13-cis-Retinoic acid alters intracellular serotonin, increases 5-HT1A receptor, and serotonin reuptake transporter levels in vitro

A clinical guide to rare male sexual disorders

Conditions referred to as 'male sexual dysfunctions' usually include erectile dysfunction, ejaculatory disorders and male hypogonadism. However, some less common male sexual disorders exist, which are under-recognized and under-treated, leading to considerable morbidity, with adverse effects on individuals' sexual health and relationships. Such conditions include post-finasteride syndrome, restless genital syndrome, post-orgasmic illness syndrome, post-selective serotonin reuptake inhibitor (SSRI) sexual dysfunction, hard-flaccid syndrome, sleep-related painful erections and post-retinoid sexual dysfunction. Information about these disorders usually originates from case-control trials or small case series; thus, the published literature is scarce. As the aetiology of these diseases has not been fully elucidated, the optimal investigational work-up and therapy are not well defined, and the available options cannot, therefore, adequately address patients' sexual problems and implement appropriate treatment. Thus, larger-scale studies - including prospective trials and comprehensive case registries - are crucial to better understand the aetiology, prevalence and clinical characteristics of these conditions. Furthermore, collaborative efforts among researchers, health-care professionals and patient advocacy groups will be essential in order to develop evidence-based guidelines and novel therapeutic approaches that can effectively address these disorders. By advancing our understanding and refining treatment strategies, we can strive towards improving the quality of life and fostering healthier sexual relationships for individuals suffering from these rare sexual disorders.

Physiological and Psychological Effects of Isotretinoin in the Treatment of Patients with Acne: A Narrative Review

Isotretinoin (ISO) is a powerful vitamin A derivative that offers the potential for treatment of permanent remission of acne; however, its potential side effects on both physiological and psychological aspects limit its application. This article reviews the side effects of ISO from physiological and psychological aspects in detail, to better screen the suitable population of ISO and improve the efficiency of clinical treatment. Our findings indicate that ISO may cause teratogenicity, skin reactions, ocular reactions, changes in blood indicators, and occasional acne fulminans. To optimize clinical treatment, more attention should be paid to identifying the specific conditions under which these reactions occur, how severe they are, and how they subside to alleviate patient concerns. Regarding the controversial issue of psychological side effects caused by ISO, researchers should shift their focus to the psychological problems that acne itself may cause.

Isotretinoin and neuropsychiatric side effects: Continued vigilance is needed

Background

Isotretinoin (13-cis-retinoic acid, marketed under the names Accutane, Roaccutane, and others) is an effective treatment for acne that has been on the market for over 30 years, although reports of neuropsychiatric side effects continue to be reported. Isotretinoin is an isomer of the active form of Vitamin A, 13-trans-retinoic acid, which has known psychiatric side effects when given in excessive doses, and is part of the family of compounds called retinoids, which have multiple functions in the central nervous system.

Methods

The literature was reviewed in pubmed and psychinfo for research related to isotretinoin and neuropsychiatric side effects including depression, suicidal thoughts, suicide, mania, anxiety, impulsivity, emotional lability, violence, aggression, and psychosis.

Results

Multiple case series have shown that successful treatment of acne with isotretinoin results in improvements in measures of quality of life and self esteem However, studies show individual cases of clinically significant depression and other neuropsychiatric events that, although not common, are persistent in the literature. Since the original cases of depression were reported to the United States Food and Drug Administration, numerous cases have been reported to regulatory agencies in the United Kingdom, France, Ireland, Denmark, Australia, Canada, and other countries, making isotretinoin one of the top five medications in the world associated with depression and other neuropsychiatric side effects. Clinicians are advised to warn patients of the risks of neuropsychiatric side effects with isotretinoin which may arise from the medication itself, and not just as a side effect of acne or youth.

Retinoids as Chemo-Preventive and Molecular-Targeted Anti-Cancer Therapies

Retinoic acid (RA) agents possess anti-tumor activity through their ability to induce cellular differentiation. However, retinoids have not yet been translated into effective systemic treatments for most solid tumors. RA signaling is mediated by the following two nuclear retinoic receptor subtypes: the retinoic acid receptor (RAR) and the retinoic X receptor (RXR), and their isoforms. The identification of mutations in retinoid receptors and other RA signaling pathway genes in human cancers offers opportunities for target discovery, drug design, and personalized medicine for distinct molecular retinoid subtypes. For example, chromosomal translocation involving RARA occurs in acute promyelocytic leukemia (APL), and all-trans retinoic acid (ATRA) is a highly effective and even curative therapeutic for APL patients. Thus, retinoid-based target discovery presents an important line of attack toward designing new, more effective strategies for treating other cancer types. Here, we review retinoid signaling, provide an update on retinoid agents and the current clinical research on retinoids in cancer, and discuss how the retinoid pathway genotype affects the ability of retinoid agents to inhibit the growth of colorectal cancer (CRC) cells. We also deliberate on why retinoid agents have not shown clinical efficacy against solid tumors and discuss alternative strategies that could overcome the lack of efficacy.

