Neuroactive steroids in schizophrenia

Chronic Antipsychotic Treatment Modulates Aromatase (CYP19A1) Expression in the Male Rat Brain

Antipsychotic drugs, known as the antagonists of dopaminergic receptors, may also affect a large spectrum of other molecular signaling pathways in the brain. Despite the numerous ongoing studies on neurosteroid action and regulation, there are no reports regarding the influence of extended treatment with typical and atypical neuroleptics on brain aromatase (CYP19A1) expression. In the present study, we assessed for the first time aromatase mRNA and protein levels in the brain of rats chronically (28 days) treated with olanzapine, clozapine, and haloperidol using quantitative real-time PCR, end-point RT-PCR, and Western blotting. Both clozapine and haloperidol, but not olanzapine treatment, led to an increase of aromatase mRNA expression in the rat brain. On the other hand, aromatase protein level remained unchanged after drug administration. These results cast a new light on the pharmacology of examined antipsychotics and contribute to a better understanding of the mechanisms responsible for their action. The present report also underlines the complex nature of potential interactions between neuroleptic pharmacological effects and physiology of brain neurosteroid pathways.

Neurosteroids: non-genomic pathways in neuroplasticity and involvement in neurological diseases

Neurosteroids are neuroactive brain-born steroids. They can act through non-genomic and/or through genomic pathways. Genomic pathways are largely described for steroid hormones: the binding to nuclear receptors leads to transcription regulation. Pregnenolone, Dehydroepiandrosterone, their respective sulfate esters and Allopregnanolone have no corresponding nuclear receptor identified so far whereas some of their non-genomic targets have been identified. Neuroplasticity is the capacity that neuronal networks have to change their structure and function in response to biological and/or environmental signals; it is regulated by several mechanisms, including those that involve neurosteroids. In this review, after a description of their biosynthesis, the effects of Pregnenolone, Dehydroepiandrosterone, their respective sulfate esters and Allopregnanolone on their targets will be exposed. We then shall highlight that neurosteroids, by acting on these targets, can regulate neurogenesis, structural and functional plasticity. Finally, we will discuss the therapeutic potential of neurosteroids in the pathophysiology of neurological diseases in which alterations of neuroplasticity are associated with changes in neurosteroid levels.

A systematic review of metabolite biomarkers of schizophrenia

Current diagnosis of schizophrenia relies exclusively on the potentially subjective interpretation of clinical symptoms and social functioning as more objective biological measurement and medical diagnostic tests are not presently available. The use of metabolomics in the discovery of disease biomarkers has grown in recent years. Metabolomic methods could aid in the discovery of diagnostic biomarkers of schizophrenia. This systematic review focuses on biofluid metabolites associated with schizophrenia. A systematic search of Web of Science and Ovid Medline databases was conducted and 63 studies investigating metabolite biomarkers of schizophrenia were included. A review of these studies revealed several potential metabolite signatures of schizophrenia including reduced levels of essential polyunsaturated fatty acids (EPUFAs), vitamin E and creatinine; and elevated levels of lipid peroxidation metabolites and glutamate. Further research is needed to validate these biomarkers and would benefit from large cohort studies and more homogeneous and well-defined subject groups.

Pregnenolone as an adjunct to risperidone for treatment of women with schizophrenia: A randomized double-blind placebo-controlled clinical trial

There have been few studies of pregnenolone therapy in schizophrenia and those that exist have been subject to several critical limitations, thus yielding inconsistent results. We attempted to assess the therapeutic effect of pregnenolone in a patient sample as homogeneous as possible. In this randomized double-blind clinical trial, 82 female inpatients with chronic schizophrenia, who had discontinued their antipsychotic medications for at least one week in case of any oral antipsychotic medication or a month for any depot antipsychotic medication, received risperidone plus either pregnenolone (50 mg/day) or placebo for 8 weeks. Inclusion criteria were acute illness with a baseline Positive and Negative Syndrome Scale (PANSS) negative subscale score of ≥20. Exclusion criteria were the presence of severe depression or other concomitant psychiatric disorders. Primary outcome was defined as the difference in the PANSS total score change from baseline to week 8 in the pregnenolone group compared to the placebo group. No significant difference was found in the PANSS total score changes between the two arms (mean difference (CI 95%) = -9.41 (-20.24 to 1.41); p = 0.087). Significant differences were initially found for PANSS negative change scores (mean difference (CI 95%) = -2.61 (-5.03 to -0.19); p = 0.035) and general psychopathology change scores (mean difference (CI 95%) = -5.93 (-11.37 to -0.48); p = 0.033). However, these findings did not survive Bonferroni correction for multiple testing. While this trial may suggest a potential effect of pregnenolone on schizophrenia symptoms, further studies are warranted.

