Neuroprotective actions of sex steroids in Parkinson's disease

Differences in Parkinson's Disease Risk with Caffeine Intake and Postmenopausal Hormone Use

BACKGROUND

Caffeine intake has been associated with a lower risk of Parkinson's disease (PD). This association is robust in men, but inconsistent in women due to a possible interaction with post-menopausal hormone (PMH) use.

OBJECTIVE

To (1) evaluate the association between caffeine intake and PD risk and (2) assess potential effect modification of the association by PMH use among women.

METHODS

We examined associations between caffeine intake and incident PD risk in the Nurses' Health Study (NHS) (N = 121,701 women) and the Health Professionals Follow-up Study (HPFS) (N = 51,529 men). Dietary data on coffee and caffeine from other sources were collected every four years using a validated semi-quantitative food frequency questionnaire for both cohorts. Information on lifestyle and incident PD diagnosis was updated biennially and PD diagnoses were confirmed by medical record review. We estimated hazard ratios (HR) and 95% confidence intervals (CI) using Cox proportional hazards models.

RESULTS

We documented a total of 1,219 PD cases over the follow-up period. The multivariable-adjusted HR comparing the highest to lowest quintile of caffeine intake was 0.50 (95% CI: 0.37, 0.68; Ptrend<0.0001) in the HPFS. Among women, there was a suggestion of an interaction between coffee intake and PMH use (P = 0.08). In the pooled analyses combining men and women who have never used PMH, the risk of PD was lower as coffee intake increased (Ptrend<0.001).

CONCLUSIONS

Our results support previous findings that increased caffeine intake may be associated with a decreased PD risk in men and women who have never used PMH.

Sex differences in progression to mild cognitive impairment and dementia in Parkinson's disease

INTRODUCTION

Identification of factors associated with progression of cognitive symptoms in Parkinson's disease (PD) is important for treatment planning, clinical care, and design of future clinical trials. The current study sought to identify whether prediction of cognitive progression is aided by examining baseline cognitive features, and whether this differs according to stage of cognitive disease.

METHODS

Participants with PD in the Pacific Udall Center Clinical Consortium who had longitudinal data available and were nondemented at baseline were included in the study (n = 418). Logistic and Cox regression models were utilized to examine the relationship between cognitive, demographic, and clinical variables with risk and time to progression from no cognitive impairment to mild cognitive impairment (PD-MCI) or dementia (PDD), and from PD-MCI to PDD.

RESULTS

Processing speed (OR = 1.05, p = 0.009) and working memory (OR = 1.01, p = 0.03) were associated with conversion to PDD among those with PD-MCI at baseline, over and above demographic variables. Conversely, the primary predictive factor in the transition from no cognitive impairment to PD-MCI or PDD was male sex (OR = 4.47, p = 0.004), and males progressed more rapidly than females (p = 0.01). Further, among females with shorter disease duration, progression was slower than for their male counterparts, and poor baseline performance on semantic verbal fluency was associated with shorter time to cognitive impairment in females but not in males.

CONCLUSIONS

This study provides evidence for sex differences in the progression to cognitive impairment in PD, while specific cognitive features become more important indicators of progression with impending conversion to PDD.

Sex steroid hormones as neuroprotective elements in ischemia models

Among sex steroid hormones, progesterone and estradiol have a wide diversity of physiological activities that target the nervous system. Not only are they carried by the blood stream, but also they are locally synthesized in the brain and for this reason, estradiol and progesterone are considered 'neurosteroids'. The physiological actions of both hormones range from brain development and neurotransmission to aging, illustrating the importance of a deep understanding of their mechanisms of action. In this review, we summarize key roles that estradiol and progesterone play in the brain. As numerous reports have confirmed a substantial neuroprotective role for estradiol in models of neurodegenerative disease, we focus this review on traumatic brain injury and stroke models. We describe updated data from receptor and signaling events triggered by both hormones, with an emphasis on the mechanisms that have been reported as 'rapid' or 'cytoplasmic actions'. Data showing the therapeutic effects of the hormones, used alone or in combination, are also summarized, with a focus on rodent models of middle cerebral artery occlusion (MCAO). Finally, we draw attention to evidence that neuroprotection by both hormones might be due to a combination of 'cytoplasmic' and 'nuclear' signaling.

Estradiol Activates PI3K/Akt/GSK3 Pathway Under Chronic Neurodegenerative Conditions Triggered by Perinatal Asphyxia

Perinatal asphyxia (PA) remains as one of the most important causes of short-term mortality, psychiatric and neurological disorders in children, without an effective treatment. In previous studies we have observed that the expression of different neurodegenerative markers increases in CA1 hippocampal area of 4-months-old male rats born by cesarean section and exposed for 19 min to PA. We have also shown that a late treatment with 17β estradiol (daily dose of 250 μg/kg for 3 days) was able to revert the brain alterations observed in those animals. Based on these previous results, the main aim of the present study was to explore the mechanism by which the estrogenic treatment is involved in the reversion of the chronic neurodegenerative conditions induced by PA. We demonstrated that estradiol treatment of adult PA exposed animals induced an increase in estrogen receptor (ER) α and insulin-like growth factor receptor (IGF-1R) protein levels, an activation of the phosphatidylinositol 3-kinase/Akt/glycogen synthase kinase 3 beta/β-catenin signaling pathway and an increase in Bcl-2/Bax ratio in the hippocampus in comparison to PA exposed animals treated with vehicle. Taking together, our data suggest that the interaction between ERα and IGF-IR, with the subsequent downstream activation, underlies the beneficial effects of estradiol observed in late treatment of PA.

New 3D-printed sorbent for extraction of steroids from human plasma preceding LC-MS analysis

In recent years, there has been an increasing worldwide interest in the use of alternative sample preparation methods that are proceeded by separation techniques. Fused deposition modeling (FDM) is a 3D printing technique that is based the consecutive layering of softened/melted thermoplastic materials. In this study, a group of natural steroids and sexual hormones - namely, aldosterone, cortisol, β-estradiol, testosterone, dihydrotestosterone, and synthetic methyltestosterone and betamethasone - were separated and determined using an optimized high-performance liquid chromatography coupled to mass spectrometry (LC-MS) method in positive ionization mode. 3D-printed sorbents were selected as the pre-concentration technique because they are generally low cost, fast, and simple to make and automate. Furthermore, the use of 3D-printed sorbents helps to minimize potential errors due to their repeatability and reproducibility, and their ability to eliminate carry over by using one printed sorbent for a single extraction of steroids from biological matrices. The extraction procedure was optimized and the parameters influencing 3D-printed Layfomm 60^® based sorbent and LC-MS were studied, including the type of extraction solvent used, sorption and desorption times, temperature, and the salting-out effect. To demonstrate this method's applicability for biological sample analysis, the SPME-LC-MS method was validated for its ability to simultaneously quantify endogenous steroids. This evaluation confirmed good linearity and an R² that was between 0.9970 and 0.9990. The recovery rates for human plasma samples were 86.34-93.6% for the studied steroids with intra- and inter-day RSDs of 1.44-7.42% and 1.44-9.46%, respectively. To our knowledge, this study is the first time that 3D-printed sorbents have been used to extract trace amounts of endogenous low-molecular-weight compounds, such as steroids, from biological samples, such as plasma.

