Dysregulation of the Hypothalamic-Pituitary-Gonadal Axis with Menopause and Andropause Promotes Neurodegenerative Senescence

Prevalence and clinicopathological features of primary age-related tauopathy (PART): A large forensic autopsy study

INTRODUCTION

Primary age-related tauopathy (PART), often regarded as a minimally symptomatic pathology of old age, lacks comprehensive cohorts across various age groups.

METHODS

We examined PART prevalence and clinicopathologic features in 1589 forensic autopsy cases (≥40 years old, mean age ± SD 70.2 ± 14.2 years).

RESULTS

PART cases meeting criteria for argyrophilic grain diseases (AGD) were AGD+PART (n = 181). The remaining PART cases (n = 719, 45.2%) were classified as comorbid conditions (PART-C, n = 90) or no comorbid conditions (pure PART, n = 629). Compared to controls (n = 208), Alzheimer's disease (n = 133), and AGD+PART, PART prevalence peaked in the individuals in their 60s (65.5%) and declined in the 80s (21.5%). No significant clinical background differences were found (excluding controls). However, PART-C in patients inclusive of age 80 had a higher suicide rate than pure PART (p < 0.05), and AGD+PART showed more dementia (p < 0.01) and suicide (p < 0.05) than pure PART.

DISCUSSION

Our results advocate a reevaluation of the PART concept and its diagnostic criteria.

HIGHLIGHTS

We investigated 1589 forensic autopsy cases to investigate the features of primary age-related tauopathy (PART). PART peaked in people in their 60s in our study. Many PART cases over 80s had comorbid pathologies in addition to neurofibrillary tangles pathology. Argyrophilic grain disease and Lewy pathology significantly affected dementia and suicide rates in PART. Our results suggest that the diagnostic criteria of PART need to be reconsidered.

Metabolic hormones are integral regulators of female reproductive health and function

The female reproductive system is strongly influenced by nutrition and energy balance. It is well known that food restriction or energy depletion can induce suppression of reproductive processes, while overnutrition is associated with reproductive dysfunction. However, the intricate mechanisms through which nutritional inputs and metabolic health are integrated into the coordination of reproduction are still being defined. In this review, we describe evidence for essential contributions by hormones that are responsive to food intake or fuel stores. Key metabolic hormones-including insulin, the incretins (glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1), growth hormone, ghrelin, leptin, and adiponectin-signal throughout the hypothalamic-pituitary-gonadal axis to support or suppress reproduction. We synthesize current knowledge on how these multifaceted hormones interact with the brain, pituitary, and ovaries to regulate functioning of the female reproductive system, incorporating in vitro and in vivo data from animal models and humans. Metabolic hormones are involved in orchestrating reproductive processes in healthy states, but some also play a significant role in the pathophysiology or treatment strategies of female reproductive disorders. Further understanding of the complex interrelationships between metabolic health and female reproductive function has important implications for improving women's health overall.

Endocrine Dyscrasia in the Etiology and Therapy of Alzheimer's Disease

The increase in the incidence of dementia over the last century correlates strongly with the increases in post-reproductive lifespan during this time. As post-reproductive lifespan continues to increase it is likely that the incidence of dementia will also increase unless therapies are developed to prevent, slow or cure dementia. A growing body of evidence implicates age-related endocrine dyscrasia and the length of time that the brain is subjected to this endocrine dyscrasia, as a key causal event leading to the cognitive decline associated with aging and Alzheimer's disease (AD), the major form of dementia in our society. In particular, the elevations in circulating gonadotropins, resulting from the loss of gonadal sex hormone production with menopause and andropause, appear central to the development of AD neuropathology and cognitive decline. This is supported by numerous cell biology, preclinical animal, and epidemiological studies, as well as human clinical studies where suppression of circulating luteinizing hormone and/or follicle-stimulating hormone with either gonadotropin-releasing hormone analogues, or via physiological hormone replacement therapy, has been demonstrated to halt or significantly slow cognitive decline in those with AD. This review provides an overview of past and present studies demonstrating the importance of hypothalamic-pituitary-gonadal hormone balance for normal cognitive functioning, and how targeting age-related endocrine dyscrasia with hormone rebalancing strategies provides an alternative treatment route for those with AD.

Effect of exercise on the hypothalamic-pituitary-gonadal axis in a rat model of Alzheimer's disease

Hypothalamic-pituitary-gonadal (HPG) axis dysregulation was suggested to play a crucial role in Alzheimer's disease (AD). This study investigated the effects of exercise on HPG hormones in an AD rat model, as a possible mechanism underlying the favorable effect of exercise on AD. Forty male Wistar albino rats 2-3 months old were subdivided randomly into two groups (n = 20 each): AD group (injected intraperitoneally with aluminum chloride (70 mg/kg/day) for 6 weeks) and Control group. Each group was subdivided into exercised or non-exercised group (n = 10 each). Exercised groups were subjected to a swimming protocol (60 min/day, 5 days/week, 4 weeks). Serum HPG hormones, hippocampal β-amyloid levels and Morris water-maze cognition were assessed. Results demonstrated higher levels of β-amyloid, gonadotropin releasing hormone (GnRH), luteinizing hormone (LH) and follicle stimulating hormone (FSH) together with lower testosterone levels and cognitive impairment in the AD rats compared to controls. Β-amyloid levels negatively correlated with testosterone levels and positively correlated with GnRH, LH and FSH among the AD rats. Higher testosterone and lower GnRH, LH, FSH and β-amyloid levels, as well as cognitive improvement, were observed in the exercised compared to non-exercised AD rats, suggesting a modulatory role of exercise training on AD-associated HPG axis dysregulation.

Neuroendocrine regulation in stroke

The neuroendocrine system, a crosstalk between the central nervous system and endocrine glands, balances and controls hormone secretion and their functions. Neuroendocrine pathways and mechanisms often get dysregulated following stroke, leading to altered hormone secretion and aberrant receptor expression. Dysregulation of the hypothalamus-pituitary-thyroid (HPT) axis and hypothalamus-pituitary-adrenal (HPA) axis often led to severe stroke outcomes. Post-stroke complications such as cognitive impairment, depression, infection etc. are directly or indirectly influenced by the altered neuroendocrine activity that plays a crucial role in stroke vulnerability and susceptibility. Therefore, it is imperative to explore various neurohormonal inter-relationships in regulating stroke, its outcome, and prognosis. Here, we review the biology of different hormones associated with stroke and explore their regulation with a view towards prospective therapeutics.

The association between Parkinson's disease and Sexual dysfunction: Clinical correlation and therapeutic implications

Sexual function which comprises of desire, arousal, orgasm and satisfaction and pain, involves coordinated physiologic responses from multiple different pathways. Sexual dysfunction (SD) occurs when these domains of the sexual response cycle are affected. SD is a common but under-recognized non-motor feature in Parkinson's disease (PD), a common age-related neurodegenerative disorder. SD significantly affects the quality of life of PD patients and their partners. Advanced age, gender, hormone deficiency, neuropsychiatric and medical comorbidities contribute to SD in PD. Possible potential pathological mechanisms include vasculogenic, endocrinologic, neurogenic and psychogenic factors. Various therapeutic interventions, both pharmacological and non-pharmacological modalities have been suggested to improve SD in PD. However, erectile dysfunction (ED) is the only SD with evidence-based treatment available. Non-pharmacological therapies are also offering promising evidence in the improvement of SD. A multidisciplinary approach in the assessment, investigation, and treatment is needed to address the real life complex issues (gender and comorbidities, neurobiological, vasoactive, hormonal as well as psychosocial aspects). Future clinical studies with validated and standardized methods in assessing SD as well as experimental models will be necessary for better insight into the pathophysiology. This would facilitate appropriate therapy and improve sexual rehabilitation in PD patients.

