Gender and the injured brain

Flutamide Enhances Neuroprotective Effects of Testosterone during Experimental Cerebral Ischemia in Male Rats

Testosterone has been shown to worsen histological and neurological impairment during cerebral ischemia in animal models. Cell culture studies revealed that testosterone is implicated in protecting neural and glial cells against insults, and they started to elucidate testosterone pathways that underlie these protective effects. These studies support the hypothesis that testosterone can be neuroprotective throughout an episode of cerebral ischemia. Therefore, we evaluated the mechanisms underlying the shift between testosterone protective and deleterious effects via block testosterone aromatization and androgen receptors in rats subjected to 60-minute middle cerebral artery occlusion. Fifty rats were divided into five equal groups: gonadally intact male; castrated male; intact male + flutamide; intact male + letrozole; intact male + combination flutamide and letrozole. Our results indicated that castration has the ability to reduce histological damage and to improve neurological score 24 hours after middle cerebral artery occlusion. Moreover, flutamide improved histologic and neurological impairment better than castration. Letrozole induced increases in striatal infarct volume and seizures in gonadally intact rats. Combination of flutamide and letrozole showed that letrozole can reverse beneficial effects of flutamide. In conclusion, it seems that the beneficial effects of flutamide are the prevention of the deleterious effects and enhancement of neuroprotective effects of testosterone during cerebral ischemia.

Sex and steroid hormones in early brain injury

Brain injury during development can have severe, long-term consequences. Using an array of animal models, we have an understanding of the etiology of perinatal brain injury. However, we have only recently begun to address the consequences of endogenous factors such as genetic sex and developmental steroid hormone milieu. Our limited understanding has sometimes led researchers to make over-generalizing and potentially dangerous statements regarding treatment for brain injury. Therefore this review acts as a cautionary tale, speaking to our need to understand the effects of sex and steroid hormone environment on the response to brain trauma in the neonate.

Epileptiform activity in neurocritical care patients

BACKGROUND

Non-convulsive seizures have been reported to be common in neurocritical care patients. Many jurisdictions do not have sufficient resources to enable routine continuous electroencephalography (cEEG) and instead use primarily intermittent EEG, for which the diagnostic yield remains uncertain. Determining risk factors for epileptiform activity and seizures could help identify patients who might particularly benefit from EEG monitoring.

METHODS

We performed a cohort study involving neurocritical care patients with admission Glascow Coma Scale (GCS) scores ≤ 12, who underwent ≥ 1 EEG. EEGs were reviewed for presence of interictal discharges, periodic epileptiform discharges (PEDs), and seizures. Multivariate analysis was used to identify predictors of these findings and to describe their prognostic implications.

RESULTS

393 patients met inclusion criteria. 34 underwent cEEG, usually because epileptiform activity was first detected on a routine EEG. The prevalence of PEDs or electrographic seizures was 13%, and was highest with anoxic encephalopathy and central nervous system infections. Other independent predictors for epileptiform activity included a history of convulsive seizure(s), increasing age, deeper coma, and female gender. Although patients with epileptiform activity had higher mortality, this association disappeared after adjustment for confounders.

CONCLUSION

Approximately 7-8 neurocritical care patients must undergo intermittent EEG monitoring in order to diagnose one with PEDs or seizures. The predictors we identified could potentially help guide use of resources. Repeated intermittent studies, or cEEG, should be considered in patients with multiple risk factors, or when interictal discharges are identified on an initial EEG. It remains unclear whether aggressive prevention and treatment of electrographic seizures improves neurologic outcomes.