Role of Estrogen and Other Sex Hormones in Brain Aging. Neuroprotection and DNA Repair

Aging is an inevitable biological process characterized by a progressive decline in physiological function and increased susceptibility to disease. The detrimental effects of aging are observed in all tissues, the brain being the most important one due to its main role in the homeostasis of the organism. As our knowledge about the underlying mechanisms of brain aging increases, potential approaches to preserve brain function rise significantly. Accumulating evidence suggests that loss of genomic maintenance may contribute to aging, especially in the central nervous system (CNS) owing to its low DNA repair capacity. Sex hormones, particularly estrogens, possess potent antioxidant properties and play important roles in maintaining normal reproductive and non-reproductive functions. They exert neuroprotective actions and their loss during aging and natural or surgical menopause is associated with mitochondrial dysfunction, neuroinflammation, synaptic decline, cognitive impairment and increased risk of age-related disorders. Moreover, loss of sex hormones has been suggested to promote an accelerated aging phenotype eventually leading to the development of brain hypometabolism, a feature often observed in menopausal women and prodromal Alzheimer's disease (AD). Although data on the relation between sex hormones and DNA repair mechanisms in the brain is still limited, various investigations have linked sex hormone levels with different DNA repair enzymes. Here, we review estrogen anti-aging and neuroprotective mechanisms, which are currently an area of intense study, together with the effect they may have on the DNA repair capacity in the brain.

Role of Estrogen and Other Sex Hormones in Brain Aging. Neuroprotection and DNA Repair

Aging is an inevitable biological process characterized by a progressive decline in physiological function and increased susceptibility to disease. The detrimental effects of aging are observed in all tissues, the brain being the most important one due to its main role in the homeostasis of the organism. As our knowledge about the underlying mechanisms of brain aging increases, potential approaches to preserve brain function rise significantly. Accumulating evidence suggests that loss of genomic maintenance may contribute to aging, especially in the central nervous system (CNS) owing to its low DNA repair capacity. Sex hormones, particularly estrogens, possess potent antioxidant properties and play important roles in maintaining normal reproductive and non-reproductive functions. They exert neuroprotective actions and their loss during aging and natural or surgical menopause is associated with mitochondrial dysfunction, neuroinflammation, synaptic decline, cognitive impairment and increased risk of age-related disorders. Moreover, loss of sex hormones has been suggested to promote an accelerated aging phenotype eventually leading to the development of brain hypometabolism, a feature often observed in menopausal women and prodromal Alzheimer's disease (AD). Although data on the relation between sex hormones and DNA repair mechanisms in the brain is still limited, various investigations have linked sex hormone levels with different DNA repair enzymes. Here, we review estrogen anti-aging and neuroprotective mechanisms, which are currently an area of intense study, together with the effect they may have on the DNA repair capacity in the brain.

The analysis of relationship between selected sociodemografic factors and disorders of speech organs in Parkinson`s patients

Background

Evaluation of speech disorders in PD taking into account sociodemographic conditions is not frequent. This paper aims to establish correlations between articulation disorders in PD patients and factors such as the patients’ sex, age, education and residence.

Methods

The study included 92 patients with idiopathic PD diagnosed by means of multiple neurological examinations, biochemical tests, MRI and CT scanning carried out in accordance with the United Kingdom Parkinson’s Disease Society Brain Bank (UKPDSBB) criteria. A speech and language test involved the assessment of the mobility of the speech organs as well as the reflexes inside the oral cavity. Frenchay Dysarthria Assessment was applied for an objective evaluation of dysarthria.

Results

The study revealed the existence of significant relationship between the functionality of articulators in PD patients and their education and residence. Big city dwellers demonstrated lower incidence of disorders within speech organs, particularly those affecting mobility of the soft palate while eating. Disorders of moderate intensity were more frequently found in subjects living in villages. Subjects with a university education displayed better position of the lips at rest and better performance of both lips and the mandible while speaking.

Conclusions

Abnormal functioning of the articulatory organs was observed more frequently in PD patients residing in rural areas than in those inhabiting urban areas. As for education, our cohort university graduates displayed a better position of the lips at rest and better performance of the lips and jaw during speaking than those with secondary and vocational education.

Role of Sex Hormones on Brain Mitochondrial Function, with Special Reference to Aging and Neurodegenerative Diseases

The mitochondria have a fundamental role in both cellular energy supply and oxidative stress regulation and are target of the effects of sex steroids, particularly the neuroprotective ones. Aging is associated with a decline in the levels of different steroid hormones, and this decrease may underline some neural dysfunctions. Besides, modifications in mitochondrial functions associated with aging processes are also well documented. In this review, we will discuss studies that describe the modifications of brain mitochondrial function and of steroid levels associated with physiological aging and with neurodegenerative diseases. A special emphasis will be placed on describing and discussing our recent findings concerning the concomitant study of mitochondrial function (oxidative phosphorylation, oxidative stress) and brain steroid levels in both young (3-month-old) and aged (20-month-old) male and female mice.

Prooxidant-antioxidant balance, advanced oxidation protein products and lipid peroxidation in Serbian patients with Parkinson's disease

BACKGROUND

Biomarkers of oxidative stress are relevant in the evaluation of the disease status and prooxidant-antioxidant balance, advanced oxidation protein products and lipid peroxidation products (malondialdehyde and 4-hydroxynonenal) are being extensively evaluated regarding their relationship with clinical presentation and disease severity.

AIM OF THE STUDY

The aim of this study was to evaluate the levels of the above-mentioned parameters in plasma of 39 men and 17 women with Parkinson's disease, originated from the Republic of Serbia and their relation to clinicopathological characteristics (gender, age at examination, duration of the disease, and Hoehn and Yahr score) and oxidative status.

RESULTS

The incidence of disease was 2:1 towards males. The investigated oxidative parameters were gender and Hoehn and Yahr related. Significant association of higher Hoehn and Yahr scores was observed for malondialdehyde (p = 0.01) and prooxidant-antioxidant balance (p = 0.02). Relation between oxidant-antioxidant status was further supported by observed positive correlation between 4-hydroxynonenal (p = 0.04) and prooxidant-antioxidant balance (p = 0.03). Finally, the multivariate analysis indicated that prooxidant-antioxidant balance and malondialdehyde were partially determined by gender (10.6% and 7.6%) and Hoehn and Yahr scores (13.6% and 18.8%), while Hoehn and Yahr scores contributed to the variance of advanced oxidation protein products with 13.2%.

CONCLUSION

Our results indicate the higher level of oxidative stress (oxidant-antioxidant imbalance) and possible relation of several markers with gender and disease stage in patients with Parkinson's disease. The analyzed markers could be used to specify the severity of oxidative stress; however, their potential value should be analyzed in further studies.

17β-estradiol and tamoxifen protect mice from manganese-induced dopaminergic neurotoxicity

Chronic exposure to manganese (Mn) causes neurotoxicity, referred to as manganism, with common clinical features of parkinsonism. 17β-estradiol (E2) and tamoxifen (TX), a selective estrogen receptor modulator (SERM), afford neuroprotection in several neurological disorders, including Parkinson's disease (PD). In the present study, we tested if E2 and TX attenuate Mn-induced neurotoxicity in mice, assessing motor deficit and dopaminergic neurodegeneration. We implanted E2 and TX pellets in the back of the neck of ovariectomized C57BL/6 mice two weeks prior to a single injection of Mn into the striatum. One week later, we assessed locomotor activity and molecular mechanisms by immunohistochemistry, real-time quantitative PCR, western blot and enzymatic biochemical analyses. The results showed that both E2 and TX attenuated Mn-induced motor deficits and reversed the Mn-induced loss of dopaminergic neurons in the substantia nigra. At the molecular level, E2 and TX reversed the Mn-induced decrease of (1) glutamate aspartate transporter (GLAST) and glutamate transporter 1 (GLT-1) mRNA and protein levels; (2) transforming growth factor-α (TGF-α) and estrogen receptor-α (ER-α) protein levels; and (3) catalase (CAT) activity and glutathione (GSH) levels, and Mn-increased (1) malondialdehyde (MDA) levels and (2) the Bax/Bcl-2 ratio. These results indicate that E2 and TX afford protection against Mn-induced neurotoxicity by reversing Mn-reduced GLT1/GLAST as well as Mn-induced oxidative stress. Our findings may offer estrogenic agents as potential candidates for the development of therapeutics to treat Mn-induced neurotoxicity.