Estropause, Sex Hormones and Metal Homeostasis in the Mouse Brain

Alterations in brain metal ion homeostasis have been reported with aging and are implicated in the pathogenesis of neurodegenerative diseases. To assess whether age-related changes in hypothalamic-pituitary-gonadal (HPG) hormones might be involved in modulating brain metal ion homeostasis, we treated 7.5-month intact, sham-ovariecomized and ovariectomized C57B6SJL mice with vehicle or leuprolide acetate (for 9-months) to differentiate between whether sex steroids or gonadotropins might modulate brain metal ion concentrations. Unlike other aging mammals, there was no increase in plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) concentrations following estropause in mice, suggesting there was sufficient residual production by the follicle depleted ovary, of sex steroids like estrogens and protein hormones like the inhibins, in order to suppress pituitary LH/FSH production. Castration on the other hand induced significant increases in circulating LH and FSH. Modulation of plasma sex steroid and gonadotropin levels did not significantly alter the concentrations of brain metals tested (Fe, Zn, Cu, Mn, Co, Ni, Al, Li), although there was a tendency for a decrease in all brain metals following ovariectomy (low estrogens and progesterone, high gonadotropins), a response that was reversed with leuprolide acetate treatment (low sex steroids, low gonadotropins). Brain Cu concentration was the only metal correlated with plasma LH (−0.37, n = 30, p < 0.05) and FSH (−0.42, n = 29, p < 0.01). This study demonstrates that sex hormones do not markedly alter brain metal ion homeostasis, unlike previously reported studies of circulating metal ion homeostasis. The role of gonadotropins in regulating metal ion homeostasis does however warrant further study.

The hypothalamic-pituitary-gonadal axis controls muscle stem cell senescence through autophagosome clearance

BACKGROUND

With organismal aging, the hypothalamic-pituitary-gonadal (HPG) activity gradually decreases, resulting in the systemic functional declines of the target tissues including skeletal muscles. Although the HPG axis plays an important role in health span, how the HPG axis systemically prevents functional aging is largely unknown.

METHODS

We generated muscle stem cell (MuSC)-specific androgen receptor (Ar) and oestrogen receptor 2 (Esr2) double knockout (dKO) mice and pharmacologically inhibited (Antide) the HPG axis to mimic decreased serum levels of sex steroid hormones in aged mice. After short-term and long-term sex hormone signalling ablation, the MuSCs were functionally analysed, and their aging phenotypes were compared with those of geriatric mice (30-month-old). To investigate pathways associated with sex hormone signalling disruption, RNA sequencing and bioinformatic analyses were performed.

RESULTS

Disrupting the HPG axis results in impaired muscle regeneration [wild-type (WT) vs. dKO, P < 0.0001; Veh vs. Antide, P = 0.004]. The expression of DNA damage marker (in WT = 7.0 ± 1.6%, dKO = 32.5 ± 2.6%, P < 0.01; in Veh = 13.4 ± 4.5%, Antide = 29.7 ± 5.5%, P = 0.028) and senescence-associated β-galactosidase activity (in WT = 3.8 ± 1.2%, dKO = 10.3 ± 1.6%, P < 0.01; in Veh = 2.1 ± 0.4%, Antide = 9.6 ± 0.8%, P = 0.005), as well as the expression levels of senescence-associated genes, p16^Ink4a and p21^Cip1 , was significantly increased in the MuSCs, indicating that genetic and pharmacological inhibition of the HPG axis recapitulates the progressive aging process of MuSCs. Mechanistically, the ablation of sex hormone signalling reduced the expression of transcription factor EB (Tfeb) and Tfeb target gene in MuSCs, suggesting that sex hormones directly induce the expression of Tfeb, a master regulator of the autophagy-lysosome pathway, and consequently autophagosome clearance. Transduction of the Tfeb in naturally aged MuSCs increased muscle mass [control geriatric MuSC transplanted tibialis anterior (TA) muscle = 34.3 ± 2.9 mg, Tfeb-transducing geriatric MuSC transplanted TA muscle = 44.7 ± 6.7 mg, P = 0.015] and regenerating myofibre size [eMyHC⁺ tdTomato⁺ myofibre cross-section area (CSA) in control vs. Tfeb, P = 0.002] after muscle injury.

CONCLUSIONS

Our data show that the HPG axis systemically controls autophagosome clearance in MuSCs through Tfeb and prevents MuSCs from senescence, suggesting that sustained HPG activity throughout life regulates autophagosome clearance to maintain the quiescence of MuSCs by preventing senescence until advanced age.

Testicular Atrophy and Hypothalamic Pathology in COVID-19: Possibility of the Incidence of Male Infertility and HPG Axis Abnormalities

Coronavirus disease 2019 (COVID-19), which resulted from the pandemic outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causes a massive inflammatory cytokine storm leading to multi-organ damage including that of the brain and testes. While the lungs, heart, and brain are identified as the main targets of SARS-CoV-2-mediated pathogenesis, reports on its testicular infections have been a subject of debate. The brain and testes are physiologically synchronized by the action of gonadotropins and sex steroid hormones. Though the evidence for the presence of the viral particles in the testicular biopsies and semen samples from COVID-19 patients are highly limited, the occurrence of testicular pathology due to abrupt inflammatory responses and hyperthermia has incresingly been evident. The reduced level of testosterone production in COVID-19 is associated with altered secretion of gonadotropins. Moreover, hypothalamic pathology which results from SARS-CoV-2 infection of the brain is also evident in COVID-19 cases. This article revisits and supports the key reports on testicular abnormalities and pathological signatures in the hypothalamus of COVID-19 patients and emphasizes that testicular pathology resulting from inflammation and oxidative stress might lead to infertility in a significant portion of COVID-19 survivors. Further investigations are required to monitor the reproductive health parameters and HPG axis abnormalities related to secondary pathological complications in COVID-19 patients and survivors.

Bioavailable testosterone is associated with symptoms of depression in adult men

Objective

This study aimed to determine the relationship between serum testosterone levels and depressive symptoms in an adult male population.

Methods

We conducted a cross-sectional study of 1166 male participants from Zunyi, Guizhou, China. Each participant completed a questionnaire, a brief clinical exam, and had a fasting blood sample taken. We measured serum testosterone, sex hormone-binding globulin, and luteinizing hormone levels. Multiple linear regression was used to evaluate the effect of demographic factors on the relationship between the depressive symptom score and serum sex hormone levels.

Results

Mean testosterone, sex hormone-binding globulin, and luteinizing hormone levels were significantly higher in the depressive symptom group than in the non-depressed group. The mean calculated free serum testosterone level and free testosterone index (FTI) were significantly lower in the depressive symptom group than in the non-depressed group. Additionally, the mean FTI was significantly negatively correlated with the Beck Depression Inventory scale score in the multiple linear regression model (95% confidence interval: −3.274 to −0.406).