Effects of gender on gene expression in the blood of ischemic stroke patients

This study examined the effects of gender on RNA expression after ischemic stroke (IS). RNA obtained from blood of IS patients (n=51; 153 samples at < or =3, 5, and 24 hours) and from matched controls (n=52) were processed on Affymetrix microarrays. Analyses of covariance for stroke versus control samples were performed separately for both genders and the regulated genes for females compared with males. In all, 242, 227, and 338 male-specific genes were regulated at < or =3, 5, and 24 hours after IS, respectively, of which 59 were regulated at all time points. Overall, 774, 3,437, and 571 female-specific stroke genes were regulated at < or =3, 5, and 24 hours, respectively, of which 152 were regulated at all time points. Male-specific stroke genes were associated with integrin, integrin-liked kinase, actin, tight junction, Wnt/β-catenin, RhoA, fibroblast growth factors (FGF), granzyme, and tumor necrosis factor receptor (TNFR)2 signaling. Female-specific stroke genes were associated with p53, high-mobility group box-1, hypoxia inducible factor (HIF)1α, interleukin (IL)1, IL6, IL12, IL18, acute-phase response, T-helper, macrophage, and estrogen signaling. Cell death signaling was overrepresented in both genders, although the molecules and pathways differed. Gender affects gene expression in the blood of IS patients, which likely implies gender differences in immune, inflammatory, and cell death responses to stroke.

Chronic Opium Treatment Can Differentially Induce Brain and Liver Cells Apoptosis in Diabetic and Non-diabetic Male and Female Rats

It has been shown that some opium derivatives promote cell death via apoptosis. This study was designed to examine the influence of opium addiction on brain and liver cells apoptosis in male and female diabetic and non-diabetic Wistar rats. This experimental study was performed on normal, opium-addicted, diabetic and diabetic opium-addicted male and female rats. Apoptosis was evaluated by TUNEL and DNA fragmentation assays. Results of this study showed that apoptosis in opium-addicted and diabetic opium-addicted brain and liver cells were significantly higher than the both normal and diabetic rats. In addition, we found that apoptosis in brain cells of opium-addicted and diabetic opium-addicted male rats were significantly higher than opium-addicted and diabetic opium-addicted female, whereas apoptosis in liver cells of opium-addicted and diabetic opium-addicted female rats were significantly higher than opium-addicted and diabetic opium-addicted male. Overall, these results indicate that opium probably plays an important role in brain and liver cells apoptosis, therefore, leading neurotoxicity and hepatotoxicity. These findings also in away possibly means that male brain cells are more susceptible than female and interestingly liver of females are more sensitive than males in induction of apoptosis by opium.

GPR30 FORMS AN INTEGRAL PART OF E2-PROTECTIVE PATHWAY IN EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS

A major focus of our laboratory has been an in-depth evaluation as to how estrogens exert a pronounced protective effect on clinical and histological disease in the animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE). An important issue regarding their therapeutic application has been the undesirable estrogenic side effects thought to be mediated primarily through 17β-estradiol (E2) binding to intracellular estrogen receptor alpha (ERα). With the discovery and characterization of GPR30 as the putative membrane estrogen receptor, we sought to study whether signaling through GPR30 was sufficient to mediate protection against EAE without engagement of ERα. Treatment of EAE in WT mice with G-1, a selective GPR30 agonist, retained estradiol's ability to protect against clinical and histological EAE without estrogenic side effects. G-1 treatment deviated cytokine profiles and enhanced suppressive activity of CD4(+)Foxp3(+) Treg cells through a GPR30- and programmed death 1 (PD-1)-dependent mechanism. This novel finding was indicative of the protective effect of GPR30 activation in EAE and provides a strong foundation for the clinical application of GPR30 agonists such as G-1 in MS. However, future studies are needed to elucidate cross-signaling and evaluate possible additive effects of combined signaling through both GPR30 and ER-α. Deciphering the possible mechanism of involvement of GPR30 in estrogen-mediated protection against EAE may result in lowering treatment doses of E2 and GPR30 agonists that could minimize risks and maximize immunoregulation and therapeutic effects in MS. Alternatively, one might envision using E2 derivatives with reduced estrogenic activity alone or in combination with GPR30 agonists as therapies for both male and female MS patients.

