Naltrexone is neuroprotective against traumatic brain injury in mu opioid receptor knockout mice

AimsNaltrexone is a mu opioid receptor (MOR) antagonist used to treat drug dependence in patients. Previous reports indicated that MOR antagonists reduced neurodegeneration and inflammation after brain injury. The purpose of this study was to evaluate the neuroprotective effect of naltrexone in cell culture and a mouse model of traumatic brain injury (TBI).MethodsThe neuroprotective effect of naltrexone was examined in primary cortical neurons co‐cultured with BV2 microglia. Controlled cortical impact (CCI) was delivered to the left cerebral cortex of adult male MOR wild‐type (WT) and knockout (KO) mice. Naltrexone was given daily for 4 days, starting from day 2 after lesioning. Locomotor activity was evaluated on day 5 after the CCI. Brain tissues were collected for immunostaining, Western, and qPCR analysis.ResultsGlutamate reduced MAP2 immunoreactivity (‐ir), while increased IBA1‐ir in neuron/BV2 co‐culture; both responses were antagonized by naltrexone. TBI significantly reduced locomotor activity and increased the expression of IBA1, iNOS, and CD4 in the lesioned cortex. Naltrexone significantly and equally antagonized the motor deficits and expression of IBA1 and iNOS in WT and KO mice. TBI‐mediated CD4 protein production was attenuated by naltrexone in WT mice, but not in KO mice.ConclusionNaltrexone reduced TBI‐mediated neurodegeneration and inflammation in MOR WT and KO mice. The protective effect of naltrexone involves non‐MOR and MOR mechanisms.     

Donor‐to‐recipient weight ratio is a risk factor for hepatic artery thrombosis after whole‐liver transplantation in children under 25 kg

Hepatic artery thrombosis (HAT) following pediatric liver transplantation increases morbidity and risk of graft failure. We performed a retrospective chart review of all patients who underwent deceased‐donor liver transplantation from August 2002 to July 2016. Multi‐organ transplant recipients were excluded. We examined the incidence of HAT at our institution and sought to identify associated donor or recipient risk factors. A total of 127 deceased‐donor liver transplant patients with a median age of 1.7 years (IQR 0.67‐6.7) were identified. Of those, 14 developed HAT, all weighing under 25 kg. Among 100 patients under 25 kg, whole‐liver graft recipients had an odds ratio of 3.98 (95% confidence interval [CI]: 1.03, 15.34; P = .045) for developing HAT compared with split‐liver graft recipients. Within the whole‐liver recipient group under 25 kg, 11 patients developed HAT with a median donor‐to‐recipient ratio (DRWR) of 0.9 (IQR: 0.7‐1.2) compared with a median DRWR of 1.4 (IQR: 1.1‐1.9) for those who did not develop HAT. Multivariate analysis showed DRWR to be an independent risk factor for HAT in patients weighing under 25 kg who received whole organ grafts, with an odds ratio of 3.89 (95% CI: 1.43, 10.54; P = .008) for each 0.5 unit decrease in DRWR. Our results suggest that in recipients under 25 kg 1) split‐liver grafts may have a lower rate of HAT and 2) selecting whole organ donors with a higher DRWR may decrease the incidence of HAT.