Conclusions

Decreased bioactive testosterone levels might be a contributing factor of depression in adult men. The FTI could be the most sensitive biomarker reflecting the level of bioavailable testosterone in patients with depression.

Development of Classification Models for the Prediction of Alzheimer's Disease Utilizing Circulating Sex Hormone Ratios

BACKGROUND

While sex hormones are essential for normal cognitive health, those individuals with greater endocrine dyscrasia around menopause and with andropause are more likely to develop cognitive loss and Alzheimer's disease (AD).

OBJECTIVE

To assess whether circulating sex hormones may provide an etiologically significant, surrogate biomarker, for cognitive decline.

METHODS

Plasma (n = 152) and serum (n = 107) samples from age- and gender-matched AD and control subjects from the Wisconsin Alzheimer's Disease Research Center (ADRC) were analyzed for 11 steroids and follicle-stimulating hormone. Logistic regression (LR), correlation analyses, and recursive partitioning (RP) were used to examine the interactions of hormones and hormone ratios and their association with AD. Models generated were then tested on an additional 43 ADRC samples.

RESULTS

The wide variation and substantial overlap in the concentrations of all circulating sex steroids across control and AD groups precluded their use for predicting AD. Classification tree analyses (RP) revealed interactions among single hormones and hormone ratios that associated with AD status, the most predictive including only the hormone ratios identified by LR. The strongest associations were observed between cortisol, cortisone, and androstenedione with AD, with contributions from progesterone and 17β-estradiol. Utilizing this model, we correctly predicted 81% of AD test cases and 64% of control test cases.

CONCLUSION

We have developed a diagnostic model for AD, the Wisconsin Hormone Algorithm Test for Cognition (WHAT-Cog), that utilizes classification tree analyses of hormone ratios. Further refinement of this technology could provide a quick and cheap diagnostic method for screening those with AD.

Testosterone, sex steroids, and aging in neurodegenerative disease after acquired brain injury: a commentary

PRIMARY OBJECTIVE

Traumatic brain injury (TBI) is associated with higher incidence of neurodegenerative disease and the effects of aging appear more pronounced after TBI. This paper examines the potential interaction of aging, TBI, and change in male testosterone production.

METHODS AND PROCEDURES

An abbreviated review of literature documenting hypogonadism after TBI is provided. Potential mechanisms of endocrine dysgrasia associated with aging are reviewed as they relate and interact with endocrine change after TBI in males. These factors align to suggest the need for development of surveillance guidelines for male individuals living with TBI.

OUTCOMES AND RESULTS

The neuroprotectant, neuroactivation, growth, and cell therapy characteristics of testosterone in the central nervous system are considerable. Age-related decrements in testosterone production may be accelerated after TBI.

CONCLUSIONS

Testosterone deficiency in male individuals after TBI can be present after TBI or can develop during aging. Age-related decreases in testosterone production after TBI may act to amplify endocrine dysfunction after TBI. Ongoing clinical surveillance for testosterone deficiency associated with both TBI and aging may be reasonable.

A review on how stress modulates fear conditioning: Let's not forget the role of sex and sex hormones

Stress and fear are two fields of research that have evolved simultaneously. It was not until the eighties that these domains converged in order to better characterize the impact of stress on fear memory formation. Here, we reviewed the effects of stress occurring before fear acquisition on the main phases of fear conditioning protocols (acquisition training, extinction training, extinction retention test), with a specific focus on sex and sex hormones. We also paid close attention to methodological aspects in order to better understand and characterize discrepant findings across studies. In men, stress appears to potentiate fear acquisition at a physiological level but induces lower activations of fear-related brain regions. In women, results are inconsistent. Although some studies have shown that stress lowers physiological fear responses and heightens brain activations in women during fear acquisition, many studies report no significant effects. Irrespective of sex, pre-acquisition stress seems to induce fear extinction learning resistance. Overall, few studies have taken into account sex hormones, despite their impact on both the fear and stress brain networks. As methodological variability makes it complex to draw strong conclusions, several methodological aspects are discussed with the aim of orienting future research.

Poor Diet, Stress, and Inactivity Converge to Form a "Perfect Storm" That Drives Alzheimer's Disease Pathogenesis

North American incidence of Alzheimer's disease (AD) is expected to more than double over the coming generation. Although genetic factors surrounding the production and clearance of amyloid-β and phosphorylated tau proteins are known to be responsible for a subset of early-onset AD cases, they do not explain the pathogenesis of the far more prevalent sporadic late-onset variant of the disease. It is thus likely that lifestyle and environmental factors contribute to neurodegenerative processes implicated in the pathogenesis of AD. Herein, we review evidence that (1) excess sucrose consumption induces AD-associated liver pathologies and brain insulin resistance, (2) chronic stress overdrives activity of locus coeruleus neurons, leading to loss of function (a common event in neurodegeneration), (3) high-sugar diets and stress promote the loss of neuroprotective sex hormones in men and women, and (4) Western dietary trends set the stage for a lithium-deficient state. We propose that these factors may intersect as part of a "perfect storm" to contribute to the widespread prevalence of neurodegeneration and AD. In addition, we put forth the argument that exercise and supplementation with trace lithium can counteract many of the deleterious consequences associated with excessive caloric intake and perpetual stress. We conclude that lifestyle and environmental factors likely contribute to AD pathogenesis and that simple lifestyle and dietary changes can help counteract their effects.

Possible Existence of the Hypothalamic-Pituitary-Hippocampal (HPH) Axis: A Reciprocal Relationship Between Hippocampal Specific Neuroestradiol Synthesis and Neuroblastosis in Ageing Brains with Special Reference to Menopause and Neurocognitive Disorders

The hippocampus-derived neuroestradiol plays a major role in neuroplasticity, independent of circulating estradiol that originates from gonads. The response of hypothalamus-pituitary regions towards the synthesis of neuroestradiol in the hippocampus is an emerging scientific concept in cognitive neuroscience. Hippocampal plasticity has been proposed to be regulated via neuroblasts, a major cellular determinant of functional neurogenesis in the adult brain. Defects in differentiation, integration and survival of neuroblasts in the hippocampus appear to be an underlying cause of neurocognitive disorders. Gonadotropin receptors and steroidogenic enzymes have been found to be expressed in neuroblasts in the hippocampus of the brain. However, the reciprocal relationship between hippocampal-specific neuroestradiol synthesis along neuroblastosis and response of pituitary based feedback regulation towards regulation of estradiol level in the hippocampus have not completely been ascertained. Therefore, this conceptual article revisits (1) the cellular basis of neuroestradiol synthesis (2) a potential relationship between neuroestradiol synthesis and neuroblastosis in the hippocampus (3) the possible involvement of aberrant neuroestradiol production with mitochondrial dysfunctions and dyslipidemia in menopause and adult-onset neurodegenerative disorders and (4) provides a hypothesis for the possible existence of the hypothalamic-pituitary-hippocampal (HPH) axis in the adult brain. Eventually, understanding the regulation of hippocampal neurogenesis by abnormal levels of neuroestradiol concentration in association with the feedback regulation of HPH axis might provide additional cues to establish a neuroregenerative therapeutic management for mood swings, depression and cognitive decline in menopause and neurocognitive disorders.