Isoflurane preconditioning protects neurons from male and female mice against oxygen and glucose deprivation and is modulated by estradiol only in neurons from female mice

The volatile anesthetic, isoflurane, can protect the brain if administered before an insult such as an ischemic stroke. However, this protective "preconditioning" response to isoflurane is specific to males, with females showing an increase in brain damage following isoflurane preconditioning and subsequent focal cerebral ischemia. Innate cell sex is emerging as an important player in neuronal cell death, but its role in the sexually dimorphic response to isoflurane preconditioning has not been investigated. We used an in vitro model of isoflurane preconditioning and ischemia (oxygen and glucose deprivation, OGD) to test the hypotheses that innate cell sex dictates the response to isoflurane preconditioning and that 17β-estradiol attenuates any protective effect from isoflurane preconditioning in neurons via nuclear estrogen receptors. Sex-segregated neuron cultures derived from postnatal day 0-1 mice were exposed to either 0% or 3% isoflurane preconditioning for 1 h. In separate experiments, 17β-estradiol and the non-selective estrogen receptor antagonist ICI 182,780 were added 24 h before preconditioning and then removed at the end of the preconditioning period. Twenty-three hours after preconditioning, all cultures underwent 2 h of OGD. Twenty-four hours following OGD, cell viability was quantified using calcein-AM fluorescence. We observed that isoflurane preconditioning increased cell survival following subsequent OGD regardless of innate cell sex, but that the presence of 17β-estradiol before and during isoflurane preconditioning attenuated this protection only in female neurons independent of nuclear estrogen receptors. We also found that independent of preconditioning treatment, female neurons were less sensitive to OGD compared with male neurons and that transient treatment with 17β-estradiol protected both male and female neurons from subsequent OGD. More studies are needed to determine how cell type, cell sex, and sex steroids like 17β-estradiol may impact on anesthetic preconditioning and subsequent ischemic outcomes in the brain.

Microglia and cyclooxygenase-2: possible therapeutic targets of progesterone for stroke

Previous studies have demonstrated that progesterone (PROG) may be a pleiotropic neuroprotective agent. Although there have been reports about the neurotoxicity of activated microglia and cyclooxygenase-2 (COX-2) in animal models of ischemic stroke, the influence of PROG on the activation of microglia and the expression of COX-2 after stroke has not been examined in detail. In this investigation, we carried out research about the influence of PROG on cultured microglia by detection of the expression of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) in their supernatant fluid before and after induced with lipopolysaccharide (LPS) or influenced by PROG with Enzyme-Linked Immunosorbent Assay technique in vitro. Moreover, the expression of COX-2 and ionized calcium-binding adapter molecule 1 (Iba1) was also detected in the cortex of rats that underwent permanent middle cerebral artery occlusion and received PROG or vehicle treatment by immunohistochemistry and western blot technique. The results revealed that PROG significantly reduced the expression of TNF-α and IL-1β in cultured microglia after activated with LPS in vitro. In addition, PROG also valuably inhibited the expression of Iba1 and COX-2 after stroke in vivo. These observations raised the possibility that PROG can exert its neuroprotective effects by inhibiting the activation of microglia and the over expression of COX-2 after stroke.

17β-estradiol increases astrocytic vascular endothelial growth factor (VEGF) in adult female rat hippocampus

Vascular endothelial growth factor (VEGF) is critical to angiogenesis and vascular permeability. It is also important in the endocrine system, in which VEGF mediates the vascular effects of estrogens in target tissues such as the uterus, a response attributed to an estrogen response element on the VEGF gene. Here we asked whether 17β-estradiol increases VEGF levels in the brain. We focused on the hippocampus, in which 17β-estradiol and VEGF both have important actions, and used immunocytochemistry to evaluate VEGF protein. VEGF immunoreactivity was compared in adult female rats sampled during the estrous cycle when serum levels of 17β-estradiol peak (proestrous morning) as well as when they are low (metestrous morning). In addition, adult rats were ovariectomized and compared after treatment with 17β-estradiol or vehicle. The results demonstrated that VEGF immunoreactivity was increased when serum levels of 17β-estradiol were elevated. Confocal microscopy showed that VEGF immunofluorescence was predominantly nonneuronal, often associated with astrocytes. Glial VEGF labeling was primarily punctate rather than diffuse and labile because glial VEGF immunoreactivity was greatly reduced if tissue sections were left in an aqueous medium overnight. We conclude that VEGF protein in normal female hippocampus is primarily nonneuronal rather than neuronal and suggest that glial VEGF immunoreactivity has been underestimated by past studies with other methods because there is a labile extracellular pool. We suggest that estrogens may exert actions on female hippocampal structure and function by increasing hippocampal VEGF.

