Progesterone in the clinical treatment of acute traumatic brain injury

Update on Neuroprotection after Traumatic Brain Injury

Traumatic brain injury (TBI) is a prevalent cause of morbidity and mortality worldwide. A focus on neuroprotective agents to prevent the secondary injury cascade that follows moderate-to-severe TBI has informed the field greatly but has not yielded any viable therapeutic options to date. New strategies and pharmacotherapy options for neuroprotection continue to be evaluated, including tranexamic acid, progesterone, cerebrolysin, cyclosporin A, citicholine, memantine, and lactate. Biomarkers of injury that can aid in diagnosis and prognosis have also been elucidated and are incrementally being used in clinical practice. The spectrum of TBI severity has also gained increasing attention as it relates to mild TBI or concussion, blast injury, and subacute or chronic subdural hematomas. In this review, we review the pathophysiology, recent clinical trials, and future directions for acute TBI.

Assessment of the Sex Hormone Profile and Its Predictive Role in Consciousness Recovery Following Severe Traumatic Brain Injury

INTRODUCTION

Traumatic brain injuries (TBIs) are conditions affecting brain function caused by blunt or penetrating forces to the head. Symptoms may include confusion, impaired consciousness, coma, seizures, and focal or sensory neurological motor injuries.

OBJECTIVE

This study evaluated sex hormone profiles and their predictive role in returning consciousness after severe traumatic brain injury.

MATERIALS AND METHODS

We included 120 patients with TBIs and collected comprehensive information about each patient, including the cause of the trauma, age, gender, Glasgow Coma Scale (GCS) score, Injury Severity Score (ISS), and neuroradiological imaging data. The ISS was used to assess the severity of the trauma. At the same time, the lowest GCS score was recorded either before sedation and intubation in the emergency room or by emergency medical services personnel. For female participants, samples were collected during the luteal phase of the menstrual cycle (days 18 to 23).

RESULTS

The mean age of male patients was 33.40 years, ranging from 23 to 45 years, while female patients had an average age of 34.25 years, ranging from 25 to 48 years. The primary cause of injury for both genders was motor vehicle accidents. In male patients, testosterone levels were significantly higher in those classified as responsive (RC) compared to those non-responsive (NRC), with levels of 2.56 ± 0.47 ng/mL versus 0.81 ± 0.41 ng/mL (p = 0.003). A cut-off point of 1.885 ng/mL for testosterone levels in males was established, achieving a sensitivity and specificity of 86.7% and 86.7%, respectively. In female patients, progesterone levels were elevated in those who regained consciousness, measuring 1.80 ± 0.31 ng/mL compared to 0.62 ± 0.31 ng/mL (p = 0.012). A cut-off point of 1.335 ng/mL for progesterone levels in females was determined, with a sensitivity and specificity of 93.3% and 86.7%, respectively.

CONCLUSIONS

We can conclude that sex hormone levels in the acute phase of TBIs can vary between males and females. Notably, serum testosterone levels in males and progesterone levels in females with TBIs are significant prognostic factors for assessing the likelihood of regaining consciousness after such injuries. These findings underscore the importance of considering sex hormone profiles in TBI recovery prognosis.

The evolving pathophysiology of TBI and the advantages of temporally-guided combination therapies

Several clinical and experimental studies have demonstrated that traumatic brain injury (TBI) activates cascades of biochemical, molecular, structural, and pathological changes in the brain. These changes combine to contribute to the various outcomes observed after TBI. Given the breadth and complexity of changes, combination treatments may be an effective approach for targeting multiple detrimental pathways to yield meaningful improvements. In order to identify targets for therapy development, the temporally evolving pathophysiology of TBI needs to be elucidated in detail at both the cellular and molecular levels, as it has been shown that the mechanisms contributing to cognitive dysfunction change over time. Thus, a combination of individual mechanism-based therapies is likely to be effective when maintained based on the time courses of the cellular and molecular changes being targeted. In this review, we will discuss the temporal changes of some of the key clinical pathologies of human TBI, the underlying cellular and molecular mechanisms, and the results from preclinical and clinical studies aimed at mitigating their consequences. As most of the pathological events that occur after TBI are likely to have subsided in the chronic stage of the disease, combination treatments aimed at attenuating chronic conditions such as cognitive dysfunction may not require the initiation of individual treatments at a specific time. We propose that a combination of acute, subacute, and chronic interventions may be necessary to maximally improve health-related quality of life (HRQoL) for persons who have sustained a TBI.

The Uncoupling Effect of 17β-Estradiol Underlies the Resilience of Female-Derived Mitochondria to Damage after Experimental TBI

Current literature finds females have improved outcomes over their male counterparts after severe traumatic brain injury (TBI), while the opposite seems to be true for mild TBI. This begs the question as to what may be driving these sex differences after TBI. Estrogen is thought to be neuroprotective in certain diseases, and its actions have been shown to influence mitochondrial function. Mitochondrial impairment is a major hallmark of TBI, and interestingly, this dysfunction has been shown to be more severe in males than females after brain injury. This suggests estrogen could be playing a role in promoting "mitoprotection" following TBI. Despite the existence of estrogen receptors in mitochondria, few studies have examined the direct role of estrogen on mitochondrial function, and no studies have explored this after TBI. We hypothesized ex vivo treatment of isolated mitochondria with 17β-estradiol (E2) would improve mitochondrial function after experimental TBI in mice. Total mitochondria from the ipsilateral (injured) and contralateral (control) cortices of male and female mice were isolated 24 h post-controlled severe cortical impact (CCI) and treated with vehicle, 2 nM E2, or 20 nM E2 immediately before measuring reactive oxygen species (ROS) production, bioenergetics, electron transport chain complex (ETC) activities, and β-oxidation of palmitoyl carnitine. Protein expression of oxidative phosphorylation (OXPHOS) complexes was also measured in these mitochondrial samples to determine whether this influenced functional outcomes with respect to sex or injury. While mitochondrial ROS production was affected by CCI in both sexes, there were other sex-specific patterns of mitochondrial injury 24 h following severe CCI. For instance, mitochondria from males were more susceptible to CCI-induced injury with respect to bioenergetics and ETC complex activities, whereas mitochondria from females showed only Complex II impairment and reduced β-oxidation after injury. Neither concentration of E2 influenced ETC complex activities themselves, but 20 nM E2 appeared to uncouple mitochondria isolated from the contralateral cortex in both sexes, as well as the injured ipsilateral cortex of females. These studies highlight the significance of measuring mitochondrial dysfunction in both sexes after TBI and also shed light on another potential neuroprotective mechanism in which E2 may attenuate mitochondrial dysfunction after TBI in vivo.

Neuroprotection or Sex Bias: A Protective Response to Traumatic Brain Injury in the Females

Traumatic brain injury (TBI) is a major healthcare problem and a common cause of mortality and morbidity. Clinical and preclinical research suggests sex-related differences in short- and longterm outcomes following TBI; however, males have been the main focus of TBI research. Females show a protective response against TBI. Female animals in preclinical studies and women in clinical trials have shown comparatively better outcomes against mild, moderate, or severe TBI. This reflects a favorable protective nature of the females compared to the males, primarily attributed to various protective mechanisms that provide better prognosis and recovery in the females after TBI. Understanding the sex difference in the TBI pathophysiology and the underlying mechanisms remains an elusive goal. In this review, we provide insights into various mechanisms related to the anatomical, physiological, hormonal, enzymatic, inflammatory, oxidative, genetic, or mitochondrial basis that support the protective nature of females compared to males. Furthermore, we sought to outline the evidence of multiple biomarkers that are highly potential in the investigation of TBI's prognosis, pathophysiology, and treatment and which can serve as objective measures and novel targets for individualized therapeutic interventions in TBI treatment. Implementations from this review are important for the understanding of the effect of sex on TBI outcomes and possible mechanisms behind the favorable response in females. It also emphasizes the critical need to include females as a biological variable and in sufficient numbers in future TBI studies.