Isotretinoin Use and Risk of Depression in Acne Vulgaris Patients in Riyadh, Saudi Arabia

Background The association between isotretinoin administration and depression in acne patients remains controversial. We aim to estimate the prevalence of depression among patients with acne vulgaris before and after treatment with isotretinoin in Riyadh, Saudi Arabia. Methods This was a prospective study on patients attending the King Khalid University Hospital (KKUH), a tertiary institution, who were prescribed isotretinoin for the treatment of acne vulgaris for the first time. The Beck Depression Inventory (BDI) was used to screen for depressive symptoms.  Results A total of 179 patients were included in the study. The patients were then divided into two groups based on the treatment modality that they received: one group taking isotretinoin and the other treatment group who used other medications, including Retin-A (tretinoin) and Tazorac (tazarotene). A total of 119 patients were in the isotretinoin group with 91.6%, 2.5%, 1.7%, and 3.4% of those patients having a normal mood, mild depression, moderate depression, and severe depression scores before starting isotretinoin treatment, respectively. After three months of treatment, 94.1%, 1.7%, 0.8%, and 2.5% of patients had normal mood, mild depression, moderate depression, and severe depression, respectively. Meanwhile, after six months of treatment, 95.8%, 0.8%, 0%, and 1.7% of patients had normal mood, mild depression, moderate depression, and severe depression, respectively. The mean BDI score at the baseline was 3.31 ± 6.98 for isotretinoin and 3.17 ± 6.27 for other treatments. Compared to the baseline, patients using the isotretinoin showed a significant reduction in depression scores at three months (2.64 ± 6.17; p-value < 0.001), six months (1.99 ± 5.08; p-value < 0.001), and across all follow-up points (p-value < 0.001). Similar results were also estimated for the other treatment group, including Retin-A (tretinoin), adapalene, benzoyl peroxide, and doxycycline; however, no significant difference was noticed between the two groups (p-value = 0.885). Conclusion Isotretinoin treatment for acne does not appear to be associated with a statistically significant increased risk of depression in our population. Therefore, more studies are needed to understand this reflection in Saudi Arabia.

The role of the retinoids in schizophrenia: genomic and clinical perspectives

Signalling by retinoid compounds is vital for embryonic development, with particular importance for neurogenesis in the human brain. Retinoids, metabolites of vitamin A, exert influence over the expression of thousands of transcripts genome wide, and thus, act as master regulators of many important biological processes. A significant body of evidence in the literature now supports dysregulation of the retinoid system as being involved in the aetiology of schizophrenia. This includes mechanistic insights from large-scale genomic, transcriptomic and, proteomic studies, which implicate disruption of disparate aspects of retinoid biology such as transport, metabolism, and signalling. As a result, retinoids may present a valuable clinical opportunity in schizophrenia via novel pharmacotherapies and dietary intervention. Further work, however, is required to expand on the largely observational data collected thus far and confirm causality. This review will highlight the fundamentals of retinoid biology and examine the evidence for retinoid dysregulation in schizophrenia.

Use of isotretinoin and risk of depression in patients with acne: a systematic review and meta-analysis

OBJECTIVE

This study aimed to investigate the association between the use of isotretinoin and the risk of depression in patients with acne.

DESIGN

This was a meta-analysis in which the standardised mean difference (SMD) and the relative risk (RR) were used for data synthesis employing the random-effects model.

SETTING

Studies were identified via electronic searches of PubMed, Embase and the Cochrane Library from inception up to 28 December 2017.

PARTICIPANTS

Patients with acne.

INTERVENTIONS

Studies comparing isotretinoin with other interventions in patients with acne were included.

RESULTS

Twenty studies were selected. The analysis of 17 studies showed a significant association of the use of isotretinoin with improved symptoms compared with the baseline before treatment (SMD = -0.33, 95% CI -0.51 to -0.15, p<0.05; I²=76.6%, p<0.05)). Four studies were related to the analysis of the risk of depression. The pooled data indicated no association of the use of isotretinoin with the risk of depressive disorders (RR=1.15, 95% CI 0.60 to 2.21, p=0.14). The association of the use of isotretinoin with the risk of depressive disorders was statistically significant on pooling retrospective studies (RR=1.39, 95% CI 1.05 to 1.84, p=0.02), but this association was not evident on pooling prospective studies (RR=0.85, 95% CI 0.60 to 2.21, p=0.86).

CONCLUSIONS

This study suggested an association of the use of isotretinoin in patients with acne with significantly improved depression symptoms. Future randomised controlled trials are needed to verify the present findings.

6-MOMIPP, a novel brain-penetrant anti-mitotic indolyl-chalcone, inhibits glioblastoma growth and viability

PURPOSE

3-(6-Methoxy-2-methyl-1H-indol-3-yl)-1-(4-pyridinyl)-2-propene-1-one (6-MOMIPP) is a novel indole-based chalcone that disrupts microtubules. The present study aims to define the mechanism through which 6-MOMIPP induces cell death and to evaluate the efficacy of the compound in penetrating the blood-brain barrier and inhibiting growth of glioblastoma xenografts.

METHODS

The effects of 6-MOMIPP were evaluated in cultured U251 glioblastoma cells, using viability, flow cytometry, and tubulin polymerization assays. Scintillation proximity and tubulin crosslinking methods were used to identify the binding site of 6-MOMIPP on tubulin, and western blots were performed to define the signaling pathways that contribute to cell death. LC/MS assays were used to study the pharmacokinetic behavior of 6-MOMIPP in mice. Subcutaneous and intracerebral xenograft models were utilized to assess the effects of 6-MOMIPP on growth of U251 glioblastoma in vivo.

