased blood glucose and insulin resistance after traumatic brain injury in rats].

OBJECTIVE: To study the pattern of the alterations of blood glucose, insulin and insulin sensitivity after traumatic brain injury in rats, and verify the occurrence of insulin resistance after the injury. METHODS: Based on Feeney's model of brain injury, the blood glucose and insulin concentration of the dogs measured 30 min before and at 6, 12, 24, 48, 72 and 120 h after injury. BG60-120, GIR60-120, and insulin sensitivity index (ISI) reflecting the insulin sensitivity were measured at 6, 24, 48, and 72 hours following severe traumatic brain injury using euglycemic-hyperinsulinemic clamp. RESULTS: Both the blood glucose and insulin concentration increased markedly in rats following moderate and severe brain injury. BG60-120 increased markedly, and GIR60-120 and ISI decreased significantly 6, 24, 48, and 72 h after severe brain trauma as compared with those of the sham operation group. Blood glucose concentration of rats following severe injury was positively correlated with insulin concentration and BG60-120 at the corresponding time points, but negatively with GIR60-120 and ISI. CONCLUSION: Both the blood glucose and insulin concentration increase markedly in rats following severe brain injury. Increased blood glucose even in the presence of high-level insulin is due to acute insulin resistance occurring after traumatic brain injury.