Gender Discrepancy in Patients with Traumatic Brain Injury: A Retrospective Study from a Level 1 Trauma Center

Objectives. The objective of this study is to explore the gender discrepancy in patients with traumatic brain injury (TBI). Methods. A retrospective analysis of Qatar Trauma Registry (QTR) was conducted among patients (age ≥14y) who were hospitalized with TBI. Data were collected and analyzed based on the gender and age. Results. Over 5 years (2014-2019), 9, 309 trauma patients (90% males and 10% females) were admitted to the trauma center. Of these, 1, 620 (17.4%) patients were hospitalized with TBI (94% males and 6% females). Motor vehicle crash was the main mechanism of injury (MOI) in females, and fall from height was predominant among males. Subdural hematoma (SDH) was the more frequent type of TBI in both genders, but it was more prevalent in male patients ≥55 years. Injury severity score, Glasgow coma scale, and head abbreviated injury score were comparable between males and females. The length of stay in the ICU and hospital and mortality were similar in both genders. However, mortality was higher among males ≥55 years when compared to 14-54 years within the same gender (21% vs. 12%, $p=0.002$ ). The crude and adjusted odds ratio did not show that gender is a significant predictor of mortality among TBI patients. Conclusions. Although the incidence and MOI of TBI show significant differences between male and female patients, the severity and outcomes are comparable.

Evaluation of Progesterone Receptor Antagonist and Maxi-K Channel Agonist as Neuroprotective in Feeney's Weight Drop Model of TBI

Background

Neuroprotection in traumatic brain injury (TBI) is an unmet medical need.

Objective

We evaluated two agents, aglepristone (progesterone receptor antagonist) and N-salicyloyltryptamine (STP) (activator of Maxi-K channel in GH3 cells), for neuroprotection in Feeney's weight drop model of TBI.

Material and Methods

Forty-eight male Wistar rats were divided into six groups (n = 8 per group). A battery of six neurobehavioral tests was evaluated at the end of the first week (EO1W), second week (EO2W), and third week (EO3W). In addition, histopathological and immunohistochemistry (BAX, Bcl-2, and M30 Cytodeath) tests were performed at EO3W.

Results

Aglepristone at 10 mg/kg showed significant neuroprotection compared to control as assessed by Rota-rod test at EO1W, VEFP right paw and 28-point neurobehavioral test at EO2W, MWM test at EO3W, and positive histopathological and IHC findings. Aglepristone at 20 mg/kg showed negative results as assessed by BAX expression, downregulation of Bcl-2, and positive M30 Cytodeath, thereby suggesting toxicity at higher doses. STP 100 mg/kg showed modest neuroprotective activity but failed to show a dose-response relationship at a dose of 50 mg/kg.

Conclusion

The study shows that progesterone receptor antagonists have neuroprotection at lower doses and toxicity at higher doses.

The epithelial potassium channel Kir7.1 is stimulated by progesterone

The choroid plexus (CP) epithelium secretes cerebrospinal fluid and plays an important role in healthy homeostasis of the brain. CP function can be influenced by sex steroid hormones; however, the precise molecular mechanism of such regulation is not well understood. Here, using whole-cell patch-clamp recordings from male and female murine CP cells, we show that application of progesterone resulted in specific and strong potentiation of the inwardly rectifying potassium channel Kir7.1, an essential protein that is expressed in CP and is required for survival. The potentiation was progesterone specific and independent of other known progesterone receptors expressed in CP. This effect was recapitulated with recombinant Kir7.1, as well as with endogenous Kir7.1 expressed in the retinal pigment epithelium. Current-clamp studies further showed a progesterone-induced hyperpolarization of CP cells. Our results provide evidence of a progesterone-driven control of tissues in which Kir7.1 is present.

Use of Hormone Therapy in Postmenopausal Women with Alzheimer's Disease: A Systematic Review

BACKGROUND

Around two-thirds of patients with Alzheimer's disease (AD) are women, which could be related to the depletion of female sexual hormones at menopause. The replacement of these hormones with hormone therapy (HT) to possibly decrease AD risk or treat AD patients has generated conflicting results in the literature.

OBJECTIVE

Our aim was to systematically review the relationship between HT use in postmenopausal women with AD and the risk of developing or treating AD symptoms.

DATA SOURCES

The PubMed, LILACS, Scopus, Scielo, and Web of Science databases were searched from January 1994 to December 2020 using the descriptors 'Alzheimer Disease OR Alzheimer's Disease' and 'Hormone Replacement Therapy OR Estrogen Replacement Therapy'.

STUDY SELECTION

Observational and controlled clinical trials including postmenopausal women diagnosed with AD and evaluating HT efficacy were eligible for inclusion.

DATA EXTRACTION

Extracted data comprise study design, covariates, inclusion criteria for sample selection, AD diagnosis criteria, biases, HT regimen, and cognitive measurement tools used.

RESULTS

Overall, 25 studies were selected. Among the 14 observational studies, 8 reported an improvement in cognitive function and a decrease in AD risk, especially in younger postmenopausal women. Five observational studies did not demonstrate any association between HT and AD, and one study reported an increase in AD risk, regardless of time of HT initiation. Of the 11 controlled clinical trials included, 7 showed an amelioration in cognitive function after HT. The remaining 4 trials saw no difference between HT and control.

CONCLUSION

Both observational and controlled clinical trials had methodological issues and discrepancies in inclusion criteria and HT protocols. These inconsistencies made it difficult to establish an association between HT and AD.

Progesterone's Effects on Cognitive Performance of Male Mice Are Independent of Progestin Receptors but Relate to Increases in GABAA Activity in the Hippocampus and Cortex

Progestogens' (e.g., progesterone and its neuroactive metabolite, allopregnanolone), cognitive effects and mechanisms among males are not well-understood. We hypothesized if progestogen's effects on cognitive performance are through its metabolite allopregnanolone, and not actions via binding to traditional progestin receptors (PRs), then progesterone administration would enhance performance in tasks mediated by the hippocampus and cortex, coincident with increasing allopregnanolone concentrations, brain derived neurotrophic factor (BDNF) and/or muscimol binding of PR knock out (PRKO) and wild-type PR replete mice. Experiment 1: Progesterone (4 mg/kg, subcutaneously (SC; n = 12/grp), or oil vehicle control, was administered to gonadally-intact adult male mice PRKO mice and their wild-type counterparts and cognitive behaviors in object recognition, T-maze and water maze was examined. Progesterone, compared to vehicle, when administered post-training increased time investigating novel objects by the PRKO and wild-type mice in the object recognition task. In the T-maze task, progesterone administration to wild-type and PRKO mice had significantly greater number of spontaneous alternations compared to their vehicle-administered counterparts. In the water maze task, PRKO mice administered vehicle spent significantly fewer seconds in the quadrant associated with the escape platform on testing compared to all other groups. Experiment 2: Progesterone administered to wild-type and PRKO mice increased plasma progesterone and allopregnanolone levels (n = 5/group). PRKO mice had higher allopregnanolone levels in plasma and hippocampus, but not cortex, when administered progesterone and compared to wild-type mice. Experiment 3: Assessment of PR binding revealed progesterone administered wild-type mice had significantly greater levels of PRs in the hippocampus and cortex, compared to all other groups (n = 5/group). Wild-type mice administered progesterone, but not vehicle, had increased BDNF levels in the hippocampus, but not the cortex, compared to PRKOs. Wild-type as well as PRKO mice administered progesterone experienced significant increases in maximal GABAA agonist, muscimol, binding in hippocampus and cortex, compared to their vehicle-administered counterparts. Thus, adult male mice can be responsive to progesterone for cognitive performance, and such effects may be independent of PRs trophic actions of BDNF levels in the hippocampus and/or increases in GABAA activity in the hippocampus and cortex.