RESULTS

The findings indicate that 6-MOMIPP targets the colchicine site on β-tubulin. At concentrations ≥ 250 nm, 6-MOMIPP induces mitotic arrest, caspase activation and loss of cell viability. Cells are protected by caspase inhibitors, pointing to an apoptotic mechanism of cell death. Loss of cell viability is preceded by activation of Cdk1(Cdc2) and phosphorylation of Bcl-2 and Bcl-xL. Inhibition of both events with a Cdk1 inhibitor prevents cell death. 6-MOMIPP has broad activity against the viability of multiple glioblastoma, melanoma and lung carcinoma cell lines. Viability of normal cells, including differentiated neurons, is not significantly affected at a drug concentration (1 µM) that reduces viability in most cancer lines. Pharmacokinetic studies in mice show that concentrations of 6-MOMIPP in the brain mirror those in the plasma, indicating that 6-MOMIPP readily penetrates the blood-brain barrier. Studies with mice bearing human U251 glioblastoma xenografts demonstrate that 6-MOMIPP is effective in suppressing growth of subcutaneous and intracerebral tumors without causing general toxicity.

CONCLUSIONS

The results indicate that 6-MOMIPP is a novel microtubule disruptor that targets the colchicine binding site on β-tubulin to induce mitotic arrest and cell death. The ability of 6-MOMIPP to penetrate the blood-brain barrier and inhibit growth of glioblastoma xenografts suggests that it warrants further preclinical evaluation as potential small-molecule therapeutic that may have advantages in treating primary and metastatic brain tumors.

New Insights Into the Roles of Retinoic Acid Signaling in Nervous System Development and the Establishment of Neurotransmitter Systems

Secreted chiefly from the underlying mesoderm, the morphogen retinoic acid (RA) is well known to contribute to the specification, patterning, and differentiation of neural progenitors in the developing vertebrate nervous system. Furthermore, RA influences the subtype identity and neurotransmitter phenotype of subsets of maturing neurons, although relatively little is known about how these functions are mediated. This review provides a comprehensive overview of the roles played by RA signaling during the formation of the central and peripheral nervous systems of vertebrates and highlights its effects on the differentiation of several neurotransmitter systems. In addition, the evolutionary history of the RA signaling system is discussed, revealing both conserved properties and alternate modes of RA action. It is proposed that comparative approaches should be employed systematically to expand our knowledge of the context-dependent cellular mechanisms controlled by the multifunctional signaling molecule RA.

Chronic retinoic acid treatment suppresses adult hippocampal neurogenesis, in close correlation with depressive-like behavior

Clinical studies have highlighted an association between retinoid treatment and depressive symptoms. As we had shown before that chronic application of all-trans retinoic acid (RA) potently activated the hypothalamus-pituitary-adrenal (HPA) stress axis, we here questioned whether RA also induced changes in adult hippocampal neurogenesis, a form of structural plasticity sensitive to stress and implicated in aspects of depression and hippocampal function. RA was applied intracerebroventricularly (i.c.v.) to adult rats for 19 days after which animals were subjected to tests for depressive-like behavior (sucrose preference) and spatial learning and memory (water maze) performance. On day 27, adult hippocampal neurogenesis and astrogliosis was quantified using BrdU (newborn cell survival), PCNA (proliferation), doublecortin (DCX; neuronal differentiation), and GFAP (astrocytes) as markers. RA was found to increase retinoic acid receptor-α (RAR-α) protein expression in the hippocampus, suggesting an activation of RA-induced signaling mechanisms. RA further potently suppressed cell proliferation, newborn cell survival as well as neurogenesis, but not astrogliosis. These structural plasticity changes were significantly correlated with scores for anhedonia, a core symptom of depression, but not with water maze performance. Our results suggest that RA-induced impairments in hippocampal neurogenesis correlate with depression-like symptoms but not with spatial learning and memory in this design. Thus, manipulations aimed to enhance neurogenesis may help ameliorate emotional aspects of RA-associated mood disorders. © 2016 Wiley Periodicals, Inc.

The 5-HT1A receptor in Major Depressive Disorder

Major Depressive Disorder (MDD) is a highly prevalent psychiatric diagnosis that is associated with a high degree of morbidity and mortality. This debilitating disorder is currently one of the leading causes of disability nationwide and is predicted to be the leading cause of disease burden by the year 2030. A large body of previous research has theorized that serotonergic dysfunction, specifically of the serotonin (5-HT) 1A receptor, plays a key role in the development of MDD. The purpose of this review is to describe the evolution of our current understanding of the serotonin 1A (5-HT1A) receptor and its role in the pathophysiology MDD through the discussion of animal, post-mortem, positron emission tomography (PET), pharmacologic and genetic studies.

Decreased vitamin B12 and folic Acid concentrations in acne patients after isotretinoin therapy: a controlled study

Background:

Oral isotretinoin treatment might influence the levels of vitamin B₁₂ and folic acid.

Aims and Objectives:

The aim of this study is to compare vitamin B₁₂ and folic acid levels in patients with moderate and severe acne vulgaris with those of the healthy control group and to investigate the effect of isotretinoin treatment on these vitamins.