Effects of gender in amyotrophic lateral sclerosis

BACKGROUND

There is evidence that amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND), is more common in men than in women and that gender influences the clinical features of the disease. The causes of this are unknown.

OBJECTIVE

This review examines the gender differences that are found in ALS and postulates reasons for these differences.

METHODS

A literature review of PubMed (with no date limits) was performed to find information about gender differences in the incidence, prevalence, and clinical features of ALS, using the search terms ALS or MND and gender or sex, ALS prevalence, and SOD1 mice and gender. Articles were reviewed for information about gender differences, together with other articles that were already known to the authors.

RESULTS

The incidence and prevalence of ALS are greater in men than in women. This gender difference is seen in large studies that included all ALS patients (sporadic and familial), but is not seen when familial ALS is studied independently. Men predominate in the younger age groups of patients with ALS. Sporadic ALS has different clinical features in men and women, with men having a greater likelihood of onset in the spinal regions, and women tending to have onset in the bulbar region. Gender appears to have no clear effect on survival. In animals with superoxide dismutase 1 (sod1) mutations, sex does affect the clinical course of disease, with earlier onset in males. Possible reasons for the differences in ALS between men and women include different exposures to environmental toxins, different biological responses to exogenous toxins, and possibly underlying differences between the male and female nervous systems and different abilities to repair damage.

CONCLUSIONS

There is a complex interaction between gender and clinical phenotypes in ALS. Understanding the causes of the gender differences could give clues to processes that modify the disease.

Role of gender in multiple sclerosis: clinical effects and potential molecular mechanisms

Multiple sclerosis (MS) is more prevalent in females than males, and this female predominance is increasing as time goes by. Additionally, gender appears to play critical roles in development, progression and treatment of MS, and is therefore an aspect that should always be considered in the design and interpretation of research and clinical trials for MS. In this review, factors that could potentially explain the gender-biased observations in MS are discussed. These include sex-specific differences between the male and female immune systems and nervous systems, genetic and epigenetic or environmental-related effects, the effects of gonadal hormones, and materno-fetal interactions.

Sex differences in the injured brain

Observations obtained in human and in experimental models clearly demonstrate sex differences in degenerative events occurring in the central nervous system. The present review focuses on potential factors that may contribute to these sex-dimorphic features; in particular, morphological organization of the central nervous system and functional influence by neuroactive steroids, genes, and immune system are considered.

Effects of progesterone and testosterone on ICH-induced brain injury in rats

Studies have shown that progesterone reduces brain injury, whereas testosterone increases lesion size after ischemic stroke. This study examined the effects of progesterone and testosterone on intracerebral hemorrhage (ICH)-induced brain injury. Male Sprague-Dawley rats received an injection of 100 μL autologous whole blood into the right basal ganglia. Progesterone (16 mg/kg), testosterone (15 mg/kg) or vehicle was given intraperitoneally 2 h after ICH. Behavioral tests were performed, and the rats were killed after 24 h for brain edema measurement. Perihematomal brain edema was reduced in progesterone-treated rats compared to vehicle-treated rats (p<0.05). Progesterone also improved functional outcome following ICH (p<0.05). Testosterone treatment did not affect perihematomal edema formation, but resulted in lower forelimb placing score (p<0.05). In conclusion, progesterone can reduce brain edema and improve functional outcome, whereas testosterone may have a deleterious effect after ICH in male rats.