Neuroactive Steroids: Receptor Interactions and Responses

Neuroactive steroids (NASs) are naturally occurring steroids, which are synthesized centrally as de novo from cholesterol and are classified as pregnane, androstane, and sulfated neurosteroids (NSs). NASs modulate many processes via interacting with gamma-aminobutyric acid (GABA), N-methyl-d-aspartate, serotonin, voltage-gated calcium channels, voltage-dependent anion channels, α-adrenoreceptors, X-receptors of the liver, transient receptor potential channels, microtubule-associated protein 2, neurotrophin nerve growth factor, and σ1 receptors. Among these, NSs (especially allopregnanolone) have high potency and extensive GABA-A receptors and hence demonstrate anticonvulsant, anesthetic, central cytoprotectant, and baroreflex inhibitory effects. NSs are also involved in mood and learning via serotonin and anti-nociceptive activity via T-type voltage-gated Ca2+ channels. Moreover, they are modulators of mitochondrial function, synaptic plasticity, or regulators of apoptosis, which have a role in neuroprotective via voltage-dependent anion channels receptors. For proper functioning, NASs need to be in their normal level, whereas excess and deficiency may lead to abnormalities. When they are below the normal, NSs could have a part in development of depression, neuro-inflammation, multiple sclerosis, experimental autoimmune encephalitis, epilepsy, and schizophrenia. On the other hand, stress and attention deficit disorder could occur during excessive level. Overall, NASs are very important molecules with major neuropsychiatric activity.

Suppressed oligodendrocyte steroidogenesis in multiple sclerosis: Implications for regulation of neuroinflammation

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). Neurosteroids are reported to exert anti-inflammatory effects in several neurological disorders. We investigated the expression and actions of the neurosteroid, dehydroepiandrosterone (DHEA), and its more stable 3β-sulphated ester, DHEA-S, in MS and associated experimental models. CNS tissues from patients with MS and animals with experimental autoimmune encephalomyelitis (EAE) displayed reduced DHEA concentrations, accompanied by diminished expression of the DHEA-synthesizing enzyme CYP17A1 in oligodendrocytes (ODCs), in association with increased expression of inflammatory genes including interferon (IFN)-γ and interleukin (IL)-1β. CYP17A1 was expressed variably in different human neural cell types but IFN-γ exposure selectively reduced CYP17A1 detection in ODCs. DHEA-S treatment reduced IL-1β and -6 release from activated human myeloid cells with minimal effect on lymphocyte viability. Animals with EAE receiving DHEA-S treatment showed reduced Il1b and Ifng transcript levels in spinal cord compared to vehicle-treated animals with EAE. DHEA-S treatment also preserved myelin basic protein immunoreactivity and reduced axonal loss in animals with EAE, relative to vehicle-treated EAE animals. Neurobehavioral deficits were reduced in DHEA-S-treated EAE animals compared with vehicle-treated animals with EAE. Thus, CYP17A1 expression in ODCs and its product DHEA were downregulated in the CNS during inflammatory demyelination while DHEA-S provision suppressed neuroinflammation, demyelination, and axonal injury that was evident as improved neurobehavioral performance. These findings indicate that DHEA production is an immunoregulatory pathway within the CNS and its restoration represents a novel treatment approach for neuroinflammatory diseases.

