Time- and Dose-Dependent Neuroprotective Effects of Sex Steroid Hormones on Inflammatory Cytokines after a Traumatic Brain Injury

Progesterone (P4) ameliorates cigarette smoke-induced chronic obstructive pulmonary disease (COPD)

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease associated with high morbidity and mortality worldwide. Oxidative injury and mitochondrial dysfunction in the airway epithelium are major events in COPD progression.

METHODS AND RESULTS

The therapeutic effects of Progesterone (P4) were investigated in vivo and in vitro in this study. In vivo, in a cigarette smoke (CS) exposure-induced COPD mouse model, P4 treatment significantly ameliorated CS exposure-induced physiological and pathological characteristics, including inflammatory cell infiltration and oxidative injury, in a dose-dependent manner. The c-MYC/SIRT1/PGC-1α pathway is involved in the protective function of P4 against CS-induced COPD. In vitro, P4 co-treatment significantly ameliorated H2O2-induced oxidative injury and mitochondrial dysfunctions by promoting cell proliferation, increasing mitochondrial membrane potential, decreasing ROS levels and apoptosis, and increasing ATP content. Moreover, P4 co-treatment partially attenuated H2O2-caused inhibition in Nrf1, Tfam, Mfn1, PGR-B, c-MYC, SIRT1, and PGC-1α levels. In BEAS-2B and ASM cells, the c-MYC/SIRT1 axis regulated P4's protective effects against H2O2-induced oxidative injury and mitochondrial dysfunctions.

CONCLUSION

P4 activates the c-MYC/SIRT1 axis, ameliorating CS-induced COPD and protecting both airway epithelial cells and smooth muscle cells against H2O2-induced oxidative damage. PGC-1α and downstream mitochondrial signaling pathways might be involved.

Neuroactive Steroids, Toll-like Receptors, and Neuroimmune Regulation: Insights into Their Impact on Neuropsychiatric Disorders

Pregnane neuroactive steroids, notably allopregnanolone and pregnenolone, exhibit efficacy in mitigating inflammatory signals triggered by toll-like receptor (TLR) activation, thus attenuating the production of inflammatory factors. Clinical studies highlight their therapeutic potential, particularly in conditions like postpartum depression (PPD), where the FDA-approved compound brexanolone, an intravenous formulation of allopregnanolone, effectively suppresses TLR-mediated inflammatory pathways, predicting symptom improvement. Additionally, pregnane neurosteroids exhibit trophic and anti-inflammatory properties, stimulating the production of vital trophic proteins and anti-inflammatory factors. Androstane neuroactive steroids, including estrogens and androgens, along with dehydroepiandrosterone (DHEA), display diverse effects on TLR expression and activation. Notably, androstenediol (ADIOL), an androstane neurosteroid, emerges as a potent anti-inflammatory agent, promising for therapeutic interventions. The dysregulation of immune responses via TLR signaling alongside reduced levels of endogenous neurosteroids significantly contributes to symptom severity across various neuropsychiatric disorders. Neuroactive steroids, such as allopregnanolone, demonstrate efficacy in alleviating symptoms of various neuropsychiatric disorders and modulating neuroimmune responses, offering potential intervention avenues. This review emphasizes the significant therapeutic potential of neuroactive steroids in modulating TLR signaling pathways, particularly in addressing inflammatory processes associated with neuropsychiatric disorders. It advances our understanding of the complex interplay between neuroactive steroids and immune responses, paving the way for personalized treatment strategies tailored to individual needs and providing insights for future research aimed at unraveling the intricacies of neuropsychiatric disorders.

Integrative Analysis of Cytokine and Lipidomics Datasets Following Mild Traumatic Brain Injury in Rats

Traumatic brain injury (TBI) is a significant source of disability in the United States and around the world and may lead to long-lasting cognitive deficits and a decreased quality of life for patients across injury severities. Following the primary injury phase, TBI is characterized by complex secondary cascades that involve altered homeostasis and metabolism, faulty signaling, neuroinflammation, and lipid dysfunction. The objectives of the present study were to (1) assess potential correlations between lipidome and cytokine changes after closed-head mild TBI (mTBI), and (2) examine the reproducibility of our acute lipidomic profiles following TBI. Cortices from 54 Sprague Dawley male and female rats were analyzed by ultra-high-performance liquid chromatography mass spectrometry (LC-MS) in both positive and negative ionization modes and multiplex cytokine analysis after single (smTBI) or repetitive (rmTBI) closed-head impacts, or sham conditions. Tissue age was a variable, given that two cohorts (n = 26 and n = 28) were initially run a year-and-a-half apart, creating inter-batch variations. We annotated the lipidome datasets using an in-house data dictionary based on exact masses of precursor and fragment ions and removed features with statistically significant differences between sham control batches. Our results indicate that lipids with high-fold change between injury groups moderately correlate with the cytokines eotaxin, IP-10, and TNF-α. Additionally, we show a significant decrease in the pro-inflammatory markers IL-1β and IP-10, TNF-α, and RANTES in the rmTBI samples relative to the sham control. We discuss the major challenges in correlating high dimensional lipidomic data with functional cytokine profiles and the implications for understanding the biological significance of two related but disparate analysis modes in the study of TBI, an inherently heterogeneous neurological disorder.

Evaluating the neuroprotective effects of progesterone receptors on experimental traumatic brain injury: The PI3K/Akt pathway

BACKGROUND

Studies have confirmed the salutary effects of progesterone (P4) on traumatic brain injury (TBI). This study investigated the beneficial effects of P4 via its receptors on TBI, and also whether progesterone receptors (PRs) can modulate TBI through PI3K/Akt pathway.

MATERIAL AND METHODS

Marmarou method was utilized to induce diffuse TBI in ovariectomized rats. P4 (1.7 mg/kg) or the vehicle (oil) was administered 30 min after TBI induction. Moreover, RU486 (PR antagonist) and its vehicle (DMSO) were injected before TBI induction and P4 injection. Brain Evans blue content, brain water content (WC), various oxidative stress parameters, IL-1β levels, tumor necrosis factor-α (TNF-α), histopathological alterations, and also phosphorylated Akt (p-Akt) and PI3K expressions in the brain were assessed 24 h after TBI. The veterinary comma scale (VCS) was measured before and after TBI at different times.

RESULTS

The findings revealed that P4 caused an increase in VCS and a decrease in brain WC, oxidative stress, TNF-α and IL-1β levels. RU486 inhibited the beneficial effects of P4 on these indices. Moreover, RU486 prevented the reduction of brain edema, inflammation, and apoptosis caused by P4. Moreover, P4 following TBI increased the expression of PI3K/p-Akt protein in the brain. RU486 eliminated the effects of P4 on PI3K/p-Akt expression.

CONCLUSION

According to these findings, PRs are acting as critical mediators for the neuroprotective properties of P4 on oxidative stress, pro-inflammatory cytokine levels, and neurological outcomes. PRs also play an important role in regulating the PI3K/p-Akt expression and nongenomic function of P4.