Role of estrogen receptor beta in neural differentiation of mouse embryonic stem cells

The ability to propagate mature cells and tissue from pluripotent stem cells offers enormous promise for treating many diseases, including neurodegenerative diseases. Before such cells can be used successfully in neurodegenerative diseases without causing unwanted cell growth and migration, genes regulating growth and migration of neural stem cells need to be well characterized. Estrogen receptor beta (ERβ) is essential for migration of neurons and glial cells in the developing mouse brain. To examine whether ERβ influences differentiation of mouse embryonic stem cells (mESC) into neural lineages, we compared control and ERβ knockout (BERKO) mESCs at defined stages of neural development and examined the effects of an ERβ-selective ligand (LY3201) with a combination of global and targeted gene-expression profiling and the expression of key pluripotency markers. We found that ERβ was induced in embryoid bodies (EBs) and neural precursor cells (NPCs) during development. Proliferation was higher in BERKO NPCs and was inhibited by LY3201. Neurogenesis was reduced in BERKO ES cells, and oligodendrogliogenesis was enhanced. BERKO EBs expressed higher levels of key ectodermal and neural progenitor markers and lower levels of markers for mesoderm and endoderm lineages. ERβ-regulated factors are involved in cell adhesion, axon guidance, and signaling of Notch and GABA receptor pathways, as well as factors important for the differentiation of neuronal precursors into dopaminergic neurons (Engrailed 1) and for the oligodendrocyte fate acquisition (Olig2). Our data suggest that ERβ is an important component for differentiation into midbrain neurons as well as for preventing precocious oligodendrogliogenesis.

Steroid and Xenobiotic Receptor Signalling in Apoptosis and Autophagy of the Nervous System

Apoptosis and autophagy are involved in neural development and in the response of the nervous system to a variety of insults. Apoptosis is responsible for cell elimination, whereas autophagy can eliminate the cells or keep them alive, even in conditions lacking trophic factors. Therefore, both processes may function synergistically or antagonistically. Steroid and xenobiotic receptors are regulators of apoptosis and autophagy; however, their actions in various pathologies are complex. In general, the estrogen (ER), progesterone (PR), and mineralocorticoid (MR) receptors mediate anti-apoptotic signalling, whereas the androgen (AR) and glucocorticoid (GR) receptors participate in pro-apoptotic pathways. ER-mediated neuroprotection is attributed to estrogen and selective ER modulators in apoptosis- and autophagy-related neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases, stroke, multiple sclerosis, and retinopathies. PR activation appeared particularly effective in treating traumatic brain and spinal cord injuries and ischemic stroke. Except for in the retina, activated GR is engaged in neuronal cell death, whereas MR signalling appeared to be associated with neuroprotection. In addition to steroid receptors, the aryl hydrocarbon receptor (AHR) mediates the induction and propagation of apoptosis, whereas the peroxisome proliferator-activated receptors (PPARs) inhibit this programmed cell death. Most of the retinoid X receptor-related xenobiotic receptors stimulate apoptotic processes that accompany neural pathologies. Among the possible therapeutic strategies based on targeting apoptosis via steroid and xenobiotic receptors, the most promising are the selective modulators of the ER, AR, AHR, PPARγ agonists, flavonoids, and miRNAs. The prospective therapies to overcome neuronal cell death by targeting autophagy via steroid and xenobiotic receptors are much less recognized.

β-Estradiol-3-benzoate confers neuroprotection in Parkinson MPP+ rat model through inhibition of lipid peroxidation

Estradiol (E2), in addition to its known hormone function, is a neuroactive steroid that has shown neuroprotective profile in several models of neurological diseases. The present study explores the antioxidant effect of β-estradiol-3-benzoate (EB) on the neurotoxicity elicited by MPP⁺ in rat striatum. Male Wistar rats, that were gonadectomized 30days prior to EB, were given 100µgEB per rat every 48h for 11days and animals were infused with MPP⁺ via intrastriatal at day six after beginning EB treatment. EB treatment completely prevented the fall in dopamine caused by MPP⁺, such result was related with decreased lipid peroxidation, a marker of oxidative stress; diminished number of ipsilateral-to-lesion turns and increased signal of the dopamine-synthesizing enzyme Tyrosin Hydroxylase in substantia nigra. The protection elicited by EB was not related to Mn or Cu-Zn superoxide dismutase enzymatic activities or glutathione modulation since none of these parameters were influenced by EB at the times assayed. Whereas, increased expression of PON2 as a result of EB treatment was observed, this phenomenon could be one of the mechanism by which the steroid conferred protection to dopaminergic cells against MPP⁺ injury.

Dietary antioxidants and risk of Parkinson's disease in two population-based cohorts

Background: A neuroprotective effect of dietary antioxidants on Parkinson's disease (PD) risk has been suggested, but epidemiological evidence is limited.

Objectives: To examine the associations between intake of dietary antioxidant vitamins and total antioxidant capacity and risk of PD.

Methods: We prospectively assessed the relationships of dietary antioxidant vitamins C and E, ß‐carotene, and total antioxidant capacity with PD risk in two population‐based cohorts (38,937 women and 45,837 men).

Results: During a mean 14.9‐year follow‐up period, 1,329 PD cases were identified. Dietary intake of ß‐carotene was associated with a lower risk of PD (hazard ratio: 0.86; 95% confidence interval: 0.78‐0.95; P_trend < 0.01 for women and hazard ratio: 0.91; 95% confidence interval: 0.84‐0.99; P_trend = 0.05 for men). An inverse association between dietary vitamin E and PD risk was found in women (hazard ratio: 0.87; 95% confidence interval: 0.79‐0.96; P_trend = 0.02). Dietary intake of vitamin C was inversely associated with PD risk in women at borderline significance (hazard ratio: 0.91; 95% confidence interval: 0.83‐1.00; P_trend = 0.04). There was no association between dietary total antioxidant capacity and PD risk in either women (hazard ratio: 0.93; 95% confidence interval: 0.84‐1.02; P_trend = 0.35) or men (hazard ratio: 1.00; 95% confidence interval: 0.93‐1.07; P_trend = 0.97).

Conclusion: Intake of dietary vitamin E and ß‐carotene was associated with a lower risk of PD. © 2017 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Exploring the potential of natural and synthetic neuroprotective steroids against neurodegenerative disorders: A literature review

Neurodegeneration is a complex process, which leads to progressive brain damage due to loss of neurons. Despite exhaustive research, the cause of neuronal loss in various degenerative disorders is not entirely understood. Neuroprotective steroids constitute an important line of attack, which could play a major role against the common mechanisms associated with various neurodegenerative disorders like Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Natural endogenous steroids induce the neuroprotection by protecting the nerve cells from neuronal injury through multiple mechanisms, therefore the structural modifications of the endogenous steroids could be helpful in the generation of new therapeutically useful neuroprotective agents. The review article will keep the readers apprised of the detailed description of natural as well as synthetic neuroprotective steroids from the medicinal chemistry point of view, which would be helpful in drug discovery efforts aimed toward neurodegenerative diseases.

