Pregnenolone as a novel therapeutic candidate in schizophrenia: emerging preclinical and clinical evidence

A Novel Bio-Psychosocial-Behavioral Treatment Model in Schizophrenia

Despite the substantial burden of illness in schizophrenia, there has been a discrepancy between the beneficial effects of an increased use of antipsychotic medications and achieving limited recovery or remission. Because the focus of the most common antipsychotic medications is on dopamine, which is associated with positive symptoms, there is an unmet need for patients with negative symptoms. Since cognitive and negative symptoms rather than positive symptoms are more closely associated with psychosocial impairments in patients with schizophrenia, the non-dopaminergic systems including glutamate and γ-aminobutyric acid (GABA) of the prefrontal cortex should be of concern as well. The balance of excitation and inhibition has been associated with epigenetic modifications and thus can be analyzed in terms of a neurodevelopmental and neural circuitry perspective. Hence, a novel bio-psychosocial-behavioral model for the treatment of schizophrenia is needed to account for the non-dopaminergic systems involved in schizophrenia, rather than dopaminergic mechanisms. This model can be understood from the viewpoint of neurodevelopment and neural circuitry and should include the staging care, personalized care, preventive care, reducing the cognitive deficits, and reducing stigma. Thomas R. Insel proposed this as a goal for schizophrenia treatment to be achieved by 2030.

Progesterone: The neglected hormone in schizophrenia? A focus on progesterone-dopamine interactions

Sex differences appear to be an important factor in schizophrenia. Women with schizophrenia tend to exhibit less disease impairment than men, typically presenting with a later age-at-onset, lower overall incidence and less severe symptoms. These observations underpin the estrogen hypothesis of schizophrenia, which postulates a protective role of estrogen against the development and severity of the disorder. While there has been significant attention placed on the impact of estrogens in schizophrenia, less consideration has been afforded to the role of progesterone, the other main female gonadal hormone. This narrative review discusses the role of progesterone as a neuroactive steroid and how it may be dysregulated in schizophrenia. Preclinical and molecular studies relevant to schizophrenia are discussed with a particular focus on the interactions between progesterone and the dopaminergic system. Notably, existing data on progesterone in relation to schizophrenia is inconsistent, with some studies suggesting a neuroprotective role for the hormone (e.g. animal models of cognitive dysfunction and positive symptoms), while other studies posit a disruptive impact of the hormone (e.g. negative correlations with symptom modulation in patients). This review aims to thoroughly address these discrepancies, concluding that altogether the data suggest that progesterone is a key modulator of central systems implicated in schizophrenia. On this basis, we argue that a more inclusive, considered effort of future studies to understand the intricacies of the interactions between progesterone and estrogen. Such an effort may enhance our understanding of the roles of sex hormones in schizophrenia, thus leading to avenues for novel therapeutic approaches.

Chiropractic Management of a Patient With Chronic Fatigue: A Case Report

OBJECTIVE

The purpose of this case report was to describe the examination and management of a patient with chronic fatigue.

CLINICAL FEATURES

A 34-year-old woman presented to a chiropractic clinic with complaints of fatigue and inability to lose weight for 2 years. When tested, she was found to have high serum thyroglobulin antibodies, low serum vitamin D3, low saliva dehydroepiandrosterone-sulfate, and low saliva total and diurnal cortisol.

INTERVENTION AND OUTCOME

The patient was placed on an anti-inflammatory ancestral diet and given recommendations to decrease the aerobic intensity of her exercise routine. On the basis of the result of conventional and functional laboratory tests, she was prescribed a treatment plan of targeted supplementation. After 12 weeks of application of dietary, lifestyle, and supplementation recommendations, the patient reported experiencing increased energy and weight loss of 15 pounds. Her thyroglobulin antibodies returned within reference range, salivary cortisol increased and closely followed the proper circadian rhythm, and dehydroepiandrosterone-sulfate increased.

CONCLUSIONS

This report describes improvement in a patient with chronic fatigue with the use of nonpharmaceutical polytherapy involving dietary changes, lifestyle modification, and supplementation.

NPAS3 Regulates Transcription and Expression of VGF: Implications for Neurogenesis and Psychiatric Disorders

Neuronal PAS domain protein 3 (NPAS3) and VGF (VGF Nerve Growth Factor (NGF) Inducible) are important for neurogenesis and psychiatric disorders. Previously, we have demonstrated that NPAS3 regulates VGF at the transcriptional level. In this study, VGF (non-acronymic) was found regulated by NPAS3 in neuronal stem cells. However, the underlying mechanism of this regulation remains unclear. The aim of this study was to explore the correlation of NPAS3 and VGF, and their roles in neural cell proliferation, in the context of psychiatric illnesses. First, we focused on the structure of NPAS3, to identify the functional domain of NPAS3. Truncated NPAS3 lacking transactivation domain was also found to activate VGF, which suggested that not only transactivation domain but other structural motifs were also involved in the regulation. Second, Mutated enhancer box (E-box) of VGF promoter showed a significant response to this basic helix-loop-helix (bHLH) transcription factor, which suggested an indirect regulatory mechanism for controlling VGF expression by NPAS3. κB site within VGF promoter was identified for VGF activation induced by NPAS3, apart from direct binding to E-box. Furthermore, ectopically expressed NPAS3 in PC12 cells produced parallel responses for nuclear factor kappa-light-chain-enhancer of activated B cells [NF-κB (P65)] expression, which specifies that NPAS3 regulates VGF through the NF-κB signaling pathway. Over-expression of NPAS3 also enhances the cell proliferation, which can be blocked by knockdown of VGF. Finally, NPAS3 was found to influence proliferation of neural cells through VGF. Therefore, downstream signaling pathways that are responsible for NPAS3-VGF induced proliferation via glutamate receptors were explored. Combining this work and published literature, a potential network composed by NPAS3, NF-κB, Brain-Derived Neurotrophic Factor (BDNF), NGF and VGF, was proposed. This network collectively detailed how NPAS3 connects with VGF and intersected neural cell proliferation, synaptic activity and psychiatric disorders.

TSPO activation modulates the effects of high pressure in a rat ex vivo glaucoma model

We previously reported that elevated pressure induces axonal swelling and facilitates the synthesis of the neurosteroid, allopregnanolone (AlloP), in the ex vivo rat retina. Exogenously applied AlloP attenuates the axonal swelling, suggesting that the neurosteroid plays a neuroprotective role against glaucomatous pressure-induced injuries, although mechanisms underlying neurosteroidogenesis have not been clarified. The aim of this study was to determine whether AlloP synthesis involves activation of translocator protein 18 kD (TSPO) and whether TSPO modulates pressure-induced retinal injury. Ex vivo rat retinas were exposed to various pressures (10, 35, or 75 mmHg) for 24 h. Expression of TSPO, 5α-reductase (5aRD), and AlloP was examined by quantitative real-time RT-PCR, ELISA, immunohistochemistry, and LC-MS/MS. We also examined the effects of TSPO ligands on AlloP synthesis and retinal damage. In this acute model, quantitative real-time RT-PCR and ELISA analyses revealed that elevated pressure facilitated TSPO expression. Similarly, these methods also detected enhanced 5aRD (mostly type II), which was observed in retinal ganglion cells (RGC) and the inner nuclear layer (INL). Atriol, a TSPO antagonist, suppressed pressure mediated AlloP synthesis and induced more severe histological changes in the inner retina when combined with elevated pressure. PK11195, a TSPO ligand that facilitates AlloP synthesis by itself, remarkably diminished pressure-mediated retinal degeneration. These results suggest that AlloP synthesis is induced by sequential activation of TSPO and 5aRD in an ex vivo glaucoma model, and that TSPO agonists may serve as potential therapeutic agents for the prevention of pressure-induced retinal damage.