Upregulation of multiple toll-like receptors in ferret brain after blast exposure: potential targets for treatment

Although blast-induced traumatic brain injury (bTBI) has been designated as the signature injury of recent combat operations, its precise pathological mechanism(s) has not been identified thus far. Prior preclinical studies on bTBI demonstrated acute neuroinflammatory cascades which are known to be contributing to neurodegeneration. Danger-associated chemical patterns are released from the injured cells, which activate non-specific pattern recognition receptors, such as toll-like receptors (TLRs) leading to increased expression of inflammatory genes and release of cytokines. Upregulation of specific TLRs in the brain has been described as a mechanism of injury in diverse brain injury models unrelated to blast exposure. However, the expression profile of various TLRs in bTBI has not been investigated thus far. Hence, we have evaluated the expression of transcripts for TLR1-TLR10 in the brain of a gyrencephalic animal model of bTBI. We exposed ferrets to tightly coupled repeated blasts and determined the differential expression of TLRs (TLR1-10) by quantitative RT-PCR in multiple brain regions at 4 hr, 24 hr, 7 days and 28 days post-blast injury. The results obtained indicate that multiple TLRs are upregulated in the brain at 4 hr, 24 hr, 7 days and 28 days post-blast. Specifically, upregulation of TLR2, TLR4 and TLR9 was noted in different brain regions, suggesting that multiple TLRs might play a role in the pathophysiology of bTBI and that drugs that can inhibit multiple TLRs might have enhanced efficacy to attenuate brain damage and thereby improve bTBI outcome. Taken together, these results suggest that several TLRs are upregulated in the brain after bTBI and participate in the inflammatory response and thereby provide new insights into the disease pathogenesis. Therefore, inhibition of multiple TLRs, including TLR2, 4 and 9, simultaneously might be a potential therapeutic strategy for the treatment of bTBI.

Drosophila melanogaster as a model to study age and sex differences in brain injury and neurodegeneration after mild head trauma

Repetitive physical insults to the head, including those that elicit mild traumatic brain injury (mTBI), are a known risk factor for a variety of neurodegenerative conditions including Alzheimer's disease (AD), Parkinson's disease (PD), and chronic traumatic encephalopathy (CTE). Although most individuals who sustain mTBI typically achieve a seemingly full recovery within a few weeks, a subset experience delayed-onset symptoms later in life. As most mTBI research has focused on the acute phase of injury, there is an incomplete understanding of mechanisms related to the late-life emergence of neurodegeneration after early exposure to mild head trauma. The recent adoption of Drosophila-based brain injury models provides several unique advantages over existing preclinical animal models, including a tractable framework amenable to high-throughput assays and short relative lifespan conducive to lifelong mechanistic investigation. The use of flies also provides an opportunity to investigate important risk factors associated with neurodegenerative conditions, specifically age and sex. In this review, we survey current literature that examines age and sex as contributing factors to head trauma-mediated neurodegeneration in humans and preclinical models, including mammalian and Drosophila models. We discuss similarities and disparities between human and fly in aging, sex differences, and pathophysiology. Finally, we highlight Drosophila as an effective tool for investigating mechanisms underlying head trauma-induced neurodegeneration and for identifying therapeutic targets for treatment and recovery.

The outcome of severely injured patients following traumatic brain injury is affected by gender-A retrospective, multicenter, matched-pair analysis utilizing data of the TraumaRegister DGU®

INTRODUCTION

Traumatic brain injury (TBI) causes a major health-concern globally. Gender-dependent differences in mortality outcome after TBI have been controversially discussed.

MATERIALS AND METHODS

We conducted a retrospective, multicenter, matched-pair analysis using data collected by the TraumaRegister DGU® of the German Trauma Society between 2009 and 2020. All patients after severe trauma with the leading injury of TBI (AIS ≥ 3), above 18 years of age were included. Thereby, 42,034 cases were identified. We used 12 different matching criteria to ensure highly accurate matching and were able to match 11,738 pairs of one female and one male patient.

RESULTS

Average age at injury was 67.5 ± 19.6 years in women and 66.7 ± 19.1 years in men. Mean Injury Severity Score (ISS) was 21.3 ± 8.1 in women and 21.6 ± 8.2 in men. While women were more likely to die within the first week after trauma, the mortality was significantly higher in men overall (30.8 vs. 29.2%, p < 0.002). Women were less likely to suffer from multi organ failure (MOF) (27.5 vs. 33.0%) or sepsis (4.5 vs. 7.1%). When comparing younger (≤ 45-years) and older (> 45 years) patients, overall mortality was lower in men (13.1% men vs. 13.4% women) in the younger age group, but in the older group mortality was lower in women (33.8% men vs. 31.8% women).

DISCUSSION

Gender-specific differences in the clinical outcome of severely injured patients with leading TBI could be detected. While women are overall characterized by an advantage in survival, this feature is not equally reproducible in premenopausal women. Therefore, the exact pathophysiological reasons for the described survival advantages of women will have to be explored in further prospective clinical studies.

The effect of two types of diet on apoptosis indexes, lipid profile and histopathological outcome in acute kidney injury during exercise

Background

Exercise and some pre-AKI diets have been shown to improve injury, apoptosis, and lipid profile. In this study, the effect of two different diets along with exercise training on acute kidney injury (AKI) was investigated. 

Materials and methods

Laboratory rats were randomly divided into four groups of control, standard diet + exercise, exercise + calorie restriction (CR) and exercise + time restriction (TR). Each group was divided into two subgroups of AKI and no AKI. The animals received endurance training and diet regimens before AKI. Fasting blood glucose, serum creatinine, Bcl-2-associated X protein (Bax), B-cell lymphoma 2 (Bcl2) and histopathological outcome of renal tissue as well as serum lipid profile of animals were assessed 24 h after AKI. 

Results

The percentage of changes in renal Bcl2 and Bax after AKI in the group with previous exercise was lower than the group without previous exercise (p < 0.01). After induction of AKI, serum lipid profile changed in non-exercised rats (p < 0.001). Also, after injury, fasting blood glucose levels increased in non-exercised rats (p < 0.05). After injury, the start of both CR and TR diets during exercise caused less change in Bcl2 and Bax of non-exercised rats compared to exercised rats (p < 0.001). CR diet along with exercise improved lipid profile, and also CR diet along exercise decreased fasting blood glucose levels (p < 0.001). Also, both the CR and TR diets during exercise caused fewer changes in histopathological outcome after AKI.

Conclusion

Exercise alone decreased changes in apoptotic and histopathological indexes, fasting blood glucose, as well as lipid profile of rats after AKI. Reduction of apoptosis and improvement of histopathological outcome after AKI appeared more when CR and TR diets were commenced during exercise. The reduction of lipid profile changes was more pronounced in the group that received CR diet during exercise.

Ten-Year Institutional Experience to Predict Risk of Calvarial Bone Flap Loss Using Long-Term Outcome Data

BACKGROUND

Calvarial bone flap (CBF) loss is a common complication following craniotomy and subsequent skull reconstruction can be challenging. Defining predictors of CBF failure not only improves patient outcomes but reduces the need for complex reconstruction often requiring plastic surgery consultation. As CBF failure can occur many years following craniotomy, this study aimed to determine risk factors of CBF loss using long-term follow-up.

MATERIALS AND METHODS

This retrospective study included patients who underwent craniotomy with CBF reinsertion between 2003 and 2013 at a tertiary academic institution. Patients were included if demographics, comorbidities, and long-term outcomes were available. Multivariable logistic regression modeled the odds of CBF failure, defined as permanent removal for bone flap-related issues. The median follow-up was 6.9 years (interquartile range: 1.8-10.8 y).

RESULTS

There were 222 patients who met inclusion criteria and underwent craniotomy with CBF reinsertion, primarily for tumor resection or intracranial pressure relief. CBF failure occurred in 76 (34.2%) patients. Up to 4 CBF reinsertions were performed in both failure and nonfailure groups. The risks of CBF loss increased with each additional CBF elevation by 17-fold (P<0.001), male sex by 3-fold (P=0.005), and tumor etiology by 3-fold (P=0.033) (C-index=0.942).