Sex shapes experimental ischemic brain injury

Biologic sex and sex steroids are important factors in clinical and experimental stroke. This review evaluates key evidence that biological sex strongly alters mechanisms and outcomes from cerebral ischemia. The role of androgens in male stroke is understudied and important to pursue given that male sex is a well known risk factor for human stroke. To date, male sex steroids remain largely evaluated at the bench rather than the bedside. We review recent advances in our understanding of androgens in the context of ischemic cell death and neuroprotection. We also highlight some possible molecular mechanisms by which androgens impact ischemic outcomes.

Sex differences in β-amyloid accumulation in 3xTg-AD mice: role of neonatal sex steroid hormone exposure

The risk of Alzheimer's disease (AD) is higher in women than in men, a sex difference that likely results from the effects of sex steroid hormones. To investigate this relationship, we first compared progression of β-amyloid (Aβ) pathology in male and female triple transgenic (3xTg-AD) mice. We found that female 3xTg-AD mice exhibit significantly greater Aβ burden and larger behavioral deficits than age-matched males. Next, we evaluated how the organizational effects of sex steroid hormones during postnatal development may affect adult vulnerability to Aβ pathology. We observed that male 3xTg-AD mice demasculinized during early development exhibit significantly increased Aβ accumulation in adulthood. In contrast, female mice defeminized during early development exhibit a more male-like pattern of Aβ pathology in adulthood. Taken together, these results demonstrate significant sex differences in pathology in 3xTg-AD mice and suggest that these differences may be mediated by organizational actions of sex steroid hormones during development.

Acute management of acquired brain injury part II: an evidence-based review of pharmacological interventions

PRIMARY OBJECTIVE

To review the research literature on pharmacological interventions used in the acute phase of acquired brain injury (ABI) to manage ICP and improve neural recovery.

MAIN OUTCOMES

A literature search of multiple databases (CINAHL, EMBASE, MEDLINE and PSYCHINFO) and hand searched articles covering the years 1980-2008 was performed. Peer reviewed articles were assessed for methodological quality using the PEDro scoring system for randomized controlled trials (RCTs) and the Downs and Black tool for RCTs and non-randomized trials. Levels of evidence were assigned and recommendations were made.

RESULTS

In total, 11 pharmacological interventions used in the acute management of ABI were evaluated. These included propofol, barbiturates, opioids, midazolam, mannitol, hypertonic saline, corticosteroids, progesterone, bradykinin antagonists, dimethyl sulphoxide and cannabinoids. Of these interventions, corticosteroids were found to be contraindicated and cannabinoids were reported as ineffective. The other nine interventions demonstrated some benefit for treatment of acute ABI. However, rarely did these benefits result in improved long-term patient outcomes.

CONCLUSIONS

Substantial research has been devoted to evaluating the use of pharmacological interventions in the acute management of ABI. However, much of this research has focused on the application of individual interventions in small single-site trials. Future research will need to establish larger patient samples to evaluate the benefits of combined interventions within specific patient populations.

Sex differences in the long-term neuropsychological outcome of mild traumatic brain injury

PRIMARY OBJECTIVE

To investigate possible sex differences in neuropsychological functioning among patients following mild traumatic brain injury (TBI).

METHODS AND PROCEDURES

Retrospective records analysis of the neuropsychological test results of 102 participants with head injury, including 62 males and 40 females.

MAIN OUTCOME AND RESULTS

A multivariate analysis of variance indicated that females and males performed similarly on neuropsychological tests, on average, approximately 2 years after minor head trauma. A sex-by-age interaction effect was found on the Category and Trail Making A Tests, with a pattern similar to those obtained in a previous research.

CONCLUSIONS

Although past research has found that females develop more TBI-related neuropsychological deficits than males in the immediate post-injury period, the present study found that, overall, sex differences in the performance of patients with mild TBI on a variety of neuropsychological tests were insignificant. More investigation into the sex-by-age interaction effect appears warranted.