Celecoxib Adjunctive Treatment to Antipsychotics in Schizophrenia: A Review of Randomized Clinical Add-On Trials

Schizophrenia is a severe, chronic and debilitating mental disorder. Past literature has reported various hypotheses about the psychopathology of schizophrenia. Recently, a growing literature has been trying to explain the role of inflammation in the etiopathogenesis of schizophrenia. In the past, numerous immune modulation and anti-inflammatory treatment options have been proposed for schizophrenia, but sometimes the results were inconsistent. Electronic search was carried out in November 2015. PubMed and Scopus databases have been used to find studies to introduce in this review. Only randomized-placebo-controlled add-on trials were taken into account. In this way, six articles were obtained for the discussion. Celecoxib showed beneficial effects mostly in early stages of schizophrenia. In chronic schizophrenia, the data are controversial, possibly in part for methodological reasons.

Nongenomic actions of neurosteroid pregnenolone and its metabolites

Steroids have been widely used in the clinical setting. They bind and activate nuclear receptors to regulate gene expression. In addition to activating genomic transcription, steroids also exert nongenomic actions. The current article focuses on the nongenomic actions of neurosteroids, including pregnenolone (P5), 7α-hydroxypregnenolone, pregnenolone sulfate and allopregnanolone. Pregnenolone and its derivatives promote neuronal activity by enhancing learning and memory, relieving depression, enhancing locomotor activity, and promoting neuronal cell survival. They exert these effects by activating various target proteins located in the cytoplasm or cell membrane. Pregnenolone and its metabolites bind to receptors such as microtubule-associated proteins and neurotransmitter receptors to elicit a series of reactions including stabilization of microtubules, increase of ion flux into cells, and dopamine release. The wide actions of neurosteroids indicate that pregnenolone derivatives have great potential in future treatment of neurological diseases.

Prenatal phencyclidine treatment induces behavioral deficits through impairment of GABAergic interneurons in the prefrontal cortex

RATIONALE

We previously reported that prenatal treatment with phencyclidine (PCP) induces glutamatergic dysfunction in the prefrontal cortex (PFC), leading to schizophrenia-like behavioral deficits in adult mice. However, little is known about the prenatal effect of PCP treatment on other types of neurons.

OBJECTIVES

We focused on γ-aminobutyric acid (GABA)-ergic interneurons and evaluated the effect of prenatal PCP exposure on the neurodevelopment of GABAergic interneurons in the PFC.

METHODS

PCP was administered at the dose of 10 mg/kg/day to pregnant dams from embryonic day 6.5 to 18.5. After the pups were reared to adult, we analyzed their GABAergic system in the PFC using immunohistological, biochemical, and behavioral analyses in adulthood.

RESULTS

The prenatal PCP treatment decreased the density of parvalbumin-positive cells and reduced the expression level of glutamic acid decarboxylase 67 (GAD67) and GABA content of the PFC in adults. Additionally, prenatal PCP treatment induced behavioral deficits in adult mice, such as hypersensitivity to PCP and prepulse inhibition (PPI) deficits. These behavioral deficits were ameliorated by pretreatment with the GABAB receptor agonist baclofen. Furthermore, the density of c-Fos-positive cells was decreased after the PPI test in the PFC of mice treated with PCP prenatally, and this effect was ameliorated by pretreatment with baclofen.

CONCLUSIONS

These findings suggest that prenatal treatment with PCP induced GABAergic dysfunction in the PFC, which caused behavioral deficits.

Neurosteroids and potential therapeutics: Focus on pregnenolone

Considerable evidence from preclinical and clinical studies shows that steroids and in particular neurosteroids are important endogenous modulators of several brain-related functions. In this context, it remains to be elucidated whether neurosteroids may serve as biomarkers in the diagnosis of disorders and might have therapeutic potential for the treatment of these disorders. Pregnenolone (PREG) is the main steroid synthesized from cholesterol in mammals and invertebrates. PREG has three main sources of synthesis, the gonads, adrenal glands and brain and is submitted to various metabolizing pathways which are modulated depending on various factors including species, steroidogenic tissues and steroidogenic enzymes. Looking at the whole picture of steroids, PREG is often known as the precursor to other steroids and not as an active steroid per se. Actually, physiological and brain functions have been studied mainly for steroids that are very active either binding to specific intracellular receptors, or modulating with high affinity the abundant membrane receptors, GABAA or NMDA receptors. However, when high sensitive and specific methodological approaches were available to analyze low concentrations of steroids and then match endogenous levels of different steroid metabolomes, several studies have reported more significant alterations in PREG than in other steroids in extraphysiological or pathological conditions, suggesting that PREG could play a functional role as well. Additionally, several molecular targets of PREG were revealed in the mammalian brain and beneficial effects of PREG have been demonstrated in preclinical and clinical studies. On this basis, this review will be divided into three parts. The first provides a brief overview of the molecular targets of PREG and the pharmacological effects observed in animal and human studies. The second will focus on the possible functional role of PREG with an outline of the modulation of PREG levels in animal and in human research. Finally, the review will highlight the possible therapeutic uses of PREG that point towards the development of pregnenolone-like molecules.

Association between the CYP11 family and six cancer types

Cytochromes P450 (CYPs) are a major source of variability in pharmacokinetics and drug response. CYPs utilize a variety of small and large molecules as substrates in enzymatic reactions. The CYP genes may be divided into two groups: Endogenous CYPs (CYP family 7–51) and xenobiotic CYPs (CYP family 1–4). The aim of the present study was to investigate whether endogenous CYPs exhibit similar gene expression and mutations in various cancer types. The gene expression profiles and somatic mutations exhibited in colon adenocarcinoma, kidney renal clear cell carcinoma, liver hepatocellular carcinoma, lung squamous cell carcinoma, prostate adenocarcinoma and uterine corpus endometrial carcinoma were analyzed using data obtained from The Cancer Genome Atlas. The expression of CYP11A1 was significantly downregulated in all six cancer types. In addition, CYP11B1 and CYP11B2 exhibited the highest number of mutations among endogenous CYPs in all samples. As the CYP11 family is important for steroid biosynthesis, and previous studies have demonstrated that steroid hormones are associated with certain cancers, these results indicate a common role of the CYP11 family in various cancer types.

Neuroactive Steroids in First-Episode Psychosis: A Role for Progesterone?

Neuroactive steroids may play a role in the pathophysiology of psychotic disorders, but few studies examined this issue. We compared serum levels of cortisol, testosterone, dehydroepiandrosterone, and progesterone between a representative sample of first-episode psychosis (FEP) patients and age- and gender-matched healthy subjects. Furthermore, we analyzed the associations between neuroactive steroids levels and the severity of psychotic symptom dimensions. Male patients had lower levels of progesterone than controls (p = 0.03). Progesterone levels were inversely associated with the severity of positive symptoms (p = 0.007). Consistent with preclinical findings, results suggest that progesterone might have a role in the pathophysiology of psychotic disorders.

Targeting neurosteroid synthesis as a therapy for schizophrenia-related alterations induced by early psychosocial stress

BACKGROUND

Cogent evidence has shown that schizophrenia vulnerability is enhanced by psychosocial stress in adolescence, yet the underpinnings of this phenomenon remain elusive. One of the animal models that best capture the relationship between juvenile stress and schizophrenia is isolation rearing (IR). This manipulation, which consists in subjecting rats to social isolation from weaning through adulthood, results in neurobehavioral alterations akin to those observed in schizophrenia patients. In particular, IR-subjected rats display a marked reduction of the prepulse inhibition (PPI) of the startle reflex, which are posited to reflect imbalances in dopamine neurotransmission in the nucleus accumbens (NAcc). We recently documented that the key neurosteroidogenic enzyme 5α-reductase (5αR) plays an important role in the dopaminergic regulation of PPI; given that IR leads to a marked down-regulation of this enzyme in the NAcc, the present study was designed to further elucidate the functional role of 5αR in the regulation of PPI of IR-subjected rats.