Systemic QSAR and phenotypic virtual screening: chasing butterflies in drug discovery

Current advances in systems biology suggest a new change of paradigm reinforcing the holistic nature of the drug discovery process. According to the principles of systems biology, a simple drug perturbing a network of targets can trigger complex reactions. Therefore, it is possible to connect initial events with final outcomes and consequently prioritize those events, leading to a desired effect. Here, we introduce a new concept, 'Systemic Chemogenomics/Quantitative Structure-Activity Relationship (QSAR)'. To elaborate on the concept, relevant information surrounding it is addressed. The concept is challenged by implementing a systemic QSAR approach for phenotypic virtual screening (VS) of candidate ligands acting as neuroprotective agents in Parkinson's disease (PD). The results support the suitability of the approach for the phenotypic prioritization of drug candidates.

Non-human primate models of PD to test novel therapies

Non-human primate (NHP) models of Parkinson disease show many similarities with the human disease. They are very useful to test novel pharmacotherapies as reviewed here. The various NHP models of this disease are described with their characteristics including the macaque, the marmoset, and the squirrel monkey models. Lesion-induced and genetic models are described. There is no drug to slow, delay, stop, or cure Parkinson disease; available treatments are symptomatic. The dopamine precursor, L-3,4-dihydroxyphenylalanine (L-Dopa) still remains the gold standard symptomatic treatment of Parkinson. However, involuntary movements termed L-Dopa-induced dyskinesias appear in most patients after chronic treatment and may become disabling. Dyskinesias are very difficult to manage and there is only amantadine approved providing only a modest benefit. In this respect, NHP models have been useful to seek new drug targets, since they reproduce motor complications observed in parkinsonian patients. Therapies to treat motor symptoms in NHP models are reviewed with a discussion of their translational value to humans. Disease-modifying treatments tested in NHP are reviewed as well as surgical treatments. Many biochemical changes in the brain of post-mortem Parkinson disease patients with dyskinesias are reviewed and compare well with those observed in NHP models. Non-motor symptoms can be categorized into psychiatric, autonomic, and sensory symptoms. These symptoms are present in most parkinsonian patients and are already installed many years before the pre-motor phase of the disease. The translational usefulness of NHP models of Parkinson is discussed for non-motor symptoms.

Effects of progesterone administered after MPTP on dopaminergic neurons of male mice

Progesterone neuroprotection of striatal dopamine (DA) in male mice lesioned with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was previously reported when administered before MPTP or an hour after. A dose of MPTP to induce a partial lesion was used to model early stages or prodromal Parkinson. We hypothesized that brain DA can be restored by progesterone administered early (24 h) or later (5 days) after MPTP. Male mice received 4 injections of MPTP (8 mg/kg) and progesterone (8 mg/kg) once daily for 5 days started 24 h or 5 days after MPTP. The lesion decreased striatal DA and its metabolites but not serotonin contents. MPTP mice treated with progesterone starting 24 h but not 5 days after MPTP had higher striatal DA and its metabolites content than vehicle-treated MPTP mice. Striatal DA transporter (DAT) and vesicular monoamine transporter 2 (VMAT2) specific binding decreased in lesioned mice and were corrected with progesterone treatment starting 24 h but not 5 days after MPTP. Striatal glial fibrillary acidic protein (GFAP) levels, a marker of activated astrocytes, were elevated by the MPTP lesion and were corrected with progesterone treatment starting 24 h after MPTP. Striatal brain derived neurotrophic factor (BDNF) levels were decreased by the MPTP lesion and were prevented by progesterone treatments whereas no change of Akt, GSK3β, ERK1 and 2 and their phosphorylated forms were observed. Thus, progesterone administered after MPTP in mice protected dopaminergic neurons through modulation of neuroinflammation and BDNF. In humans, progesterone could possibly be used as a disease-modifying drug in prodromal Parkinson.

Gender-based analysis of cortical thickness and structural connectivity in Parkinson's disease

Parkinson's disease (PD) is a progressive neurological disorder and appears to have gender-specific symptoms. Studies have observed a higher frequency for development of PD in male than in female. In the current study, we evaluated the gender-based changes in cortical thickness and structural connectivity in PD patients. With informed consent, 64 PD (43 males and 21 females) patients, and 46 (12 males and 34 females) age-matched controls underwent clinical assessment including Mini-Mental State Examination (MMSE) and magnetic resonance imaging on a 1.5 Tesla clinical MR scanner. Whole brain high-resolution T1-weighted images were acquired from all subjects and used to measure cortical thickness and structural network connectivity. No significant difference in MMSE score was observed between male and female both in control and PD subjects. Male PD patients showed significantly reduced cortical thickness in multiple brain regions including frontal, parietal, temporal, and occipital lobes as compared with those in female PD patients. The graph theory-based network analysis depicted lower connection strengths, lower clustering coefficients, and altered network hubs in PD male than in PD female. Male-specific cortical thickness changes and altered connectivity in PD patients may derive from behavioral, physiological, environmental, and genetical differences between male and female, and may have significant implications in diagnosing and treating PD among genders.

Dose-Response Analysis of the Effect of Carbidopa-Levodopa Extended-Release Capsules (IPX066) in Levodopa-Naive Patients With Parkinson Disease

Parkinson disease is an age-related disorder of the central nervous system principally due to loss of dopamine-producing cells in the midbrain. Levodopa, in combination with carbidopa, is widely regarded as an effective treatment for the symptoms of Parkinson disease. A dose-response relationship is established for carbidopa-levodopa extended-release capsules (IPX066) in levodopa-naive Parkinson disease patients using a disease progression model. Unified Parkinson Disease Rating Scale (UPDRS) part II plus part III scores from 171 North American patients treated with placebo or IPX066 for approximately 30 weeks from a double-blind, parallel-group, dose-ranging study were used to develop the pharmacodynamic model. The model comprised 3 components: a linear function describing disease progression, a component describing placebo (or nonlevodopa) effects, and a component to describe the effect of levodopa. Natural disease progression in early Parkinson disease as measured by UPDRS was 11.6 units/year and faster in patients with more severe disease (Hoehn-Yahr stage 3). Maximum placebo/nonlevodopa response was 23.0% of baseline UPDRS. Maximum levodopa effect from IPX066 was 76.7% of baseline UPDRS, and the ED50 was 450 mg levodopa. Equilibration half-life for the effect compartment was 62.8 days. Increasing age increased and being female decreased equilibration half-life. The quantitative model allowed description of the entire time course of response to clinical trial intervention.

Estrogen receptors modulate striatal metabotropic receptor type 5 in intact and MPTP male mice model of Parkinson's disease

Glutamate is the most important brain excitatory neurotransmitter and glutamate overactivity is well documented in Parkinson's disease (PD). Metabotropic glutamate (mGlu) receptors are reported to interact with membrane estrogen receptors (ERs) and more specifically the mGlu5 receptor subtype. 17β-estradiol and mGlu5 antagonists have neuroprotective effects in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. We previously reported that ERα and ERβ are involved in neuroprotection following MPTP toxicity. The present study investigated the implication of ERs on the mGlu5 receptor adaptive response to MPTP toxicity in the brain of wild type (WT), ER knockout (ERKO)α and ERKOβ male mice. Autoradiography of [(3)H]ABP688 specific binding to striatal mGlu5 receptors showed a dorsal/ventral gradient similar for WT, ERKOα and ERKOβ mice with higher values ventrally. The lateral septum had highest [(3)H]ABP688 specific binding that remained unchanged in all experimental groups. ERKOα and ERKOβ mice had similarly lower striatal [(3)H]ABP688 specific binding than WT mice as measured also by Western blots. MPTP dose-dependently decreased striatal [(3)H]ABP688 specific binding in WT but not in ERKOα and ERKOβ mice; this correlated positively with striatal dopamine concentrations. A 17β-estradiol treatment for 10 days left unchanged striatal [(3)H]ABP688 specific binding of unlesioned mice of the three genotypes. 17β-estradiol treatment for 5 days before MPTP and for 5 days after partially prevented the mGlu5 receptor decrease only in WT MPTP mice and this was associated with higher BDNF striatal contents. These results thus show that in male mice ERs affect striatal mGlu5 receptor levels and their response to MPTP.