Liquid chromatography-mass spectrometry applications for quantification of endogenous sex hormones

Liquid chromatography, coupled with tandem mass spectrometry, presents a powerful tool for the quantification of the sex steroid hormones 17-β estradiol, progesterone and testosterone from biological matrices. The importance of accurate quantification with these hormones, even at endogenous levels, has evolved with our understanding of the role these regulators play in human development, fertility and disease risk and manifestation. Routine monitoring of these analytes can be accomplished by immunoassay techniques, which face limitations on specificity and sensitivity, or using gas chromatography-mass spectrometry. LC-MS/MS is growing in capability and acceptance for clinically relevant quantification of sex steroid hormones in biological matrices and is able to overcome many of the limitations of immunoassays. Analyte specificity has improved through the use of novel derivatizing agents, and sensitivity has been refined through the use of high-resolution chromatography and mass spectrometric technology. This review highlights these innovations, among others, in LC-MS/MS steroid hormone analysis captured in the literature over the last decade.

Acute effects of human protein S administration after traumatic brain injury in mice

Despite years of effort, no effective acute phase treatment has been discovered for traumatic brain injury. One impediment to successful drug development is entangled secondary injury pathways. Here we show that protein S, a natural multifunctional protein that regulates coagulation, inflammation, and apoptosis, is able to reduce the extent of multiple secondary injuries in traumatic brain injury, and therefore improve prognosis. Mice subjected to controlled cortical impact were treated acutely (10–15 minutes post-injury) with a single dose of either protein S (1 mg/kg) or vehicle phosphate buffered saline via intravenous injection. At 24 hours post-injury, compared to the non-treated group, the protein S treated group showed substantial improvement of edema and fine motor coordination, as well as mitigation of progressive tissue loss. Immunohistochemistry and western blot targeting caspase-3, B-cell lymphoma 2 (Bcl-2) along with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay revealed that apoptosis was suppressed in treated animals. Immunohistochemistry targeting CD11b showed limited leukocyte infiltration in the protein S-treated group. Moreover, protein S treatment increased the ipsilesional expression of aquaporin-4, which may be the underlying mechanism of its function in reducing edema. These results indicate that immediate intravenous protein S treatment after controlled cortical impact is beneficial to traumatic brain injury prognosis. Animal Use Protocols (AUPs) were approved by the University Committee on Animal Resources (UCAR) of University of Rochester Medical Center (approval No. UCAR-2008-102R) on November 12, 2013.

Progesterone exerts antidepressant-like effect in a mouse model of maternal separation stress through mitigation of neuroinflammatory response and oxidative stress

Context: Experiencing early-life adversity plays a key role in the development of mood disorders in adulthood. Experiencing adversities during early life period negatively affects brain development. Sex steroids such as progesterone affect the brain structure and functions and subsequently affects behaviour.Objective: We assess the antidepressant-like effect of progesterone in a mouse model of maternal separation (MS) stress, focussing on its anti-neuroinflammatory and antioxidative effects.Materials and methods: NMRI mice were treated with progesterone (10, 50, and 100 mg/kg, i.p., respectively) for 14 days. Valid behavioural tests including forced swimming test (FST), splash test and open field test (OFT) were used. Quantitative reverse transcription-PCR (qRT-PCR) was used for evaluation of genetic expression in the hippocampus. Antioxidant capacity was assessed by the FRAP method and the level of malondialdehide by TBA.Results: MS provoked depressive-like behaviour in mice. Treatment of MS mice with progesterone increased the grooming activity time in the splash test and decreased the immobility time in the FST. In addition, progesterone decreased the expression of inflammatory genes related to neuroinflammation (IL-1β, TNF-α, TLR4 and NLRP3) as well as increased the antioxidant capacity and decreased the lipid peroxidation (MDA) in the hippocampus.Discussion and Conclusion: Administration of progesterone significantly mitigated the negative effects of MS on behaviours relevant to depressive-like behaviour as well as attenuated neuro-immune response and oxidative stress in the hippocampus of MS mice. In this context, we conclude that progesterone, at least partially, via attenuation of oxidative stress and neuroinflammation, exerts antidepressant-like effects.

Sex Differences in Sex Hormone Profiles and Prediction of Consciousness Recovery After Severe Traumatic Brain Injury

Objective: The clinical course of unconsciousness after traumatic brain injury (TBI) is commonly unpredictable and it remains a challenge with limited therapeutic options. The aim of this study was to evaluate the early changes in serum sex hormone levels after severe TBI (sTBI) and the use of these hormones to predict recovery from unconsciousness with regard to sex. Methods: We performed a retrospective study including patients with sTBI. A statistical of analysis of serum sex hormone levels and recovery of consciousness at 6 months was made to identify the effective prognostic indicators. Results: Fifty-five male patients gained recovery of consciousness, and 37 did not. Of the female patients, 22 out of 32 patients regained consciousness. Male patients (n = 92) with sTBI, compared with healthy subjects (n = 60), had significantly lower levels of follicular stimulating hormone (FSH), testosterone and progesterone and higher levels of prolactin. Female patients (n = 32) with sTBI, compared with controls (n = 60), had significantly lower levels of estradiol, progesterone, and testosterone and significantly higher levels of FSH and prolactin. Testosterone significantly predicted consciousness recovery in male patients. Normal or elevated testosterone levels in the serum were associated with a reduced risk of the unconscious state in male patients with sTBI. For women patients with sTBI, sex hormone levels did not contribute to the prediction of consciousness recovery. Conclusion: These findings indicate that TBI differentially affects the levels of sex-steroid hormones in men and women patients. Plasma levels of testosterone could be a good candidate blood marker to predict recovery from unconsciousness after sTBI for male patients.

Acute Subdural Hematoma Evacuation: Predictive Factors of Outcome

BACKGROUND

Acute subdural hematoma (aSDH) is a major cause of admission at Neurosurgical Emergency Department. Nevertheless, concerns regarding surgical indication in patients with multiple comorbidities, poor neurological status, antithrombotic therapy, and older age still persist. Therefore, a correct recognition of predictive outcome factors at hospital discharge is crucial to an appropriate neurosurgical treatment.

METHODS

Eighty-nine medical records of consecutive patients with age ≥18 years old who were submitted to aSDH evacuation between January 2008 and May 2012 were reviewed. Demographic characteristics, neurological status on admission, anticoagulant or antiplatelet therapy, and outcome on discharge were collected. Patients with insufficient data concerning these variables were excluded from the study.

RESULTS

Sixty-nine patients were included; 52% were male; 74% were older than 65 years; 41% were under oral antithrombotic therapy (OAT); at admission, 54% presented with Glasgow coma scale (GCS) ≤8; 23% were submitted to a craniectomy instead of a craniotomy; 26% of the patients died, 32% were dependent, and 42% were independent on discharge. Crude analysis revealed craniectomy, A/A pupils, GCS ≤8 at admission statistically significant related with the worst outcome (P < 0.05). In the adjusted evaluation only A/A pupils (P = 0.04) was associated to poor outcome (spontaneous etiology P = 0.052). Considering daily living independency at hospital discharge, either male gender (P = 0.044) and A/A pupils (P = 0.030) were related to the worst outcome. No effect of age in outcome was observed.

CONCLUSIONS

Male gender and A/A pupils are associated with lower probability of achieving independency living at hospital discharge. A/A pupils, low GCS at admission, spontaneous etiology, and craniectomy were associated with the worst outcome. Age and OAT were not predictive factors in this series. Caution should be taken when considering these factors in the surgical decision.