CONCLUSIONS

Each CBF reinsertion dramatically increases the risk of CBF loss. This finding may optimize patient selection and surgical planning. Early multidisciplinary discussions between plastic surgeons and neurosurgeons may avoid multiple CBF elevations and prevent the adverse sequela of high-risk calvarial reconstruction efforts.

The Effect of Oral Mucosal Mesenchymal Stem Cells on Pathological and Long-Term Outcomes in Experimental Traumatic Brain Injury

Background

Neuroprotective effects of stem cells have been shown in some neurologic diseases. In this study, the effect of oral mucosal mesenchymal stem cells (OMSCs) on traumatic brain injury (TBI) was evaluated in long term.

Materials and Methods

TBI was induced by Marmarou's method. The number of 2 × 10⁶ OMSCs was intravenously injected 1 and 24 h after the injury. Brain edema and pathological outcome were assessed at 24 h and 21 days after the injury. Besides, long-term neurological, motor, and cognitive outcomes were evaluated at days 3, 7, 14, and 21 after the injury.

Results

OMSCs administration could significantly inhibit microglia proliferation, and reduce brain edema and neuronal damage, at 24 h and 21 days after the injury. Neurological function improvement was observed in the times evaluated in OMSCs group. Cognitive and motor function dysfunction and anxiety-like behavior were prevented especially at 14 and 21 days after the injury in the treatment group.

Conclusion

According to the results of this study, OMSCs administration after TBI reduced brain edema and neuronal damage, improved neurologic outcome, and prevented memory and motor impairments and anxiety-like behavior in long term.

Estrogen receptor agonists induce anti‑edema effects by altering α and β estrogen receptor gene expression

The present study aimed to examine whether the attenuation of estrogen receptor expression is prevented by propyl pyrazole triol (PPT), an agonist for estrogen receptor α (ERα) or and diarypropiolnitrile (DPN), an agonist for estrogen receptor β (ERβ) after traumatic brain injury (TBI). The tests performed on ovariectomized female Wistar rats included sham group, vehicle group, and treated groups: PPT, DPN, and PPT+DPN 30 minutes after TBI. Blood‑brain barrier (BBB) disruption and brain water content were estimated. RT‑PCR and\r\nwestern blotting were utilized to evaluate ESR1 and ESR2 gene and protein expression. The data indicated that PPT, DPN, and PPT+DPN attenuated TBI‑induced brain edema. Also, BBB disruption after TBI was prevented in PPT, DPN, and PPT+DPN‑treated TBI animals. Estrogen agonist‑treated animals showed a significant elevation in Esr1 mRNA and protein expression levels in the brain tissue of TBI rats. In addition, the data indicated a significant elevation of Esr2 mRNA and protein expression levels in the brain tissue of estrogen agonist‑treated TBI rats. The data shows that both ESR1 and ESR2 agonists can enhance ER mRNA and protein levels in TBI animals' brain. It appears that this effect contributes to the neuroprotective function of ER agonists.

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

Endogenous opiates are suggested to have a role in the pathophysiology of traumatic brain injury (TBI). Furthermore, administration of opioidergic agents in TBI injured animals have been shown to affect the brain injury and provide neuroprotection post-TBI. This study aims to investigate the potential neuroprotective effects of morphine through inhibition of neuroinflammatory pathways in acute severe TBI. Male Wistar rats were divided into seven groups (24 rats per group): Sham, Vehicle (TBI + intraperitoneal (i.p) injection of normal saline), TBI + i.p injection of morphine in 1, 5 and 10 mg/kg doses (MOR 1, MOR 5 and MOR 10 groups), TBI + morphine (5 mg/kg i.p) + Naloxone (NAL + MOR), and TBI + morphine (5 mg/kg i.p) + Naltrindole (NALT + MOR). A severe diffuse TBI model (weight dropping Marmarou model) was used to induce TBI in rats. The veterinary coma scale (VCS), beam-walk, and beam-balance tasks were used to assess short-term neurological deficits. Histolopathological changes of brain tissue was evaluated using light microscopy and hematoxilin and eosin staining. Blood-Brain barrier (BBB) disruption was evaluated by the Evans Blue method 6 h post-injury. Brain water content and cerebrospinal fluid (CSF) content of IL-1β and IL-10 were assessed by the wet-dry method and enzyme-linked immunosorbent assay (ELISA), respectively. Morphine (1 and 5 mg/kg doses) attenuated BBB leakage, improved VCS score, pathological changes of brain tissue, and vestibulomotor function compared to the vehicle group (p < 0.0001). Only 5 mg/kg morphine attenuated brain edema (p < 0.0001). Furthermore, 1 and 5 mg/kg morphine significantly changed CSF concentration of IL-1β and IL-10 compared to the vehicle group (p < 0.0001). Inhibition of opioid receptors by naloxone and naltrindole abolished morphine neuroprotective effects (p < 0.0001 vs. MOR 5 group). This study suggests that morphine administration inhibits TBI-mediated neuroinflammation via opioid receptors and improves neurobehavioral function following TBI, which provides a potential therapeutic opportunity in the treatment of traumatic brain injury.

Sex-Dependent Cortical Volume Changes in Patients with Degenerative Cervical Myelopathy

Degenerative cervical myelopathy (DCM) is a progressive condition characterized by degeneration of osseocartilaginous structures within the cervical spine resulting in compression of the spinal cord and presentation of clinical symptoms. Compared to healthy controls (HCs), studies have shown DCM patients experience structural and functional reorganization in the brain; however, sex-dependent cortical differences in DCM patients remains largely unexplored. In the present study, we investigate the role of sex differences on the structure of the cerebral cortex in DCM and determine how structural differences may relate to clinical measures of neurological function. T1-weighted structural MRI scans were acquired in 85 symptomatic and asymptomatic patients with DCM and 90 age-matched HCs. Modified Japanese Orthopedic Association (mJOA) scores were obtained for patients. A general linear model was used to determine vertex-level significant differences in gray matter volume (GMV) between the following groups (1) male HCs and female HCs, (2) male patients and female patients, (3) male patients and male HCs, and (4) female patients and female HCs. Within patients, males exhibited larger GMV in motor, language, and vision related brain regions compared to female DCM patients. Males demonstrated a significant positive correlation between GMV and mJOA score, in which patients with worsening neurological symptoms exhibited decreasing GMV primarily across somatosensory and motor related cortical regions. Females exhibited a similar association, albeit across a broader range of cortical areas including those involved in pain processing. In sensorimotor regions, female patients consistently showed smaller GMV compared with male patients, independent of mJOA score. Results from the current study suggest strong sex-related differences in cortical volume in patients with DCM, which may reflect hormonal influence or differing compensation mechanisms.

Neuropharmacology in traumatic brain injury: from preclinical to clinical neuroprotection?

Traumatic brain injury (TBI) constitutes a major health problem worldwide and is a leading cause of death and disability in individuals, contributing to devastating socioeconomic consequences. Despite numerous promising pharmacological strategies reported as neuroprotective in preclinical studies, the translation to clinical trials always failed, albeit the great diversity of therapeutic targets evaluated. In this review, first, we described epidemiologic features, causes, and primary and secondary injuries of TBI. Second, we outlined the current literature on animal models of TBI, and we described their goals, their advantages and disadvantages according to the species used, the type of injury induced, and their clinical relevance. Third, we defined the concept of neuroprotection and discussed its evolution. We also identified the reasons that might explain the failure of clinical translation. Then, we reviewed post‐TBI neuroprotective treatments with a focus on the following pleiotropic drugs, considered “low hanging fruit” with high probability of success: glitazones, glibenclamide, statins, erythropoietin, and progesterone, that were largely tested and demonstrated efficient in preclinical models of TBI. Finally, our review stresses the need to establish a close cooperation between basic researchers and clinicians to ensure the best clinical translation for neuroprotective strategies for TBI.