Estrogen modulation of calretinin and BDNF expression in midbrain dopaminergic neurons of ovariectomised mice

Estrogen attenuates the loss of dopamine neurons from the substantia nigra in animal models of Parkinson's disease (PD) and excitatory amino-acid induced neurotoxicity by interactions with brain-derived neurotrophic factor (BDNF), and calretinin (CR) containing dopaminergic (DA) neurons. To examine this interaction more closely, we treated the ovariectomised (OVX) mice with estrodial for 10days, and compared these mice to those OVX mice injected with the vehicle or control mice. Estrogen treatment in OVX mice had significantly more tyrosine hydroxylase (TH) positive neurons in the substantia nigra pars compacta (SNpc). Dopamine transporter (DAT) mRNA and BDNF mRNA levels in the midbrain were also significantly increased by estrogen treatment (P<0.05). OVX markedly decreased the number of TH/CR double stained cells in the SNpc (P<0.05), a trend which could be reversed by estrogen treatment. However, the number of GFAP positive cells in the substantia nigra did not show significant changes (P >0.05) after vehicle or estrodial treatment. Furthermore, we found that estrogen treatment abrogated the OVX-induced decrease in the phosphorylated AKT (p-AKT), but not p-ERK. We hypothesize that short-term treatment with estrogen confers neuroprotection to DA neurons by increasing CR in the DA neurons and BDNF in the midbrain, which possibly related to activation of the PI3K/Akt signaling pathway.

Assessment of neuroactive steroids in cerebrospinal fluid comparing acute relapse and stable disease in relapsing-remitting multiple sclerosis

Previous studies have reported an involvement of neuroactive steroids as neuroprotective and anti-inflammatory agents in neurological disorders such as multiple sclerosis (MS); an analysis of their profile during a specific clinical phase of MS is largely unknown. The pregnenolone (PREG), dehydroepiandrosterone (DHEA), and allopregnanolone (ALLO) profile was evaluated in cerebrospinal fluid (CSF) in relapsing-remitting multiple sclerosis (RR-MS) patients as well as those in patients affected by non-inflammatory neurological (control group I) and without neurological disorders (control group II). An increase of PREG and DHEA values was shown in CSF of male and female RR-MS patients compared to those observed in both control groups. The ALLO values were significantly lower in female RR-MS patients than those found in male RR-MS patients and in female without neurological disorder. During the clinical relapse, we observed female RR-MS patients showing significantly increased PREG values compared to female RR-MS patients in stable phase, while their ALLO values showed a significant decrease compared to male RR-MS patients of the same group. Male RR-MS patients with gadolinium-enhanced lesions showed PREG and DHEA values higher than those found in female RR-MS patients with gadolinium-enhanced lesions. Similary, male RR-MS patients with gadolinium-enhanced lesions showed PREG and DHEA values higher than male without gadolinium-enhanced lesions. Female RR-MS patients with gadolinium-enhanced lesions showed DHEA values higher than those found in female RR-MS patients with gadolinium-enhanced lesions. Male and female RR-MS patients with gadolinium-enhanced lesions showed ALLO values higher than those found in respective gender groups without gadolinium-enhanced lesions. ALLO values were lower in male than in female RR-MS patients without gadolinium-enhanced lesions. Considering the pharmacological properties of neuroactive steroids and the observation that neurological disorders influence their concentrations, these endogenous compounds may have an important role as prognostic factors of the disease and used as markers of MS activity such as relapses.

Neuroprotective Effect of Progesterone in MPTP-Treated Male Mice

BACKGROUND

Numerous studies have reported on the neuroprotective activity of estradiol, whereas the effect of the other ovarian steroid, progesterone, is much less documented.

METHODS

This study sought to investigate neuroprotection with a low dose of progesterone (1 µg) in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated male mice to model Parkinson's disease and compare it to the effect of this steroid in intact mice (experiment 1). We also investigated if high doses of progesterone could protect dopaminergic neurons already exposed to MPTP (experiment 2). We measured progesterone effects on various dopaminergic markers [dopamine and its metabolites, dopamine transporter (DAT) and vesicular monoamine transporter 2 (VMAT2)] and on neuroactive steroids in both plasma and the brain.

RESULTS

For experiment 1, our results showed that progesterone completely prevented the effect of MPTP toxicity on dopamine concentrations, on the increase in the 3-methoxytyramine/dopamine ratio, as well as on VMAT2-specific binding in the striatum and the substantia nigra. Progesterone decreased MPTP effects on 3,4-dihydroxyphenylacetic acid concentrations and DAT-specific binding in the lateral part of the anterior striatum and in the middle striatum (medial and lateral parts). Progesterone treatment of intact mice had no effect on the markers investigated. For experiment 2, measures of dopaminergic markers in the striatum showed that 8 mg/kg of progesterone was the most effective dose to reduce MPTP effects, and more limited effects were observed with 16 mg/kg. We found that progesterone treatment increases the levels of brain progesterone itself as well as of its metabolites.

CONCLUSION

Our result showed that progesterone has neuroprotective effects on dopaminergic neurons in MPTP-treated male mice.

Is Estrogen a Therapeutic Target for Glaucoma?

This article's objective is to provide an overview of the association between estrogen and glaucoma. A literature synthesis was conducted of articles published in peer-reviewed journals screened through May 5, 2015, using the PubMed database. Keywords used were "estrogen and glaucoma," "reproductive factors and glaucoma," and "estrogen, nitric oxide and eye." Forty-three journal articles were included. Results indicated that markers for lifetime estrogen exposure have been measured by several studies and show that the age of menarche onset, oral contraceptive (OC) use, bilateral oophorectomy, age of menopause onset and duration between menarche to menopause are associated with primary open-angle glaucoma (POAG) risk. The Blue Mountain Eye Study found a significantly increased POAG risk with later (>13 years) compared with earlier (≤12 years) age of menarche. Nurses' Health Study (NHS) investigators found that OC use of greater than 5 years was associated with a 25% increased risk of POAG. The Mayo Clinic Cohort Study of Oophorectomy and Aging found that women who underwent bilateral oophorectomy before age 43 years had an increased risk of glaucoma. The Rotterdam Study found that women who went through menopause before reaching the age of 45 years had a higher risk of open-angle glaucoma (2.6-fold increased risk), while the NHS showed a reduced risk of POAG among women older than 65 who entered menopause after age ≥ 54 years. Increased estrogen states may confer a reduced risk of glaucoma or glaucoma-related traits such as reduced intraocular pressure (IOP). Pregnancy, a hyperestrogenemic state, is associated with decreased IOP during the third trimester. Though the role of postmenopausal hormone (PMH) use in the reduction of IOP is not fully conclusive, PMH use may reduce the risk of POAG. From a genetic epidemiologic perspective, estrogen metabolic pathway single nucleotide polymorphisms (SNPs) were associated with POAG in women and polymorphisms in endothelial nitric oxide synthase, a gene receptive to estrogen regulation, are associated with glaucoma. The study concluded that increasing evidence suggests that lifetime exposure to estrogen may alter the pathogenesis of glaucoma. Estrogen exposure may have a neuroprotective effect on the progression of POAG but further studies need to confirm this finding. The role of sex-specific preventive and therapeutic treatment may be on the horizon.