Materials and Methods:

Patients who completed 6 months of isotretinoin therapy for moderate and severe forms of acne vulgaris and a control group consisting of healthy individuals between February 2011 and March 2012 were included in the study. Before isotretinoin therapy and at 6.- months of the therapy, serum vitamin B₁₂ and folic acid levels were measured. In the healthy control group, vitamin B₁₂ and folic acid levels were assessed only once.

Results:

In total, 120 patients with moderate and severe acne vulgaris who completed 6 months isotretinoin therapy and 100 healthy individuals who constituted the control group were included in the study. Pre-treatment vitamin B₁₂ values of the patient group were found to be statistically significantly higher (P = 0.002), but any statistically significant difference was not detected in folic acid measurements (P = 0.566). A statistically significant decrease was detected in post-treatment vitamin B₁₂ and folic acid levels (P < 0.05).

Conclusion:

Vitamin B₁₂/folic acid treatment should be given under medical surveillance before and during isotretinoin therapy. Supplementation of these vitamins should be recommended in cases of their deficiency, so as to decrease the risks of neuropsychiatric and occlusive vascular diseases.

A representative prescription for emotional disease, Ding-Zhi-Xiao-Wan restores 5-HT system deficit through interfering the synthesis and transshipment in chronic mild stress-induced depressive rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ding-Zhi-Xiao-Wan (DZ, also known as Kai-Xin-San) is a famous traditional Chinese medicine used for the treatment of emotional disease. Previously, we have found that in a variety of animal models of depression (such as tail suspension model, model of chronic fatigue and forced swimming model) DZ demonstrated significant antidepressant behavior and promoted the production of 5-hydroxytryptamine (5-HT). However, the mechanisms of 5-HT regulation are still unclear. Therefore, the current study is designed to further investigate the antidepressant effect of DZ by observing its influence on 5-HT synthesis, metabolism, transport and other key links, so as to clarify the molecular mechanism of its 5-HT regulation.

MATERIALS AND METHODS

Solitary rising combined with the chronic unpredictable mild stress (CMS) was used to establish the rat model of depression. The rats were given DZ for 3 weeks, the behavior change and the following items in hippocampus and prefrontal cortex were detected simultaneously: 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), tryptophan hydroxylase (TPH), aromatic amino acid decarboxylase (AADC), monoamine oxidase (MAO) and 5-HT transporter (5-HTT) were observed.

RESULTS

Our results showed that treatment with the DZ significantly improved the behavior and simultaneously increased the 5-HT level in the hippocampus, prefrontal cortex tissues and hippocampus extracellular of depressive rats. In future studies revealed that DZ could significantly increase the protein and mRNA expression of the key enzymes TPH during the 5-HT synthesis process in the hippocampus and prefrontal cortex of the depressed rats, and suppress the expression of 5-HTT protein and mRNA at the same time. But it had no effects on MAO-A and MAO-B activities.

CONCLUSION

We believe that antidepressant effect of DZ is caused by the increase of 5-HT synthesis and reduction of 5-HT re-uptake, and eventually increase the content of 5-HT in the brain and the synaptic gaps.

Retinoic acid signaling in spinal cord development

Retinoic acid (RA) is an important signaling molecule mediating intercellular communication through vertebrate development. Here, we present and discuss recent information on the roles of the RA signaling pathway in spinal cord development. RA is an important player in the patterning and definition of the spinal cord territory from very early stages of development, even before the appearance of the neural plate and further serves a role in the patterning of the spinal cord both along the dorsoventral and anteroposterior axes, particularly in the promotion of neuronal differentiation. It is thus required to establish a variety of neuronal cell types at specific positions of the spinal cord. The main goal of this review is to gather information from vertebrate models, including fish, frogs, chicken and mice, and to put this information in a comparative context in an effort to visualize how the RA pathway was incorporated into the evolving vertebrate spinal cord and to identify mechanisms that are both common and different in the various vertebrate models. In doing so, we try to reconstruct how spinal cord development has been regulated by the RA signaling cascade through vertebrate diversification, highlighting areas which require further studies to obtain a better understanding of the evolutionary events that shaped this structure in the vertebrate lineage.

Imaging the serotonin 1A receptor using [11C]WAY100635 in healthy controls and major depression

As a neurotransmitter, serotonin (5-HT) is widely used throughout the brain and known to play a role in many processes including emotion and brain development. Of the 15 subtypes of 5-HT receptors, the 1A receptor (5-HT(1A)) has been implicated in depression and suicide. Using the [carbonyl-(11)C]WAY100635 ([(11)C]WAY) ligand and positron emission tomography, we have studied the 5-HT(1A) receptor, first in a group of healthy controls, then in two separate groups of subjects with major depressive disorder (MDD) (antidepressant exposed and not recently medicated), and, lastly, in a group of subjects remitted from MDD. All MDD subjects were medication-free at the time of scan. We found higher 5-HT(1A) binding potential (BP(F)) in MDD subjects not recently exposed to an antidepressant compared with controls and recently medicated MDD subjects; and higher BP(F) in subjects with the C(-1019)G promoter polymorphism. We replicated these findings in a novel cohort and reconciled our discrepant findings with other groups using alternate quantification techniques. We also reported higher BP(F) in subjects remitted from a major depressive episode than in controls. From this work, we proposed a temporal model in which 5-HT(1A) BP(F) may be a trait abnormality of MDD. To further explore the genetic components of MDD and utility of 5-HT(1A) imaging as a potential tool for biomarker or treatment response prediction, these findings should be replicated in a larger cohort using the [(11)C]CUMI-101 agonist tracer.