METHODS

We studied the impact of the prototypical 5αR inhibitor finasteride (FIN) on the PPI deficits and NAcc steroid profile of IR-subjected male rats, in comparison with socially reared (SR) controls.

RESULTS

FIN (25-100 mg/kg, i.p.) dose-dependently countered IR-induced PPI reduction, without affecting gating integrity in SR rats. The NAcc and striatum of IR-subjected rats displayed several changes in neuroactive steroid profile, including a reduction in pregnenolone in both SR and IR-subjected groups, as well as a decrease in allopregnanolone content in the latter group; both effects were significantly opposed by FIN.

CONCLUSIONS

These results show that 5αR inhibition counters the PPI deficits induced by IR, possibly through limbic changes in pregnenolone and/or allopregnanolone concentrations.

New steps forward in the neuroactive steroid field

Evidence accumulated in recent years suggests that the systemic treatment with neuroactive steroids, or the pharmacological modulation of its production by brain cells, represent therapeutic options to promote neuroprotection. However, new findings, which are reviewed in this paper, suggest that the factors to be considered for the design of possible therapies based on neuroactive steroids are more complex than previously thought. Thus, although as recently reported, the nervous system regulates neuroactive steroid synthesis and metabolism in adaptation to modifications in peripheral steroidogenesis, the neuroactive steroid levels in the brain do not fully reflect its levels in plasma. Even, in some cases, neuroactive steroid level modifications occurring in the nervous tissues, under physiological and pathological conditions, are in the opposite direction than in the periphery. This suggests that the systemic treatment with these molecules may have unexpected outcomes on neural steroid levels. In addition, the multiple metabolic pathways and signaling mechanisms of neuroactive steroids, which may change from one brain region to another, together with the existence of regional and sex differences in its neural levels are additional sources of complexity that should be clarified. This complexity in the levels and actions of these molecules may explain why in some cases these molecules have detrimental rather than beneficial actions for the nervous system. This article is part of a Special Issue entitled 'Steroid Perspectives'.

Estrogen-mediated regulation of steroid metabolism in rat glial cells; effects on neurosteroid levels via regulation of CYP7B1-mediated catalysis

Many neuroactive steroids, including dehydroepiandrosterone (DHEA), pregnenolone, 27-hydroxycholesterol and 17β-estradiol, are known to affect development and function of the brain and nervous system. These and other steroids can undergo tissue and/or cell-specific enzymatic conversions into steroid metabolites. Carefully regulated production of steroids with various physiological effects is important for cells of the nervous system. Astrocytes express many steroidogenic enzymes and are considered important producers of brain steroids. The quantitative roles of different pathways for steroid metabolism in rat astrocytes are not clear. In the current study we examined effects of estrogens on steroid metabolism catalyzed by CYP7B1 and other enzymes in primary cultures of rat astrocytes. The CYP7B1 enzyme, which has been linked to neurodegenerative disease, is involved in the metabolism of several important neurosteroids. In the present study, we found that 7α-hydroxylation, performed by CYP7B1, is the quantitatively most important pathway for DHEA metabolism in rat astrocytes. In addition, our present experiments on catalytic steroid conversions revealed that estrogens significantly suppress the CYP7B1-catalyzed metabolism of not only DHEA but also of pregnenolone and 27-hydroxycholesterol in rat astrocytes. These novel findings point to a regulatory mechanism for control of the cellular levels of these neurosteroids via CYP7B1. Our hypothesis that estrogens can regulate neurosteroid levels via this enzymatic reaction was supported by experiments using ELISA to assay levels of DHEA and pregnenolone in the presence or absence of estrogen. Furthermore, the present results show that estrogen suppresses CYP7B1-catalyzed 7α-hydroxylation also in primary cultures of rat Schwann cells, indicating that regulation by estrogen via this enzyme may be of relevance in both the CNS and the PNS.

Neurosteroids are endogenous neuroprotectants in an ex vivo glaucoma model

PURPOSE

Allopregnanolone is a neurosteroid and powerful modulator of neuronal excitability. The neuroprotective effects of allopregnanolone involve potentiation of γ-aminobutyric acid (GABA) inhibitory responses. Although glutamate excitotoxicity contributes to ganglion cell death in glaucoma, the role of GABA in glaucoma remains uncertain. The aim of this study was to determine whether allopregnanolone synthesis is induced by high pressure in the retina and whether allopregnanolone modulates pressure-mediated toxicity.

METHODS

Ex vivo rat retinas were exposed to hydrostatic pressure (10, 35, and 75 mm Hg) for 24 hours. Endogenous allopregnanolone production was determined by liquid chromatography and tandem mass spectrometry (LC-MS/MS) and immunochemistry. We also examined the effects of allopregnanolone, finasteride, and dutasteride (inhibitors of 5α-reductase), picrotoxin (a GABA(A) receptor antagonist), and D-2-amino-5-phosphonovalerate (APV, a broad-spectrum N-methyl-D-aspartate receptor [NMDAR] antagonist).

RESULTS

Pressure loading at 75 mm Hg significantly increased allopregnanolone levels as measured by LC-MS/MS. Elevated hydrostatic pressure also increased neurosteroid immunofluorescence, especially in the ganglion cell layer and inner nuclear layers. Staining was negligible at lower pressures. Enhanced allopregnanolone levels and immunostaining were substantially blocked by finasteride, but more effectively inhibited by dutasteride and APV. Administration of exogenous allopregnanolone suppressed pressure-induced axonal swelling in a concentration-dependent manner, while picrotoxin overcame these neuroprotective effects.

CONCLUSIONS

These results indicate that the synthesis of allopregnanolone is enhanced mainly via NMDARs in the pressure-loaded retina, and that allopregnanolone diminishes pressure-mediated retinal degeneration via GABAA receptors. Allopregnanolone and other related neurosteroids may serve as potential novel therapeutic targets for the prevention of pressure-induced retinal damage in glaucoma.

Proof-of-concept randomized controlled trial of pregnenolone in schizophrenia

RATIONALE

Preclinical and clinical data suggest that pregnenolone may be a promising therapeutic in schizophrenia. Pregnenolone is neuroprotective and enhances learning and memory, myelination, and microtubule polymerization. Treatment with pregnenolone elevates allopregnanolone (a neurosteroid that enhances GABAA receptor responses) and pregnenolone sulfate (a positive NMDA receptor modulator). Pregnenolone could thus potentially mitigate GABA dysregulation and/or NMDA receptor hypofunction in schizophrenia via metabolism to other neurosteroids.

OBJECTIVE

The objective of this study is to conduct a randomized controlled trial of adjunctive pregnenolone in schizophrenia.

METHODS

Following a placebo lead-in, 120 participants were randomized to pregnenolone or placebo for 8 weeks (Institute for Mental Health, Singapore). Primary endpoints were changes in MATRICS Consensus Cognitive Battery (MCCB) composite scores (cognitive symptoms), UCSD Performance-based Skills Assessment-Brief (UPSA-B) composite scores (functional capacity), and Scale for Assessment of Negative Symptoms (SANS) total scores (negative symptoms). A modified intent-to-treat analysis approach was utilized.