Targeting Retinoid Receptors to Treat Schizophrenia: Rationale and Progress to Date

This review provides the rationale and reports on the progress to date regarding the targeting of retinoid receptors for the treatment of schizophrenia and schizoaffective disorder and the role of retinoic acid in functions of the normal brain, and in psychotic states. After a brief introduction, we describe the normal function of retinoic acid in the brain. We then examine the evidence regarding retinoid dysregulation in schizophrenia. Finally, findings from two add-on clinical trials with a retinoid (bexarotene) are discussed. The authors of this review suggest that targeting retinoid receptors may be a novel approach to treat schizophrenia and schizoaffective disorder. Further studies are warranted.

Association between Serum Cortisol and DHEA-S Levels and Response to Antipsychotic Treatment in Schizophrenia

BACKGROUND

Previous studies suggested that alterations in serum cortisol and DHEA-S levels may play a role in the pathophysiology of schizophrenia.

AIM

To compare serum cortisol and DHEA-S levels between patients with schizophrenia and healthy controls and to evaluate their association with the response to antipsychotic treatment.

MATERIAL AND METHODS

In this clinical prospective study were included 60 patients with schizophrenia and 40 healthy age and sex matched control subjects. Clinical evaluation of patients was performed using the Positive and Negative Symptom Scale. A questionnaire for socio-demographic and clinical data collection was used. For the purposes of the study, the examined group was divided in two subgroups: responders and nonresponders. Serum cortisol and DHEA-S levels were measured at baseline in all participants and after 3 and 6 weeks of the antipsychotic treatment in patients with schizophrenia.

RESULTS

Patients with schizophrenia had significantly higher serum cortisol and DHEA-S levels in comparison to the control group. Responders had significantly higher serum cortisol and DHEA-S levels compared with nonresponders.

CONCLUSION

Elevated serum cortisol and DHEA-S levels may play a role in the pathophysiology of schizophrenia and they may be related to positive response to antipsychotic treatment in patients with schizophrenia.

3α5β-Pregnanolone glutamate, a use-dependent NMDA antagonist, reversed spatial learning deficit in an animal model of schizophrenia

Neuroactive steroids modulate receptors for neurotransmitters in the brain and thus might be efficacious in the treatment of various diseases of the central nervous system such as schizophrenia. We have designed and synthetized a novel use-dependent NMDA receptor antagonist 3α5β-pregnanolone glutamate (3α5β-P-Glu). In this study, we evaluate procognitive properties of 3α5β-P-Glu in an animal model of schizophrenia induced by systemic application of MK-801. The procognitive properties were evaluated using active place avoidance on a rotating arena (Carousel maze). We evaluated effects of 3α5β-P-Glu on the avoidance, on locomotor activity, and anxiety. 3α5β-P-Glu alone altered neither spatial learning nor locomotor activity in control animals. In the model animals, 3α5β-P-Glu reversed the MK-801-induced cognitive deficit without reducing hyperlocomotion. The highest dose of 3α5β-P-Glu also showed anxiolytic properties. Taken together, 3α5β-P-Glu may participate in the restoration of normal brain functioning and these results may facilitate the development of new promising drugs improving cognitive functioning in schizophrenia.

Sex differences and hormonal influences in human sensorimotor gating: implications for schizophrenia

Prepulse inhibition (PPI) of the startle response serves to prevent the interruption of ongoing perceptual and early sensory analysis and provides a simple operational measure of sensorimotor gating. In line with postulated deficits in early stages of information processing, PPI is disrupted in schizophrenia. PPI is considered a valid candidate for an endophenotypic marker in genetic studies of schizophrenia and has also been extensively used in translational research. Importantly, there are well-replicated sex differences and menstrual phase effects in prepulse-elicited startle modulation of nonclinical young populations. Lack of knowledge about the precise roles of sex differences and hormonal effects in prepulse-elicited startle modulation and in the schizophrenia disease process presents a stumbling block to continuous progress in this field. This chapter reviews a wealth of data demonstrating sex and hormonal influences in prepulse-elicited startle modulation and considers their implications for our understanding of the pathophysiology, genetics, and potential treatments of schizophrenia.