Influence of chronic amphetamine treatment and acute withdrawal on serotonin synthesis and clearance mechanisms in the rat ventral hippocampus

Amphetamine withdrawal in both humans and rats is associated with increased anxiety states, which are thought to contribute to drug relapse. Serotonin in the ventral hippocampus mediates affective behaviors, and reduced serotonin levels in this region are observed in rat models of high anxiety, including during withdrawal from chronic amphetamine. This goal of this study was to understand the mechanisms by which reduced ventral hippocampus serotonergic neurotransmission occurs during amphetamine withdrawal. Serotonin synthesis (assessed by accumulation of serotonin precursor as a measure of the capacity of in vivo tryptophan hydroxylase activity), expression of serotonergic transporters, and in vivo serotonergic clearance using in vivo microdialysis were assessed in the ventral hippocampus in adult male Sprague Dawley rats at 24 h withdrawal from chronic amphetamine. Overall, results showed that diminished extracellular serotonin at 24 h withdrawal from chronic amphetamine was not accompanied by a change in capacity for serotonin synthesis (in vivo tryptophan hydroxylase activity), or serotonin transporter expression or function in the ventral hippocampus, but instead was associated with increased expression and function of organic cation transporters (low-affinity, high-capacity serotonin transporters). These findings suggest that 24 h withdrawal from chronic amphetamine reduces the availability of extracellular serotonin in the ventral hippocampus by increasing organic cation transporter-mediated serotonin clearance, which may represent a future pharmacological target for reversing anxiety states during drug withdrawal.

Effects of isotretinoin treatment on sleep in patients with severe acne: a pilot study

BACKGROUND

  There are a few case reports in literature that isotretinoin treatment may alter sleep architecture. Also studies in mice suggest a role of retinoids in the contribution of delta oscillations to the sleep electroencephalography.

OBJECTIVES

  The aim of this study was to investigate the effect of isotretinoin treatment on sleep architecture using polysomnography (PSG).

PATIENTS AND METHODS

  Twelve severe acne vulgaris patients without any psychiatric and sleep disorders were treated with 0.5 mg/kg of isotretinoin. Clinician-administered acne questionnaire, psychiatric examination, Epworth sleepiness scale and PSG recordings were performed after the first month of treatment.

RESULTS

  Sleep efficiency was increased from 83.5% (62.8-89.0%, quartiles) to 89.5% (81.5-93.5%, quartiles; P = 0.036) and sleep latency decreased from 18.0 min (11.1-36.3, quartiles) to 15.5 min (9.3-19.0, quartiles; P = 0.023) following 1-month isotretinoin treatment. There were no significant changes in other sleep parameters of PSG and scores of Epworth sleepiness scale.

CONCLUSIONS

  This study suggests that isotretinoin treatment slightly improves night-time sleep without any effects on sleep stages and daytime sleepiness.

An enzymatic mechanism for generating the precursor of endogenous 13-cis retinoic acid in the brain

13-cis Retinoic acid (13cRA), a stereoisomeric form of retinoic acid, is naturally generated in the body and is also used clinically to treat acute promyelocytic leukemia, some skin diseases and cancer. Furthermore, it has been suggested that 13cRA modulates brain neurochemical systems because increased 13cRA levels are correlated with depression and increased suicidal tendencies. However, the mechanism for the generation of endogenous 13cRA is not well understood. The present study identified and characterized a novel enzyme in zebrafish brain, 13-cis isomerohydrolase (13cIMH) (EC 5.2.1.7), which exclusively generated 13-cis retinol and can be oxidized to 13cRA. 13cIMH shares 74% amino acid sequence identity with human retinal pigment epithelium specific 65 kDa protein (RPE65), an 11-cis isomerohydrolase in the visual cycle, and retains the key residues essential for the isomerohydrolase activity of RPE65. Similar to RPE65, 13cIMH is a membrane-associated protein, requires all-trans retinyl ester as its intrinsic substrate, and its enzymatic activity is dependent on iron. The purified 13cIMH converted all-trans retinyl ester exclusively to 13-cis retinol with K(m)  = 2.6 μm and k(cat) = 4.4 × 10(-4) ·s(-1) . RT-PCR, western blot analysis and immunohistochemistry detected 13cIMH expression in the brain. These results suggest that 13cIMH may play a key role in the generation of 13cRA, as well as in the modulation of neuronal functions in the brain.