RESULTS

No significant changes compared to placebo were demonstrated in composite MCCB scores. In contrast, participants randomized to pregnenolone (n = 56) demonstrated greater improvements in functional capacity (UPSA-B composite changes) compared to placebo (n = 55), p = 0.03. Pregnenolone was also superior to placebo in the communication subscale of the UPSA-B (p < 0.001). Serum pregnenolone changes post-treatment were correlated with UPSA-B composite score changes in females (r s = 0.497, p < 0.042, n = 17) but not in males. Mean total SANS scores were very low at baseline and did not improve further post-treatment. Pregnenolone was well-tolerated.

CONCLUSIONS

Pregnenolone improved functional capacity in participants with schizophrenia, but did not improve cognitive symptoms over an 8-week treatment period. Neurosteroid changes correlated with functional improvements in female participants. Neurosteroid interventions may exhibit promise as new therapeutic leads for schizophrenia.

5α-reductase type I expression is downregulated in the prefrontal cortex/Brodmann's area 9 (BA9) of depressed patients

RATIONALE

The implications of the neurosteroid 3α-hydroxy-5α-pregnan-20-one [allopregnanolone (Allo)] in neuropsychiatric disorders have been highlighted in several recent clinical investigations. For instance, Allo levels are decreased in the cerebrospinal fluid (CSF) of patients with posttraumatic stress disorder (PTSD) and major unipolar depression. Neurosteroidogenic antidepressants [i.e., selective brain steroidogenic stimulants (SBSSs)], including fluoxetine and analogs, correct this decrease in a manner that correlates with improved depressive symptoms. Allo positively and allosterically modulates GABA action at postsynaptic and extrasynaptic GABAA receptors. It is synthesized in both the human and rodent brain cortices by principal glutamatergic pyramidal neurons from progesterone by the sequential action of 5α-reductase type I (5α-RI), which is the rate-limiting step enzyme in Allo biosynthesis, and 3α-hydroxysteroid dehydrogenase (3α-HSD), which converts 5α-dehydroprogesterone into Allo.

HYPOTHESIS

We thus hypothesized that decreased CSF levels of Allo in depressed patients could reflect a brain dysfunction of 5α-RI.

METHODS

In a pilot study of samples from six patients per group [six depressed patients and six nonpsychiatric subjects (NPS)], we studied the expression of 5α-RI messenger RNA (mRNA) in prefrontal cortex Brodmann's area 9 (BA9) and cerebellum from depressed patients obtained from the Maryland Brain Collection at the Maryland Psychiatric Research Center (Baltimore, MD) that were age-matched with NPS.

RESULTS

The levels of 5α-RI mRNA were decreased from 25 ± 5.8 in NPS to 9.1 ± 3.1 fmol/pmol neuronal specific enolase (NSE) (t1,10 = 2.7, P = 0.02) in depressed patients. These differences are absent in the cerebellum of the same patients. The levels of neurosteroids were determined in the prefrontal cortex BA9 of depressed patients obtained from the Stanley Foundation Brain Bank Neuropathology Consortium, Bethesda (MD). The BA9 levels of Allo in male depressed patients failed to reach statistical difference from the levels of NPS (1.63 ± 1.01 pg/mg, n = 8, in NPS and 0.82 ± 0.33 pg/mg, n = 5, in nontreated depressed patients). However, depressed patients who had received antidepressant treatment (three patients SSRI and one TCA) exhibited increased BA9 Allo levels (6.16 ± 2.5 pg/mg, n = 4, t1,9 = 2.4, P = 0.047) when compared with nontreated depressed patients.

CONCLUSIONS

Although in a small number of patients, this finding is in-line with previous reports in the field that have observed an increase of Allo levels in CSF and plasma of depressed patients following antidepressant treatment. Hence, the molecular mechanisms underlying major depression may include a GABAergic neurotransmission deficit caused by a brain Allo biosynthesis downregulation, which can be normalized by SBSSs.

Pregnenolone sulfate as a modulator of synaptic plasticity

RATIONALE

The neurosteroid pregnenolone sulfate (PregS) acts as a cognitive enhancer and modulator of neurotransmission, yet aligning its pharmacological and physiological effects with reliable measurements of endogenous local concentrations and pharmacological and therapeutic targets has remained elusive for over 20 years.

OBJECTIVES

New basic and clinical research concerning neurosteroid modulation of the central nervous system (CNS) function has emerged over the past 5 years, including important data involving pregnenolone and various neurosteroid precursors of PregS that point to a need for a critical status update.

RESULTS

Highly specific actions of PregS affecting excitatory N-methyl-D-aspartate receptor (NMDAR)-mediated synaptic transmission and the pharmacological effects of PregS on various receptors and ion channels are discussed. The discovery of a high potency (nanomolar) signal transduction pathway for PregS-induced NMDAR trafficking to the cell surface via a Ca(2+)- and G protein-coupled receptor (GPCR)-dependent mechanism and a potent (EC50 ~ 2 pM) direct enhancement of intracellular Ca(2+) levels is discussed in terms of its agonist effects on long-term potentiation (LTP) and memory. Lastly, preclinical and clinical studies assessing the promnestic effects of PregS and pregnenolone toward cognitive dysfunction in schizophrenia, and altered serum levels in epilepsy and alcohol dependence, are reviewed.

CONCLUSIONS

PregS is present in human and rodent brain at physiologically relevant concentrations and meets most of the criteria for an endogenous neurotransmitter/neuromodulator. PregS likely plays a significant role in modulation of glutamatergic excitatory synaptic transmission underlying learning and memory, yet the molecular target(s) for its action awaits identification.

Assessment of pregnenolone effects on alcohol intake and preference in male alcohol preferring (P) rats

Neuroactive steroids can modulate a variety of neurobehavioral functions via the GABAergic system. This study was conducted to determine the importance of the neurosteroid pregnenolone on the regulation of alcohol intake. The effects of acute and chronic administration of pregnenolone on alcohol intake were assessed in alcohol preferring (P) rats. The rats were injected i.p. with the vehicle or pregnenolone (25, 50 or 75 mg/kg) and their alcohol and water intake were recorded at 2, 4, 6 and 24 h. Also, the chronic effects of 50 mg/kg (i.p.) pregnenolone on alcohol intake were determined. Our results show that although the main effect of i.p. injection of pregnenolone in reducing alcohol intake was not quite significant compared with the vehicle, pregnenolone at 75 mg/kg significantly (P<0.025) reduced alcohol intake. Regarding alcohol preference, acute administration of pregnenolone both at 50 mg/kg (P<0.05) and at 75 mg/kg (P<0.025) significantly reduced alcohol preference. In chronic experiments pregnenolone given for 10 consecutive days did not show a significant effect on alcohol intake and alcohol preference. Overall, although pregnenolone given i.p. acutely and significantly reduced alcohol intake and preference, the fact that chronic treatment did not show an effect diminishes its promise to be considered for the treatment of alcoholism. However, its profile of effects might be different in human alcoholics.

Development of novel therapy of schizophrenia in children and adolescents

INTRODUCTION

Typical and atypical antipsychotics are efficacious treatments for early-onset schizophrenia (EOS) with very subtle differences in their efficacy. Therefore, when choosing an antipsychotic, the side-effect profile of the individual antipsychotic needs to be taken into account. There is a growing body of neurobiological and genetic evidence for early-onset patients, but these findings have not yet translated into the clinic.

AREAS COVERED

The authors summarize the current treatment options for EOS and discuss the novel treatment options that are under evaluation. The authors focus specifically on Phase II and Phase III clinical trials.

EXPERT OPINION

Currently, there are no truly groundbreaking pharmacological treatment options emerging in EOS. There are several newer antipsychotic agents (iloperidone, lurasidone, asenapine, blonanserin) that are currently in clinical trials. It is unclear whether therapeutic efficacy of any of these agents will be superior or even similar to the existing treatment and the main differentiating factor between individual drugs remains to be their side-effect profile. Beyond these antipsychotics, oxytocin and N-acetylcysteine are the only new pharmacological treatment options that are being evaluated in EOS. Therefore, a major change in the treatment development paradigm is necessary to identify novel and efficacious drugs.