Putative Gonadotropin-Releasing Hormone Agonist Therapy and Dementia: An Application of Medicare Hospitalization Claims Data

BACKGROUND

Estrogen and hormone replacement therapies to reduce Alzheimer's disease (AD) have yielded conflicting results. However, this study proposes that the well-characterized increase in serum gonadotropins following menopause or andropause are accountable for the increased risk of developing AD among the elderly population.

OBJECTIVE

To determine the role of gonadotropins in the development of AD and investigate gonadotropin-releasing hormone (GnRH) agonist therapy as a potential preventative and/or disease-modifying approach to AD management.

METHODS

Male Medicare beneficiaries aged 67 to 75 and hospitalized with prostate cancer (n = 115,789) were compared to three control groups: men of the same demographics undergoing a cholecystectomy (n = 97,267), herniorrhaphy (n = 68,778), or transurethral prostatectomy (n = 267,691). A proportion of the patients hospitalized with prostate cancer were assumed to have low concentrations of serum gonadotropins and sex steroids as a result of GnRH agonist therapy, while those in the control groups were assumed to have elevated gonadotropin but lowered sex steroid levels that are associated with andropause in this age group.

RESULTS

The rates of development of select diagnoses of dementia, including AD, over a twelve-year follow-up period following surgery. When compared to control patients, men hospitalized with prostate cancer have a protection against dementia after twelve years of follow-up, with relative risks ranging from 0.48 to 0.83.

CONCLUSION

Patients with prostate cancer are treated with the GnRH analogue leuprolide acetate, our data suggest that leuprolide acetate may be therapeutic for AD via its downregulation of serum gonadotropins.

Role of Hypothalamic-Pituitary-Adrenal Axis, Hypothalamic-Pituitary-Gonadal Axis and Insulin Signaling in the Pathophysiology of Alzheimer's Disease

Alzheimer's disease (AD), the commonest progressive neurodegenerative disorder of the brain, is clinically characterized by the formation of extracellular amyloid plaques and intracellular neurofibrillary tangles. Recent studies suggest a relationship between the endocrinal dysregulation and the neuronal loss during the AD pathology. Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and hypothalamic-pituitary-gonadal (HPG) axis regulating circulating levels of glucocorticoid hormones has been implicated in the pathophysiology of AD. Likewise, dysregulated insulin signaling, impaired glucose uptake and insulin resistance are some of the prime factors in the onset/progression of AD. In this review, we have discussed the changes in HPA and HPG axes, implicated insulin resistance/signaling and glucose regulation during the onset/progression of AD. Therefore, simultaneous detection of these endocrinal markers in the early or presymptomatic stages may help in the early diagnosis of AD. This evidence for implicated endocrinal functions supports the fact that modulation of endocrinal pathways can be used as therapeutic targets for AD. Future studies need to determine how the induction or inhibition of endocrinal targets could be used for predictable neuroprotection in AD therapies.

In Silico Investigation of the Pharmacological Mechanisms of Beneficial Effects of Ginkgo biloba L. on Alzheimer's Disease

Based on compelling experimental and clinical evidence, Ginkgo biloba L. exerts a beneficial effect in ameliorating mild to moderate dementia in patients with Alzheimer’s disease (AD) and other neurological disorders, although the pharmacological mechanisms remain unknown. In the present study, compounds, their putative target proteins identified using an inverse docking approach, and clinically tested AD-related target proteins were systematically integrated together with applicable bioinformatics methods in silico. The results suggested that the beneficial effects of G. biloba on AD may be contributed by the regulation of hormone sensitivity, improvements in endocrine homeostasis, maintenance of endothelial microvascular integrity, and proteolysis of tau proteins, particularly prior to amyloid β-protein (Aβ) plaque formation. Moreover, we identified six putative protein targets that are significantly related to AD, but have not been researched or have had only preliminary studies conducted on the anti-AD effects of G. biloba. These mechanisms and protein targets are very significant for future scientific research. In addition, the existing mechanisms were also verified, such as the reduction of oxidative stress, anti-apoptotic effects, and protective effects against amyloidogenesis and Aβ aggregation. The discoveries summarized here may provide a macroscopic perspective that will improve our understanding of the molecular mechanism of medicinal plants or dietary supplements, as well as new clues for the future development of therapeutic strategies for AD.

Effect of Reproductive History and Exogenous Hormone Use on Cognitive Function in Mid- and Late Life

OBJECTIVES

To investigate the association between reproductive history indicators of hormonal exposure, including reproductive period, pregnancy, and use of hormonal contraceptives, and mid- and late-life cognition in postmenopausal women.

DESIGN

Analysis of baseline data from two randomized clinical trials: the Women's Isoflavone Soy Health and the Early vs Late Intervention Trial of Estradiol.

SETTING

University academic research center.

PARTICIPANTS

Naturally menopausal women (N = 830).

MEASUREMENTS

Participants were uniformly evaluated using a cognitive battery and a structured reproductive history questionnaire. Outcomes were composite scores for verbal episodic memory, executive function, and global cognition. Reproductive variables included ages at pregnancies, menarche, and menopause; reproductive period; number of pregnancies; and use of hormones for contraception and menopausal symptoms. Multivariable linear regression was used to evaluate associations between cognitive scores (dependent variable) and reproductive factors (independent variables), adjusting for age, race and ethnicity, income, and education.

RESULTS

On multivariable modeling, age at menarche of 13 and older was inversely associated with global cognition (P = .05). Last pregnancy after age 35 was positively associated with verbal memory (P = .03). Use of hormonal contraceptives was positively associated with global cognition (P trend = .04), and verbal memory (P trend = .007). The association between hormonal contraceptive use and verbal memory and executive function was strongest for more than 10 years of use. Reproductive period was positively associated with global cognition (P = .04) and executive function (P = .04).

CONCLUSION

In this sample of healthy postmenopausal women, reproductive life events related to sex hormones, including earlier age at menarche, later age at last pregnancy, longer reproductive period, and use of oral contraceptives are positively related to aspects of cognition in later life.

A Unified Hypothesis of Early- and Late-Onset Alzheimer's Disease Pathogenesis

Early-onset familial Alzheimer's disease (EOFAD) and late-onset sporadic AD (LOSAD) both follow a similar pathological and biochemical course that includes: neuron and synapse loss and dysfunction, microvascular damage, microgliosis, extracellular amyloid-β deposition, tau phosphorylation, formation of intracellular neurofibrillary tangles, endoreduplication and related cell cycle events in affected brain regions. Any mechanistic explanation of AD must accommodate these biochemical and neuropathological features for both forms of the disease. In this insight paper we provide a unifying hypothesis for EOFAD and LOSAD that proposes that the aberrant re-entry of terminally differentiated, post-mitotic neurons into the cell division cycle is a common pathway that explains both early and late-onset forms of AD. Cell cycle abnormalities appear very early in the disease process, prior to the appearance of plaques and tangles, and explain the biochemical (e.g. tau phosphorylation), neuropathological (e.g. neuron hypertrophy; polypoidy) and cognitive changes observed in EOFAD and LOSAD. Genetic mutations in AβPP, PSEN1, and PSEN2 that alter amyloid-β precursor protein and Notch processing drive reactivation of the cell cycle in EOFAD, while age-related reproductive endocrine dyscrasia that upregulates mitogenic TNF signaling and AβPP processing toward the amyloidogenic pathway drives reactivation of the cell cycle in LOSAD. In essence, AβPP and presenilin mutations initiate early, what endocrine dyscrasia initiates later: aberrant cell cycle re-entry of post-mitotic neurons leading to neurodegeneration and cognitive decline in AD. Inhibition of cell cycle re-entry in post-mitotic neurons may be a useful therapeutic strategy to prevent, slow or halt disease progression.