Microarray Expression Analysis for the Paradoxical Roles of Acanthopanax senticosus Harms in Treating α-Synucleinopathies

α-Synuclein is a key player in the pathogenesis of neurodegenerative disorders with Lewy bodies. Our previous studies have also showed that Acanthopanax senticosus harms (AS) could significantly suppress α-synuclein overexpression and toxicity. Identifying the RNAs related to α-synucleinopathies may facilitate understanding the pathogenesis of the diseases and the safe application of AS in the clinic. Microarray expression profiling of long non-coding RNAs (lncRNAs) and mRNAs was undertaken in control non-transgenic and human α-synuclein transgenic mice. The effects of AS on central nervous system (CNS) in pathology and physiology were investigated based on the lncRNA/mRNA targets analysis. In total, 341 lncRNAs and 279 mRNAs were differentially expressed by α-synuclein stimulus, among which 29 lncRNAs and 25 mRNAs were involved in the anti-α-synucleinopathies mechanism of AS. However, the levels of 19/29 lncRNAs and 12/25 mRNAs in AS group were similar to those in α-synuclein group, which may cause potential neurotoxicity analogous to α-synuclein. This study demonstrated that some of lncRNAs/mRNAs were involved in α-synuclein related pathophysiology, and AS produced the bidirectional effects on CNS under pathological and physiological conditions.

Rescue from Sexually Dimorphic Neuronal Cell Death by Estradiol and PI3 Kinase Activity

Responses of primary hippocampal and cortical neurons derived from male and female rats to cellular stressors were studied. It is demonstrated that 17β-estradiol (E2), a potent neuroprotectant, protected the female neurons but had no effects on the male neurons from CoCl2- and glutamate-induced toxicity. Agonists of the estrogen receptor (ER) subtypes ERα and ERβ, DPN and PPT, respectively, had similar effects to E2. By contrast, effects of E2 were abolished by the ER antagonist ICI-182780, further corroborating the neuroprotective role of ERs. In male neurons, CoCl2 predominately activated the apoptosis-inducing factor (AIF)-dependent pathway and AIF translocation from the cytosol to the nucleus. In comparison, CoCl2 activated the caspase pathway and cytochrome c release in female neurons. The inhibitors of these pathways, namely DiQ for AIF and zVAD for caspase, specifically rescued CoCl2-induced cell death in male and female neurons, respectively. When zVAD and ICI-182780, and E2 were applied in combination, it was demonstrated E2 acted on the caspase pathway leading to female-specific neuroprotection. Furthermore, the PI3 kinase (PI3K) inhibitor blocked the rescue effects of DiQ and zVAD on the male and female neurons, respectively, suggesting that PI3K is a common upstream regulator for both pathways. The present study suggested that both sex-specific and nonspecific mechanisms played a role in neuronal responses to stressors and protective reagents.

Gender Differences in Age-Related Striatal Dopamine Depletion in Parkinson's Disease

Objective

Gender differences are a well-known clinical characteristic of Parkinson’s disease (PD). In-vivo imaging studies demonstrated that women have greater striatal dopamine transporter (DAT) activity than do men, both in the normal population and in PD patients. We hypothesize that women exhibit more rapid aging-related striatal DAT reduction than do men, as the potential neuroprotective effect of estrogen wanes with age.

Methods

This study included 307 de novo PD patients (152 men and 155 women) who underwent DAT scans for an initial diagnostic work-up. Gender differences in age-related DAT decline were assessed in striatal sub-regions using linear regression analysis.

Results

Female patients exhibited greater DAT activity compared with male patients in all striatal sub-regions. The linear regression analysis revealed that age-related DAT decline was greater in the anterior and posterior caudate, and the anterior putamen in women compared with men; we did not observe this difference in other sub-regions.

Conclusions

This study demonstrated the presence of gender differences in age-related DAT decline in striatal sub-regions, particularly in the antero-dorsal striatum, in patients with PD, presumably due to aging-related decrease in estrogen. Because this difference was not observed in the sensorimotor striatum, this finding also suggests that women may not have a greater capacity to tolerate PD pathogenesis than do men.

The 5α-reductase inhibitor Dutasteride but not Finasteride protects dopamine neurons in the MPTP mouse model of Parkinson's disease

Finasteride and Dutasteride are 5α-reductase inhibitors used in the clinic to treat endocrine conditions and were recently found to modulate brain dopamine (DA) neurotransmission and motor behavior. We investigated if Finasteride and Dutasteride have a neuroprotective effect in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) male mice as a model of Parkinson's disease (PD). Experimental groups included saline treated controls and mice treated with saline, Finasteride (5 and 12.5 mg/kg) or Dutasteride (5 and 12.5 mg/kg) for 5 days before and 5 days after MPTP administration (4 MPTP injections, 6.5 mg/kg on day 5 inducing a moderate DA depletion) and then they were euthanized. MPTP administration decreased striatal DA contents measured by HPLC while serotonin contents remained unchanged. MPTP mice treated with Dutasteride 5 and 12.5 mg/kg had higher striatal DA and metabolites (DOPAC and HVA) contents with a decrease of metabolites/DA ratios compared to saline-treated MPTP mice. Finasteride had no protective effect on striatal DA contents. Tyrosine hydroxylase (TH) mRNA levels measured by in situ hybridization in the substantia nigra pars compacta were unchanged. Dutasteride at 12.5 mg/kg reduced the effect of MPTP on specific binding to striatal DA transporter (DAT) and vesicular monoamine transporter 2 (VMAT2) measured by autoradiography. MPTP reduced compared to controls plasma testosterone (T) and dihydrotestosterone (DHT) concentrations measured by liquid chromatography-tandem mass spectrometry; Dutasteride and Finasteride increased plasma T levels while DHT levels remained low. In summary, our results showed that a 5α-reductase inhibitor, Dutasteride has neuroprotective activity preventing in male mice the MPTP-induced loss of several dopaminergic markers.

Female gender doubles executive dysfunction risk in ALS: a case-control study in 165 patients

BACKGROUND

Cognitive impairment, mainly characterised by executive dysfunction, occurs in about half of cases in amyotrophic lateral sclerosis (ALS). There is evidence that gender influences some clinical features of the disease, but its influence on the cognitive spectrum is unknown. Our objective was to investigate the impact of gender on cognitive profiles of patients with ALS.

METHODS

A retrospective study based on an exhaustive neuropsychological battery was performed in a group of 165 (70 females, 95 males) sporadic, non-demented patients with ALS compared with 134 healthy control participants. This assessment primarily focused on executive, memory and language functions.

RESULTS

47 (29%) patients revealed impairment in executive function and 30 (18%) patients revealed cognitive non-executive impairment. Independent from mood tone and clinical variables, a significantly greater executive impairment was determined in female patients than in male patients and control participants. The relative risk for ALS females having impairment in executive function compared with male patients was 2.6 (95% CI 1.6 to 4.4; p=0.0003). ALS females scored lower in Phonemic Fluency, Trial Making, and Wisconsin Card Sorting test.

CONCLUSIONS

Results highlight a significant vulnerability of ALS female patients to develop cognitive dysfunctions peculiar to the disease, independently of bulbar onset. The explicative hypotheses of the data are focused on two interpretative lines not mutually exclusive: the role of gonadal hormones and gender-related brain asymmetry pre-existing to the disease. These findings, never reported before in the literature, can have important implications for models of ALS pathogenesis and for future clinical trial designs.