Pregnenolone, a cholesterol metabolite, induces glioma cell apoptosis via activating extrinsic and intrinsic apoptotic pathways

Gliomas are one of the most common types of malignant tumors worldwide, however, an effective therapeutic strategy not yet been fully determined. The present study aimed to investigate the anti-glioma activity and underlying mechanisms of pregnenolone, which originates from cholesterol and is metabolized into important steroid hormones in the body. The results demonstrated that 100 μM pregnenolone induced a significant loss of cell viability in various malignant glioma cell lines. In the U-87 MG, LN-18 and C6 cell lines, the loss of cell viability resulted from cell apoptosis, which was evidenced by apoptotic nuclear morphology changes and caspase 3 activation. Moreover, the increased activities of caspase 8 and 9 strongly indicated that pregnenolone activated the extrinsic and intrinsic pathways of apoptosis. Additionally, glioma cell apoptosis was prevented by the general caspase inhibitor, Z-VAD-FMK. In the C6 cells, upregulation of Fas and Fas ligand triggered the activation of the extrinsic pathway, whereas knockdown of Fas significantly abrogated the cell apoptosis that was induced by pregnenolone. Furthermore, downregulation of the anti-apoptotic protein, B-cell lymphoma 2 and upregulation of pro-apoptotic proteins, such as Bax and Bak, activated the intrinsic pathway. In conclusion, pregnenolone induced glioma cell apoptosis in a caspase-dependent manner, which was mediated by activation of the extrinsic and intrinsic apoptotic pathways.

VGF (TLQP-62)-induced neurogenesis targets early phase neural progenitor cells in the adult hippocampus and requires glutamate and BDNF signaling

The neuropeptide VGF (non-acronymic), which has antidepressant-like effects, enhances adult hippocampal neurogenesis as well as synaptic activity and plasticity in the hippocampus, however the interaction between these processes and the mechanism underlying this regulation remain unclear. In this study, we demonstrate that VGF-derived peptide TLQP-62 specifically enhances the generation of early progenitor cells in nestin-GFP mice. Specifically, TLQP-62 significantly increases the number of Type 2a neural progenitor cells (NPCs) while reducing the number of more differentiated Type 3 cells. The effect of TLQP-62 on proliferation rather than differentiation was confirmed using NPCs in vitro; TLQP-62 but not scrambled peptide PEHN-62 increases proliferation in a cell line as well as in primary progenitors from adult hippocampus. Moreover, TLQP-62 but not scrambled peptide increases Cyclin D mRNA expression. The proliferation of NPCs induced by TLQP-62 requires synaptic activity, in particular through NMDA and metabotropic glutamate receptors. The activation of glutamate receptors by TLQP-62 activation induces phosphorylation of CaMKII through NMDA receptors and protein kinase D through metabotropic glutamate receptor 5 (mGluR5). Furthermore, pharmacological antagonists to CaMKII and PKD inhibit TLQP-62-induced proliferation of NPCs indicating that these signaling molecules downstream of glutamate receptors are essential for the actions of TLQP-62 on neurogenesis. We also show that TLQP-62 gradually activates Brain-Derived Neurotrophic Factor (BDNF)-receptor TrkB in vitro and that Trk signaling is required for TLQP-62-induced proliferation of NPCs. Understanding the precise molecular mechanism of how TLQP-62 influences neurogenesis may reveal mechanisms by which VGF-derived peptides act as antidepressant-like agents.

Negative symptoms of schizophrenia: clinical characteristics, pathophysiological substrates, experimental models and prospects for improved treatment

Schizophrenia is a complex and multifactorial disorder generally diagnosed in young adults at the time of the first psychotic episode of delusions and hallucinations. These positive symptoms can be controlled in most patients by currently-available antipsychotics. Conversely, they are poorly effective against concomitant neurocognitive dysfunction, deficits in social cognition and negative symptoms (NS), which strongly contribute to poor functional outcome. The precise notion of NS has evolved over the past century, with recent studies - underpinned by novel rating methods - suggesting two major sub-domains: "decreased emotional expression", incorporating blunted affect and poverty of speech, and "avolition", which embraces amotivation, asociality and "anhedonia" (inability to anticipate pleasure). Recent studies implicate a dysfunction of frontocortico-temporal networks in the aetiology of NS, together with a disruption of cortico-striatal circuits, though other structures are also involved, like the insular and parietal cortices, amygdala and thalamus. At the cellular level, a disruption of GABAergic-glutamatergic balance, dopaminergic signalling and, possibly, oxytocinergic and cannibinoidergic transmission may be involved. Several agents are currently under clinical investigation for the potentially improved control of NS, including oxytocin itself, N-Methyl-d-Aspartate receptor modulators and minocycline. Further, magnetic-electrical "stimulation" strategies to recruit cortical circuits and "cognitive-behavioural-psychosocial" therapies likewise hold promise. To acquire novel insights into the causes and treatment of NS, experimental study is crucial, and opportunities are emerging for improved genetic, pharmacological and developmental modelling, together with more refined readouts related to deficits in reward, sociality and "expression". The present article comprises an integrative overview of the above issues as a platform for this Special Issue of European Neuropsychopharmacology in which five clinical and five preclinical articles treat individual themes in greater detail. This Volume provides, then, a framework for progress in the understanding - and ultimately control - of the debilitating NS of schizophrenia.

Psychopharmacology of the negative symptoms: current status and prospects for progress

The past decade has witnessed a resurgence of interest in the development of novel pharmacological agents to treat the negative symptoms of schizophrenia. This review provides an overview of pharmacological approaches that have been evaluated as potential treatments and describes the emergence of several promising new approaches. First, we briefly describe recent methodological developments, including consensus-based clinical trial guidelines for patient selection criteria, symptom assessment, and trial duration. Next, we overview mono- and adjunctive-therapies that have been evaluated, including first- and second-generation antipsychotics, antidepressants, psychostimulants, molecules targeting cholinergic and glutamatergic systems, and hormones. We highlight the most promising pharmacological agents on the horizon, including glycine transporter-1 inhibitors, α7-nicotinic receptor positive allosteric modulators, and oxytocin, as well as non-pharmacological electromagnetic stimulation approaches. Further investigations, using optimal clinical trial design, hold considerable promise for discovering effective treatments for these functionally disabling symptoms in the near future.

Progesterone and its metabolites as therapeutic targets in psychiatric disorders

INTRODUCTION

Neurosteroids are molecules that regulate physiological functions of the CNS. There is increasing evidence suggesting that impaired neurosteroid biosynthesis has been associated with distinct psychiatric disorders. This review summarizes data from studies that have investigated the relationship between progesterone (PROG) and psychiatric disorders as well as the mechanisms potentially involved in PROG-induced neuroprotection.

AREAS COVERED

The review covers the role of PROG and its metabolites in psychiatric disorders, focusing on results from preclinical and some clinical studies that support the relationship between alterations on PROG levels and pathophysiology of psychiatric illness. We also discussed the main mechanisms underlying the neuroprotective effects of PROG metabolites.

EXPERT OPINION

Our review points out the possible relationship between PROG and its metabolites and the pathophysiology of psychiatric disorders. Furthermore, both preclinical and clinical studies show that certain treatments (antidepressants or antipsychotics) may normalize the levels of PROG, suggesting that the amelioration of psychiatric symptoms may occur due to upregulation of PROG metabolites. Therefore, these results give support to new possibilities of treatment for patients with psychiatric symptoms from anxiety- and depressive-like behaviors to aggressive behaviors.