Chronic administration of 13-cis-retinoic acid does not alter the number of serotoninergic neurons in the mouse raphe nuclei

The synthetic retinoid 13-cis-retinoic acid (13-cis-RA), prescribed for the treatment of severe nodular acne, has been linked to an increased incidence of depression. Chronic treatment studies in rodents have shown that 13-cis-RA induces an increase in depression-related behaviours and a functional uncoupling of the hippocampus and dorsal raphe nucleus (DRN). Changes in the number of serotoninergic neurons in the DRN have been reported in depressed human patients. Given that retinoids have apoptotic effects, we hypothesized that a decrease in the number of serotoninergic neurons in the DRN or median raphe nucleus (MRN) would lead to decreased serotoninergic tone and in turn to the behavioural changes seen with 13-cis-RA administration. Here, we used immunolabelling and unbiased stereological methods to estimate the number of serotonin (5-hydroxytryptamine, 5-HT) neurons in the MRN and DRN of vehicle control and 13-cis-RA-treated adult mice. In the MRN, the number of 5-HT immunolabelled cells was 1815±194 in control, compared with 1954±111 in 13-cis-RA treated tissues. The number of 5-HT immunolabelled cells was much higher in the DRN, with 7148±377 cells in the control, compared with 7578±424 in the 13-cis-RA treated group. Further analysis of the DRN revealed that there were no changes in the number of 5-HT neurons within distinct subregions of the DRN. Similarly, changes in the density of serotoninergic neurons or in the volume of the MRN or DRN were not observed in 13-cis-RA treated animals. These data show that apoptotic actions of 13-cis-RA do not occur in vivo at drug concentrations that induce changes in depression-related behaviour and functional uncoupling of the DRN and hippocampus. The potential pro-depressant behavioural and molecular effects associated with chronic administration of 13-cis-RA may result from changes in serotoninergic activity rather than changes in the number of serotoninergic neurons.

Association of suicide attempts with acne and treatment with isotretinoin: retrospective Swedish cohort study

OBJECTIVE

To assess the risk of attempted suicide before, during, and after treatment with isotretinoin for severe acne.

DESIGN

Retrospective cohort study linking a named patient register of isotretinoin users (1980-9) to hospital discharge and cause of death registers (1980-2001).

SETTING

Sweden, 1980-2001. Population 5756 patients aged 15 to 49 years prescribed isotretinoin for severe acne observed for 17 197 person years before, 2905 person years during, and 87 120 person years after treatment.

MAIN OUTCOME MEASURES

Standardised incidence ratio (observed number divided by expected number of suicide attempts standardised by sex, age, and calendar year), calculated up to three years before, during, and up to 15 years after end of treatment.

RESULTS

128 patients were admitted to hospital for attempted suicide. During the year before treatment, the standardised incidence ratio for attempted suicide was raised: 1.57 (95% confidence interval 0.86 to 2.63) for all (including repeat) attempts and 1.36 (0.65 to 2.50) counting only first attempts. The standardised incidence ratio during and up to six months after treatment was 1.78 (1.04 to 2.85) for all attempts and 1.93 (1.08 to 3.18) for first attempts. Three years after treatment stopped, the observed number of attempts was close to the expected number and remained so during the 15 years of follow-up: standardised incidence ratio 1.04 (0.74 to 1.43) for all attempts and 0.97 (0.64 to 1.40) for first attempts. Twelve (38%) of 32 patients who made their first suicide attempt before treatment made a new attempt or committed suicide thereafter. In contrast, 10 (71%) of the 14 who made their first suicide attempt within six months after treatment stopped made a new attempt or committed suicide during follow-up (two sample test of proportions, P=0.034). The number needed to harm was 2300 new six month treatments per year for one additional first suicide attempt to occur and 5000 per year for one additional repeat attempt.

CONCLUSIONS

An increased risk of attempted suicide was apparent up to six months after the end of treatment with isotretinoin, which motivates a close monitoring of patients for suicidal behaviour for up to a year after treatment has ended. However, the risk of attempted suicide was already rising before treatment, so an additional risk due to the isotretinoin treatment cannot be established. As patients with a history of suicide attempts before treatment made new attempts to a lesser extent than did patients who started such behaviour in connection with treatment, patients with severe acne should not automatically have isotretinoin treatment withheld because of a history of attempted suicide.

13-Cis-retinoic acid decreases hypothalamic cell number in vitro

13-Cis-retinoic acid (13-cis-RA) causes depression-related behavior in mice. Hypothalamic dysregulation has been implicated in clinical depression. In fact, apoptosis of hypothalamic neurons may lead to depression after myocardial infarction. Our objective was to determine if 13-cis-RA affects cultured hypothalamic cell number. Treatment of GT1-7 hypothalamic cells with 10μM 13-cis-RA for 48h decreased cell growth to 45.6±13% of control. To determine if this decrease in cell number was due to 13-cis-RA acting as an oxidant, cells were treated with 13-cis-RA and ascorbic acid or butylated hydroxyanisole (BHA) for 24 or 48h. Neither antioxidant alleviated the inhibitory affects of 13-cis-RA. In addition, 13-cis-RA treatment did not increase superoxide anion production, indicating 13-cis-RA was not acting as an oxidant. To determine if 13-cis-RA was acting via retinoic acid receptors (RARs) to decrease cell number, GT1-7 cells were treated with 13-cis-RA and the RAR pan-antagonist, AGN 193109. Treatment with the RAR-antagonist blocked the ability of 13-cis-RA to decrease cell number, indicating this phenomenon was a RAR-independent mechanism. We hypothesize that the ability of 13-cis-RA to decrease hypothalamic cell number may contribute to the increased depression-related behaviors observed in mice.