Improved spatial memory, neurobehavioral outcomes, and neuroprotective effect after progesterone administration in ovariectomized rats with traumatic brain injury: Role of RU486 progesterone receptor antagonist

OBJECTIVES

The contribution of classic progesterone receptors (PR) in interceding the neuroprotective efficacy of progesterone (P4) on the prevention of brain edema and long-time behavioral disturbances was assessed in traumatic brain injury (TBI).

MATERIALS AND METHODS

Female Wistar rats were ovariectomized and apportioned into 6 groups: sham, TBI, oil, P4, vehicle, and RU486. P4 or oil was injected following TBI. The antagonist of PR (RU486) or DMSO was administered before TBI. The brain edema and destruction of the blood-brain barrier (BBB) were determined. Intracranial pressure (ICP), cerebral perfusion pressure (CPP), and beam walk (BW) task were evaluated previously and at various times post-trauma. Long-time locomotor and cognitive consequences were measured one day before and on days 3, 7, 14, and 21 after the trauma.

RESULTS

RU486 eliminated the inhibitory effects of P4 on brain edema and BBB leakage (P<0.05, P<0.001, respectively). RU486 inhibited the decremental effect of P4 on ICP as well as the increasing effect of P4 on CPP (P<0.001) after TBI. Also, RU486 inhibited the effect of P4 on the increase in traversal time and reduction in vestibulomotor score in the BW task (P<0.001). TBI induced motor, cognitive, and anxiety-like disorders, which lasted for 3 weeks after TBI; but, P4 prevented these cognitive and behavioral abnormalities (P<0.05), and RU486 opposed this P4 effect (P<0.001).

CONCLUSION

The classic progesterone receptors have neuroprotective effects and prevent long-time behavioral and memory deficiency after brain trauma.

The Role of Estradiol in Traumatic Brain Injury: Mechanism and Treatment Potential

Patients surviving traumatic brain injury (TBI) face numerous neurological and neuropsychological problems significantly affecting their quality of life. Extensive studies over the past decades have investigated pharmacological treatment options in different animal models, targeting various pathological consequences of TBI. Sex and gender are known to influence the outcome of TBI in animal models and in patients, respectively. Apart from its well-known effects on reproduction, 17β-estradiol (E2) has a neuroprotective role in brain injury. Hence, in this review, we focus on the effect of E2 in TBI in humans and animals. First, we discuss the clinical classification and pathomechanism of TBI, the research in animal models, and the neuroprotective role of E2. Based on the results of animal studies and clinical trials, we discuss possible E2 targets from early to late events in the pathomechanism of TBI, including neuroinflammation and possible disturbances of the endocrine system. Finally, the potential relevance of selective estrogenic compounds in the treatment of TBI will be discussed.

E2-BSA and G1 exert neuroprotective effects and improve behavioral abnormalities following traumatic brain injury: The role of classic and non-classic estrogen receptors

The role of classical and non-classical estrogen receptors (ERs) in mediating the neuroprotective effects of this hormone on brain edema and long-term behavioral disorders was evaluated after traumatic brain injury (TBI). Ovariectomized rats were divided as follows: E2 (17 β-estradiol), E2-BSA (E2 conjugated to bovine serum albumin), G1 [G-protein-coupled estrogen receptor agonist (GPER)] or their vehicle was injected following TBI, whereas ICI (classical estrogen receptor antagonist), G15 (GPER antagonist), ICI + G15, and their vehicle were injected before the induction of TBI and the injection of E2 and E2-BSA. Brain water (BWC) and Evans blue (EB) contents were measured 24 h and 5 h after TBI, respectively. Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were measured before and at different times after TBI. Locomotor activity, anxiety-like behavior, and spatial memory were assessed on days 3, 7, 14, and 21 after injury. E2, E2-BSA, and G1 prevented the increase of BWC and EB content after TBI, and these effects were inhibited by ICI and G15. ICI and G15 also inhibited the beneficial effects of E2, E2-BSA on ICP, as well as CPP, after trauma. E2, E2-BSA, and G1 prevented the cognitive deficiency and behavioral abnormalities induced by TBI. Similar to the above parameters, ICI and G15 also reversed this E2 and E2-BSA effects on days 3, 7, 14, and 21. Our findings indicated that the beneficial effects of E2-BSA and E2 were inhibited by both ICI and G15, suggesting that GPER and classic ERs were involved in mediating the long-term effects of E2.

Acute peripheral inflammation and post-traumatic sleep differ between sexes after experimental diffuse brain injury

Identifying differential responses between sexes following traumatic brain injury (TBI) can elucidate the mechanisms behind disease pathology. Peripheral and central inflammation in the pathophysiology of TBI can increase sleep in male rodents, but this remains untested in females. We hypothesized that diffuse TBI would increase inflammation and sleep in males more so than in females. Diffuse TBI was induced in C57BL/6J mice and serial blood samples were collected (baseline, 1, 5, 7 days post-injury [DPI]) to quantify peripheral immune cell populations and sleep regulatory cytokines. Brains and spleens were harvested at 7DPI to quantify central and peripheral immune cells, respectively. Mixed-effects regression models were used for data analysis. Female TBI mice had 77%-124% higher IL-6 levels than male TBI mice at 1 and 5DPI, whereas IL-1β and TNF-α levels were similar between sexes at all timepoints. Despite baseline sex differences in blood-measured Ly6Chigh monocytes (females had 40% more than males), TBI reduced monocytes by 67% in TBI mice at 1DPI. Male TBI mice had 31%-33% more blood-measured and 31% more spleen-measured Ly6G+ neutrophils than female TBI mice at 1 and 5DPI, and 7DPI, respectively. Compared with sham, TBI increased sleep in both sexes during the first light and dark cycles. Male TBI mice slept 11%-17% more than female TBI mice, depending on the cycle. Thus, sex and TBI interactions may alter the peripheral inflammation profile and sleep patterns, which might explain discrepancies in disease progression based on sex.

Using the NGF/IL-6 ratio as a reliable criterion to show the beneficial effects of progesterone after experimental diffuse brain injury

Acute progesterone injection has been shown to reduce brain edema following traumatic brain injury (TBI) due to its neuroprotective effect. We investigated the effects of sustained release of progesterone through implantation of subcutaneous capsules on rat's brain edema and alteration of cerebrospinal fluid (CSF), and serum ratio of NGF/IL-6 after TBI. This experiment was performed on ovariectomized (OVX) rats and the brain injury was induced by Marmarou's method. A high and a low dose of progesterone (HP and LP) was injected intraperitoneally two h after the brain injury. In addition, in the capsule progesterone-treated group (CP), the intervention was implemented 6 h after the brain injury. Brain edema, NGF and IL-6 biomarkers in serum and cerebrospinal fluid (CSF) were measured 48 h after the TBI in injection groups and one week after the TBI in the CP group. No significant difference was found in the two groups or in the admonition methods. After TBI, the NGF level increased and IL-6 level decreased by injection of both doses, as well as by taking the capsule. Ratio of NGF/IL-6 in CSF increased significantly by all forms of progesterone administration. The increase in the level of NGF and IL-6 after TBI was higher in CSF than in serum. These results indicated that effects of progesterone in capsule form were better than the injection form. Progesterone probably works by increasing NGF and reducing IL-6. Future studies should investigate the ratio of these biomarkers as a variable to determine the neuroprotective effects of another drug.