Neonatal finasteride administration alters hippocampal α4 and δ GABAAR subunits expression and behavioural responses to progesterone in adult rats

Allopregnanolone is a neurosteroid that has been reported to fluctuate during early developmental stages. Previous experiments reported the importance of neonatal endogenous allopregnanolone levels for the maturation of the central nervous system and particularly for the hippocampus. Changes in neonatal allopregnanolone levels have been related to altered adult behaviour and with psychopathological susceptibility, including anxiety disorders, schizophrenia and drug abuse. However, the mechanism underlying these changes remains to be elucidated. In the present study we assessed changes in hippocampal expression of α4 and δ GABAA receptor (GABAAR) subunits as a consequence of neonatal finasteride (a 5-α reductase inhibitor) administration during early development (PD6 to PD15) in male rats. We observed that the treatment altered the temporal window of the natural peak in the expression of these subunits during development. Additionally, the level of these subunits were higher than in non-handled and control animals in the adult hippocampus. We observed that in adulthood, neonatal finasteride-treated animals presented an anxiogenic-like profile in response to progesterone administration which was absent in the rest of the groups. In conclusion, these results corroborate the relevance of neonatal maintenance of neurosteroid levels for behavioural anxiety responses in the adult, and point to some of the mechanisms involved in this alterations.

Addressing the unmet needs of patients with persistent negative symptoms of schizophrenia: emerging pharmacological treatment options

The negative symptoms of schizophrenia represent an impairment of normal emotional responses, thought processes and behaviors, and include blunting or flattening of affect, alogia/aprosody, avolition/apathy, anhedonia, and asociality. Negative symptoms contribute to a reduced quality of life, increased functional disability, increased burden of illness, and poorer long-term outcomes, to a greater degree than positive symptoms. Primary negative symptoms are prominent and persistent in up to 26% of patients with schizophrenia, and they are estimated to occur in up to 58% of outpatients at any given time. Negative symptoms respond less well to medications than positive symptoms, and to date treatment options for negative symptoms have been limited, with no accepted standard treatment. Modest benefits have been reported with a variety of different agents, including second-generation antipsychotics and add-on therapy with antidepressants and other pharmacological classes. Recent clinical research focusing on negative symptoms target novel biological systems, such as glutamatergic neurotransmission. Different approaches include: enhancing N-methyl-D-aspartate receptor function with agents that bind directly to the glycine ligand site or with glycine reuptake inhibitors; influencing the metabotropic glutamate receptor (mGluR2/3) with positive allosteric modulators; and stimulating nicotinic acetylcholine receptors. In conclusion, the lack of clearly efficacious pharmacological treatments for the management of negative symptoms represents a significant unmet need, especially considering the importance of these symptoms on patient outcomes. Hence, further research to identify and characterize novel pharmacological treatments for negative symptoms is greatly needed.

Synergistic effect of 5-HT1A and σ1 receptor activation on prefrontal dopaminergic transmission under circulating steroid deficiency

Serotonin (5-HT)1A and σ1 receptors have been implicated in psychiatric disorders. We previously found that combined 5-HT reuptake inhibition and σ1 receptor activation has a synergistic effect on prefrontal dopaminergic transmission in adrenalectomized/castrated mice lacking circulating steroid hormones. In the present study, we examined the mechanisms underlying this neurochemical synergism. Systemic administration of fluvoxamine, a selective 5-HT reuptake inhibitor with agonistic activity towards the σ1 receptor, increased prefrontal dopamine (DA) levels, and adrenalectomy/castration potentiated this fluvoxamine-induced increase in DA. This enhancement of DA release was blocked by WAY100635 (a 5-HT1A receptor antagonist), but not by ritanserin (a 5-HT2 receptor antagonist), azasetron (a 5-HT3 receptor antagonist) or SB269970 (a 5-HT7 receptor antagonist). Individually, osemozotan (a 5-HT1A receptor agonist) and (+)-SKF-10,047 (a σ1 receptor agonist) did not alter prefrontal monoamine levels in adrenalectomized/castrated and sham-operated mice differentially. In contrast, co-administration of these drugs increased prefrontal DA levels to a greater extent in adrenalectomized/castrated mice than in sham-operated animals. Furthermore, co-administration of osemozotan and (+)-SKF-10,047 increased expression of the neuronal activity marker c-Fos in the ventral tegmental area of adrenalectomized/castrated mice, but not in sham-operated animals. These findings suggest that combined activation of 5-HT1A and σ1 receptors has a synergistic effect on prefrontal dopaminergic transmission under circulating steroid deficiency, and that this interaction may play an important role in the regulation of the prefrontal DA system.

The role of allopregnanolone in depression and anxiety

Neuroactive steroids such as allopregnanolone do not only act as transcriptional factors in the regulation of gene expression after intracellular back-oxidation into the 5-α pregnane steroids but may also alter neuronal excitability through interactions with specific neurotransmitter receptors. In particular, certain 3α-reduced metabolites of progesterone such as 3α,5α-tetrahydroprogesterone (allopregnanolone) and 3α,5β-tetrahydroprogesterone (pregnanolone) are potent positive allosteric modulators of the GABA(A) receptor complex. During the last years, the downregulation of neurosteroid biosynthesis has been intensively discussed to be a possible contributor to the development of anxiety and depressive disorder. Reduced levels of allopregnanolone in the peripheral blood or cerebrospinal fluid were found to be associated with major depression, anxiety disorders, premenstrual dysphoric disorder, negative symptoms in schizophrenia, or impulsive aggression. The importance of allopregnanolone for the regulation of emotion and its therapeutical use in depression and anxiety may not only involve GABAergic mechanisms, but probably also includes enhancement of neurogenesis, myelination, neuroprotection, and regulatory effects on HPA axis function. Certain pharmacokinetic obstacles limit the therapeutic use of natural neurosteroids (low bioavailability, oxidation to the ketone). Until now synthetic neuroactive steroids could not be established in the treatment of anxiety disorders or depression. However, the translocator protein (18 kDa) (TSPO) which is important for neurosteroidogenesis has been identified as a potential novel target. TSPO ligands such as XBD 173 increase neurosteroidogenesis and have anxiolytic effects with a favorable side effect profile.

Comparison of plasma and cerebrospinal fluid levels of neuroactive steroids with their brain, spinal cord and peripheral nerve levels in male and female rats

Physiological changes and pathological alterations in the nervous system of rodents are associated with modifications in the levels of neuroactive steroids in the brain, spinal cord and/or peripheral nerves. Measures of tissue levels of steroids in the nervous system present serious limitations for human studies and for longitudinal studies in animals. In this study we have explored whether levels of neuroactive steroids in plasma and the cerebrospinal fluid reflect their levels in neural tissues. To this aim, we have evaluated by liquid chromatography-tandem mass spectrometry the levels of several neuroactive steroids in plasma, cerebrospinal fluid, cerebral cortex, cerebellum, hippocampus, spinal cord and sciatic nerve of male and female rats. Data indicate that plasma and cerebrospinal fluid levels of steroids do not fully reflect their tissue levels. However, the interindividual variations in the levels of all the steroids assessed, with the exception of dehydroepiandrosterone, showed a positive correlation in plasma and cerebral cortex. Most steroids also showed a positive correlation in plasma and the cerebellum, the spinal cord and the sciatic nerve. In the hippocampus, the levels of tetrahydroprogesterone, testosterone and testosterone metabolites showed a significant positive correlation with their respective levels in plasma. The cerebrospinal fluid levels of some steroids, such as testosterone and dihydrotestosterone, showed a full correlation with tissue levels. In addition, cerebrospinal fluid levels of pregnenolone, progesterone, and 17β-estradiol showed a positive correlation with their corresponding levels in the majority of the neural structures analyzed. These findings suggest that the levels of some neuroactive steroids in cerebrospinal fluid as well as in plasma may be valuable to predict their levels in the nervous system.