Women of child-bearing age have better inhospital cardiac arrest survival outcomes than do equal-aged men

OBJECTIVES

Estrogen and progesterone improve neurologic outcomes in experimental models of cardiac arrest and stroke. Our objective was to determine whether women of child-bearing age are more likely than men to survive to hospital discharge after in-hospital cardiac arrest.

DESIGN

Prospective, observational study.

SETTING

Five hundred nineteen hospitals in the National Registry of Cardiopulmonary Resuscitation database.

PATIENTS

Patients included 95,852 men and women 15-44 yrs and 56 yrs or older with pulseless cardiac arrests from January 1, 2000 through July 31, 2008.

MEASUREMENTS AND MAIN RESULTS

Patients were stratified a priori by gender and age groups (15-44 yrs and > or =56 yrs). Fixed-effects regression conditioning on hospital was used to examine the relationship between age, gender, and survival outcomes. The unadjusted survival to discharge rate for younger women of child-bearing age (15-44 yrs) was 19% (940/4887) vs. 17% (1203/7025) for younger men (p = .013). The adjusted hospital discharge difference between these younger women and men was 2.8% (95% confidence interval, 1.0% to 4.6%; p = .002), and these younger women also had a 2.6% (95% confidence interval, 0.9% to 4.3%; p = .002) absolute increase in favorable neurologic outcome. For older women compared with men (> or =56 yrs), there were no demonstrable differences in discharge rates (18% vs. 18%; adjusted difference, -0.1%; 95% confidence interval, -0.9% to 0.6%; p = .68) or favorable neurologic outcome (14% vs. 14%; adjusted difference, -0.1%; 95% confidence interval, -0.7% to 0.5%; p = .74).

CONCLUSIONS

Women of child-bearing age were more likely than comparably aged men to survive to hospital discharge after in-hospital cardiac arrest, even after controlling for etiology of arrest and other important variables.

Estradiol and G1 reduce infarct size and improve immunosuppression after experimental stroke

Reduced risk and severity of stroke in adult females is thought to depend on normal endogenous levels of estrogen, a well-known neuroprotectant and immunomodulator. In male mice, experimental stroke induces immunosuppression of the peripheral immune system, characterized by a reduction in spleen size and cell numbers and decreased cytokine and chemokine expression. However, stroke-induced immunosuppression has not been evaluated in female mice. To test the hypothesis that estradiol (E2) deficiency exacerbates immunosuppression after focal stroke in females, we evaluated the effect of middle cerebral artery occlusion on infarct size and peripheral and CNS immune responses in ovariectomized mice with or without sustained, controlled levels of 17-beta-E2 administered by s.c. implant or the putative membrane estrogen receptor agonist, G1. Both E2- and G1-replacement decreased infarct volume and partially restored splenocyte numbers. Moreover, E2-replacement increased splenocyte proliferation in response to stimulation with anti-CD3/CD28 Abs and normalized aberrant mRNA expression for cytokines, chemokines, and chemokine receptors and percentage of CD4(+)CD25(+)FoxP3(+) T regulatory cells observed in E2-deficient animals. These beneficial changes in peripheral immunity after E2 replacement were accompanied by a profound reduction in expression of the chemokine, MIP-2, and a 40-fold increased expression of CCR7 in the lesioned brain hemisphere. These results demonstrate for the first time that E2 replacement in ovariectomized female mice improves stroke-induced peripheral immunosuppression.

