Genome-wide association study of panic disorder reveals genetic overlap with neuroticism and depression.

Panic disorder (PD) has a lifetime prevalence of 2-4% and heritability estimates of 40%. The contributory genetic variants remain largely unknown, with few and inconsistent loci having been reported. The present report describes the largest genome-wide association study (GWAS) of PD to date comprising genome-wide genotype data of 2248 clinically well-characterized PD patients and 7992 ethnically matched controls. The samples originated from four European countries (Denmark, Estonia, Germany, and Sweden). Standard GWAS quality control procedures were conducted on each individual dataset, and imputation was performed using the 1000 Genomes Project reference panel. A meta-analysis was then performed using the Ricopili pipeline. No genome-wide significant locus was identified. Leave-one-out analyses generated highly significant polygenic risk scores (PRS) (explained variance of up to 2.6%). Linkage disequilibrium (LD) score regression analysis of the GWAS data showed that the estimated heritability for PD was 28.0-34.2%. After correction for multiple testing, a significant genetic correlation was found between PD and major depressive disorder, depressive symptoms, and neuroticism. A total of 255 single-nucleotide polymorphisms (SNPs) with p < 1 × 10-4 were followed up in an independent sample of 2408 PD patients and 228,470 controls from Denmark, Iceland and the Netherlands. In the combined analysis, SNP rs144783209 showed the strongest association with PD (pcomb = 3.10 × 10-7). Sign tests revealed a significant enrichment of SNPs with a discovery p-value of <0.0001 in the combined follow up cohort (p = 0.048). The present integrative analysis represents a major step towards the elucidation of the genetic susceptibility to PD.

A Complex Impact of Systemically Administered 5-HT2A Receptor Ligands on Conditioned Fear.

BACKGROUND: Though drugs binding to serotonergic 5-HT2A receptors have long been claimed to influence human anxiety, it remains unclear if this receptor subtype is best described as anxiety promoting or anxiety dampening. Whereas conditioned fear expressed as freezing in rats is modified by application of 5-HT2A-acting drugs locally into different brain regions, reports on the effect of systemic administration of 5-HT2A receptor agonists and 5-HT2A antagonists or inverse agonists on this behavior remain sparse. METHODS: We assessed the possible impact of systemic administration of 5-HT2A receptor agonists, 5-HT2A receptor inverse agonists, and a selective serotonin reuptake inhibitor (SSRI)-per se or in combination-on the freezing displayed by male rats when re-exposed to a conditioning chamber in which they received foot shocks 7 days earlier. RESULTS: The 5-HT2A receptor agonists psilocybin and 25CN-NBOH induced a reduction in conditioned fear that was countered by pretreatment with 5-HT2A receptor inverse agonist MDL 100907. While both MDL 100907 and another 5-HT2A receptor inverse agonist, pimavanserin, failed to impact freezing per se, both compounds unmasked a robust fear-reducing effect of an SSRI, escitalopram, which by itself exerted no such effect. CONCLUSIONS: The results indicate that 5-HT2A receptor activation is not a prerequisite for normal conditioned freezing in rats but that this receptor subtype, when selectively over-activated prior to expression, exerts a marked fear-reducing influence. However, in the presence of an SSRI, the 5-HT2A receptor, on the contrary, appears to counter an anti-freezing effect of the enhanced extracellular serotonin levels following reuptake inhibition.

Low SSRI dosing in clinical practice-a register-based longitudinal study.

OBJECTIVE: Since several recent meta-analyses report a dose-response relationship for the antidepressant effect of the selective serotonin reuptake inhibitors (SSRIs), we investigated how these drugs are dosed in clinical practice. METHODS: Through linkage of nation- or region-wide registers, we describe SSRI doses in 50,365 individuals residing in Region Västra Götaland, Sweden, with an incident diagnosis of depression and initiating SSRI treatment between 2007 and 2016. The primary question was to elucidate to what extent these individuals had been prescribed a daily dose that according to recent meta-analyses is required to elicit the maximum antidepressant effect, that is >20 mg citalopram, >10 mg escitalopram, >10 mg fluoxetine, >10 mg paroxetine or >50 mg sertraline. RESULTS: In all, 21,049 (54%) out of 38,868 individuals <65 years of age, and 9,131 (79%) out of 11,497 individuals ≥65 years of age, never received an SSRI dose reported to exert maximum antidepressant effect. These prescribing practices were seen for citalopram, escitalopram and sertraline, but not for fluoxetine and paroxetine, and were frequent in both primary and secondary/tertiary care. Suggesting that doses here defined as maximum efficacy doses, when prescribed, are usually not intolerable, between 59% and 68% of individuals <65 years of age received such a dose also for the subsequent prescription, that is as frequently as in those prescribed a sub-maximum efficacy dose (52-69%). CONCLUSION: Most patients being prescribed an SSRI to treat their depression never receive the dose that according to recent meta-analyses is most likely to effectively combat their condition. The lack of consensus regarding effective dosing of SSRIs may have contributed to this state of affairs.