Allopregnanolone elevations following pregnenolone administration are associated with enhanced activation of emotion regulation neurocircuits

BACKGROUND

The neurosteroid allopregnanolone is a potent allosteric modulator of the gamma-aminobutyric acid type A receptor with anxiolytic properties. Exogenous administration of allopregnanolone reduces anxiety, and allopregnanolone blockade impairs social and affective functioning. However, the neural mechanism whereby allopregnanolone improves mood and reduces anxiety is unknown. In particular, brain imaging has not been used to link neurosteroid effects to emotion regulation neurocircuitry.

METHODS

To investigate the brain basis of allopregnanolone's impact on emotion regulation, participants were administered 400 mg of pregnenolone (n=16) or placebo (n=15) and underwent 3T functional magnetic resonance imaging while performing the shifted-attention emotion appraisal task, which probes emotional processing and regulation.

RESULTS

Compared with placebo, allopregnanolone was associated with reduced activity in the amygdala and insula across all conditions. During the appraisal condition, allopregnanolone increased activity in the dorsal medial prefrontal cortex and enhanced connectivity between the amygdala and dorsal medial prefrontal cortex, an effect that was associated with reduced self-reported anxiety.

CONCLUSIONS

These results demonstrate that in response to emotional stimuli, allopregnanolone reduces activity in regions associated with generation of negative emotion. Furthermore, allopregnanolone may enhance activity in regions linked to regulatory processes. Aberrant activity in these regions has been linked to anxiety psychopathology. These results thus provide initial neuroimaging evidence that allopregnanolone may be a target for pharmacologic intervention in the treatment of anxiety disorders and suggest potential future directions for research into neurosteroid effects on emotion regulation neurocircuitry.

The neuroactive steroid pregnenolone sulfate stimulates trafficking of functional N-methyl D-aspartate receptors to the cell surface via a noncanonical, G protein, and Ca2+-dependent mechanism

N-methyl D-aspartate (NMDA) receptors (NMDARs) mediate fast excitatory synaptic transmission and play a critical role in synaptic plasticity associated with learning and memory. NMDAR hypoactivity has been implicated in the pathophysiology of schizophrenia, and clinical studies have revealed reduced negative symptoms of schizophrenia with a dose of pregnenolone that elevates serum levels of the neuroactive steroid pregnenolone sulfate (PregS). This report describes a novel process of delayed-onset potentiation whereby PregS approximately doubles the cell's response to NMDA via a mechanism that is pharmacologically and kinetically distinct from rapid positive allosteric modulation by PregS. The number of functional cell-surface NMDARs in cortical neurons increases 60-100% within 10 minutes of exposure to PregS, as shown by surface biotinylation and affinity purification. Delayed-onset potentiation is reversible and selective for expressed receptors containing the NMDAR subunit subtype 2A (NR2A) or NR2B, but not the NR2C or NR2D, subunits. Moreover, substitution of NR2B J/K helices and M4 domain with the corresponding region of NR2D ablates rapid allosteric potentiation of the NMDA response by PregS but not delayed-onset potentiation. This demonstrates that the initial phase of rapid positive allosteric modulation is not a first step in NMDAR upregulation. Delayed-onset potentiation by PregS occurs via a noncanonical, pertussis toxin-sensitive, G protein-coupled, and Ca(2+)-dependent mechanism that is independent of NMDAR ion channel activation. Further investigation into the sequelae for PregS-stimulated trafficking of NMDARs to the neuronal cell surface may uncover a new target for the pharmacological treatment of disorders in which NMDAR hypofunction has been implicated.

Schizophrenia: linking prenatal infection to cytokines, the tryptophan catabolite (TRYCAT) pathway, NMDA receptor hypofunction, neurodevelopment and neuroprogression

In 1995, the macrophage-T lymphocyte theory of schizophrenia (Smith and Maes, 1995) considered that activated immuno-inflammatory pathways may account for the higher neurodevelopmental pathology linked with gestational infections through the detrimental effects of activated microglia, oxidative and nitrosative stress (O&NS), cytokine-induced activation of the tryptophan catabolite (TRYCAT) pathway and consequent modulation of the N-methyl d-aspartate receptor (NMDAr) and glutamate production. The aim of the present paper is to review the current state-of-the art regarding the role of the above pathways in schizophrenia. Accumulating data suggest a powerful role for prenatal infection, both viral and microbial, in driving an early developmental etiology to schizophrenia. Models of prenatal rodent infection show maintained activation of immuno-inflammatory pathways coupled to increased microglia activation. The ensuing activation of immuno-inflammatory pathways in schizophrenia may activate the TRYCAT pathway, including increased kynurenic acid (KA) and neurotoxic TRYCATs. Increased KA, via the inhibition of the α7 nicotinic acetylcholine receptor, lowers gamma-amino-butyric-acid (GABA)ergic post-synaptic current, contributing to dysregulated glutamatergic activity. Hypofunctioning of the NMDAr on GABAergic interneurons will contribute to glutamatergic dysregulation. Many susceptibility genes for schizophrenia are predominantly expressed in early development and will interact with these early developmental driven changes in the immuno-inflammatory and TRYCAT pathways. Maternal infection and subsequent immuno-inflammatory responses are additionally associated with O&NS, including lowered antioxidants such as glutathione. This will contribute to alterations in neurogenesis and myelination. In such a scenario a) a genetic or epigenetic potentiation of immuno-inflammatory pathways may constitute a double hit on their own, stimulating wider immuno-inflammatory responses and thus potentiating the TRYCAT pathway and subsequent NMDAr dysfunction and neuroprogression; and b) antipsychotic-induced changes in immuno-inflammatory, TRYCAT and O&NS pathways would modulate the CNS glia-neuronal interactions that determine synaptic plasticity as well as myelin generation and maintenance.

A review of anti-inflammatory agents for symptoms of schizophrenia

Schizophrenia is a chronic debilitating mental disorder that affects about 1% of the US population. The pathophysiology and etiology remain unknown, thus new treatment targets have been challenging and few novel treatments with new mechanisms of action have come to market in the past few decades. Increasing attention has been paid to the role of inflammation in schizophrenia and new data suggests that decreasing inflammation and inflammatory biomarkers may play some role in schizophrenia treatment. This review summarizes the clinical trial literature regarding medications that possess anti-inflammatory properties that have been tested for schizophrenia symptoms and covers such medications as non-steroidal anti-inflammatory agents, such as the cyclo-oxygenase-2 (COX-2) inhibitors and aspirin, omega-3 fatty acids, neurosteroids and minocycline. Overall, there is accumulating evidence, albeit mostly adjunctive treatments, that agents working on inflammatory pathways have some benefits in people with schizophrenia. In the next few years the field will begin to see data on many treatments with anti-inflammatory properties that are currently under study. Hopefully advancements in understanding inflammation and effective treatments having anti-inflammatory properties may help revolutionize our understanding and provide new targets for prevention and treatment in schizophrenia.