Sex-specific therapeutic strategies based on neuroactive steroids: In search for innovative tools for neuroprotection

Different pathologies of the central and peripheral nervous system show sex differences in their incidence, symptomatology and/or neurodegenerative outcome. These include Parkinson's disease, Alzheimer's disease, Huntington's disease, multiple sclerosis, traumatic brain injury, stroke, autism, schizophrenia, depression, anxiety disorders, eating disorders and peripheral neuropathy. These sex differences reveal the need for sex-specific neuroprotective strategies. This review article and other manuscripts published in this issue of Hormones and Behavior analyze possible sex-specific therapeutic strategies based on neuroactive steroids. In particular in our introductory article, the possibility that sex differences in the levels or in the action of neuroactive steroids may represent causative factors for sex differences in the incidence or manifestation of pathologies of the nervous system is considered.

Poly (ADP-ribose) polymerase-1 initiated neuronal cell death pathway--do androgens matter?

Activation of poly (ADP-ribose) polymerases (PARP) contributes to ischemic damage by causing neuronal nicotinamide adenine dinucleotide (NAD(+)) depletion, release of apoptosis-inducing factor and consequent caspase-independent cell death. PARP-mediated cell death is sexually dimorphic, participating in ischemic damage in the male brain, but not the female brain. We tested the hypothesis that androgen signaling is required for this male-specific neuronal cell death pathway. We observed smaller damage following focal cerebral ischemia (MCAO) in male PARP-1 knockout mice compared to wild type (WT) as well as decreased damage in male mice treated with the PARP inhibitor PJ34. Protection from ischemic damage provided by PJ-34 in WT mice is lost after removal of testicular androgens (CAST) and rescued by androgen replacement. CAST PARP-1 KO mice exhibit increased damage compared to intact male KO mice, an effect reversed by androgen replacement in an androgen receptor-dependent manner. Lastly, we observed that ischemia causes an increase in PARP-1 expression that is diminished in the absence of testicular androgens. Our data indicate that PARP-mediated neuronal cell death in the male brain requires intact androgen-androgen receptor signaling.

Changes in the expression of insulin-like growth factor 1 variants in the postnatal brain development and in neonatal hypoxia-ischaemia

Insulin-like growth factor-1 (IGF-1) is a multifunctional peptide of which numerous isoforms exist. The predominant form, IGF-1Ea is involved in physiological processes while IGF-1Ec (mechano-growth factor, MGF) is expressed in response to a different set of stimuli. We have identified specific changes in the expression patterns of these IGF-1 variants in brain development in normal rats and following neonatal hypoxia-ischaemia (HI). Both IGF-1Ea and IGF-1Ec are expressed during normal postnatal brain development, albeit with highly specific temporal distributions. In contrast, HI produced increased and prolonged expression of the IGF-1Ec isoform only. Importantly, hypoxia alone stimulated the expression of IGF-1Ec as well. Thus, IGF-1Ec may play a role in HI pathology. Neonatal hypoxia-ischaemia occurs in approximately 1:4000-1:10,000 newborns and causes neurological deficits in approximately 75% of those affected. Unfortunately, no specific treatment is available. IGF-1 is known to have neuroprotective activity and its IGF-1Ec variant appears to be an endogenous protective factor in hypoxia-ischaemia. Therefore, IGF-1Ec could potentially be developed into a therapeutic modality for the attenuation or prevention of neuronal damage in this and related disorders.

Mechanisms of gender-linked ischemic brain injury

Biological sex is an important determinant of stroke risk and outcome. Women are protected from cerebrovascular disease relative to men, an observation commonly attributed to the protective effect of female sex hormones, estrogen and progesterone. However, sex differences in brain injury persist well beyond the menopause and can be found in the pediatric population, suggesting that the effects of reproductive steroids may not completely explain sexual dimorphism in stroke. We review recent advances in our understanding of sex steroids (estradiol, progesterone and testosterone) in the context of ischemic cell death and neuroprotection. Understanding the molecular and cell-based mechanisms underlying sex differences in ischemic brain injury will lead to a better understanding of basic mechanisms of brain cell death and is an important step toward designing more effective therapeutic interventions in stroke.

Metabolic diseases and associated complications: sex and gender matter!