Sex differences in traumatic brain injury: a multi-dimensional exploration in genes, hormones, cells, individuals, and society

Traumatic brain injury (TBI) is exceptionally prevalent in society and often imposes a massive burden on patients' families and poor prognosis. The evidence reviewed here suggests that gender can influence clinical outcomes of TBI in many aspects, ranges from patients' mortality and short-term outcome to their long-term outcome, as well as the incidence of cognitive impairment. We mainly focused on the causes and mechanisms underlying the differences between male and female after TBI, from both biological and sociological views. As it turns out that multiple factors contribute to the gender differences after TBI, not merely the perspective of gender and sex hormones. Centered on this, we discussed how female steroid hormones exert neuroprotective effects through the anti-inflammatory and antioxidant mechanism, along with the cognitive impairment and the social integration problems it caused. As to the treatment, both instant and long-term treatment of TBI requires adjustments according to gender. A further study with more focus on this topic is therefore suggested to provide better treatment options for these patients.

Neurosteroids as regulators of neuroinflammation

Neuroinflammation is a physiological protective response in the context of infection and injury. However, neuroinflammation, especially if chronic, may also drive neurodegeneration. Neurodegenerative diseases, such as multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD) and traumatic brain injury (TBI), display inflammatory activation of microglia and astrocytes. Intriguingly, the central nervous system (CNS) is a highly steroidogenic environment synthesizing steroids de novo, as well as metabolizing steroids deriving from the circulation. Neurosteroid synthesis can be substantially affected by neuroinflammation, while, in turn, several steroids, such as 17β-estradiol, dehydroepiandrosterone (DHEA) and allopregnanolone, can regulate neuroinflammatory responses. Here, we review the role of neurosteroids in neuroinflammation in the context of MS, AD, PD and TBI and describe underlying molecular mechanisms. Moreover, we introduce the concept that synthetic neurosteroid analogues could be potentially utilized for the treatment of neurodegenerative diseases in the future.

Immune-Based Therapies for Traumatic Brain Injury: Insights from Pre-Clinical Studies

Traumatic Brain Injury (TBI) is a major public health problem. It is the leading cause of death and disability, especially among children and young adults. The neurobiology basis underlying TBI pathophysiology remains to be fully revealed. Over the past years, emerging evidence has supported the hypothesis that TBI is an inflammatory based condition, paving the way for the development of potential therapeutic targets. There is no treatment capable to prevent or minimize TBIassociated outcomes. Therefore, the search for effective therapies is a priority goal. In this context, animal models have become valuable tools to study molecular and cellular mechanisms involved in TBI pathogenesis as well as novel treatments. Herein, we discuss therapeutic strategies to treat TBI focused on immunomodulatory and/or anti-inflammatory approaches in the pre-clinical setting.

Progesterone anti-inflammatory properties in hereditary retinal degeneration

The interactions between steroid gonadal hormones and the retina (a part of the visual system and the central nervous system (CNS)) have received limited attention and beneficial effects of these hormones in retinal diseases is controversial. Retinitis pigmentosa (RP) is the most common cause of retinal hereditary blindness and to date no treatment is available. However, results regarding the effects of progesterone on the progression of RP are promising. With the idea of demonstrating if the progesterone retinal protection in RP is related to its possible anti-inflammatory properties, we have administered orally progesterone to rd10 mice, an animal model of RP. We observed that progesterone decreased photoreceptors cell death, reactive gliosis and the increase in microglial cells caused by RP. We also examined the expression of neuronal and inducible nitric oxide synthase (nNOS and iNOS), the enzyme responsible for NO production. The results demonstrated a decrease in nNOS expression only in control mice treated with progesterone. Inflammation has been related with an increase in lipid peroxidation. Noticeably progesterone administration was able to diminish retinal malondialdehyde (MDA, a lipid peroxidation product) concentrations in rd10 mice. Altogether, we can conclude that progesterone could be a good therapeutic option not only in RP but also for other retinal diseases that have been associated with inflammation and lipid peroxidation.

Astrocytes Mediate Protective Actions of Estrogenic Compounds after Traumatic Brain Injury

Traumatic brain injury (TBI) is a serious public health problem. It may result in severe neurological disabilities and in a variety of cellular metabolic alterations for which available therapeutic strategies are limited. In the last decade, the use of estrogenic compounds, which activate protective mechanisms in astrocytes, has been explored as a potential experimental therapeutic approach. Previous works have suggested estradiol (E2) as a neuroprotective hormone that acts in the brain by binding to estrogen receptors (ERs). Several steroidal and nonsteroidal estrogenic compounds can imitate the effects of estradiol on ERs. These include hormonal estrogens, phytoestrogens and synthetic estrogens, such as selective ER modulators or tibolone. Current evidence of the role of astrocytes in mediating protective actions of estrogenic compounds after TBI is reviewed in this paper. We conclude that the use of estrogenic compounds to modulate astrocytic properties is a promising therapeutic approach for the treatment of TBI.

Neuroprotective effects of gallic acid in a rat model of traumatic brain injury: behavioral, electrophysiological, and molecular studies

Objective(s):

Traumatic brain injury (TBI) is one of the main causes of intellectual and cognitive disabilities. Clinically, it is essential to limit the development of cognitive impairment after TBI. In the present study, the neuroprotective effects of gallic acid (GA) on neurological score, memory, long-term potentiation (LTP) from hippocampal dentate gyrus (hDG), brain lipid peroxidation and cytokines after TBI were evaluated.

Materials and Methods:

Seventy-two adult male Wistar rats divided randomly into three groups with 24 in each: Veh + Sham, Veh + TBI and GA + TBI (GA; 100 mg/kg, PO for 7 days before TBI induction). Brain injury was made by Marmarou’s method. Briefly, a 200 g weight was fallen down from a 2 m height through a free-falling tube onto the head of anesthetized animal.

Results:

Veterinary coma scores (VCS), memory and recorded hDG -LTP significantly reduced in Veh + TBI group at 1 and 24 hr after TBI when compared to Veh + Sham (P<0.001), respectively, while brain tissue content of interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α) and malondialdehyde (MDA) were increased significantly (P<0.001). Pretreatment of TBI rats with GA improved clinical signs, memory and hDG-LTP significantly (P<0.001) compared to Veh + TBI group, while brain tissue content of IL-1β, IL-6, TNF-α and MDA were decreased significantly (P<0.001).

Conclusion:

Our results propose that GA has neuroprotective effect on memory and LTP impairment due to TBI through decrement of brain lipid peroxidation and cerebral pro-inflammatory cytokines.

Estrogen Modulates the Sensitivity of Lung Vagal C Fibers in Female Rats Exposed to Intermittent Hypoxia

Obstructive sleep apnea is mainly characterized by intermittent hypoxia (IH), which is associated with hyperreactive airway diseases and lung inflammation. Sensitization of lung vagal C fibers (LVCFs) induced by inflammatory mediators may play a central role in the pathogenesis of airway hypersensitivity. In females, estrogen interferes with inflammatory signaling pathways that may modulate airway hyperreactivity. In this study, we investigated the effects of IH on the reflex and afferent responses of LVCFs to chemical stimulants and lung inflammation in adult female rats, as well as the role of estrogen in these responses. Intact and ovariectomized (OVX) female rats were exposed to room air (RA) or IH for 14 consecutive days. On day 15, IH enhanced apneic responses to right atrial injection of chemical stimulants of LVCFs (e.g., capsaicin, phenylbiguanide, and α,β-methylene-ATP) in intact anesthetized females. Rats subjected to OVX prior to IH exposure exhibited an augmented apneic response to the same dose of stimulants compared with rats subjected to other treatments. Apneic responses to the stimulants were completely abrogated by bilateral vagotomy or perivagal capsaicin treatment, which blocked the neural conduction of LVCFs. Electrophysiological experiments revealed that in IH-exposed rats, OVX potentiated the excitability of LVCFs to stimulants. Moreover, LVCF hypersensitivity in rats subjected to OVX prior to IH exposure was accompanied by enhanced lung inflammation, which was reflected by elevated inflammatory cell infiltration in bronchoalveolar lavage fluid, lung lipid peroxidation, and protein expression of inflammatory cytokines. Supplementation with 17β-estradiol (E2) at a low concentration (30 μg/ml) but not at high concentrations (50 and 150 μg/ml) prevented the augmenting effects of OVX on LVCF sensitivity and lung inflammation caused by IH. These results suggest that ovarian hormones prevent the enhancement of LVCF sensitivity and lung inflammation by IH in female rats, which are related to the effect of low-dose estrogen.