Sex and laterality differences in parkinsonian impairment and transcranial ultrasound in never-treated schizophrenics and their first degree relatives in an Andean population

We tested the hypothesis that loss of substantia nigra neurons in subjects at risk of schizophrenia (1), as reflected by midbrain hyperechogenicity (2) and parkinsonian motor impairment (3), is asymmetric and influenced by sex. We evaluated 62 subjects with never-treated chronic schizophrenia, 80 of their adult, unaffected first degree relatives and 62 healthy controls (matched by sex and age to the cases), part of an Andean population of Northern Argentina. Parkinsonism was scored blindly using UPDRS-3 (Unified Parkinson's Disease Rating Scale) on videotaped exams by 2 independent raters. Transcranial ultrasound was performed by an expert sonographist blind to subject condition with a 2.5 MHz transducer through a temporal bone window. Quantification of echogenic area was carried out on saved images by a different evaluator. We found a significant difference in parkinsonian motor impairment between patients, their relatives as well as controls. All three groups showed worse parkinsonism on the left side than the right, corresponding with increased echogenicity on the right substantia nigra compared with the left. Females had significantly more right echogenicity than males, and patients and unaffected relatives were significantly more echogenic than controls on that side. On the left, only female patients had significant echogenicity. Our data supports the notion that unaffected relatives of schizophrenic subjects have increased parkinsonism and concomitant brainstem abnormalities which may represent a vulnerability to the disease. Both motor and brainstem abnormalities are asymmetric and influenced by sex.

Delay in post-ovariectomy estrogen replacement negates estrogen-induced augmentation of post-exercise muscle satellite cell proliferation

This study examined the effects of a delay in post-ovariectomy replacement of 17β-estradiol (estrogen) on the post-exercise proliferation of muscle satellite cells. Nine-week-old, ovariectomized, female Sprague-Dawley rats (n = 64) were distributed among 8 groups based on estrogen status (0.25 mg estrogen pellet or sham), exercise status (90 min run at 17 m·min(-1) and a grade of -13.5° or unexercised), and estrogen replacement ("proximal", estrogen replacement within 2 weeks; or "delayed", estrogen replacement at 11 weeks following ovariectomy). Significant increases in satellite cells were found in the soleus and white gastrocnemius muscle (immunofluorescent colocalization of nuclei with Pax7) 72 h following eccentric exercise (p < 0.05) in all exercised groups. Proximal E2 replacement resulted in a further augmentation of muscle satellite cells in exercised rats (p < 0.05) relative to the delayed estrogen replacement group. Expression of PI3K was unaltered and phosphorylation of Akt relative to total Akt increased following estrogen supplementation and exercise. Exercise alone did not alter the expression levels of Akt. An 11 week delay in post-ovariectomy estrogen replacement negated the augmenting influence seen with proximal (2 week delay) post-ovariectomy estrogen replacement on post-exercise muscle satellite cell proliferation. This effect appears to be independent of the PI3K-Akt signaling pathway.

Progesterone Exerts a Neuromodulatory Effect on Turning Behavior of Hemiparkinsonian Male Rats: Expression of 3 α -Hydroxysteroid Oxidoreductase and Allopregnanolone as Suggestive of GABAA Receptors Involvement

There is a growing amount of evidence for a neuroprotective role of progesterone and its neuroactive metabolite, allopregnanolone, in animal models of neurodegenerative diseases. By using a model of hemiparkinsonism in male rats, injection of the neurotoxic 6-OHDA in left striatum, we studied progesterone's effects on rotational behavior induced by amphetamine or apomorphine. Also, in order to find potential explanatory mechanisms, we studied expression and activity of nigrostriatal 3α-hydroxysteroid oxidoreductase, the enzyme that catalyzes progesterone to its active metabolite allopregnanolone. Coherently, we tested allopregnanolone for a possible neuromodulatory effect on rotational behavior. Also, since allopregnanolone is known as a GABAA modulator, we finally examined the action of GABAA antagonist bicuculline. We found that progesterone, in addition to an apparent neuroprotective effect, also increased ipsilateral expression and activity of 3α-hydroxysteroid oxidoreductase. It was interesting to note that ipsilateral administration of allopregnanolone reversed a clear sign of motor neurodegeneration, that is, contralateral rotational behavior. A possible GABAA involvement modulated by allopregnanolone was shown by the blocking effect of bicuculline. Our results suggest that early administration of progesterone possibly activates genomic mechanisms that promote neuroprotection subchronically. This, in turn, could be partially mediated by fast, nongenomic, actions of allopregnanolone acting as an acute modulator of GABAergic transmission.

Researching glutamate - induced cytotoxicity in different cell lines: a comparative/collective analysis/study

Although glutamate is one of the most important excitatory neurotransmitters of the central nervous system, its excessive extracellular concentration leads to uncontrolled continuous depolarization of neurons, a toxic process called, excitotoxicity. In excitotoxicity glutamate triggers the rise of intracellular Ca²⁺ levels, followed by up regulation of nNOS, dysfunction of mitochondria, ROS production, ER stress, and release of lysosomal enzymes. Excessive calcium concentration is the key mediator of glutamate toxicity through over activation of ionotropic and metabotropic receptors. In addition, glutamate accumulation can also inhibit cystine (CySS) uptake by reversing the action of the CySS/glutamate antiporter. Reversal of the antiporter action reinforces the aforementioned events by depleting neurons of cysteine and eventually glutathione’s reducing potential. Various cell lines have been employed in the pursuit to understand the mechanism(s) by which excitotoxicity affects the cells leading them ultimately to their demise. In some cell lines glutamate toxicity is exerted mainly through over activation of NMDA, AMPA, or kainate receptors whereas in other cell lines lacking such receptors, the toxicity is due to glutamate induced oxidative stress. However, in the greatest majority of the cell lines ionotropic glutamate receptors are present, co-existing to CySS/glutamate antiporters and metabotropic glutamate receptors, supporting the assumption that excitotoxicity effect in these cells is accumulative. Different cell lines differ in their responses when exposed to glutamate. In this review article the responses of PC12, SH-SY5Y, HT-22, NT-2, OLCs, C6, primary rat cortical neurons, RGC-5, and SCN2.2 cell systems are systematically collected and analyzed.

The link between Parkinson's disease and breast and prostate cancers: A meta-analysis

PURPOSE

Clinical observations have shown an increased morbidity for breast cancer or prostate cancer in patients with Parkinson's disease (PD), however, other reports have noted contradictory results. This pooled analysis was utilized to test whether PD is associated with the risk of breast or prostate cancer.

METHODS

We searched PubMed, Embase and Cochrane library and conducted a meta-analysis to clarify the correlation of PD with breast and/or prostate cancer risk. We identified 16 eligible articles from which odds ratios with 95% confident intervals were assessed as main measures in the pooled estimation. Subgroup analyses and cumulative meta-analysis were also performed.

RESULTS

Our results showed no PD risk associated with breast or prostate cancer in the overall population, which was supported by the results of cumulative meta-analyses. The subgroup analyses suggested no significant risk of breast or prostate cancer in patients with PD within relevant subsets, i.e. gender, ethnicity, PD diagnosis time or study design. No evidence of publication bias was observed across the involved studies.

CONCLUSIONS

This meta-analysis indicates a lack of association between PD and risk of breast or prostate cancer.