Neuroprotective strategies for retinal disease

Diseases that affect the eye, including photoreceptor degeneration, diabetic retinopathy, and glaucoma, affect 11.8 million people in the US, resulting in vision loss and blindness. Loss of sight affects patient quality of life and puts an economic burden both on individuals and the greater healthcare system. Despite the urgent need for treatments, few effective options currently exist in the clinic. Here, we review research on promising neuroprotective strategies that promote neuronal survival with the potential to protect against vision loss and retinal cell death. Due to the large number of neuroprotective strategies, we restricted our review to approaches that we had direct experience with in the laboratory. We focus on drugs that target survival pathways, including bile acids like UDCA and TUDCA, steroid hormones like progesterone, therapies that target retinal dopamine, and neurotrophic factors. In addition, we review rehabilitative methods that increase endogenous repair mechanisms, including exercise and electrical stimulation therapies. For each approach, we provide background on the neuroprotective strategy, including history of use in other diseases; describe potential mechanisms of action; review the body of research performed in the retina thus far, both in animals and in humans; and discuss considerations when translating each treatment to the clinic and to the retina, including which therapies show the most promise for each retinal disease. Despite the high incidence of retinal diseases and the complexity of mechanisms involved, several promising neuroprotective treatments provide hope to prevent blindness. We discuss attractive candidates here with the goal of furthering retinal research in critical areas to rapidly translate neuroprotective strategies into the clinic.

Progesterone treatment shows greater protection in brain vs. retina in a rat model of middle cerebral artery occlusion: Progesterone receptor levels may play an important role

BACKGROUND/OBJECTIVE

To determine whether inflammation increases in retina as it does in brain following middle cerebral artery occlusion (MCAO), and whether the neurosteroid progesterone, shown to have protective effects in both retina and brain after MCAO, reduces inflammation in retina as well as brain.

METHODS

MCAO rats treated systemically with progesterone or vehicle were compared with shams. Protein levels of cytosolic NF-κB, nuclear NF-κB, phosphorylated NF-κB, IL-6, TNF-α, CD11b, progesterone receptor A and B, and pregnane X receptor were assessed in retinas and brains at 24 and 48 h using western blots.

RESULTS

Following MCAO, significant increases were observed in the following inflammatory markers: pNF-κB and CD11b at 24 h in both brain and retina, nuclear NF-κB at 24 h in brain and 48 h in retina, and TNF-α at 24 h in brain.Progesterone treatment in MCAO animals significantly attenuated levels of the following markers in brain: pNF-κB, nuclear NF-κB, IL-6, TNF-α, and CD11b, with significantly increased levels of cytosolic NF-κB. Retinas from progesterone-treated animals showed significantly reduced levels of nuclear NF-κB and IL-6 and increased levels of cytosolic NF-κB, with a trend for reduction in other markers. Post-MCAO, progesterone receptors A and B were upregulated in brain and downregulated in retina.

CONCLUSION

Inflammatory markers increased in both brain and retina after MCAO, with greater increases observed in brain. Progesterone treatment reduced inflammation, with more dramatic reductions observed in brain than retina. This differential effect may be due to differences in the response of progesterone receptors in brain and retina after injury.

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.

Progesterone Provides the Pleiotropic Neuroprotective Effect on Traumatic Brain Injury Through the Nrf2/ARE Signaling Pathway

Objective

This study was to investigate the role of Nrf2/ARE signaling pathway in the pleiotropic neuroprotective effect of progesterone (PROG) on traumatic brain injury (TBI).

Methods

The Nrf2-knockout (Nrf2−/−) and C57 mice were respectively subjected to a lateral cortical impact injury caused by a free-falling object and randomly divided into three groups: sham-operated, trauma, and trauma + PROG treatment group. The PROG treatment group was given PROG (32 mg/kg of body weight, intraperitoneal injection) immediately after injury. For all groups, a series of brain samples were obtained after trauma at 24 and 72 h, respectively. The cerebral edema was evaluated; the expression of IL-1β, IL-6, and TNF-α was measured using ELISA array, and the apoptosis index was detected by TUNEL. Flow cytometry was used to detect the intracellular calcium concentration.

Results

The water content, the apoptosis index, the levels of inflammatory cytokine, and the intracellular calcium ion were significantly decreased with the PROG treatment in C57 mice with TBI model. However, the effect of PROG on TBI was not found in the Nrf2−/− mouse model of TBI.

Conclusions

PROG reduced cerebral edema, apoptosis, inflammatory reaction, and intracellular calcium ion overload effects after TBI. These beneficial effects were not seen in the Nrf2−/− mouse model of TBI. The results from this study suggested that the Nrf2/ARE signal pathway may be involved in the pleiotropic neuroprotective effect of PROG on TBI.

Progesterone-based compounds affect immune responses and susceptibility to infections at diverse mucosal sites

Over 100 million women worldwide are currently on progesterone-based contraceptives to improve their health outcomes through reduced maternal mortality and family planning. In addition to their role in reproduction, progesterone-based compounds modulate immune responses throughout the body, particularly at mucosal sites. By binding to receptors located in immune cells, including natural killer cells, macrophages, dendritic cells, and T cells, as well in non-immune cells, such as epithelial and endothelial cells, progesterone-based compounds alter cellular signaling and activity to affect the outcome of infections at diverse mucosal sites, including the genital, gastrointestinal, and respiratory tracts. As the use of progesterone-based compounds, in the form of contraceptives and hormone-based therapies, continue to increase worldwide, greater consideration should be given to how the immunomodulatory effects these compounds alter the outcome of diseases at mucosal sites beyond the reproductive tract, which has profound implications for women's health.

Formulation, Optimization, Characterization, and Pharmacokinetics of Progesterone Intravenous Lipid Emulsion for Traumatic Brain Injury Therapy

Traumatic brain injury (TBI) is a major cause of mortality and disability throughout the world. Progesterone (PROG) plays an important role in neurologic treatment. The aim of this study was to develop a progesterone formulation with good physical and chemical stability. Progesterone intravenous lipid emulsion (PILE) was prepared based on one-factor-at-a-time experiments and orthogonal design. The optimal PILE was evaluated for mean particle size, particle size distribution, zeta potential, morphology, pH, osmolarity, entrapment efficiency, storage stability, and pharmacokinetics in ICR mice compared with the commercial progesterone products. The droplets of PILE had the smallest possible diameters of 218.0 ± 1.8 nm and adequate zeta potential of -41.1 ± 0.9 mV. The volume percentage of droplets exceeding 5 μm (PFAT₅) of PILE was 0.003 ± 0.0015% and much less than the specified standard. The TEM imaging proved that emulsion droplets had a smooth spherical appearance. Chemically and physically stable PILE was obtained with excellent entrapment efficiency that was up to 95.23%, with suitable pH at 7.15 ± 0.01 and osmolarity at 301.3 ± 1.2 mOsmol/l. Storage stability tests indicated that the emulsion was stable long term under ambient temperature conditions. Animal studies demonstrated that the emulsion was more effective with the higher progesterone concentration in the brain compared with commercial products. Therefore, the optimized PILE would offer great promise as a means of progesterone delivery for TBI therapy.

Subcortical gray matter changes in transgender subjects after long-term cross-sex hormone administration

Sex-steroid hormones are primarily involved in sexual differentiation and development and are thought to underlie processes related to cognition and emotion. However, divergent results have been reported concerning the effects of hormone administration on brain structure including side effects like brain atrophy and dementia. Cross-sex hormone therapy in transgender subjects offers a unique model for studying the effects of sex hormones on the living human brain. In this study, 25 Female-to-Male (FtM) and 14 Male-to-Female (MtF) subjects underwent MRI examinations at baseline and after a period of at least 4-months of continuous cross-sex hormone administration. While MtFs received estradiol and anti-androgens, FtM subjects underwent high-dose testosterone treatment. The longitudinal processing stream of the FreeSurfer software suite was used for the automated assessment and delineation of brain volumes to assess the structural changes over the treatment period of cross-sex hormone administration. Most prominent results were found for MtFs receiving estradiol and anti-androgens in the form of significant decreases in the hippocampal region. Further analysis revealed that these decreases were reflected by increases in the ventricles. Additionally, changes in progesterone levels correlated with changes in gray matter structures in MtF subjects. In line with prior studies, our results indicate hormonal influences on subcortical structures related to memory and emotional processing. Additionally, this study adds valuable knowledge that progesterone may play an important role in this process.