Sigma-1 receptor chaperone and brain-derived neurotrophic factor: emerging links between cardiovascular disease and depression

Epidemiological studies have demonstrated a close relationship between depression and cardiovascular disease (CVD). Although it is known that the central nervous system (CNS) contributes to this relationship, the detailed mechanisms involved in this process remain unclear. Recent studies suggest that the endoplasmic reticulum (ER) molecular chaperone sigma-1 receptor and brain-derived neurotrophic factor (BDNF) play a role in the pathophysiology of CVD and depression. Several meta-analysis studies have showed that levels of BDNF in the blood of patients with major depressive disorder (MDD) are lower than normal controls, indicating that blood BDNF might be a biomarker for depression. Furthermore, blood levels of BDNF in patients with CVD are also lower than normal controls. A recent study using conditional BDNF knock-out mice in animal models of myocardial infarction highlighted the role of CNS-mediated mechanisms in the cardioprotective effects of BDNF. In addition, a recent study shows that decreased levels of sigma-1 receptor in the mouse brain contribute to the association between heart failure and depression. Moreover, sigma-1 receptor agonists, including the endogenous neurosteroid dehydroepiandosterone (DHEA) and the selective serotonin reuptake inhibitor (SSRI) fluvoxamine, show potent cardioprotective and antidepressive effects in rodents, via sigma-1 receptor stimulation. Interestingly, agonist activation of sigma-1 receptors increased the secretion of mature BDNF from its precursor proBDNF via chaperone activity in the ER. Given the role of ER stress in the pathophysiology of CVD and MDD, the author will discuss the potential link between sigma-1 receptors and BDNF-TrkB pathway in the pathophysiology of these two diseases. Finally, the author will make a case for potent sigma-1 receptor agonists and TrkB agonists as new potential therapeutic drugs for depressive patients with CVD.

Pregnenolone rescues schizophrenia-like behavior in dopamine transporter knockout mice

Pregnenolone belongs to a class of endogenous neurosteroids in the central nervous system (CNS), which has been suggested to enhance cognitive functions through GABA(A) receptor signaling by its metabolites. It has been shown that the level of pregnenolone is altered in certain brain areas of schizophrenic patients, and clozapine enhances pregnenolone in the CNS in rats, suggesting that pregnenolone could be used to treat certain symptoms of schizophrenia. In addition, early phase proof-of-concept clinical trials have indicated that pregnenolone is effective in reducing the negative symptoms and cognitive deficits of schizophrenia patients. Here, we evaluate the actions of pregnenolone on a mouse model for schizophrenia, the dopamine transporter knockout mouse (DAT KO). DAT KO mice mirror certain symptoms evident in patients with schizophrenia, such as the psychomotor agitation, stereotypy, deficits of prepulse inhibition and cognitive impairments. Following acute treatment, pregnenolone was found to reduce the hyperlocomotion, stereotypic bouts and pre-pulse inhibition (PPI) deficits in DAT KO mice in a dose-dependent manner. At 60 mg/kg of pregnenolone, there were no significant differences in locomotor activities and stereotypy between wild-type and DAT KO mice. Similarly, acute treatment of 60 mg/kg of pregnenolone fully rescued PPI deficits of DAT KO mice. Following chronic treatment with pregnenolone at 60 mg/kg, the cognitive deficits of DAT KO mice were rescued in the paradigms of novel object recognition test and social transmission of food preference test. Pregnenolone thus holds promise as a therapeutic candidate in schizophrenia.

Special biological issues in the management of women with schizophrenia

Schizophrenia is a debilitating and pervasive mental illness with devastating effects on psychological, cognitive and social wellbeing, and for which current treatment options are far from ideal. Gender differences and the influence of the female reproductive life cycle on the onset, course and symptoms of schizophrenia and the discovery of estrogen's remarkable psychoprotective properties in animal models led to the proposal of the 'estrogen protection hypothesis' of schizophrenia. This has fueled the recent successful investigation of estradiol as a potential adjuvant therapeutic agent in the management of schizophrenia in women. This review explains the scientific rationale behind the estrogen hypothesis and how it can be clinically utilized to address concerns unique to the care of women with schizophrenia.

Neurosteroid-mediated regulation of brain innate immunity in HIV/AIDS: DHEA-S suppresses neurovirulence

Neurosteroids are cholesterol-derived molecules synthesized within the brain, which exert trophic and protective actions. Infection by human and feline immunodeficiency viruses (HIV and FIV, respectively) causes neuroinflammation and neurodegeneration, leading to neurological deficits. Secretion of neuroinflammatory host and viral factors by glia and infiltrating leukocytes mediates the principal neuropathogenic mechanisms during lentivirus infections, although the effect of neurosteroids on these processes is unknown. We investigated the interactions between neurosteroid-mediated effects and lentivirus infection outcomes. Analyses of HIV-infected (HIV(+)) and uninfected human brains disclosed a reduction in neurosteroid synthesis enzyme expression. Human neurons exposed to supernatants from HIV(+) macrophages exhibited suppressed enzyme expression without reduced cellular viability. HIV(+) human macrophages treated with sulfated dehydroepiandrosterone (DHEA-S) showed suppression of inflammatory gene (IL-1β, IL-6, TNF-α) expression. FIV-infected (FIV(+)) animals treated daily with 15 mg/kg body weight. DHEA-S treatment reduced inflammatory gene transcripts (IL-1β, TNF-α, CD3ε, GFAP) in brain compared to vehicle-(β-cyclodextrin)-treated FIV(+) animals similar to levels found in vehicle-treated FIV(-) animals. DHEA-S treatment also increased CD4(+) T-cell levels and prevented neurobehavioral deficits and neuronal loss among FIV(+) animals, compared to vehicle-treated FIV(+) animals. Reduced neuronal neurosteroid synthesis was evident in lentivirus infections, but treatment with DHEA-S limited neuroinflammation and prevented neurobehavioral deficits. Neurosteroid-derived therapies could be effective in the treatment of virus- or inflammation-mediated neurodegeneration.

Neurosteroids, stress and depression: potential therapeutic opportunities

Neurosteroids are potent and effective neuromodulators that are synthesized from cholesterol in the brain. These agents and their synthetic derivatives influence the function of multiple signaling pathways including receptors for γ-aminobutyric acid (GABA) and glutamate, the major inhibitory and excitatory neurotransmitters in the central nervous system (CNS). Increasing evidence indicates that dysregulation of neurosteroid production plays a role in the pathophysiology of stress and stress-related psychiatric disorders, including mood and anxiety disorders. In this paper, we review the mechanisms of neurosteroid action in brain with an emphasis on those neurosteroids that potently modulate the function of GABA(A) receptors. We then discuss evidence indicating a role for GABA and neurosteroids in stress and depression, and focus on potential strategies that can be used to manipulate CNS neurosteroid synthesis and function for therapeutic purposes.

Stress abnormalities in individuals at risk for psychosis: a review of studies in subjects with familial risk or with "at risk" mental state

Increased sensitivity to stress is known to play an important role in the transition to first episode psychosis (FEP). Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, and, in general, an increased sensitivity to stress, have been hypothesised to be components of the vulnerability to psychosis, but whether these abnormalities are already present before the onset of psychosis has not yet been systematically reviewed. Here we have reviewed all studies examining psychological and biological markers of the stress response in the relatives of psychotic patients and in individuals at Ultra High Risk (UHR) for psychosis. In relatives, there is evidence of increased sensitivity to stress, as shown by increased emotional reactivity to daily life stress, increased adrenocorticotropic hormone (ACTH) in response to stress, increased pituitary volume and reduced hippocampal volume. However, evidence of increased cortisol levels is less consistent. On the other hand, subjects who experience attenuated psychotic symptoms show increased cortisol levels as well as increased pituitary and reduced hippocampal volumes. Moreover, this HPA axis hyperactivity seems to be even greater among those individuals who subsequently develop frank psychosis. In summary, an enhanced HPA axis response to stress appears to be part of the biological vulnerability to psychosis which is present prior to the onset of psychosis. A further increase in cortisol levels during the transition to FEP suggests the presence of an additive factor, possibly environmental, at this stage of the illness. Possible causes and consequences of HPA axis impairment in risk for psychosis are discussed.