The Direct and Long-Term Effects of Raloxifene as Adjunctive Treatment for Schizophrenia-Spectrum Disorders: A Double-Blind, Randomized Clinical Trial

Unveiling the potential of estrogen: Exploring its role in neuropsychiatric disorders and exercise intervention

Neuropsychiatric disorders shorten human life spans through multiple ways and become major threats to human health. Exercise can regulate the estrogen signaling, which may be involved in depression, Alzheimer's disease (AD) and Parkinson's disease (PD), and other neuropsychiatric disorders as well in their sex differences. In nervous system, estrogen is an important regulator of cell development, synaptic development, and brain connectivity. Therefore, this review aimed to investigate the potential of estrogen system in the exercise intervention of neuropsychiatric disorders to better understand the exercise in neuropsychiatric disorders and its sex specific. Exercise can exert a protective effect in neuropsychiatric disorders through regulating the expression of estrogen and estrogen receptors, which are involved in neuroprotection, neurodevelopment, and neuronal glucose homeostasis. These processes are mediated by the downstream factors of estrogen signaling, including N-myc downstream regulatory gene 2 (Ndrg2), serotonin (5-HT), delta like canonical Notch ligand 1 (DLL1), NOD-like receptor thermal protein domain associated protein 3 (NLRP3), etc. In addition, exercise can act on the estrogen response element (ERE) fragment in the genes of estrogenic downstream factors like β-amyloid precursor protein cleavase 1 (BACE1). However, there are few studies on the relationship between exercise, the estrogen signaling pathway, and neuropsychiatric disorders. Hence, we review how the estrogen signaling mediates the mechanism of exercise intervention in neuropsychiatric disorders. We aim to provide a theoretical perspective for neuropsychiatric disorders affecting female health and provide theoretical support for the design of exercise prescriptions.

Maternal immune activation and estrogen receptor modulation induce sex-specific dopamine-related behavioural and molecular alterations in adult rat offspring

Dopamine dysregulation contributes to psychosis and cognitive deficits in schizophrenia that can be modelled in rodents by inducing maternal immune activation (MIA). The selective estrogen receptor (ER) modulator, raloxifene, can improve psychosis and cognition in men and women with schizophrenia. However, few studies have examined how raloxifene may exert its therapeutic effects in mammalian brain in both sexes during young adulthood (age relevant to most prevalent age at diagnosis). Here, we tested the extent to which raloxifene alters dopamine-related behaviours and brain transcripts in young adult rats, both control and MIA-exposed females and males. We found that raloxifene increased amphetamine (AMPH)-induced locomotor activity in female controls, and in contrast, raloxifene reduced AMPH-induced locomotor activity in male MIA offspring. We did not detect overt prepulse inhibition (PPI) deficits in female or male MIA offspring, yet raloxifene enhanced PPI in male MIA offspring. Whereas, raloxifene ameliorated increased startle responsivity in female MIA offspring. In the substantia nigra (SN), we found reduced Drd2s mRNA in raloxifene-treated female offspring with or without MIA, and increased Comt mRNA in placebo-treated male MIA offspring relative to placebo-treated controls. These data demonstrate an underlying dopamine dysregulation in MIA animals that can become more apparent with raloxifene treatment, and may involve selective alterations in dopamine receptor levels and dopamine breakdown processes in the SN. Our findings support sex-specific, differential behavioural responses to ER modulation in MIA compared to control offspring, with beneficial effects of raloxifene treatment on dopamine-related behaviours relevant to schizophrenia found in male MIA offspring only.