Hatha Yoga practice decreases menopause symptoms and improves quality of life: A randomized controlled trial

OBJECTIVES

Yoga practice includes a group of specific psychophysical techniques. Although previous studies showed beneficial effects of yoga for health and rehabilitation, improving quality of life, there are few studies on the possible therapeutic application of yoga during the climacteric period. The purpose of this study was to investigate the psychophysiological effects of Hatha Yoga regular practice in post-menopausal women.

METHODS

Eighty-eight post-menopausal women volunteered for this 12-week trial. They were randomly assigned to one of three groups: control (no intervention), exercise, and yoga. Questionnaires were applied in order to evaluate climacteric syndrome (Menopause Rating Scale), stress (Lipp Stress Symptom Inventory), quality of life (Brief World Health Organization Quality of Life), depression (Beck Depression Inventory) and anxiety (State/Trait Anxiety Inventories). Physiological changes were evaluated through hormone levels (cortisol, FSH, LH, progesterone and estradiol).

RESULTS

At 12 weeks, yoga practitioners showed statistically lower scores for menopausal symptoms, stress levels and depression symptoms, as well as significantly higher scores in quality of life when compared to control and exercise groups. Only control group presented a significant increase in cortisol levels. The yoga and exercise groups showed decreased levels of FSH and LH when compared to control group.

CONCLUSIONS

These results suggest that yoga promotes positive psychophysiological changes in post-menopausal women and may be applied as a complementary therapy towards this population.

Histopathological and immunohistochemical study of the protective effect of triptorelin on the neurocytes of the hippocampus and the cerebral cortex of male albino rats after short-term exposure to cyclophosphamide

Chemotherapy treats many types of cancer effectively but it often causes side effects. Chemotherapy works on active cells, such as cancer cells, and some healthy cells. Side effects happen when chemotherapy damages these healthy cells. Today, many more drugs are available to treat side effects than in the past. Triptorelin (Decapeptyl) is a gonadotropin-releasing hormone agonist that is reported to have many therapeutic effects besides being an anti-cancer agent. In the current study, intraperitoneal cyclophosphamide (65 mg/kg/day) was administered for 4 weeks to induce marked dystrophic changes in the cerebral cortex and hippocampus of male albino rats. After 4 weeks, we observed significant degeneration of neurocytes with dystrophic changes. Subcutaneous triptorelin (0.05 mg/kg/day) for 4 weeks significantly improved histological signs of degeneration and apoptosis. Anti-Bcl2 staining of sections of the cerebral cortex and hippocampus showed that the apoptotic index was increased. This finding was confirmed by the anti-p53 staining, which showed a significant decrease in the apoptotic index. Ultimately, such improvements were accompanied by significant restoration of normal brain histology, as revealed by hematoxylin and eosin. In conclusion, triptorelin can reverse the apoptotic changes induced by cyclophosphamide therapy, which is more marked in the hippocampus than cerebral cortex.

The endocrine dyscrasia that accompanies menopause and andropause induces aberrant cell cycle signaling that triggers re-entry of post-mitotic neurons into the cell cycle, neurodysfunction, neurodegeneration and cognitive disease

This article is part of a Special Issue "SBN 2014". Sex hormones are physiological factors that promote neurogenesis during embryonic and fetal development. During childhood and adulthood these hormones support the maintenance of brain structure and function via neurogenesis and the formation of dendritic spines, axons and synapses required for the capture, processing and retrieval of information (memories). Not surprisingly, changes in these reproductive hormones that occur with menopause and during andropause are strongly correlated with neurodegeneration and cognitive decline. In this connection, much evidence now indicates that Alzheimer's disease (AD) involves aberrant re-entry of post-mitotic neurons into the cell cycle. Cell cycle abnormalities appear very early in the disease, prior to the appearance of plaques and tangles, and explain the biochemical, neuropathological and cognitive changes observed with disease progression. Intriguingly, a recent animal study has demonstrated that induction of adult neurogenesis results in the loss of previously encoded memories while decreasing neurogenesis after memory formation during infancy mitigated forgetting. Here we review the biochemical, epidemiological and clinical evidence that alterations in sex hormone signaling associated with menopause and andropause drive the aberrant re-entry of post-mitotic neurons into an abortive cell cycle that leads to neurite retraction, neuron dysfunction and neuron death. When the reproductive axis is in balance, gonadotropins such as luteinizing hormone (LH), and its fetal homolog, human chorionic gonadotropin (hCG), promote pluripotent human and totipotent murine embryonic stem cell and neuron proliferation. However, strong evidence supports menopausal/andropausal elevations in the LH:sex steroid ratio as driving aberrant mitotic events. These include the upregulation of tumor necrosis factor; amyloid-β precursor protein processing towards the production of mitogenic Aβ; and the activation of Cdk5, a key regulator of cell cycle progression and tau phosphorylation (a cardinal feature of both neurogenesis and neurodegeneration). Cognitive and biochemical studies confirm the negative consequences of a high LH:sex steroid ratio on dendritic spine density and human cognitive performance. Prospective epidemiological and clinical evidence in humans supports the premise that rebalancing the ratio of circulating gonadotropins:sex steroids reduces the incidence of AD. Together, these data support endocrine dyscrasia and the subsequent loss of cell cycle control as an important etiological event in the development of neurodegenerative diseases including AD, stroke and Parkinson's disease.

Identification and Epigenetic Analysis of a Maternally Imprinted Gene Qpct

Most imprinted genes are concerned with embryonic development, especially placental development. Here, we identified a placenta-specific imprinted gene Qpct. Our results show that Qpct is widely expressed during early embryonic development and can be detected in the telecephalon, midbrain, and rhombencephalon at E9.5b-E11.5. Moreover, Qpct is strikingly expressed in the brain, lung and liver in E15.5. Expression signals for Qpct achieved a peak at E15.5 during placental development and were only detected in the labyrinth layer in E15.5 placenta. ChIP assay results suggest that the modification of histone H3K4me3 can result in maternal activating of Qpct.