Sex-related responses after traumatic brain injury: Considerations for preclinical modeling

Traumatic brain injury (TBI) has historically been viewed as a primarily male problem, since men are more likely to experience a TBI because of more frequent participation in activities that increase risk of head injuries. This male bias is also reflected in preclinical research where mostly male animals have been used in basic and translational science. However, with an aging population in which TBI incidence is increasingly sex-independent due to falls, and increasing female participation in high-risk activities, the attention to potential sex differences in TBI responses and outcomes will become more important. These considerations are especially relevant in designing preclinical animal models of TBI that are more predictive of human responses and outcomes. This review characterizes sex differences following TBI with a special emphasis on the contribution of the female sex hormones, progesterone and estrogen, to these differences. This information is potentially important in developing and customizing TBI treatments.

Effects of progesterone on the neonatal brain following hypoxia-ischemia

Progesterone displays a strong potential for the treatment of neonatal hypoxic-ischemic encephalopathy since it has been shown to be beneficial in the treatment of the central nervous system injuries in adult animals. Here, we evaluated the effects of the administration of progesterone (10 mg/kg) in seven-days-old male Wistar rats submitted to neonatal hypoxia-ischemia (HI). Progesterone was administered immediately before ischemia and/or 6 and 24 h after the onset of hypoxia. The body weight of the animals, the volume of brain lesion and the expression of p-Akt and procaspase-3 in the hippocampus were evaluated. All animals submitted to HI showed a reduction in the body weight. However, this reduction was more remarkable in those animals which received progesterone before surgery. Administration of progesterone was unable to reduce the volume of brain damage caused by HI. Moreover, no significant differences were observed in the expression of p-Akt and procaspase-3 in animals submitted to HI and treated with either progesterone or vehicle. In summary, progesterone did not show a neuroprotective effect on the volume of brain lesion in neonatal rats submitted to hypoxia-ischemia. Furthermore, progesterone was unable to modulate p-Akt and procaspase-3 signaling pathways, which may explain the absence of neuroprotection. On the other hand, it seems that administration of progesterone before ischemia exerts some systemic effect, leading to a remarkable reduction in the body weight.

Effects of pregabalin on brain edema, neurologic and histologic outcomes in experimental traumatic brain injury

Brain edema and increased intracranial pressure (ICP) are among the main causes of neurological disturbance and mortality following traumatic brain injury (TBI). Since pregabalin neuroprotective effects have been shown, this study was performed to evaluate the possible neuroprotective effects of pregabalin in experimental TBI of male rats. Adult male Wistar rats were divided into 4 groups: sham, vehicle, pregabalin 30 mg/kg and pregabalin 60 mg/kg. TBI was induced in vehicle and pregabalin groups by Marmarou method. Pregabalin was administered 30 min after TBI. Sham and vehicle groups received saline. Brain water and Evans blue content and histopathological changes were evaluated 24, 5 and 24 h after TBI, respectively. The ICP and neurological outcomes (veterinary coma scale, VCS) were recorded before, 1 h and 24 h post TBI. The results showed a significant reduction in brain water content and ICP, and a significant increase in VCS of pregabalin group (60 mg/kg) as compared to vehicle group (P < 0.05). Also, pregabalin reduced brain edema and apoptosis score as compared to vehicle group. Post TBI pregabalin administration revealed a delayed but significant improvement in ICP and neurological outcomes in experimental TBI. The underlying mechanism(s) was not determined and needs further investigation.

Progesterone attenuates airway remodeling and glucocorticoid resistance in a murine model of exposing to ozone

Airway remodeling is a vital component of chronic obstructive pulmonary disease (COPD). Despite the broad anti-inflammation effects of glucocorticoids, they exhibit relatively little therapeutic benefit in COPD, indicating the accelerating demands of new agents for COPD. We aim to explore the effect of progesterone on airway remodeling in a murine modeling of exposing to ozone and to further examine the potential effect of progesterone on glucocorticoid insensitivity. C57/BL6 mice were exposed to ozone for 12 times over 6 weeks, and were administered with progesterone alone or combined with budesonide (BUD) after each exposure until the 10th week. The peribronchial collagen deposition was measured. The protein levels of MMP8 and MMP9 in bronchoalveolar lavage fluid (BALF) and lungs were assessed. Western blot analysis was used to detect the levels of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), a-smooth muscle actin (α-SMA), glycogen synthase kinase-3β (GSK-3β). The expression of VEGF and histone deacetylase 2 (HDAC2) in the lung were determined by Immunohistochemical analyses. We observe that progesterone attenuates the peribronchial collagen deposition, as well as the expression of MMP8, MMP9, HIF-1α, VEGF, α-SMA, and GSK-3β in BALF or lung tissues. Progesterone or BUD monotherapy has no effect on HDAC2 production. Progesterone combines with BUD induce dramatically enhanced effects. Thus, these results demonstrate novel roles of progesterone for the pathogenesis and airway remodeling in COPD. Progesterone plus BUD administration exerts more significant inhibition on airway remodeling with dose-independent. Additionally, progesterone may, to some extent, improve the glucocorticoid insensitivity.

Does the administration of melatonin during post-traumatic brain injury affect cytokine levels?

Increased levels of inflammatory cytokines after traumatic brain injury (TBI) can lead to brain edema and neuronal death. In this study, the effect of melatonin on pro-inflammatory (IL-1ß, IL-6, and TNF-α) and anti-inflammatory (IL-10) cytokines following TBI was investigated considering anti-inflammatory effect of melatonin. Male Wistar rats were divided into five groups: Sham, TBI, TBI + VEH (vehicle), TBI + 5 mg dose of melatonin (MEL5), TBI + 20 mg dose of melatonin (MEL20). Diffuse TBI was induced by Marmarou method. Melatonin was administered 1, 24, 48 and 72 h after TBI through i.p. Brain water content and brain levels of pro-inflammatory (IL-1ß, IL-6 and TNF-α) and anti-inflammatory (IL-10) cytokines were measured 72 h after TBI. The IL-1ß levels decreased in the TBI + MEL5 and TBI + MEL20 groups in comparison to TBI + VEH group (p < 0.001). The levels of IL-6 and TNF-α also decreased in melatonin-treated groups compared to control group (p < 0.001). The amount of IL-10 decreased after TBI. But melatonin administration increased the IL-10 levels in comparison with TBI + VEH group (p < 0.001). The results showed that melatonin administration affected the brain levels of pro-inflammatory and anti-inflammatory cytokines involving in brain edema led to neuronal protection after TBI.