Insight on stem cell preconditioning and instructive biomaterials to enhance cell adhesion, retention, and engraftment for tissue repair

Stem cells are a promising solution for the treatment of a variety of diseases. However, the limited survival and engraftment of transplanted cells due to a hostile ischemic environment is a bottleneck for effective utilization and commercialization. Within this environment, the majority of transplanted cells undergo apoptosis prior to participating in lineage differentiation and cellular integration. Therefore, in order to maximize the clinical utility of stem/progenitor cells, strategies must be employed to increase their adhesion, retention, and engraftment in vivo. Here, we reviewed key strategies that are being adopted to enhance the survival, retention, and engraftment of transplanted stem cells through the manipulation of both the stem cells and the surrounding environment. We describe how preconditioning of cells or cell manipulations strategies can enhance stem cell survival and engraftment after transplantation. We also discuss how biomaterials can enhance the function of stem cells for effective tissue regeneration. Biomaterials can incorporate or mimic extracellular function (ECM) function and enhance survival or differentiation of transplanted cells in vivo. Biomaterials can also promote angiogenesis, enhance engraftment and differentiation, and accelerate electromechanical integration of transplanted stem cells. Insight gained from this review may direct the development of future investigations and clinical trials.

Progesterone for Traumatic Brain Injury: A Meta-Analysis Review of Randomized Controlled Trials

OBJECTIVE

To conduct a meta-analysis to determine whether progesterone, compared with placebo or no treatment, influences mortality and neurologic outcome in traumatic brain injury (TBI).

METHODS

To identify eligible studies, systematic searches for randomized controlled trials of progesterone treatment in TBI were conducted in PubMed, Web of Science, EMBASE, Cochrane Library, and ClinicalTrials.gov databases. The search yielded 8 studies that were included in the meta-analysis. Included data were study characteristics, patient demographics, baseline characteristics, progesterone treatment protocol, main outcome of mortality, and secondary neurologic outcome evaluated using the Glasgow Outcome Scale.

RESULTS

The 8 studies comprised 2585 patients. The meta-analysis indicated that there was no evidence that progesterone treatment decreased the risk of mortality in patients with TBI; the overall risk ratio was 0.852 (95% confidence interval, 0.632-1.144; P = 0.284). In the secondary outcome analysis, progesterone had no neuroprotective role in improving neurologic outcome; the overall risk ratio was 1.151 (95% confidence interval, 0.0991-1.338; P = 0.06). Subgroup analysis according to the degree of injury assessed by the Glasgow Coma Scale demonstrated similar results.

CONCLUSIONS

This study is the largest meta-analysis conducted to date to determine whether progesterone is effective in the treatment of TBI. The findings indicate that progesterone treatment does not decrease mortality or improve neurologic outcome in patients with TBI.

Progesterone Treatment Shows Benefit in Female Rats in a Pediatric Model of Controlled Cortical Impact Injury

Purpose

We recently showed that progesterone treatment can reduce lesion size and behavioral deficits after moderate-to-severe bilateral injury to the medial prefrontal cortex in immature male rats. Whether there are important sex differences in response to injury and progesterone treatment in very young subjects has not been given sufficient attention. Here we investigated progesterone’s effects in the same model of brain injury but with pre-pubescent females.

Methods

Twenty-eight-day-old female Sprague-Dawley rats received sham (n = 14) or controlled cortical impact (CCI) (n = 21) injury, were given progesterone (8 mg/kg body weight) or vehicle injections on post-injury days (PID) 1–7, and underwent behavioral testing from PID 9–27. Brains were evaluated for lesion size at PID 28.

Results

Lesion size in vehicle-treated female rats with CCI injury was smaller than that previously reported for similarly treated age-matched male rats. Treatment with progesterone reduced the effect of CCI on extent of damage and behavioral deficits.

Conclusion

Pre-pubescent female rats with midline CCI injury to the frontal cortex have reduced morphological and functional deficits following progesterone treatment. While gender differences in susceptibility to this injury were observed, progesterone treatment produced beneficial effects in young rats of both sexes following CCI.

Progesterone treatment reduces neuroinflammation, oxidative stress and brain damage and improves long-term outcomes in a rat model of repeated mild traumatic brain injury

BACKGROUND

Repeated mild traumatic brain injuries, such as concussions, may result in cumulative brain damage, neurodegeneration and other chronic neurological impairments. There are currently no clinically available treatment options known to prevent these consequences. However, growing evidence implicates neuroinflammation and oxidative stress in the pathogenesis of repetitive mild brain injuries; thus, these may represent potential therapeutic targets. Progesterone has been demonstrated to have potent anti-inflammatory and anti-oxidant properties after brain insult; therefore, here, we examined progesterone treatment in rats given repetitive mild brain injuries via the repeated mild fluid percussion injury model.

METHODS

Male Long-Evans rats were assigned into four groups: sham injury + vehicle treatment, sham injury + progesterone treatment (8 mg/kg/day), repeated mild fluid percussion injuries + vehicle treatment, and repeated mild fluid percussion injuries + progesterone treatment. Rats were administered a total of three injuries, with each injury separated by 5 days. Treatment was initiated 1 h after the first injury, then administered daily for a total of 15 days. Rats underwent behavioural testing at 12-weeks post-treatment to assess cognition, motor function, anxiety and depression. Brains were then dissected for analysis of markers for neuroinflammation and oxidative stress. Ex vivo MRI was conducted in order to examine structural brain damage and white matter integrity.

RESULTS

Repeated mild fluid percussion injuries + progesterone treatment rats showed significantly reduced cognitive and sensorimotor deficits compared to their vehicle-treated counterparts at 12-weeks post-treatment. Progesterone treatment significantly attenuated markers of neuroinflammation and oxidative stress in rats given repeated mild fluid percussion injuries, with concomitant reductions in grey and white matter damage as indicated by MRI.

CONCLUSIONS

These findings implicate neuroinflammation and oxidative stress in the pathophysiological aftermath of mild brain injuries and suggest that progesterone may be a viable treatment option to mitigate these effects and their detrimental consequences.

Progesterone for Acute Traumatic Brain Injury: A Systematic Review of Randomized Controlled Trials

OBJECTIVE

To evaluate the efficacy and safety of progesterone administrated in patients with acute traumatic brain injury (TBI).

METHODS

PubMed/MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials (CENTRAL), Clinicaltrials.gov, ISRCTN registry and WHO International Clinical Trials Registry Platform (ICTRP) were searched for randomized controlled trials (RCTs) comparing progesterone and placebo administrated in acute TBI patients. The primary outcome was mortality and the secondary outcomes were unfavorable outcomes and adverse events. A meta-analysis was conducted to evaluate the efficacy and safety of progesterone administrated in patients with acute TBI.

RESULTS

A total of 6 studies met inclusion criteria, involving 2,476 patients. The risk of bias was considered to be low in 4 studies but high in the other 2 studies. The results of meta-analysis indicated progesterone did not reduce the mortality (RR = 0.83, 95% CI = 0.57-1.20) or unfavorable outcomes (RR = 0.89, 95% CI = 0.78-1.02) of acute TBI patients in comparison with placebo. Sensitivity analysis yielded consistent results. Progesterone was basically safe and well tolerated in TBI patients with the exception of increased risk of phlebitis or thrombophlebitis (RR = 3.03, 95% CI = 1.96-4.66).

CONCLUSIONS

Despite some modest bias, present evidence demonstrated that progesterone was well tolerated but did not reduce the mortality or unfavorable outcomes of adult patients with acute TBI.

Progesterone treatment in two rat models of ocular ischemia

PURPOSE

To determine whether the neurosteroid progesterone, shown to have protective effects in animal models of traumatic brain injury, stroke, and spinal cord injury, is also protective in ocular ischemia animal models.