Higher serotonin 1A binding in a second major depression cohort: modeling and reference region considerations

BACKGROUND

Serotonin 1A receptors (5-HT(1A)) are implicated in major depressive disorder (MDD). We previously reported higher 5-HT(1A) binding potential (BP(F)) in antidepressant naive MDD subjects compared with control subjects, while other studies report lower BP(ND). Discrepancies can be related to differences in study population or methodology. We sought to replicate our findings in a novel cohort and determine whether choice of reference region and outcome measure could explain discrepancies.

METHODS

Nine new control subjects and 22 new not recently medicated (NRM) MDD subjects underwent positron emission tomography. BP(F) and BP(ND) were determined using a metabolite and free fraction corrected arterial input function. BP(ND) was also determined using cerebellar gray matter (CGM) and cerebellar white matter (CWM) reference regions as input functions.

RESULTS

BP(F) was higher in the new NRM cohort (p = .037) compared with new control subjects, comparable to the previous cohort (p = .04). Cohorts were combined to examine the reference region and outcome measure. BP(F) was higher in the NRM compared with control subjects (p = .0001). Neither BP(ND) using CWM (p = .86) nor volume of distribution (V(T)) (p = .374) differed between groups. When CGM was used, the NRM group had lower 5-HT(1A) BP(ND) compared with control subjects (p = .03); CGM V(T) was higher in NRM compared with control subjects (p = .007).

CONCLUSIONS

Choice of reference region and outcome measure can produce different 5-HT(1A) findings. Higher 5-HT(1A) BP(F) in MDD was found with the method with fewest assumptions about nonspecific binding and a reference region without receptors.

Onset of Kleine-Levin Syndrome in association with isotretinoin treatment

The synthetic retinoid isotretinoin is an effective treatment option for severe forms of acne vulgaris. However, several reports indicate that some patients experience altered central nervous system functions in association with treatment. We present here the first description of the onset of Kleine-Levin Syndrome (KLS), a rare disorder characterised by periodic hypersomnia and cognitive and behavioural symptoms, in close temporal relation to the start of isotretinoin treatment. We also discuss the biological potential of retinoids to affect sleep.

CONCLUSIONS

In light of a documented potential of retinoids to modulate sleep-wake regulation, the present case suggests that isotretinoin may rarely trigger the onset of KLS.

Chronic treatment with 13-cis-retinoic acid changes aggressive behaviours in the resident-intruder paradigm in rats

Retinoids, vitamin A related compounds, have an established role in the development of the nervous system and are increasingly recognized to play a role in adult brain function. The synthetic retinoid, 13-cis-retinoic acid (13-cis-RA, Roaccutane) is widely used to treat severe acne but has been linked to an increased risk of neuropsychiatric side effects, including depression. Here we report that chronic administration with 13-cis-RA (1 mg/kg i.p. daily, 7-14 days) in adult rats reduced aggression- and increased flight-related behaviours in the resident-intruder paradigm. However, in the forced swim, sucrose consumption and open field tests treatment for up to 6 weeks with 13-cis-RA did not modify behaviour in adult or juvenile animals. The behavioural change observed in the resident-intruder paradigm is directly opposite to that observed with chronic antidepressant administration. These findings indicate that when a suitably sensitive behavioural test is employed then chronic administration of 13-cis-RA in adult rats induces behavioural changes consistent with a pro-depressant action.

On the association between low resting heart rate and chronic aggression: retinoid toxicity hypothesis

Low resting heart rate is a strong and consistent predictor of conduct disorder and chronic aggression. Explanations such as fearlessness and low arousal-induced stimulus-seeking have been offered, assuming a causal association between the phenomena, but the origin of low heart rate and its significance for understanding aggression and violence remain obscure. Retinoids (vitamin A and its congeners) play important roles in embryogenesis and neural development. Several lines of evidence also suggest a causal role of retinoids in aggression as well as cognitive and mood disorders. The hypothesis is proposed that retinoid overexpression in utero induces, via a noradrenergic-to-cholinergic switch, alterations in cardiac functioning and hemodynamics resulting in low resting heart rate, brain structural and functional changes, minor physical anomalies, and persistent aggression. Retinoid toxicity occurring early in pregnancy could represent a final common pathway by which various prenatal challenges result in conduct disorder and chronic aggression (e.g., maternal cigarette smoking, alcohol consumption, drug use, exposure to environmental chemicals, stress, trauma or infection). Implications of the model for understanding related aspects of chronic aggression are discussed, as well as strategies for prevention and treatment.

Isotretinoin and psychopathology: a review

Isotretinoin, a synthetic oral retinoid that is used against severe nodulocystic acne, has been associated with various psychiatric side effects such as depression, suicidality and psychotic symptoms. A great number of reports on its effects have been published since its introduction into the market. However, a causal relationship has not been established and the link between isotretinoin use and psychiatric events remains controversial. The present paper reviews the available evidence regarding the association of isotretinoin and psychiatric side effects. All published material reporting psychiatric side effects following isotretinoin treatment, including case reports, case series, reports from adverse drug event reporting systems, prospective surveys and retrospective case-control studies, are presented. In addition, the neurobiology of the retinoids and possible biological mechanisms that may lead to psychopathology are described.

