Neuroprotection in Traumatic Brain Injury

Neurobiology of traumatic brain injury

Traumatic brain injury (TBI) involves structural damage to the brain regions causing death or disability in patients with lifelong sufferings. Accidental injuries to the brain, besides structural damage, if any, cause activation of various deleterious pathways leading to subsequent neuronal death and permanent dysfunction. However, immediate medical management/treatments could reduce the chances of disability and suffering to the patients. The objective of the current review is to review triggered molecular pathways following TBI and discuss possible targets that could restore brain functions. Understanding the pathologic process is always useful to device novel treatment strategies and may rescue the patient with TBI from death or associated co-morbidities. The current review significantly contributes to improve our understanding about the molecular pathways and neuronal death following TBI and helps us to provide possible targets that could be useful in the management/treatment of TBI.

Neuroprotective effect of nerolidol in traumatic brain injury associated behavioural comorbidities in rats

Traumatic brain injury (TBI) is an insult to the brain from an external mechanical force, leading to temporary/permanent secondary injuries, i.e. impairment of cognitive, physical, and psycho-social functions with altered consciousness. The leading mechanism responsible for neuronal damage following TBI is an increase in oxidative reactions initiated by free radicals generated by the injury along with various other mechanisms. Nerolidol is reported to have potent antioxidant and anti-neuroinflammatory properties. The present study was designed to explore the neuroprotective effect of nerolidol in weight-drop-induced TBI in rats. Animals were injured on the 1st day by dropping a free-falling weight of 200 gm from a height of 1 m through a guide pipe onto the exposed skull. After 14 days of injury, nerolidol (25, 50, and 100 mg/kg, i.p.) treatment was given for the next 14 days. Locomotor activity and motor coordination were evaluated using an actophotometer and rotarod, respectively. Cognitive impairment was observed through the Morris Water Maze and Object Recognition Test. On the 29th day, animals were sacrificed, and their brains were collected for the biochemical estimation. The weight drop model significantly decreased locomotor activity, motor coordination, increased Acetylcholinesterase (AChE) activity, oxidative stress, and induced cognitive deficits in TBI rats. Nerolidol significantly improved locomotor activity, reversed motor incoordination and cognitive impairment, and reduced the AChE activity and oxidative/nitrosative stress. The present study demonstrates the promising neuroprotective effects of nerolidol, which might improve the quality of life of TBI patients.

Propylparaben Reduces the Long-Term Consequences in Hippocampus Induced by Traumatic Brain Injury in Rats: Its Implications as Therapeutic Strategy to Prevent Neurodegenerative Diseases

BACKGROUND

Severe traumatic brain injury (TBI), an important risk factor for Alzheimer's disease, induces long-term hippocampal damage and hyperexcitability. On the other hand, studies support that propylparaben (PPB) induces hippocampal neuroprotection in neurodegenerative diseases.

OBJECTIVE

Experiments were designed to evaluate the effects of subchronic treatment with PPB on TBI-induced changes in the hippocampus of rats.

METHODS

Severe TBI was induced using the lateral fluid percussion model. Subsequently, rats received subchronic administration with PPB (178 mg/kg, TBI+PPB) or vehicle (TBI+PEG) daily for 5 days. The following changes were examined during the experimental procedure: sensorimotor dysfunction, changes in hippocampal excitability, as well as neuronal damage and volume.

RESULTS

TBI+PEG group showed sensorimotor dysfunction (p < 0.001), hyperexcitability (64.2%, p < 0.001), and low neuronal preservation ipsi- and contralateral to the trauma. Magnetic resonance imaging (MRI) analysis revealed lower volume (17.2%; p < 0.01) and great damage to the ipsilateral hippocampus. TBI+PPB group showed sensorimotor dysfunction that was partially reversed 30 days after trauma. This group showed hippocampal excitability and neuronal preservation similar to the control group. However, MRI analysis revealed lower hippocampal volume (p < 0.05) when compared with the control group.

CONCLUSION

The present study confirms that post-TBI subchronic administration with PPB reduces the long-term consequences of trauma in the hippocampus. Implications of PPB as a neuroprotective strategy to prevent the development of Alzheimer's disease as consequence of TBI are discussed.

Nanomaterial integration into the scaffolding materials for nerve tissue engineering: a review

The nervous system, which consists of a complex network of millions of neurons, is one of the most highly intricate systems in the body. This complex network is responsible for the physiological and cognitive functions of the human body. Following injuries or degenerative diseases, damage to the nervous system is overwhelming because of its complexity and its limited regeneration capacity. However, neural tissue engineering currently has some capacities for repairing nerve deficits and promoting neural regeneration, with more developments in the future. Nevertheless, controlling the guidance of stem cell proliferation and differentiation is a challenging step towards this goal. Nanomaterials have the potential for the guidance of the stem cells towards the neural lineage which can overcome the pitfalls of the classical methods since they provide a unique microenvironment that facilitates cell-matrix and cell-cell interaction, and they can manipulate the cell signaling mechanisms to control stem cells' fate. In this article, the suitable cell sources and microenvironment cues for neuronal tissue engineering were examined. Afterward, the nanomaterials that impact stem cell proliferation and differentiation towards neuronal lineage were reviewed.

Drosophila Exhibit Divergent Sex-Based Responses in Transcription and Motor Function After Traumatic Brain Injury

Every year, millions of people in the US suffer brain damage from mild to severe traumatic brain injuries (TBI) that result from a sudden impact to the head. Despite TBI being a leading cause of death and disability worldwide, sex differences that contribute to varied outcomes post-injury are not extensively studied and therefore, poorly understood. In this study, we aimed to explore biological sex as a variable influencing response to TBI using Drosophila melanogaster as a model, since flies have been shown to exhibit symptoms commonly seen in other mammalian models of TBI. After inflicting TBI using the high-impact trauma device, we isolated w¹¹¹⁸ fly brains and assessed gene transcription changes in male and female flies at control and 1, 2, and 4 hr after TBI. Our results suggest that overall, Drosophila females show more gene transcript changes than males. Females also exhibit upregulated expression changes in immune response and mitochondrial genes across all time-points. In addition, we looked at the impact of injury on mitochondrial health and motor function in both sexes before and after injury. Although both sexes report similar changes in mitochondrial oxidation and negative geotaxis, locomotor activity appears to be more impaired in males than females. These data suggest that sex-differences not only influence the response to TBI but also contribute to varied outcomes post-injury.