METHODS

Progesterone treatment was tested in two ocular ischemia models in rats: a rodent anterior ischemic optic neuropathy (rAION) model, which induces permanent monocular optic nerve stroke, and the middle cerebral artery occlusion (MCAO) model, which causes transient ischemia in both the retina and brain due to an intraluminal filament that blocks the ophthalmic and middle cerebral arteries. Visual function and retinal histology were assessed to determine whether progesterone attenuated retinal injury in these models. Additionally, behavioral testing and 2% 2,3,5-triphenyltetrazolium chloride (TTC) staining in brains were used to compare progesterone's neuroprotective effects in both retina and brain using the MCAO model.

RESULTS

Progesterone treatment showed no effect on visual evoked potential (VEP) reduction and retinal ganglion cell loss in the permanent rAION model. In the transient MCAO model, progesterone treatment reduced (1) electroretinogram (ERG) deficits, (2) MCAO-induced upregulation of glutamine synthetase (GS) and glial fibrillary acidic protein (GFAP), and (3) retinal ganglion cell loss. As expected, progesterone treatment also had significant protective effects in behavioral tests and a reduction in infarct size in the brain.

CONCLUSIONS

Progesterone treatment showed protective effects in the retina following MCAO but not rAION injury, which may result from mechanistic differences with injury type and the therapeutic action of progesterone.

Progestogens in menopausal hormone therapy

Progestogens share one common effect: the ability to convert proliferative endometrium to its secretory form. In contrast, their biological activity is varied, depending on the chemical structure, pharmacokinetics, receptor affinity and different potency of action. Progestogens are widely used in the treatment of menstrual cycle disturbances, various gynaecological conditions, contraception and menopausal hormone therapy. The administration of progestogen in menopausal hormone therapy is essential in women with an intact uterus to protect against endometrial hyperplasia and cancer. Progestogen selection should be based on the characteristics available for each progestogen type, relying on the assessment of relative potency of action in experimental models and animal models, and on the indirect knowledge brought by studies of the clinical use of different progestogen formulations. The choice of progestogen should involve the conscious use of knowledge of its benefits, with a focus on minimizing potential side effects. Unfortunately, there are no direct clinical studies comparing the metabolic effects of different progestogens.

Emerging pharmacotherapy for treatment of traumatic brain injury: targeting hypopituitarism and inflammation

INTRODUCTION

Traumatic brain injury (TBI) is a common cause of morbidity and mortality in the developed world. In particular, TBI is an important cause of death and disability in young adults with consequences ranging from physical disabilities to long-term cognitive, behavioural, psychological and social defects.

AREAS COVERED

There is a large body of evidence that suggest that TBI conditions may adversely affect pituitary function in both the acute and chronic phases of recovery. Prevalence of hypopituitarism, from total to isolated pituitary deficiency, ranges from 5 to 90%. The time interval between TBI and pituitary function evaluation is one of the major factors responsible for variations in the prevalence of hypopituitarism reported. Diagnosis of hypopituitarism and accurate treatment of pituitary disorders offers the opportunity to improve mortality and outcome in TBI conditions.

EXPERT OPINION

The aim of this paper is to review the history and pathophysiology of TBI and to summarize the best evidence of TBI as a cause of pituitary deficiency. Moreover, in this article we will describe the multiple changes which occur within the hypothalamic-pituitary-thyroid axis in critical illness, giving rise to 'sick euthyroid syndrome', focus our attention on thyroid hormones circulating levels from the initial insult to critical illness.

Progesterone for neuroprotection in pediatric traumatic brain injury

OBJECTIVE

To provide an overview of the preclinical literature on progesterone for neuroprotection after traumatic brain injury and to describe unique features of developmental brain injury that should be considered when evaluating the therapeutic potential for progesterone treatment after pediatric traumatic brain injury.

DATA SOURCES

National Library of Medicine PubMed literature review.

STUDY SELECTION

The mechanisms of neuroprotection by progesterone are reviewed, and the preclinical literature using progesterone treatment in adult animal models of traumatic brain injury is summarized. Unique features of the developing brain that could either enhance or limit the efficacy of neuroprotection by progesterone are discussed, and the limited preclinical literature using progesterone after acute injury to the developing brain is described. Finally, the current status of clinical trials of progesterone for adult traumatic brain injury is reviewed.

DATA EXTRACTION AND DATA SYNTHESIS

Progesterone is a pleiotropic agent with beneficial effects on secondary injury cascades that occur after traumatic brain injury, including cerebral edema, neuroinflammation, oxidative stress, and excitotoxicity. More than 40 studies have used progesterone for treatment after traumatic brain injury in adult animal models, with results summarized in tabular form. However, very few studies have evaluated progesterone in pediatric animal models of brain injury. To date, two human phase II trials of progesterone for adult traumatic brain injury have been published, and two multicenter phase III trials are underway.

CONCLUSIONS

The unique features of the developing brain from that of a mature adult brain make it necessary to independently study progesterone in clinically relevant, immature animal models of traumatic brain injury. Additional preclinical studies could lead to the development of a novel neuroprotective therapy that could reduce the long-term disability in head-injured children and could potentially provide benefit in other forms of pediatric brain injury (global ischemia, stroke, and statue epilepticus).

Regulation of brain microglia by female gonadal steroids

Microglial cells are the primary mediators of the CNS immune defense system and crucial for shaping inflammatory responses. They represent a highly dynamic cell population which is constantly moving and surveying their environment. Acute brain damage causes a local attraction and activation of this immune cell type which involves neuron-to-glia and glia-to-glia interactions. The prevailing view attributes microglia a "negative" role such as defense and debris elimination. More topical studies also suggest a protective and "positive" regulatory function. Estrogens and progestins exert anti-inflammatory and neuroprotective effects in the CNS in acute and chronic brain diseases. Recent work revealed that microglial cells express subsets of classical and non-classical estrogen and progesterone receptors in a highly dynamic way. In this review article, we would like to stress the importance of microglia for the spreading of neural damage during hypoxia, their susceptibility to functional modulation by sex steroids, the potency of sex hormones to switch microglia from a pro-inflammatory M1 to neuroprotective M2 phenotype, and the regulation of pro- and anti-inflammatory properties including the inflammasome. We will further discuss the possibility that the neuroprotective action of sex steroids in the brain involves an early and direct modulation of local microglia cell function. This article is part of a Special Issue entitled 'Sex steroids and brain disorders'.

Neuroprotection for traumatic brain injury

Traumatic brain injury (TBI) is a major cause of mortality and morbidity worldwide. Despite extensive preclinical research supporting the effectiveness of neuroprotective therapies for brain trauma, there have been no successful randomized controlled clinical trials to date. TBI results in delayed secondary tissue injury due to neurochemical, metabolic and cellular changes; modulating such effects has provided the basis for neuroprotective interventions. To establish more effective neuroprotective treatments for TBI it is essential to better understand the complex cellular and molecular events that contribute to secondary injury. Here we critically review relevant research related to causes and modulation of delayed tissue damage, with particular emphasis on cell death mechanisms and post-traumatic neuroinflammation. We discuss the concept of utilizing multipotential drugs that target multiple secondary injury pathways, rather than more specific "laser"-targeted strategies that have uniformly failed in clinical trials. Moreover, we assess data supporting use of neuroprotective drugs that are currently being evaluated in human clinical trials for TBI, as well as promising emerging experimental multipotential drug treatment strategies. Finally, we describe key challenges and provide suggestions to improve the likelihood of successful clinical translation.

Very early administration of progesterone for acute traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Progesterone has been shown to improve neurologic outcome in multiple experimental models and two early-phase trials involving patients with TBI.

METHODS

We conducted a double-blind, multicenter clinical trial in which patients with severe, moderate-to-severe, or moderate acute TBI (Glasgow Coma Scale score of 4 to 12, on a scale from 3 to 15, with lower scores indicating a lower level of consciousness) were randomly assigned to intravenous progesterone or placebo, with the study treatment initiated within 4 hours after injury and administered for a total of 96 hours. Efficacy was defined as an increase of 10 percentage points in the proportion of patients with a favorable outcome, as determined with the use of the stratified dichotomy of the Extended Glasgow Outcome Scale score at 6 months after injury. Secondary outcomes included mortality and the Disability Rating Scale score.