Disruption of NMDA receptor-mediated regulation of PPI in the maternal immune activation model of schizophrenia is restored by 17β-estradiol and raloxifene

Maternal immune activation (MIA) during pregnancy is known to increase the risk of development of schizophrenia in the offspring. Sex steroid hormone analogues have been proposed as potential antipsychotic treatments but the mechanisms of action involved remain unclear. Estrogen has been shown to alter N-methyl-d-aspartate (NMDA) receptor binding in the brain. We therefore studied the effect of chronic treatment with 17β-estradiol, its isomer, 17α-estradiol, and the selective estrogen receptor modulator, raloxifene, on MIA-induced psychosis-like behaviour and the effect of the NMDA receptor antagonist, MK-801. Pregnant rats were treated with saline or the viral mimetic, poly(I:C), on gestational day 15. Adult female offspring were tested for changes in baseline prepulse inhibition (PPI) and the effects of acute treatment with MK-801 on PPI and locomotor activity. Poly(I:C) offspring had significantly lower baseline PPI compared to control offspring, and this effect was prevented by 17β-estradiol and raloxifene, but not 17α-estradiol. MK-801 reduced PPI in control offspring but had no effect in poly(I:C) offspring treated with vehicle. Chronic treatment with 17β-estradiol and raloxifene restored the effect of MK-801 on PPI. There were no effects of MIA or estrogenic treatment on MK-801 induced locomotor hyperactivity. These results show that MIA affects baseline PPI as well as NMDA receptor-mediated regulation of PPI in female rats, and strengthen the view that estrogenic treatment may have antipsychotic effects.

Role of estrogen in sex differences in memory, emotion and neuropsychiatric disorders

Estrogen regulates a wide range of neuronal functions in the brain, such as dendritic spine formation, remodeling of synaptic plasticity, cognition, neurotransmission, and neurodevelopment. Estrogen interacts with intracellular estrogen receptors (ERs) and membrane-bound ERs to produce its effect via genomic and non-genomic pathways. Any alterations in these pathways affect the number, size, and shape of dendritic spines in neurons associated with psychiatric diseases. Increasing evidence suggests that estrogen fluctuation causes changes in dendritic spine density, morphology, and synapse numbers of excitatory and inhibitory neurons differently in males and females. In this review, we discuss the role of estrogen hormone in rodents and humans based on sex differences. First, we explain estrogen role in learning and memory and show that a high estrogen level alleviates the deficits in learning and memory. Secondly, we point out that estrogen produces a striking difference in emotional memories in men and women, which leads them to display sex-specific differences in underlying neuronal signaling. Lastly, we discuss that fluctuations in estrogen levels in men and women are related to neuropsychiatric disorders, including schizophrenia, autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), bipolar disorder (BPD), major depressive disorder (MDD), substance use disorder (SUD), and anxiety disorders.

Estrogen and psychosis - a review and future directions

The link between sex hormones and schizophrenia has been suspected for over a century; however, scientific evidence supporting the pharmacotherapeutic effects of exogenous estrogen has only started to emerge during the past three decades. Accumulating evidence from epidemiological and basic research suggests that estrogen has a protective effect in women vulnerable to schizophrenia. Such evidence has led multiple researchers to investigate the role of estrogen in schizophrenia and its use in treatment. This narrative review provides an overview of the effects of estrogen as well as summarizes the recent work regarding estrogen as a treatment for schizophrenia, particularly the use of new-generation selective estrogen receptor modulators.

Effects of estrogen and raloxifene on synaptic density in the hippocampal CA1 region of ovariectomized rats

INTRODUCTION

The CA1 region of the hippocampus has an important role in learning and memory. It has been shown that estrogen deficiency may reduce the synaptic density in the region and that hormone replacement therapy may attenuate the reduction.

OBJECTIVES

This study aimed to evaluate the effects of estrogen and raloxifene on the synaptic density profile in the CA1 region of the hippocampus in ovariectomized rats.

METHODS

Sixty ovariectomized three-month-old virgin rats were randomized into six groups (n = 10). Treatments started either three days (early treatment) or sixty days (late treatment) after ovariectomy. The groups received propylene glycol vehicle (0.5 mL/animal/day), equine conjugated estrogens (50 μg/animal/day), or raloxifene (3 mg/kg/day) either early or late after ovariectomy. The drugs were administered orally by gavage for 30 days. At the end of the treatments, the animals were anesthetized and transcardially perfused with ether and saline solution. The brains were removed and prepared for analysis under transmission electron microscopy and later fixed.