Chronic 13-cis-retinoic acid administration disrupts network interactions between the raphe nuclei and the hippocampal system in young adult mice

Previously, we showed that chronic administration of 13-cis-retinoic acid (13-cis-RA) induces depression-related behaviors in mice and that 13-cis-RA alters components of the serotonergic system in vitro. Work by others has shown that 13-cis-RA reduces hippocampal neurogenesis in mice and orbitofrontal cortex metabolism in humans. In the current study, we measured cytochrome oxidase activity, a metabolic marker that reflects steady state neuronal energy demand, in various regions of the brain to determine the effects of 13-cis-RA on neuronal metabolic activity and network interactions between the raphe nuclei and the hippocampal system. Brain cytochrome oxidase activity in young adult male mice was analyzed following 6 weeks of daily 13-cis-RA (1 mg/kg) or vehicle injection and behavioral testing. Chronic 13-cis-RA administration significantly decreased cytochrome oxidase activity only in the inferior rostral linear nucleus of the raphe. However, covariance analysis of interregional correlations in cytochrome oxidase activity revealed that 13-cis-RA treatment caused a functional uncoupling between the dorsal raphe nuclei and the hippocampus. Furthermore, a path analysis indicated that a network comprising lateral habenula to dorsal raphe to hippocampus was effectively uncoupled in 13-cis-RA treated animals. Finally, cytochrome oxidase activity in the dentate gyrus of 13-cis-RA treated mice was inversely correlated with depression-related behavior. Taken together, these data show that 13-cis-RA alters raphe metabolism and disrupts functional connectivity between the raphe nuclei and the hippocampal formation, which may contribute to the observed increase in depression-related behaviors.

Dietary retinoic acid affects song maturation and gene expression in the song system of the zebra finch

Vitamin A, an essential nutrient, is required in its acidic form (retinoic acid) for normal embryogenesis and neuronal development, typically within well-defined concentration ranges. In zebra finches, a songbird species, localized retinoic acid synthesis in the brain is important for the development of song, a learned behavior sharing significant commonalities with speech acquisition in humans. We tested how dietary retinoic acid affects the development of song behavior and the brain's system for song control. Supplemental doses of retinoic acid given to juveniles during the critical period for song learning resulted in more variable or plastic-like songs when the birds reached adulthood, compared to the normal songs of vehicle-fed controls. We also observed that several genes (brinp1, nrgn, rxr-alpha, and sdr2/scdr9) had altered levels of expression in specific nuclei of the song system when comparing the experimental and control diet groups. Interestingly, we found significant correlations between gene expression levels in nuclei of the anterior forebrain pathway (lMAN and area X) and the degree of variability in the recorded songs. We observed, however, no major morphological effects such as changes in the volumes of song nuclei. Overall, our results lend further support to a fundamental role of retinoic acid in song maturation and point to possible molecular pathways associated with this action. The data also demonstrate that dietary content of Vitamin A can affect the maturation of a naturally learned complex behavior.

RAR/RXR and PPAR/RXR signaling in neurological and psychiatric diseases

Retinoids are important signals in brain development. They regulate gene transcription by binding to retinoic acid receptors (RAR) and, as was discovered recently, a peroxisome proliferator-activated receptor (PPAR). Traditional ligands of PPAR are best known for their functions in lipid metabolism and inflammation. RAR and PPAR are ligand-activated transcription factors, which share members of the retinoid X receptor (RXR) family as heterodimeric partners. Both signal transduction pathways have recently been implicated in the progression of neurodegenerative and psychiatric diseases. Since inflammatory processes contribute to various neurodegenerative diseases, the anti-inflammatory activity of retinoids and PPARgamma agonists recommends them as potential therapeutic targets. In addition, genetic linkage studies, transgenic mouse models and experiments with vitamin A deprivation provide evidence that retinoic acid signaling is directly involved in physiology and pathology of motoneurons, of the basal ganglia and of cognitive functions. The activation of PPAR/RXR and RAR/RXR transcription factors has therefore been proposed as a therapeutic strategy in disorders of the central nervous system.

Retinoid-mediated regulation of mood: possible cellular mechanisms

Vitamin A and its derivatives, the retinoids, have long been studied for their ability to alter central nervous system (CNS) development. Increasingly, it is recognized that sufficient levels of retinoids may also be required for adult CNS function. However, excess dietary vitamin A, due to the consumption of supplements or foods rich in vitamin A, has been reported to induce psychosis. In addition, 13-cis-retinoic acid (13-cis-RA, isotretinoin), the active ingredient in the acne treatment Accutane, has been reported to cause adverse psychiatric events, including depression and suicidal ideation. Nevertheless, epidemiological studies have reported no consistent link between Accutane use and clinical depression in humans. Using an animal model, we have recently shown that 13-cis-RA induces an increase in depression-related behavior. Impairments in spatial learning and memory have also been demonstrated following 13-cis-RA treatment in mice. This review focuses on the behavioral and possible cellular effects of retinoid deficiency or excess in the adult brain in relation to altered mood. Specifically, we discuss the effect of retinoids on depression-related behaviors and whether norepinephrinergic, dopaminergic, or serotonergic neurotransmitter systems may be impaired. In addition, we consider the evidence that adult neurogenesis, a process implicated in the pathophysiology of depression, is reduced by retinoid signaling. We suggest that 13-cis-RA treatment may induce depression-related behaviors by decreasing adult neurogenesis and/or altering the expression of components of serotonergic neurotransmitter system, thereby leading to impaired serotonin signaling.