RESULTS

A total of 882 of the planned sample of 1140 patients underwent randomization before the trial was stopped for futility with respect to the primary outcome. The study groups were similar with regard to baseline characteristics; the median age of the patients was 35 years, 73.7% were men, 15.2% were black, and the mean Injury Severity Score was 24.4 (on a scale from 0 to 75, with higher scores indicating greater severity). The most frequent mechanism of injury was a motor vehicle accident. There was no significant difference between the progesterone group and the placebo group in the proportion of patients with a favorable outcome (relative benefit of progesterone, 0.95; 95% confidence interval [CI], 0.85 to 1.06; P=0.35). Phlebitis or thrombophlebitis was more frequent in the progesterone group than in the placebo group (relative risk, 3.03; CI, 1.96 to 4.66). There were no significant differences in the other prespecified safety outcomes.

CONCLUSIONS

This clinical trial did not show a benefit of progesterone over placebo in the improvement of outcomes in patients with acute TBI. (Funded by the National Institute of Neurological Disorders and Stroke and others; PROTECT III ClinicalTrials.gov number, NCT00822900.).

Gender differences in awareness and outcomes during acute traumatic brain injury recovery

BACKGROUND

Recent literature on traumatic brain injury (TBI), though mixed when reporting outcomes, seems collectively to suggest possible gender advantage for women in postinjury recovery, especially in executive functions. Hormonal neuroprotection, through female reproductive hormones, is often proposed as an underlying factor in these results. We explored potential gender differences in an aspect of executive functions, self-awareness (SA), which is often impaired after TBI, limits patient effort in critical rehabilitation, and increases caregiver burden.

METHODS

Within a prospective survey, repeated-measures design, 121 patients with moderate or severe TBI undergoing acute rehabilitation in a Level 1 trauma center, a family member or caregiver informant, and a treating clinician were asked to complete the Patient Competency Rating Scale (PCRS) and the Frontal Systems Behavior Scale (FrSBe) at admission and discharge.

RESULTS

Although overall, women and men with TBI showed generally similar levels of SA, women had significantly better awareness of their injury-related deficits at acute rehabilitation discharge, even when controlling for age, education, and injury severity.

CONCLUSIONS

Mixed findings in this study mirror the pattern of results that dominate the published literature on gender and TBI. Gender differences in executive dysfunction may not be as large or robust as some researchers argue. In addition, complex interplays of socialization, gender-role expectations, naturally occurring male and female ability differences, and differences in access to postinjury rehabilitation are understudied potential moderators.

Cerebrospinal fluid cortisol and progesterone profiles and outcomes prognostication after severe traumatic brain injury

Despite significant advances in the management of head trauma, there remains a lack of pharmacological treatment options for traumatic brain injury (TBI). While progesterone clinical trials have shown promise, corticosteroid trials have failed. The purpose of this study was to (1) characterize endogenous cerebrospinal fluid (CSF) progesterone and cortisol levels after TBI, (2) determine relationships between CSF and serum profiles, and (3) assess the utility of these hormones as predictors of long-term outcomes. We evaluated 130 adults with severe TBI. Serum samples (n=538) and CSF samples (n=746) were collected for 6 days post-injury, analyzed for cortisol and progesterone, and compared with healthy controls (n=13). Hormone data were linked with clinical data, including Glasgow Outcome Scale (GOS) scores at 6 and 12 months. Group based trajectory (TRAJ) analysis was used to develop temporal hormone profiles delineating distinct subpopulations. Compared with controls, CSF cortisol levels were significantly and persistently elevated during the first week after TBI, and high CSF cortisol levels were associated with poor outcome. As a precursor to cortisol, progesterone mediated these effects. Serum and CSF levels for both cortisol and progesterone were strongly correlated after TBI relative to controls, possibly because of blood-brain barrier disruption. Also, differentially impaired hormone transport and metabolism mechanisms after TBI, potential de novo synthesis of steroids within the brain, and the complex interplay of cortisol and pro-inflammatory cytokines may explain these acute hormone profiles and, when taken together, may help shed light on why corticosteroid trials have previously failed and why progesterone treatment after TBI may be beneficial.

Differential effects of synthetic progestagens on neuron survival and estrogen neuroprotection in cultured neurons

Progesterone and other progestagens are used in combination with estrogens for clinical purposes, including contraception and postmenopausal hormone therapy. Progesterone and estrogens have interactive effects in brain, however interactions between synthetic progestagens and 17β-estradiol (E2) in neurons are not well understood. In this study, we investigated the effects of seven clinically relevant progestagens on estrogen receptor (ER) mRNA expression, E2-induced neuroprotection, and E2-induced BDNF mRNA expression. We found that medroxyprogesterone acetate decreased both ERα and ERβ expression and blocked E2-mediated neuroprotection and BDNF expression. Conversely, levonorgestrel and nesterone increased ERα and or ERβ expression, were neuroprotective, and failed to attenuate E2-mediated increases in neuron survival and BDNF expression. Other progestagens tested, including norethindrone, norethindrone acetate, norethynodrel, and norgestimate, had variable effects on the measured endpoints. Our results demonstrate a range of qualitatively different actions of progestagens in cultured neurons, suggesting significant variability in the neural effects of clinically utilized progestagens.

TBI and sex: crucial role of progesterone protecting the brain in an omega-3 deficient condition

We assessed whether the protective action of progesterone on traumatic brain injury (TBI) could be influenced by the consumption of omega-3 fatty acids during early life. Pregnant Sprague-Dawley rats were fed on omega-3 adequate or deficient diet from 3rd day of pregnancy and their female offspring were kept on the same diets up to the age of 15 weeks. Ovariectomy was performed at the age of 12 weeks to deprive animals from endogenous steroids until the time of a fluid percussion injury (FPI). Dietary n-3 fatty acid deficiency increased anxiety in sham animals and TBI aggravated the effects of the deficiency. Progesterone replacement counteracted the effects of TBI on the animals reared under n-3 deficiency. A similar pattern was observed for markers of membrane homeostasis such as 4-Hydroxynonenal (HNE) and secreted phospholipases A2 (sPLA2), synaptic plasticity such as brain derived neurotrophic factor (BDNF), syntaxin (STX)-3 and growth associated protein (GAP)-43, and for growth inhibitory molecules such as myelin-associated glycoprotein (MAG) and Nogo-A. Results that progesterone had no effects on sham n-3 deficient animals suggest that the availability of progesterone is essential under injury conditions. Progesterone treatment counteracted several parameters related to synaptic plasticity and membrane stability reduced by FPI and n-3 deficiency suggest potential targets for therapeutic applications. These results reveal the importance of n-3 preconditioning during early life and the efficacy of progesterone therapy during adulthood to counteract weaknesses in neuronal and behavioral plasticity.

Progesterone treatment shows benefit in a pediatric model of moderate to severe bilateral brain injury

PURPOSE

Controlled cortical impact (CCI) models in adult and aged Sprague-Dawley (SD) rats have been used extensively to study medial prefrontal cortex (mPFC) injury and the effects of post-injury progesterone treatment, but the hormone's effects after traumatic brain injury (TBI) in juvenile animals have not been determined. In the present proof-of-concept study we investigated whether progesterone had neuroprotective effects in a pediatric model of moderate to severe bilateral brain injury.

METHODS

Twenty-eight-day old (PND 28) male Sprague Dawley rats received sham (n = 24) or CCI (n = 47) injury and were given progesterone (4, 8, or 16 mg/kg per 100 g body weight) or vehicle injections on post-injury days (PID) 1-7, subjected to behavioral testing from PID 9-27, and analyzed for lesion size at PID 28.

RESULTS

The 8 and 16 mg/kg doses of progesterone were observed to be most beneficial in reducing the effect of CCI on lesion size and behavior in PND 28 male SD rats.

