Morphine attenuates neuroinflammation and blood-brain barrier disruption following traumatic brain injury through the opioidergic system

Morphine Induced Neuroprotection in Ischemic Stroke by Activating Autophagy Via mTOR-Independent Activation of the JNK1/2 Pathway

Morphine (Mor) has exhibited efficacy in safeguarding neurons against ischemic injuries by simulating ischemic/hypoxic preconditioning (I/HPC). Concurrently, autophagy plays a pivotal role in neuronal survival during IPC against ischemic stroke. However, the involvement of autophagy in Mor-induced neuroprotection and the potential mechanisms remain elusive. Our experiments further confirmed the effect of Mor in cellular and animal models of ischemic stroke and explored its potential mechanism. The findings revealed that Mor enhanced cell viability in a dose-dependent manner by augmenting autophagy levels and autophagic flux in neurons subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). Pretreatment of Mor improved neurological outcome and reduced infarct size in mice with middle cerebral artery occlusion/reperfusion (MCAO/R) at 1, 7 and 14 days. Moreover, the use of autophagy inhibitors nullified the protective effects of Mor, leading to reactive oxygen species (ROS) accumulation, increased loss of mitochondrial membrane potential (MMP) and neuronal apoptosis in OGD/R neurons. Results further demonstrated that Mor-induced autophagy activation was regulated by mTOR-independent activation of the c-Jun NH2- terminal kinase (JNK)1/2 Pathway, both in vitro and in vivo. Overall, these findings suggested Mor-induced neuroprotection by activating autophagy, which were regulated by JNK1/2 pathway in ischemic stroke.

Morphine Preconditioning Alleviates Ischemia/Reperfusion-induced Caspase-8-dependent Neuronal Apoptosis through cPKCγ-NF-κB-cFLIPL Pathway

BACKGROUND

Perioperative cerebral ischemia/reperfusion injury is a major contributor to postoperative death and cognitive dysfunction in patients. It was reported that morphine preconditioning (MP) can mimic ischemia/hypoxia preconditioning to protect against ischemia/reperfusion injury. However, the mechanism of MP on the ischemia/reperfusion-induced neuronal apoptosis has not been fully clarified.

METHODS

The middle cerebral artery occlusion/reperfusion (MCAO/R) model of mice and the oxygen-glucose deprivation/reoxygenation (OGD/R) model in primary cortical neurons were used to mimic ischemic stroke. In vivo, the infarct size was measured by using TTC staining; NDSS, Longa score system, and beam balance test were performed to evaluate the neurological deficits of mice; the expression of the protein was detected by using a western blot. In vitro, the viability of neurons was determined by using CCK-8 assay; the expression of protein and mRNA were assessed by using western blot, RT-qPCR, and immunofluorescent staining; the level of apoptosis was detected by using TUNEL staining.

RESULTS

MP can improve the neurological functions of mice following MCAO/R (P<0.001, n=10 per group). MP can decrease the infarct size (P<0.001, n=10 per group) and the level of cleaved-caspase-3 of mice following MCAO/R (P<0.01 or 0.001, n=6 per group). MP can increase the levels of cPKCγ membrane translocation, p-p65, and cFLIPL, and decrease the levels of cleaved-caspase-8, 3 in neurons after OGD/R or MCAO/R 1 d (P<0.05, 0.01 or 0.001, n=6 per group). In addition, MP could alleviate OGD/R-induced cell apoptosis (P<0.001, n=6 per group).

CONCLUSION

MP alleviates ischemia/reperfusion-induced Caspase 8-dependent neuronal apoptosis through the cPKCγ-NF-κB-cFLIPL pathway.

Chronicity of repeated blast traumatic brain injury associated increase in oxycodone seeking in rats

Numerous epidemiological studies have found co-morbidity between non-severe traumatic brain injury (TBI) and substance misuse in both civilian and military populations. Preclinical studies have also identified this relationship for some misused substances. We have previously demonstrated that repeated blast traumatic brain injury (rbTBI) increased oxycodone seeking without increasing oxycodone self-administration, suggesting that the neurological sequelae of traumatic brain injury can elevate opioid misuse liability. Here, we determined the chronicity of this effect by testing different durations of time between injury and oxycodone self-administration and durations of abstinence. We found that the subchronic (four weeks), but not the acute (three days) or chronic (four months) duration between injury and oxycodone self-administration was associated with increased drug seeking and re-acquisition of self-administration following a 10-day abstinence. Examination of other abstinence durations (two days, four weeks, or four months) revealed no effect of rbTBI on drug seeking at any of the abstinence durations tested. Together, these data indicate that there is a window of vulnerability after TBI when oxycodone self-administration is associated with elevated drug seeking and relapse-related behaviors.

Design and optimization of metformin-loaded solid lipid nanoparticles for neuroprotective effects in a rat model of diffuse traumatic brain injury: A biochemical, behavioral, and histological study

BACKGROUND AND PURPOSE

Following traumatic brain injury, inflammation, mitochondrial dysfunction, oxidative stress, ischemia, and energy crisis can cause mortality or long-term morbidity. As an activator of AMP-activated protein kinase, metformin reduces the secondary injuries of traumatic brain injury by compensating for the lack of energy in damaged cells. But the blood-brain barrier prevents a hydrophilic drug such as metformin from penetrating the brain tissue. Solid lipid nanoparticles with their lipid nature can cross the blood-brain barrier and solve this challenge. so This study aimed to investigate the effect of metformin-loaded lipid nanoparticles (NanoMet) for drug delivery to the brain and reduce complications from traumatic brain injury.

METHOD

Different formulations of NanoMet were designed by Box-Behnken, and after formulation, particle size, zeta potential, and entrapment efficiency were investigated. For in vivo study, Male rats were divided into eight groups, and except for the intact and sham groups, the other groups underwent brain trauma by the Marmarou method. After the intervention, the Veterinary Coma Scale, Vestibular Motor function, blood-brain barrier integrity, cerebral edema, level of inflammatory cytokines, and histopathology of brain tissue were assessed.

RESULTS

The optimal formula had a size of 282.2 ± 9.05 nm, a zeta potential of -1.65 ± 0.33 mV, and entrapment efficiency of 60.61 ± 6.09% which released the drug in 1400 min. Concentrations of 5 and 10 mg/kg of this formula improved the consequences of trauma.

CONCLUSION

This study showed that nanoparticles could help target drug delivery to the brain and apply the desired result.

The Impact of General Anesthesia on Redox Stability and Epigenetic Inflammation Pathways: Crosstalk on Perioperative Antioxidant Therapy

Worldwide, the prevalence of surgery under general anesthesia has significantly increased, both because of modern anesthetic and pain-control techniques and because of better diagnosis and the increased complexity of surgical techniques. Apart from developing new concepts in the surgical field, researchers and clinicians are now working on minimizing the impact of surgical trauma and offering minimal invasive procedures due to the recent discoveries in the field of cellular and molecular mechanisms that have revealed a systemic inflammatory and pro-oxidative impact not only in the perioperative period but also in the long term, contributing to more difficult recovery, increased morbidity and mortality, and a negative financial impact. Detailed molecular and cellular analysis has shown an overproduction of inflammatory and pro-oxidative species, responsible for augmenting the systemic inflammatory status and making postoperative recovery more difficult. Moreover, there are a series of changes in certain epigenetic structures, the most important being the microRNAs. This review describes the most important molecular and cellular mechanisms that impact the surgical patient undergoing general anesthesia, and it presents a series of antioxidant therapies that can reduce systemic inflammation.