Parallels between major depressive disorder and Alzheimer's disease: role of oxidative stress and genetic vulnerability

The thesis of this review is that oxidative stress is the central factor in major depressive disorder (MDD) and Alzheimer's disease (AD). The major elements involved are inflammatory cytokines, the hypothalamic-pituitary axis, the hypothalamic-pituitary gonadal, and arginine vasopressin systems, which induce glucocorticoid and "oxidopamatergic" cascades when triggered by psychosocial stress, severe life-threatening events, and mental-affective and somatic diseases. In individuals with a genomic vulnerability to depression, these cascades may result in chronic depression-anxiety-stress spectra, resulting in MDD and other known depressive syndromes. In contrast, in subjects with genomic vulnerability to AD, oxidative stress-induced brain damage triggers specific antioxidant defenses, i.e., increased levels of amyloid-β (Aβ) and aggregation of hyper-phosphorylated tau, resulting in paired helical filaments and impaired functions related to the ApoEε4 isoform, leading to complex pathological cascades culminating in AD. Surprisingly, all the AD-associated molecular pathways mentioned in this review have been shown to be similar or analogous to those found in depression, including structural damage, i.e., hippocampal and frontal cortex atrophy. Other interacting molecular signals, i.e., GSK-3β, convergent survival factors (brain-derived neurotrophic factor and heat shock proteins), and transition redox metals are also mentioned to emphasize the vast array of intermediates that could interact via comparable mechanisms in both MDD and AD.

Transcriptome meta-analysis reveals a central role for sex steroids in the degeneration of hippocampal neurons in Alzheimer's disease

Background

Alzheimer’s disease is the most prevalent form of dementia. While a number of transcriptomic studies have been performed on the brains of Alzheimer’s specimens, no clear picture has emerged on the basis of neuronal transcriptional alterations linked to the disease. Therefore we performed a meta-analysis of studies comparing hippocampal neurons in Alzheimer’s disease to controls.

Results

Homeostatic processes, encompassing control of gene expression, apoptosis, and protein synthesis, were identified as disrupted during Alzheimer’s disease. Focusing on the genes carrying out these functions, a protein-protein interaction network was produced for graph theory and cluster exploration. This approach identified the androgen and estrogen receptors as key components and regulators of the disrupted homeostatic processes.

Conclusions

Our systems biology approach was able to identify the importance of the androgen and estrogen receptors in not only homeostatic cellular processes but also the role of other highly central genes in Alzheimer’s neuronal dysfunction. This is important due to the controversies and current work concerning hormone replacement therapy in postmenopausal women, and possibly men, as preventative approaches to ward off this neurodegenerative disorder.

Is TNF a link between aging-related reproductive endocrine dyscrasia and Alzheimer's disease?

This commentary addresses a novel mechanism by which aging-related changes in reproductive hormones could mediate their action in the brain. It presents the evidence that dyotic endocrine signals modulate the expression of tumor necrosis factor (TNF) and related cytokines, and that these cytokines are a functionally important downstream link mediating neurodegeneration and dysfunction. This convergence of dyotic signaling on TNF-mediated degeneration and dysfunction has important implications for understanding the pathophysiology of AD, stroke, and traumatic brain disease, and also for the treatment of these diseases.

Cognitive response to estradiol in postmenopausal women is modified by high cortisol

Estradiol has potent favorable effects on brain function and behavior in animals while in human trials, the results are inconsistent. A number of potential mediating variables influencing response to estradiol have been proposed to account for this variability, 1 of which includes stress. We conducted a placebo-controlled study to examine joint and independent effects of estradiol and elevated levels of the stress hormone cortisol on cognition and biomarkers of aging and neurodegenerative disease. Thirty-nine healthy postmenopausal women (56-84 years) received 0.10 mg/dL of transdermal 17β-estradiol (E2) or placebo for 8 weeks. During the last 4 days of the trial, subjects also received 90 mg/day (30 mg 3×/day) of oral hydrocortisone (CORT) to induce stress-level elevations in cortisol, or a matched placebo. The 4 groups thus included placebo (placebo patch/placebo pill), CORT-alone (placebo patch/hydrocortisone), E2-alone (estradiol patch/placebo pill), and E2+CORT (estradiol patch/hydrocortisone). Eight weeks of E2 increased plasma estradiol by 167%, and 4 days of CORT increased plasma cortisol by 119%. Overall, E2 had favorable effects on verbal memory (p = 0.03), working memory (p = 0.02), and selective attention (p = 0.04), and the magnitude of these effects was attenuated for E2+CORT. E2-alone and E2+CORT had opposing effects on plasma levels of the amyloid-β (Aβ) biomarker (Aβ40/42 ratio, p < 0.05), with the more favorable response observed for E2-alone. CORT-induced increases in insulin-like growth factor-1 were blunted by E2 coadministration. Our findings indicate that cognitive and physiological responses to estradiol are adversely affected by elevated stress hormone levels of cortisol in healthy postmenopausal women.

Gonadotropin-releasing hormone receptor system: modulatory role in aging and neurodegeneration

Receptors for hormones of the hypothalamic-pituitary-gonadal axis are expressed throughout the brain. Age-related decline in gonadal reproductive hormones cause imbalances of this axis and many hormones in this axis have been functionally linked to neurodegenerative pathophysiology. Gonadotropin-releasing hormone (GnRH) plays a vital role in both central and peripheral reproductive regulation. GnRH has historically been known as a pituitary hormone; however, in the past few years, interest has been raised in GnRH actions at non-pituitary peripheral targets. GnRH ligands and receptors are found throughout the brain where they may act to control multiple higher functions such as learning and memory function and feeding behavior. The actions of GnRH in mammals are mediated by the activation of a unique rhodopsin-like G protein-coupled receptor that does not possess a cytoplasmic carboxyl terminal sequence. Activation of this receptor appears to mediate a wide variety of signaling mechanisms that show diversity in different tissues. Epidemiological support for a role of GnRH in central functions is evidenced by a reduction in neurodegenerative disease after GnRH agonist therapy. It has previously been considered that these effects were not via direct GnRH action in the brain, however recent data has pointed to a direct central action of these ligands outside the pituitary. We have therefore summarized the evidence supporting a central direct role of GnRH ligands and receptors in controlling central nervous physiology and pathophysiology.

The reproductive-cell cycle theory of aging: an update

The Reproductive-Cell Cycle Theory posits that the hormones that regulate reproduction act in an antagonistic pleiotrophic manner to control aging via cell cycle signaling; promoting growth and development early in life in order to achieve reproduction, but later in life, in a futile attempt to maintain reproduction, become dysregulated and drive senescence. Since reproduction is the most important function of an organism from the perspective of the survival of the species, if reproductive-cell cycle signaling factors determine the rate of growth, determine the rate of development, determine the rate of reproduction, and determine the rate of senescence, then by definition they determine the rate of aging and thus lifespan. The theory is able to explain: 1) the simultaneous regulation of the rate of aging and reproduction as evidenced by the fact that environmental conditions and experimental interventions known to extend longevity are associated with decreased reproductive-cell cycle signaling factors, thereby slowing aging and preserving fertility in a hostile reproductive environment; 2) two phenomena that are closely related to species lifespan-the rate of growth and development and the ultimate size of the animal; 3). the apparent paradox that size is directly proportional to lifespan and inversely proportional to fertility between species but vice versa within a species; 4). how differing rates of reproduction between species is associated with differences in their lifespan; 5). why we develop aging-related diseases; and 6). an evolutionarily credible reason for why and how aging occurs-these hormones act in an antagonistic pleiotrophic manner via cell cycle signaling; promoting growth and development early in life in order to achieve reproduction, but later in life, in a futile attempt to maintain reproduction, become dysregulated and drive senescence (dyosis). In essence, the Reproductive-Cell Cycle Theory can explain aging in all sexually reproductive life forms.