Neuronal differentiation dictates estrogen-dependent survival and ERK1/2 kinetic by means of caveolin-1

Estrogens promote a plethora of effects in the CNS that profoundly affect both its development and mature functions and are able to influence proliferation, differentiation, survival and neurotransmission. The biological effects of estrogens are cell-context specific and also depend on differentiation and/or proliferation status in a given cell type. Furthermore, estrogens activate ERK1/2 in a variety of cellular types. Here, we investigated whether ERK1/2 activation might be influenced by estrogens stimulation according to the differentiation status and the molecular mechanisms underling this phenomenon. ERK1/2 exert an opposing role on survival and death, as well as on proliferation and differentiation depending on different kinetics of phosphorylation. Hence we report that mesencephalic primary cultures and the immortalized cell line mes-c-myc A1 express estrogen receptor α and activate ERK1/2 upon E₂ stimulation. Interestingly, following the arrest of proliferation and the onset of differentiation, we observe a change in the kinetic of ERKs phosphorylation induced by estrogens stimulation. Moreover, caveolin-1, a main constituent of caveolae, endogenously expressed and co-localized with ER-α on plasma membrane, is consistently up-regulated following differentiation and cell growth arrest. In addition, we demonstrate that siRNA-induced caveolin-1 down-regulation or disruption by means of ß-cyclodextrin treatment changes ERK1/2 phosphorylation in response to estrogens stimulation. Finally, caveolin-1 down-regulation abolishes estrogens-dependent survival of neurons. Thus, caveolin-1 appears to be an important player in mediating, at least, some of the non-genomic action of estrogens in neurons, in particular ERK1/2 kinetics of activation and survival.

Effects of genistein on neuronal apoptosis, and expression of Bcl-2 and Bax proteins in the hippocampus of ovariectomized rats

Genistein is one of several isoflavones that has a structure similar to 17β-estradiol, has a strong antioxidant effect, and a high affinity to estrogen receptors. At 15 weeks after ovariectomy, the expression of Bcl-2 in the hippocampus of rats decreased and Bax expression increased, with an obvious upregulation of apoptosis. However, intraperitoneal injection of genistein or 17β-estradiol for 15 consecutive weeks from the second day after operation upregulated Bcl-2 protein expression, downregulated Bax protein expression, and attenuated hippocampal neuron apoptosis. Our experimental findings indicate that long-term intervention with genistein can lead to a decrease in apoptosis in hippocampal neurons following ovariectomy, upregulate the expression of Bcl-2, and downregulate the expression of Bax. In addition, genistein and 17β-estradiol play equal anti-apoptotic and neuroprotective roles.

Swallowing disturbances in Parkinson's disease: a multivariate analysis of contributing factors

BACKGROUND

Swallowing disturbances are an important issue in Parkinson's disease (PD) as several studies have shown that they are associated with increased risk of aspiration pneumonia and mortality. Information about factors related to swallowing disturbances, such as disease duration, age at assessment and concomitant dementia, is limited and would be useful for their management.

METHODS

All consecutive PD out-patients evaluated at a movement disorders clinic over a 7-year period (2007-2014), were included in the present retrospective study. Presence of symptomatic swallowing disturbances was assessed using the specific item of the Non Motor Symptom Questionnaire.

RESULTS

In the whole PD population (N = 6462), prevalence of symptomatic swallowing disturbances was 11.7% (95%CI, 10.9-12.5). Multivariable logistic regression analysis (adjusted for education) disclosed a significant interaction between disease duration and gender (P = 0.009). In both gender strata, swallowing disturbances were significantly associated with longer disease duration and dementia (P < 0.001 for all). A significant effect for age at assessment was also found in male patients. In non-demented patients, swallowing disturbances were associated with male gender, age and disease duration (P < 0.02 for all). In demented patients an association was found only with male gender (P = 0.018) and disease duration (P < 0.001).

CONCLUSIONS

Gender, age, disease duration and dementia all seem to contribute to the occurrence of swallowing disturbances independently. However, the role played by these factors in sub-groups of patients stratified by gender and concomitant dementia suggests that swallowing disturbances are likely related to different neuro-degenerative patterns within the brain. The underlying mechanisms deserve further investigation.

Neuroprotective-neurotrophic effect of endogenous dehydroepiandrosterone sulfate during intense stress exposure

Recent reports demonstrate neurotrophic properties of dehydroepiandrosterone sulfate (DHEAS) in men at rest, as well as profound neurotrophic responses to stress in both men and women. Little is known of neuroprotective-neurotrophic effects of DHEAS during stress exposure, either in men or women. This translational study was designed to examine neuroprotective-neurotrophic effects of DHEAS throughout intense stress exposure in healthy men and women. The study took place within a stressful 12-day military survival course. Utilizing a longitudinal cross-sectional repeated measures design, One hundred sixteen healthy active-duty military personnel (80% male) were studied before, during, and 24h after the course. The dependent variable was the neurotrophin salivary nerve growth factor (sNGF). In terms of total hormone output, the effect of DHEAS on sNGF was mediated by testosterone. Unlike testosterone or cortisol, DHEAS reliably predicted sNGF at each time point, and change in DHEAS predicted change in sNGF across time points. Baseline DHEAS predicted total sNGF output across the stress trajectory. Consistent with preclinical as well as cross-sectional human research, this study demonstrates neuroprotective-neurotrophic effects of DHEAS in healthy men and women exposed to intense stress. Results are evaluated in relation to established criteria for causation.

Brain size, sex, and the aging brain

This study was conducted to examine the statistical influence of brain size on cortical, subcortical, and cerebellar compartmental volumes. This brain size influence was especially studied to delineate interactions with Sex and Age. Here, we studied 856 healthy subjects of which 533 are classified as young and 323 as old. Using an automated segmentation procedure cortical (gray and white matter [GM and WM] including the corpus callosum), cerebellar (GM and WM), and subcortical (thalamus, putamen, pallidum, caudatus, hippocampus, amygdala, and accumbens) volumes were measured and subjected to statistical analyses. These analyses revealed that brain size and age exert substantial statistical influences on nearly all compartmental volumes. Analyzing the raw compartmental volumes replicated the frequently reported Sex differences in compartmental volumes with men showing larger volumes. However, when statistically controlling for brain size Sex differences and Sex × Age interactions practically disappear. Thus, brain size is more important than Sex in explaining interindividual differences in compartmental volumes. The influence of brain size is discussed in the context of an allometric scaling of the compartmental volumes.

Lifetime exposure to estrogens and Parkinson's disease in California teachers

INTRODUCTION

Parkinson's disease (PD) is consistently observed to occur less frequently in women than men, prompting investigation into whether estrogen protects against neurodegeneration of dopaminergic neurons.

METHODS

We used baseline data in the California Teachers Study, a prospective cohort of women, to investigate whether reproductive factors indicating higher long-term estrogen levels are associated with PD using a nested case-control approach. We identified 228 PD cases and 3349 unaffected controls frequency matched by age and race.

RESULTS

Women who reported using combined estrogen/progesterone therapy or progesterone only formulations had a 57% increase in PD risk (OR = 1.57, 95% CI = 1.06, 2.34) compared to never having used HT. Compared to women with menopause at 50-52 years, menopause at younger (<35-46 years: OR = 0.59, 95% CI = 0.37, 0.94) and older ages (≥53 years: OR = 0.54, 95% CI = 0.36, 0.83) had lower PD risk. A derived composite estrogen summary score for women's exposure to both endogenous and exogenous estrogens throughout life indicated that women with presumed higher cumulative lifetime levels of estrogen (a score of 3-5) had a significantly reduced PD risk [(OR = 0.57, 95% CI = 0.35, 0.91) relative to those with lower lifetime estrogen exposure or a composite estrogen summary score of 0-1].

CONCLUSIONS

These results provide some support for the hypothesis that lifelong high estrogen is protective in PD, suggesting that the level and persistence of exposure over the long term may be important in PD risk reduction.