BACKGROUND

Clinicians and health professionals are increasingly challenged to understand and consider the different health needs of women and men. The increase of gender awareness and the expanding science of gender medicine will affect more and more clinical practice. This review addresses gender-specific aspects in metabolic disorders and related complications, which represent an increasing burden of this century and a great challenge to public health.

DESIGN

There is increasing evidence of gender-related differences in risk factors, clinical manifestation and sequelae of obesity and diabetes and increasing knowledge that prevention, detection and therapy of illness affect men and women differently.

RESULTS

Some gender-specific aspects, especially regarding cardiovascular disease, have been studied in more detail, but for many complications sex-related analyses of the results of both clinical trials and basic science are still missing or disregarded. Impaired glucose and lipid metabolism as well as dysregulation of energy balance and body fat distribution have a great impact on overall health via neuroendocrine changes and inflammatory pathways and deteriorate the course of many diseases with particular harm for women. Metabolic diseases dramatically affect life of men and women from infancy up to old age and are a major challenge for women during pregnancy. Great impact is attached to the intrauterine period and the lifelong implications of fetal programming.

CONCLUSIONS

Initiation of prospective studies on the impact of gender as primary outcome and investigation of gender-related pathophysiological mechanisms of chronic diseases will help to improve patient care and to implement evidence-based gender-specific prevention programs and clinical recommendations in future.

Sex and gender in psychoneuroimmunology research: past, present and future

To date, research suggests that sex and gender impact pathways central to the foci of psychoneuroimmunology (PNI). This review provides a historical perspective on the evolution of sex and gender in psychoneuroimmunology research. Gender and sexually dimorphic pathways may have synergistic effects on health differences in men and women. We provide an overview of the literature of sex and gender differences in brain structure and function, sex steroids, gender role identification, hypothalamic-pituitary-adrenal axis function, genetics, immunology and cytokine response. Specific examples shed light on the importance of attending to sex and gender methodology in PNI research and recommendations are provided.

Brain aromatization: classic roles and new perspectives

Aromatization of testosterone to estradiol by neural tissue has classically been associated with the regulation of sexual differentiation, gonadotropin secretion, and copulatory behavior. However, new data indicate that the capacity for aromatization is not restricted to the endocrine brain and demonstrate roles for locally formed estrogens in neurogenesis and in responses of brain tissue to injury. This article summaries our current understanding of the distribution and regulation of aromatase in the brain and describes the classic and novel roles it plays. A better understanding of brain aromatization could shed new light on its physiologic and pathologic functions and someday lead to new, centrally acting drug therapies.

Progesterone exerts neuroprotective effects by inhibiting inflammatory response after stroke

OBJECTIVE AND DESIGN

We evaluated the inhibitory effects of progesterone (PROG) on inflammatory response and its influence on the structure of blood-brain barrier in a permanent model of stroke.

MATERIAL

One hundred and twenty adult male Sprague-Dawley rats were used in this study.

TREATMENTS

PROG was dissolved in 22.5% 2-hydroxypropyl-bcyclodextrin and given in a dose of 15 mg/kg by intraperitoneal injection 1 h after permanent occlusion of middle cerebral artery (pMCAO). Additional injections of 15 mg/kg were administered subcutaneously 6, 24, and 48 h after pMCAO.

METHODS

The expression of tumor necrosis factor-alpha (TNF-alpha) and claudin5 was measured by immunohistochemistry and western blot technique. Brain water content was determined by the dry-wet weight method.

RESULTS

TNF-alpha were increased, but claudin5 were reduced in vehicle-treated rats after pMCAO. PROG-treated rats showed a substantial reduction in the expression of TNF-alpha compared to vehicle controls. In addition, there was significant increase in the expression of claudin5 in the pMCAO rats treated with PROG compared to vehicle. Examination of the water content of the brain also revealed that administration of PROG significantly attenuated the amount of water compared to vehicle in the ipsilateral hemispheres.

CONCLUSIONS

These data indicate that PROG is beneficial in this animal model, and may warrant further test in future clinical trials for human stroke.