Effects of Female Sex Steroids Administration on Pathophysiologic Mechanisms in Traumatic Brain Injury

Secondary brain damage following initial brain damage in traumatic brain injury (TBI) is a major cause of adverse outcomes. There are many gaps in TBI research and a lack of therapy to limit debilitating outcomes in TBI or enhance the neurogenesis, despite pre-clinical and clinical research performed in TBI. Females show harmful outcomes against brain damage including TBI less than males, independent of different TBI occurrence. A significant reduction in secondary brain damage and improvement in neurologic outcome post-TBI has been reported following the use of progesterone and estrogen in many experimental studies. Although useful features of sex steroids including progesterone have been identified in TBI clinical trials I and II, clinical trials III have been unsuccessful. This review article focuses on evidence of secondary injury mechanisms and neuroprotective effects of estrogen and progesterone in TBI. Understanding these mechanisms may enable researchers to achieve greater success in TBI clinical studies. It seems that the design of clinical studies should be revised due to translation loss of animal studies to clinical studies. The heterogeneous and complex nature of TBI, the endogenous levels of sex hormones at the time of taking these hormones, the therapeutic window of the drug, the dosage of the drug, the selection of appropriate targets in evaluation, the determination of responsive population, gender and age based on animal studies should be considered in the design of TBI human studies in future.

Diosmin improved cognitive deficit and amplified brain electrical activity in the rat model of traumatic brain injury

OBJECTIVE

Traumatic brain injury (TBI) is one of the main causes of intellectual and cognitive disabilities in humans. Clinically, it is essential to limit the progress of cognitive impairment after TBI. It is reported that diosmin has a neuroprotective effect that can limit the progress of the impairment. The aim of this study was to evaluate the effects of diosmin on neurological score, memory, tumor necrosis factor-α (TNF-α) level and long-term potentiation in hippocampal dentate gyrus after the injury.

METHODS

A total of ninety six adult male Wistar rats were used as test subjects in this study. The animals were randomly assigned into one of the following three groups (n=32/group): Sham, TBI and diosmin (100mg/kg, p.o for seven consecutive days before TBI induction). TBI was induced into the animals by Marmarou's method. Briefly, a 200g weight was dropped from a 1m height through a free-falling tube onto the head of the anesthetized rats.

RESULTS

The veterinary coma scale scores, memory and long-term potentiation in TBI group showed significant decrease at different times after the onset of TBI when compared with Sham (p<0.001). The TNF-α level in the hippocampus of the TBI group of animals was significantly higher than that found in the test subjects from the Sham group (p<0.001). The pre-treatment of the TBI group with diosmin significantly improved their neurological scores, memory and long-term potentiation (p<0.001) when compared with the TBI group. The TNF-α level in hippocampus of the diosmin group was significantly lower than the TBI group (p<0.001).

CONCLUSION

Based on the results of the present study, pre-treatment with diosmin has protective effects against TBI-induced memory and long-term potentiation impairment. The effects of diosmin may be mediated through a decrement in the TNF-α concentration of hippocampus as a pro-inflammatory cytokine.

Therapeutic effects of ellagic acid on memory, hippocampus electrophysiology deficits, and elevated TNF-α level in brain due to experimental traumatic brain injury

OBJECTIVES

Cognitive defects such as learning and memory impairment are amongst the most repetitious sequelae after sever and moderate traumatic brain injury (TBI). It was suggested that ellagic acid (EA), an innate phenol product, display neuroprotective properties against oxidative and inflammatory damages after brain injury. The object of the current study was therapeutic properties of EA on blood-brain barrier (BBB) interruption and elevated content of TNF-α in brain tissue followed by neurologic aftereffects, cognitive and brain electrophysiology deficits as outcomes of diffuse TBI in rat.

MATERIALS AND METHODS

TBI was induced by a 200 g weight falling by a 2-m height through a free-falling tube onto the head of anesthetized rat. TBI rats treated immediately after trauma with EA (100 mg/kg, IP) once every 8 hr until 48 hr later. Neurologic outcomes, passive avoidance task (PAT), hippocampal long-term potentiation (LTP), BBB permeability and content of TNF-α in brain tissue were evaluated.

RESULTS

TBI induced significant impairments in neurological score, BBB function, PAT and hippocampal LTP in TBI+Veh group in compare with Sham+Veh (P<0.001). EA treatment decreased neurologic severity score (NSS), restored increased BBB permeability, cognitive and hippocampal LTP abnormalities, and elevated brain content of TNF-α due to TBI significantly (P<0.001).

CONCLUSION

Our findings propose that EA can restore NSS, cognitive and LTP deficits and prevent brain inflammation may by restore BBB permeability as well as lowering brain content of TNF-α following TBI.

Non-Neuronal Cells in the Hypothalamic Adaptation to Metabolic Signals

Although the brain is composed of numerous cell types, neurons have received the vast majority of attention in the attempt to understand how this organ functions. Neurons are indeed fundamental but, in order for them to function correctly, they rely on the surrounding "non-neuronal" cells. These different cell types, which include glia, epithelial cells, pericytes, and endothelia, supply essential substances to neurons, in addition to protecting them from dangerous substances and situations. Moreover, it is now clear that non-neuronal cells can also actively participate in determining neuronal signaling outcomes. Due to the increasing problem of obesity in industrialized countries, investigation of the central control of energy balance has greatly increased in attempts to identify new therapeutic targets. This has led to interesting advances in our understanding of how appetite and systemic metabolism are modulated by non-neuronal cells. For example, not only are nutrients and hormones transported into the brain by non-neuronal cells, but these cells can also metabolize these metabolic factors, thus modifying the signals reaching the neurons. The hypothalamus is the main integrating center of incoming metabolic and hormonal signals and interprets this information in order to control appetite and systemic metabolism. Hence, the factors transported and released from surrounding non-neuronal cells will undoubtedly influence metabolic homeostasis. This review focuses on what is known to date regarding the involvement of different cell types in the transport and metabolism of nutrients and hormones in the hypothalamus. The possible involvement of non-neuronal cells, in particular glial cells, in physiopathological outcomes of poor dietary habits and excess weight gain are also discussed.

Cognitive performance of male and female C57BL/6J mice after repetitive concussive brain injuries

In contact sports, repetitive concussive brain injury (rCBI) is the prevalent form of head injury seen in athletes. The need for effective treatment is urgent as rCBI has been associated with a host of cognitive, behavioral and neurological complaints. There has been a growing trend in the use of female animals in pre-clinical research, but few studies have investigated possible sex differences following rCBI. The goal of the current study was to determine any differences between male and female C57BL/6J mice on assessments of learning and memory after repetitive concussive injury. Following rCBI by impact to the scalp, male mice exhibited longer righting reflexes during acute recovery. In both sexes, there were no evident histopathological changes observed in the underlying cerebral cortex or hippocampus. Reactive astrogliosis was elevated in the corpus callosum and optic tract, and astrogliosis was slightly less in the optic tract of female mice. rCBI mice exhibited impairment during the learning phase of the Morris water maze (MWM), but female mice, in comparison to male mice, were observed to have superior spatial memory during standard MWM probe trials. Female mice were overall more active, evidenced by greater distances traveled in the y-maze and greater swim speeds in the MWM. The results of this study demonstrate sex differences in cognitive performance following rCBI and support previous research suggesting the neuroprotective role of sex in brain injury.

Administration of 17β-Estradiol Improves Motoneuron Survival and Down-regulates Inflammasome Activation in Male SOD1(G93A) ALS Mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease manifested by the progressive loss of upper and lower motoneurons. The pathomechanism of ALS is complex and not yet fully understood. Neuroinflammation is believed to significantly contribute to disease progression. Inflammasome activation was recently shown in the spinal cord of human sporadic ALS patients and in the SOD1(G93A) mouse model for ALS. In the present study, we investigated the neuroprotective and anti-inflammatory effects of 17β-estradiol (E2) treatment in pre-symptomatic and symptomatic male SOD1(G93A) mice. Symptomatic mice with E2 substitution exhibited improved motor performance correlating with an increased survival of motoneurons in the lumbar spinal cord. Expression of NLRP3 inflammasome proteins and levels of activated caspase 1 and mature interleukin 1 beta were significantly reduced in SOD1(G93A) mice supplemented with E2.