Effects of cellular iron deficiency on the formation of vascular endothelial growth factor and angiogenesis. Iron deficiency and angiogenesis

Background

Young women diagnosed with breast cancer are known to have a higher mortality rate from the disease than older patients. Specific risk factors leading to this poorer outcome have not been identified. In the present study, we hypothesized that iron deficiency, a common ailment in young women, contributes to the poor outcome by promoting the hypoxia inducible factor-1α (HIF-1α and vascular endothelial growth factor (VEGF) formation. This hypothesis was tested in an in vitro cell culture model system.

Results

Human breast cancer MDA-MB-231 cells were transfected with transferrin receptor-1 (TfR1) shRNA to constitutively impair iron uptake. Cellular iron status was determined by a set of iron proteins and angiogenesis was evaluated by levels of VEGF in cells as well as by a mouse xenograft model. Significant decreases in ferritin with concomitant increases in VEGF were observed in TfR1 knockdown MDA-MB-231 cells when compared to the parental cells. TfR1 shRNA transfectants also evoked a stronger angiogenic response after the cells were injected subcutaneously into nude mice. The molecular mechanism appears that cellular iron deficiency elevates VEGF formation by stabilizing HIF-1α. This mechanism is also true in human breast cancer MCF-7 and liver cancer HepG2 cells.

Conclusions

Cellular iron deficiency increased HIF-1α, VEGF, and angiogenesis, suggesting that systemic iron deficiency might play an important part in the tumor angiogenesis and recurrence in this young age group of breast cancer patients.

Protective actions of sex steroid hormones in Alzheimer's disease

Risk for Alzheimer's disease (AD) is associated with age-related loss of sex steroid hormones in both women and men. In post-menopausal women, the precipitous depletion of estrogens and progestogens is hypothesized to increase susceptibility to AD pathogenesis, a concept largely supported by epidemiological evidence but refuted by some clinical findings. Experimental evidence suggests that estrogens have numerous neuroprotective actions relevant to prevention of AD, in particular promotion of neuron viability and reduction of beta-amyloid accumulation, a critical factor in the initiation and progression of AD. Recent findings suggest neural responsiveness to estrogen can diminish with age, reducing neuroprotective actions of estrogen and, consequently, potentially limiting the utility of hormone therapies in aged women. In addition, estrogen neuroprotective actions are also modulated by progestogens. Specifically, continuous progestogen exposure is associated with inhibition of estrogen actions whereas cyclic delivery of progestogens may enhance neural benefits of estrogen. In recent years, emerging literature has begun to elucidate a parallel relationship of sex steroid hormones and AD risk in men. Normal age-related testosterone loss in men is associated with increased risk to several diseases including AD. Like estrogen, testosterone has been established as an endogenous neuroprotective factor that not only increases neuronal resilience against AD-related insults, but also reduces beta-amyloid accumulation. Androgen neuroprotective effects are mediated both directly by activation of androgen pathways and indirectly by aromatization to estradiol and initiation of protective estrogen signaling mechanisms. The successful use of hormone therapies in aging men and women to delay, prevent, and or treat AD will require additional research to optimize key parameters of hormone therapy and may benefit from the continuing development of selective estrogen and androgen receptor modulators.

Progesterone reduces depression-like behavior in a murine model of Alzheimer's Disease

Although anxiety and depression are not the core symptoms of Alzheimer's Disease (AD), there are changes observed in mood in those with AD, as well as in the aging population. Anxiety and depression may be influenced by progesterone P(4) and/or its neuroactive metabolites, dihydroprogesterone (DHP) and 5 alpha-pregnan-3 alpha-ol-20-one (3 alpha,5 alpha-THP). To begin to investigate progestogens' role in AD, a double transgenic mouse model of early-onset familial AD that co-overexpresses mutant forms of amyloid precursor protein (APPswe) and presenilin 1 Delta exon 9 mutation was utilized. As such, the effects of long-term (from 6 to 12 months of age) administration of P(4) to ovariectomized (ovx) wildtype and APPswe+PSEN1 Delta e9 mice for changes in affective behavior was investigated. APPswe+PSEN1 Delta 9 mutant mice had increased anxiety-like (i.e., increased emergence latencies, decreased time spent on the open quadrants of the elevated zero maze) and increased depressive-like behavior (i.e., increased time spent immobile) than did wildtype mice. Compared to vehicle-administration, P(4) administration (which produced physiological circulating P(4), DHP, and 3 alpha,5 alpha-THP levels, particularly in the wildtype mice) decreased depressant-like behavior in the forced swim test. These effects occurred independent of changes in general motor behavior/coordination, pain threshold, and plasma corticosterone levels. Thus, the APPswe+PSEN1 Delta 9 mutation alters affective behavior, and P(4) treatment reversed depressive-like behavior.

Identification of a regulatory loop for the synthesis of neurosteroids: a steroidogenic acute regulatory protein-dependent mechanism involving hypothalamic-pituitary-gonadal axis receptors

Brain sex steroids are derived from both peripheral (primarily gonadal) and local (neurosteroids) sources and are crucial for neurogenesis, neural differentiation and neural function. The mechanism(s) regulating the production of neurosteroids is not understood. To determine whether hypothalamic-pituitary-gonadal axis components previously detected in the extra-hypothalamic brain comprise a feedback loop to regulate neuro-sex steroid (NSS) production, we assessed dynamic changes in expression patterns of steroidogenic acute regulatory (StAR) protein, a key regulator of steroidogenesis, and key hypothalamic-pituitary-gonadal endocrine receptors, by modulating peripheral sex hormone levels in female mice. Ovariectomy (OVX; high serum gonadotropins, low serum sex steroids) had a differential effect on StAR protein levels in the extrahypothalamic brain; increasing the 30- and 32-kDa variants but decreasing the 37-kDa variant and is indicative of cholesterol transport into mitochondria for steroidogenesis. Treatment of OVX animals with E(2), P(4), or E(2) + P(4) for 3 days, which decreases OVX-induced increases in GnRH/gonadotropin production, reversed this pattern. Suppression of gonadotropin levels in OVX mice using the GnRH agonist leuprolide acetate inhibited the processing of the 37-kDa StAR protein into the 30-kDa StAR protein, confirming that the differential processing of brain StAR protein is regulated by gonadotropins. OVX dramatically suppressed extra-hypothalamic brain gonadotropin-releasing hormone 1 receptor expression, and was further suppressed in E(2)- or P(4)-treated OVX mice. Together, these data indicate the existence of endocrine and autocrine/paracrine feedback loops that regulate NSS synthesis. Further delineation of these feedback loops that regulate NSS production will aid in developing therapies to maintain brain sex steroid levels and cognition.

Sex difference in pathology and memory decline in rTg4510 mouse model of tauopathy

Abnormal phosphorylation of tau protein is a common event in many neurodegenerative disorders, including Alzheimer's disease and other tauopathies. We investigated the relationship between hyperphosphorylated tau in brain extracts and mnemonic functions in rTg4510 mouse model of tauopathy. We report that rTg4510 mice showed rapid deterioration in spatial learning and memory, which paralleled a significant increase of hyperphosphorylated tau in the brain between 3 and 5.5 months of age. At 5.5 months, rTg4510 females showed significantly higher levels of hyperphosphorylated tau than males, with no evidence of differential tau transgene expression between the sexes. The increased levels of hyperphosphorylated tau in females were associated with more severe impairment in spatial learning and memory as compared to transgenic males. We also showed that within studied age range, the decrease in memory performance was accompanied by other behavioral disturbances in the water maze related to search strategy, like thigmotaxic swim and cue response. These findings suggest that the onset of abnormal tau biochemistry and coincident cognitive deficits in the rTg4510 mouse model is sex-dependent with females being affected earlier and more aggressively than males.