CONCLUSION

Our findings suggest that a midline CCI injury to the frontal cortex will reliably produce a moderate TBI comparable to what is seen in the adult male rat and that progesterone can ameliorate the injury-induced deficits.

Neuroprotective strategies for traumatic brain injury: improving clinical translation

Traumatic brain injury (TBI) induces secondary biochemical changes that contribute to delayed neuroinflammation, neuronal cell death, and neurological dysfunction. Attenuating such secondary injury has provided the conceptual basis for neuroprotective treatments. Despite strong experimental data, more than 30 clinical trials of neuroprotection in TBI patients have failed. In part, these failures likely reflect methodological differences between the clinical and animal studies, as well as inadequate pre-clinical evaluation and/or trial design problems. However, recent changes in experimental approach and advances in clinical trial methodology have raised the potential for successful clinical translation. Here we critically analyze the current limitations and translational opportunities for developing successful neuroprotective therapies for TBI.

The neuroprotective effects of progesterone on traumatic brain injury: current status and future prospects

Traumatic brain injury is the leading cause of morbidity and mortality in young adults. The secondary injury in traumatic brain injury consists of a complex cascade of processes that simultaneously react to the primary injury to the brain. This cascade has been the target of numerous therapeutic agents investigated over the last 30 years, but no neuroprotective treatment option is currently available that improve neurological outcome after traumatic brain injury. Progesterone has long been considered merely a female reproductive hormone. Numerous studies, however, show that progesterone has substantial pleiotropic properties as a neuroprotective agent in both animal models and humans. Here, we review the increasing evidence that progesterone can act as a neuroprotective agent to treat traumatic brain injury and the mechanisms underlying these effects. Additionally, we discuss the current progress of clinical studies on the application of progesterone in the treatment of traumatic brain injuries.

Higher pain perception and lack of recovery from neuropathic pain in females: a behavioural, immunohistochemical, and proteomic investigation on sex-related differences in mice

In experimental and clinical pain studies, the sex of subjects was rarely taken into account, even if nociceptive inputs appear to be processed and modulated by partially distinct neural mechanisms in each sex. In this study we analysed, in male and female mice, behavioural and neuronal responses in developing, maintaining, and recovering from neuropathic pain. Experiments were carried out in adult CD1 mice by using Chronic Constriction Injury (CCI) as neuropathic pain model. We investigated the temporal trend of mechanical nociceptive threshold together with functional recovery of the injured paw, and the immunofluorescence staining of proteins associated with nerve injury and repair and with spinal gliosis, 7 and 121days after CCI. A proteomic analysis on proteins extracted from sciatic nerves was also performed. Male mice showed a gradual decrease of CCI-induced allodynia, the complete recovery occurring 81days after the sciatic nerve ligation. On the contrary, in female mice, allodynia was still present 121days after CCI. Sex-dependent differences also resulted from immunofluorescence experiments: in sciatic nerve, the expression of P0 and Neu200 is greater in neuropathic males than in neuropathic females, suggesting faster nerve regeneration. Proteomic analysis confirmed sex-related differences of proteins associated with nerve regenerative processes. In addition, the reactive gliosis induced by CCI at day 7, as revealed by colocalization of glial fibrillary acidic protein (astrocytes) and CD11b (microglia) with phosphorylated p38, disappeared 121 days after CCI in male but not in female mice. These results may have important therapeutic implications for the treatment of neuropathic pain.

Progesterone reduces the expression of spinal cyclooxygenase-2 and inducible nitric oxide synthase and prevents allodynia in a rat model of central neuropathic pain

BACKGROUND

Spinal cord injury (SCI) results in the development of chronic pain that is refractory to conventional treatment. Progesterone, a neuroprotective steroid, may offer a promising perspective in pain modulation after central injury. Here, we explore the impact of progesterone administration on the post-injury inflammatory cascade involving the enzymes cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) at the spinal cord level. We also analyse pain behaviours, the profile of glial cell activation, and IκB-α mRNA levels, as an index of NF-κB transactivation.

METHODS

We used biochemical, immunohistochemical and molecular techniques, as well as behavioural studies, to investigate the effects of progesterone in a well-characterized model of central neuropathic pain.

RESULTS

Injured animals receiving progesterone presented reduced mRNA levels of the proinflammatory enzymes, as well as decreased COX-2 activity and nitrite levels, as compared to vehicle-treated injured rats. Further, animals receiving the steroid exhibited lower levels of IκB-α mRNA, suggesting decreased NF-κB transactivation. Progesterone administration also attenuated the injury-induced increase in the number of glial fibrillary acidic protein and OX-42 positive cells both at early and late time points after injury, and prevented the development of mechanical and thermal allodynia. Further, when injured rats received early progesterone administration for a critical period of time after injury, they did not display allodynic behaviours even after the treatment had stopped.

CONCLUSIONS

Our results suggest that progesterone, by modulating early neuroinflammatory events triggered after SCI, may represent a useful strategy to prevent the development of central chronic pain.

Systemic progesterone for modulating electrocautery-induced secondary brain injury

Bipolar electrocautery is an effective and commonly used haemostatic technique but it may also cause iatrogenic brain trauma due to thermal injury and secondary inflammatory reactions. Progesterone has anti-inflammatory and neuroprotective actions in traumatic brain injury. However, its potential use in preventing iatrogenic brain trauma has not been explored. We conducted a pilot animal study to investigate the effect of systemic progesterone on brain cellular responses to electrocautery-induced injury. Adult male Sprague-Dawley rats received standardized bipolar electrocautery (40 W for 2 seconds) over the right cerebral cortex. The treatment group received progesterone intraperitoneally 2 hours prior to surgery; the control group received the drug vehicle only. Immunohistochemical studies showed that progesterone could significantly reduce astrocytic hypertrophy on postoperative day 1, 3 and 7, as well as macrophage infiltration on day 3. The number of astrocytes, however, was unaffected. Our findings suggest that progesterone should be further explored as a neuroprotective agent against electrocautery-induced or other forms of iatrogenic trauma during routine neurosurgical procedures. Future studies may focus on different dosing regimens, neuronal survival, functional outcome, and to compare progesterone with other agents such as dexamethasone.

Therapeutic effects of progesterone and its metabolites in traumatic brain injury may involve non-classical signaling mechanisms

Traumatic brain injury (TBI) is an important and costly medical problem for which no clinically proven treatment currently exists. Studies in rodents and humans have shown beneficial effects of progesterone (P4) on both mortality and functional outcomes following TBI. Neuroprotective effects of P4 in TBI likely involve the classical nuclear progesterone receptors (Pgr) that are widely distributed in both glial cells and neurons of the brain. However, P4 may have critical effects not mediated through Pgr. In the brain, P4 is converted to a metabolite, allopregnanolone (ALLO), whose beneficial effects equal or exceed those of P4 in TBI. ALLO does not bind Pgr, suggesting it acts through non-classical pathways. ALLO has effects on GABA_A and pregnane X receptors, as well as on the mitochondrial permeability transition pore. In addition, ALLO is metabolized to another compound, 5alpha-dihydroprogesterone, which binds Pgr, suggesting ALLO actions may involve signaling through Pgr as well as the aforementioned mechanisms of action. P4 and ALLO also signal through a number of membrane receptors (progesterone receptor membrane component 1, and membrane progesterone receptors (mPRs) alpha, beta, gamma, delta, and epsilon) in the brain that are distinct from Pgr, although the role of these receptors in the normal brain and in the therapeutic response to P4 and ALLO following TBI is unclear. In summary, P4 has the potential to become the first clinically effective treatment for TBI, and the effects of P4 and its metabolite ALLO in TBI may involve Pgr, mPRs, and other signaling pathways. Elucidating these mechanisms will more clearly reveal the potential of classical and non-classical pathways to mediate important effects of P4 and its metabolites, and potentially offer new therapeutic approaches to TBI.