Progesterone neuroprotection: The background of clinical trial failure

Since the first pioneering studies in the 1990s, a large number of experimental animal studies have demonstrated the neuroprotective efficacy of progesterone for brain disorders, including traumatic brain injury (TBI). In addition, this steroid has major assets: it easily crosses the blood-brain-barrier, rapidly diffuses throughout the brain and exerts multiple beneficial effects by acting on many molecular and cellular targets. Moreover, progesterone therapies are well tolerated. Notably, increased brain levels of progesterone are part of endogenous neuroprotective responses to injury. The hormone thus emerged as a particularly promising protective candidate for TBI and stroke patients. The positive outcomes of small Phase 2 trials aimed at testing the safety and potential protective efficacy of progesterone in TBI patients then provided support and guidance for two large, multicenter, randomized and placebo-controlled Phase 3 trials, with more than 2000 TBI patients enrolled. The negative outcomes of both trials, named ProTECT III and SyNAPSE, came as a big disappointment. If these trials were successful, progesterone would have become the first efficient neuroprotective drug for brain-injured patients. Thus, progesterone has joined the numerous neuroprotective candidates that have failed in clinical trials. The aim of this review is a reappraisal of the preclinical animal studies, which provided the proof of concept for the clinical trials, and we critically examine the design of the clinical studies. We made efforts to present a balanced view of the strengths and limitations of the translational studies and of some serious issues with the clinical trials. We place particular emphasis on the translational value of animal studies and the relevance of TBI biomarkers. The probability of failure of ProTECT III and SyNAPSE was very high, and we present them within the broader context of other unsuccessful trials.

The Role of Steroid Hormones in the Modulation of Neuroinflammation by Dietary Interventions

Steroid hormones, such as sex hormones and glucocorticoids, have been demonstrated to play a role in different cellular processes in the central nervous system, ranging from neurodevelopment to neurodegeneration. Environmental factors, such as calorie intake or fasting frequency, may also impact on such processes, indicating the importance of external factors in the development and preservation of a healthy brain. The hypothalamic-pituitary-adrenal axis and glucocorticoid activity play a role in neurodegenerative processes, including in disorders such as in Alzheimer's and Parkinson's diseases. Sex hormones have also been shown to modulate cognitive functioning. Inflammation is a common feature in neurodegenerative disorders, and sex hormones/glucocorticoids can act to regulate inflammatory processes. Intermittent fasting can protect the brain against cognitive decline that is induced by an inflammatory stimulus. On the other hand, obesity increases susceptibility to inflammation, while metabolic syndromes, such as diabetes, are associated with neurodegeneration. Consequently, given that gonadal and/or adrenal steroids may significantly impact the pathophysiology of neurodegeneration, via their effect on inflammatory processes, this review focuses on how environmental factors, such as calorie intake and intermittent fasting, acting through their modulation of steroid hormones, impact on inflammation that contributes to cognitive and neurodegenerative processes.

Effect of estrogen and/or progesterone administration on traumatic brain injury-caused brain edema: the changes of aquaporin-4 and interleukin-6

The role of aquaporin-4 (AQP4) and interleukin-6 (IL-6) in the development of brain edema post-traumatic brain injury (TBI) has been indicated. The present study was designed to investigate the effect(s) of administration of progesterone (P) and/or estrogen (E) on brain water content, AQP4 expression, and IL-6 levels post-TBI. The ovariectomized rats were divided into 11 groups: sham, one vehicle, two vehicles, E1, E2, P1, P2, E1 + P1, E1 + P2, E2 + P1, and E2 + P2. The brain AQP4 expression, IL-6 levels, and water content were evaluated 24 h after TBI induced by Marmarou's method. The low (E1 and P1) and high (E2 and P2) doses of estrogen and progesterone were administered 30 min post-TBI. The results showed that brain water content and AQP4 expression decreased in the E1, E2, P1, and P2-treated groups. The administration of E1 decreased IL-6 levels. Addition of progesterone decreased the inhibitory effect of E1 and E2 on the accumulation of water in the brain. Administration of E1 + P1 and E1 + P2 decreased the inhibitory effect of E1 on the IL-6 levels and AQP4 protein expression. Our findings suggest that estrogen or progesterone by itself has more effective roles in decrease of brain edema than combination of both. Possible mechanism may be mediated by the alteration of AQP4 and IL-6 expression. However, further studies are required to verify the exact mechanism.

Static and Dynamic Factors Promoting Resilience following Traumatic Brain Injury: A Brief Review

Traumatic brain injury (TBI) is the greatest contributing cause of death and disability among children and young adults in the United States. The current paper briefly summarizes contemporary literature on factors that can improve outcomes (i.e., promote resilience) for children and adults following TBI. For the purpose of this paper, the authors divided these factors into static or unmodifiable factors (i.e., age, sex, intellectual abilities/education, and preinjury psychiatric history) and dynamic or modifiable factors (i.e., socioeconomic status, family functioning/social support, nutrition, and exercise). Drawing on human and animal studies, the research reviewed indicated that these various factors can improve outcomes in multiple domains of functioning (e.g., cognition, emotion regulation, health and wellness, behavior, etc.) following a TBI. However, many of these factors have not been studied across populations, have been limited to preclinical investigations, have been limited in their scope or follow-up, or have not involved a thorough evaluation of outcomes. Thus, although promising, continued research is vital in the area of factors promoting resilience following TBI in children and adults.

Gallic acid improved behavior, brain electrophysiology, and inflammation in a rat model of traumatic brain injury

Traumatic brain injury (TBI) is one of the main causes of intellectual and cognitive disabilities. In the clinic it is essential to limit the development of cognitive impairment after TBI. In this study, the effects of gallic acid (GA; 100 mg/kg, per oral, from 7 days before to 2 days after TBI induction) on neurological score, passive avoidance memory, long-term potentiation (LTP) deficits, and levels of proinflammatory cytokines including interleukin-1 beta (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α) in the brain have been evaluated. Brain injury was induced following Marmarou’s method. Data were analyzed by one-way and repeated measures ANOVA followed by Tukey’s post-hoc test. The results indicated that memory was significantly impaired (p < 0.001) in the group treated with TBI + vehicle, together with deterioration of the hippocampal LTP and increased brain tissue levels of IL-1β, IL-6, and TNF-α. GA treatment significantly improved memory and LTP in the TBI rats. The brain tissue levels of IL-1β, IL-6, and TNF-α were significantly reduced (p < 0.001) in the group treated with GA. The results suggest that GA has neuroprotective properties against TBI-induced behavioral, electrophysiological, and inflammatory disorders, probably via the decrease of cerebral proinflammatory cytokines.

Treatment of traumatic brain injury with anti-inflammatory drugs

Traumatic brain injury rapidly induces inflammation. This inflammation is produced both by endogenous brain cells and circulating inflammatory cells that enter from the brain. Together they drive the inflammatory response through a wide variety of bioactive lipids, cytokines and chemokines. A large number of drugs with anti-inflammatory action have been tested in both preclinical studies and in clinical trials. These drugs either have known anti-inflammatory action or inhibit the inflammatory response through unknown mechanisms. The results of these preclinical studies and clinical trials are reviewed. Recommendations are suggested on how to improve preclinical testing of drugs to make them more relevant to evaluate for clinical trials.