Evidence for a role of progesterone in menstrual cycle-related variability in prepulse inhibition in healthy young women

Prepulse inhibition (PPI) of the startle response is sensitive to sex, with healthy young women showing less PPI compared with age-matched men, and varies according to the menstrual cycle phase in women. Relatively less is known regarding sex and hormonal influences in prepulse facilitation (PPF). Menstrual phase-related variability in PPI is suggested to be mediated by fluctuating estrogen level, based on the observations of more PPI in women during the follicular, relative to the luteal, phase. No study has directly assessed the relationship between fluctuating hormones and PPI or PPF levels over the human ovarian cycle. To examine the roles of circulating ovarian hormones in PPI and PPF, 16 non-smoking regularly menstruating healthy women were tested during both the follicular and luteal phases on PPI and PPF and provided saliva samples for measurement of 17beta-estradiol (estrogen), progesterone and testosterone. The results showed higher levels of 17beta-estradiol and progesterone during the luteal, relative to the follicular, phase; and more PPI during the follicular phase and more PPF during the luteal phase with comparable startle amplitude and habituation during the two phases. A larger increase in progesterone was associated with a smaller decrease in PPI from the follicular to the luteal phase. No significant associations were found between changes in PPI/PPF and estrogen levels. The findings confirm lower PPI during the luteal, compared with the follicular, phase and suggest a role for progesterone, more specifically an antipsychotic-like PPI-restoration action of progesterone, during the luteal phase in PPI of young women.

Antipsychotic drugs: comparison in animal models of efficacy, neurotransmitter regulation, and neuroprotection

Various lines of evidence indicate the presence of progressive pathophysiological processes occurring within the brains of patients with schizophrenia. By modulating chemical neurotransmission, antipsychotic drugs may influence a variety of functions regulating neuronal resilience and viability and have the potential for neuroprotection. This article reviews the current literature describing preclinical and clinical studies that evaluate the efficacy of antipsychotic drugs, their mechanism of action and the potential of first- and second-generation antipsychotic drugs to exert effects on cellular processes that may be neuroprotective in schizophrenia. The evidence to date suggests that although all antipsychotic drugs have the ability to reduce psychotic symptoms via D(2) receptor antagonism, some antipsychotics may differ in other pharmacological properties and their capacities to mitigate and possibly reverse cellular processes that may underlie the pathophysiology of schizophrenia.

The biochemical womb of schizophrenia: A review

The conclusive identification of specific etiological factors or pathogenic processes in the illness of schizophrenia has remained elusive despite great technological progress. The convergence of state-of-art scientific studies in molecular genetics, molecular neuropathophysiology, in vivo brain imaging and psychopharmacology, however, indicates that we may be coming much closer to understanding the genesis of schizophrenia. In near future, the diagnosis and assessment of schizophrenia using biochemical markers may become a "dream come true" for the medical community as well as for the general population. An understanding of the biochemistry/ visa vis pathophysiology of schizophrenia is essential to the discovery of preventive measures and therapeutic intervention.

The relevance of neuroactive steroids in schizophrenia, depression, and anxiety disorders

1. Neuroactive steroids are steroid hormones that exert rapid, nongenomic effects at ligand-gated ion channels. There is increasing awareness of the possible role of these steroids in the pathology and manifestation of symptoms of psychiatric disorders. The aim of this paper is to review the current knowledge of neuroactive steroid functioning in the central nervous system, and to assess the role of neuroactive steroids in the pathophysiology and treatment of symptoms of schizophrenia, depression, and anxiety disorders. Particular emphasis will be placed on GABAA receptor modulation, given the extensive knowledge of the interactions between this receptor complex, neuroactive steroids, and psychiatric illness. 2. A brief description of neuroactive steroid metabolism is followed by a discussion of the interactions of neuroactive steroids with acute and chronic stress and the HPA axis. Preclinical and clinical studies related to psychiatric disorders that have been conducted on neuroactive steroids are also described. 3. Plasma concentrations of some neuroactive steroids are altered in individuals suffering from schizophrenia, depression, or anxiety disorders compared to values in healthy controls. Some drugs used to treat these disorders have been reported to alter plasma and brain concentrations in clinical and preclinical studies, respectively. 4. Further research is warranted into the role of neuroactive steroids in the pathophysiology of psychiatric illnesses and the possible role of these steroids in the successful treatment of these disorders.