RESULTS

Results showed a significant increase in the synaptic density profile of the hippocampal CA1 region in both the early estrogen (0.534 ± 0.026 µ/m2) and the early raloxifene (0.437 ± 0.012 µ/m2) treatment groups compared to the early or late vehicle-treated control groups (0.338 ± 0.038 µ/m2 and 0.277 ± 0.015 µ/m2 respectively).

CONCLUSIONS

The present data suggest that the raloxifene effect may be lower than that of estrogen, even early or late treatment, on synaptic density in the hippocampus.

Monitoring the Effectiveness of Treatment in Women with Schizophrenia: New Specialized Cooperative Approaches

Women with schizophrenia have specific health needs that differ from those of men and that change through successive life stages. We aimed to review the biopsychosocial literature on schizophrenia that addresses clinically important questions related to the treatment of women, including somatic morbi-mortality, hyperprolactinemia, comorbid substance use disorders, social risk factors, and medication effectiveness/safety. Data search terms were as follows: (Morbidity AND mortality) OR hyperprolactinemia OR ("substance use disorders" OR addictions) OR ("social risk factors") OR ("drug safety" OR prescription) AND women AND schizophrenia. A secondary aim was to describe a method of monitoring and interdisciplinary staff strategies. Schizophrenia patients show an increased risk of premature death from cardiovascular/respiratory disease and cancer compared to the general population. The literature suggests that close liaisons with primary care and the introduction of physical exercise groups reduce comorbidity. Various strategies for lowering prolactin levels diminish the negative long-term effects of hyperprolactinemia. Abstinence programs reduce the risk of victimization and trauma in women. Stigma associated with women who have serious psychiatric illness is often linked to reproductive functions. The safety and effectiveness of antipsychotic drug choice and dose differ between men and women and change over a woman's life cycle. Monitoring needs to be multidisciplinary, knowledgeable, and regular.

Gender differences in clinical and biochemical parameters among patients hospitalized for schizophrenia: towards precision medicine

BACKGROUND

The scientific literature shows some gender differences in the clinical course of schizophrenia. The aim of this study is to identify gender differences in clinical and biochemical parameters in subjects affected by schizophrenia. This would allow for the implementation of individualized treatment strategies.

METHODS

We examined a large set of clinical and biochemical parameters. Data were obtained from clinical charts and blood analyses from a sample of 555 schizophrenia patients consecutively admitted for exacerbation of symptoms to the inpatient clinic of Fondazione IRCCS Policlinico (Milan) or ASST Monza in Italy from 2008 to 2021. Univariate analyses, binary logistic regression, and a final logistic regression model were performed with gender as dependent variable.

RESULTS

The final logistic regression models showed that male patients (compared to females) were more prone to lifetime substance use disorders (p = 0.010). However, they also had higher GAF (global functioning) mean scores (p < 0.001) at the time of hospitalization. Univariate analyses showed that male patients (with respect to females) had an earlier age at onset (p < 0.001), a more frequent family history of multiple psychiatric disorders (p = 0.045), were more often smokers (p < 0.001), had a more frequent comorbidity with at least one psychiatric disorder (p = 0.001), and less often suffered from hypothyroidism (p = 0.011). In addition, men had higher levels of albumin (p < 0.001) and bilirubin (t = 2.139, p = 0.033), but lower levels of total cholesterol (t = 3.755, p < 0.001).

CONCLUSIONS

Our analyses indicate a less severe clinical profile in female patients. This is evident especially in the early years of the disorder, as suggested by less comorbidity with psychiatric disorders or later age at onset; this is consistent with the related literature. In contrast, female patients seem to be more vulnerable to metabolic alterations as demonstrated by more frequent hypercholesterolemia and thyroid dysfunction. Further studies are needed to confirm these results in the framework of precision medicine.