Effects of gonadotrophin-releasing hormone outside the hypothalamic-pituitary-reproductive axis

Gonadotrophin-releasing hormone (GnRH) is a hypothalamic decapeptide with an undisputed role as a primary regulator of gonadal function. It exerts this regulation by controlling the release of gonadotrophins. However, it is becoming apparent that GnRH may have a variety of other vital roles in normal physiology. A reconsideration of the potential widespread action that this traditional reproductive hormone exerts may lead to the generation of novel therapies and provide insight into seemingly incongruent outcomes from current treatments using GnRH analogues to combat diseases such as prostate cancer.

Hungry for life: How the arcuate nucleus and neuropeptide Y may play a critical role in mediating the benefits of calorie restriction

Laboratory studies consistently demonstrate extended lifespan in animals on calorie restriction (CR), where total caloric intake is reduced by 10-40% but adequate nutrition is otherwise maintained. CR has been further shown to delay the onset and severity of chronic diseases associated with aging such as cancer, and to extend the functional health span of important faculties like cognition. Less understood are the underlying mechanisms through which CR might act to induce such alterations. One theory postulates that CR's beneficial effects are intimately tied to the neuroendocrine response to low energy availability, of which the arcuate nucleus in the hypothalamus plays a pivotal role. Neuropeptide Y (NPY), a neurotransmitter in the front line of the arcuate response to low energy availability, is the primary hunger signal affected by CR and therefore may be a critical mechanism for lifespan extension.

Effect of yoga on cognitive functions in climacteric syndrome: a randomised control study

OBJECTIVE

To assess the efficacy of an integrated approach of yoga therapy (IAYT) on cognitive abilities in climacteric syndrome.

DESIGN

A randomised control study wherein the participants were divided into experimental and control groups.

SETTINGS

Fourteen centres of Swami Vivekananda Yoga Research Foundation, Bangalore, India.

SAMPLE

One hundred and eight perimenopausal women between 40 and 55 years with follicle-stimulating hormone level equal to or greater than 15 miu/ml. One hundred and twenty perimenopausal women were randomly allotted into the yoga and the control groups.

METHODS

The yoga group practised a module comprising breathing practices, sun salutation and cyclic meditation, whereas the control group practised a set of simple physical exercises, under supervision (1 hour/day, 5 days/week for 8 weeks).

MAIN OUTCOME MEASURES

Assessments were made by vasomotor symptom checklist, six-letter cancellation test (SLCT) for attention and concentration and Punit Govil Intelligence Memory Scale (PGIMS) with ten subtests.

RESULTS

The Wilcoxon test showed significant (P < 0.001) reduction in hot flushes, night sweats and sleep disturbance in yoga group, with a trend of significant difference between groups at P = 0.06 on Mann-Whitney test in night sweats. There was no change within or between groups in the control group. The SLCT score and the PGIMS showed significant improvement in eight of ten subtests in the yoga group and six of ten subtests in the control group. The yoga group performed significantly better (P < 0.001) with higher effect sizes in SLCT and seven tests of PGIMS compared with the control group.

CONCLUSIONS

Integrated approach of yoga therapy can improve hot flushes and night sweats. It also can improve cognitive functions such as remote memory, mental balance, attention and concentration, delayed and immediate recall, verbal retention and recognition tests.

Immunoreactive GnRH type I receptors in the mouse and sheep brain

Gonadotropin Releasing Hormone-I (GnRH) has been implicated in an array of functions outside the neuroendocrine reproductive axis. Previous investigations have reported extensive GnRH binding in numerous sites and this has been supported by in situ hybridization studies reporting GnRH receptor mRNA distribution. The present study on mice and sheep supports and extends these earlier investigations by revealing the distribution of cells immunoreactive for the GnRH receptor. In addition to sites previously shown to express GnRH receptors such as the hippocampus, amygdala and the arcuate nucleus, the improved resolution afforded by immunocytochemistry detected cells in the mitral cell lay of the olfactory bulb as well as the central grey of the mesencephalon. In addition, GnRH receptor immunoreactive neurons in the hippocampus and mesencephalon of the sheep were shown to colocalize with estrogen receptor beta. Although GnRH may act at some of these sites to regulate reproductive processes, evidence is accumulating to support an extra-reproductive role for this hypothalamic decapeptide.

Number of children is associated with neuropathology of Alzheimer's disease in women

OBJECTIVE

To examine the association between number of born children and neuropathology of Alzheimer's disease (AD).

METHODS

The brains of 86 subjects with data on the number of biological children born, were studied postmortem. Primary analyses included 73 subjects (average age at death=80; 42 women) devoid of cerebrovascular disease associated lesions (i.e., infarcts) or of non-AD related neuropathology. Women were significantly older at death than men (85.6 vs. 73.4; p<.0005) but did not differ significantly from men in number of children or dementia severity. Secondary analyses included 13 additional subjects who had concomitant cerebrovascular disease. Density of neuritic plaques (NPs) and neurofibrillary tangles (NFTs) in the hippocampus, entorhinal cortex, amygdala and multiple regions of the cerebral cortex, as well as composites of these indices reflecting overall neuropathology, were analyzed. For men and women separately, partial correlations, controlling for age at death and dementia severity, were used to assess the associations of number of children with these neuropathological variables.

RESULTS

Among women, all the partial correlations were positive, with statistical significance for overall neuropathology (r=.37; p=.02), overall NPs (r=.36; p=.02), and for NPs in the amygdala (r=.47; p=.002). Among men, none of the partial correlations were statistically significant. Results of the secondary analyses were similar.

CONCLUSIONS

Since the associations between number of children and neuropathology of AD were found for women only, they might reflect sex-specific mechanisms (such as variations in estrogen or luteinizing hormone levels) rather than social, economic, biological or other mechanisms common to both men and women.

Male hypogonadism

The hypothalamic-pituitary-gonadal (HPG) axis regulates the development, endocrine and reproductive function of the gonads throughout all phases of life. Male hypogonadism is defined an inadequate gonadal function, as manifested by deficiency in gametogenesis and/or secretion of gonadal hormones. In most cases, male hypogonadism is diagnosed through detailed history, physical examination and a few basic hormonal evaluations. In selected cases, however, additional tests are needed to define the aetiology and the extent of HPG axis dysfunction. These include semen analysis, pituitary imaging studies, genetic studies, bone densitometry, testicular ultrasonography, testicular biopsy and hormonal dynamic testing. The stimulation tests of the HPG are of particular importance in the differential diagnosis of congenital delayed puberty versus pre-pubertal hypogonadism in children. This review will focus on the methods, indications and limitations of endocrine testing in the characterisation and differential diagnosis of male hypogonadism at various ages. A practical hands-on guide on how to perform these tests is also provided.