Determining maximal achievable effect sizes of antidepressant therapies in placebo-controlled trials.

OBJECTIVE: Antidepressants outperform placebo with an effect size of around 0.30. It has been suggested that effect sizes as high as 0.875 are necessary for a minimal clinically important difference. Whether such effect sizes are achievable in placebo-controlled trials is unknown. Therefore, we aimed to assess what effect sizes are theoretically achievable in placebo-controlled trials of antidepressants. METHODS: Patient-level analyses comparing Hamilton Depression Rating Scale (HDRS-17) outcomes for simulated antidepressant therapies to placebo-treated participants (n = 2201) from clinical trials of selective serotonin reuptake inhibitors. RESULTS: An optimally effective antidepressant, where all treated participants achieve HDRS-17 scores comparable to those displayed by healthy volunteers (remission-type model), had a maximum effect size of 1.75, with a mean difference of 11.6 points on the HDRS-17. In simulations where patients received an additional 50% symptom reduction over that obtained with placebo (improvement-type model), the maximum effect size was 1.08 with a mean HDRS-17 difference of 7.2. When adjusting for normal rates of treatment discontinuation, maximum effect sizes were 1.10 (remission-type model) and 0.76 (improvement-type model) with HDRS-17 mean differences of 8.8 and 5.6, respectively. CONCLUSIONS: Three methodological issues (i) a large and variable placebo response, (ii) a high rate of dropout and (iii) HDRS-17-ratings significantly larger than zero in healthy volunteers, reduce the degree of treatment-placebo separation achievable in depression trials. Assuming that those who discontinue treatment have only partial response, even a highly effective antidepressant would have difficulties surpassing such effect size cut-offs as have been suggested to signify a minimal clinically important difference.

Serotonin depletion reduces both acquisition and expression of context-conditioned fear.

OBJECTIVE: Whereas numerous experimental and clinical studies suggest a complex involvement of serotonin in the regulation of anxiety, it remains to be clarified if the dominating impact of this transmitter is best described as anxiety-reducing or anxiety-promoting. The aim of this study was to assess the impact of serotonin depletion on acquisition, consolidation, and expression of conditioned fear. METHODS: Male Sprague-Dawley rats were exposed to foot shocks as unconditioned stimulus and assessed with respect to freezing behaviour when re-subjected to context. Serotonin depletion was achieved by administration of a serotonin synthesis inhibitor, para-chlorophenylalanine (PCPA) (300 mg/kg daily × 3), (i) throughout the period from (and including) acquisition to (and including) expression, (ii) during acquisition but not expression, (iii) after acquisition only, and (iv) during expression only. RESULTS: The time spent freezing was significantly reduced in animals that were serotonin-depleted during the entire period from (and including) acquisition to (and including) expression, as well as in those being serotonin-depleted during either acquisition only or expression only. In contrast, PCPA administrated immediately after acquisition, that is during memory consolidation, did not impact the expression of conditioned fear. CONCLUSION: Intact serotonergic neurotransmission is important for both acquisition and expression of context-conditioned fear.

Expression of 22 serotonin-related genes in rat brain after sub-acute serotonin depletion or reuptake inhibition.

OBJECTIVE: Although the assessment of expression of serotonin-related genes in experimental animals has become a common strategy to shed light on variations in brain serotonergic function, it remains largely unknown to what extent the manipulation of serotonin levels causes detectable changes in gene expression. We therefore chose to investigate how sub-acute depletion or elevation of brain serotonin influences the expression of a number of serotonin-related genes in six brain areas. METHODS: Male Wistar rats were administered a serotonin synthesis inhibitor, para-chlorophenylalanine (p-CPA), or a serotonin reuptake inhibitor, paroxetine, for 3 days and then sacrificed. The expression of a number of serotonin-related genes in the raphe nuclei, hypothalamus, amygdala, striatum, hippocampus and prefrontal cortex was investigated using real-time quantitative PCR (rt-qPCR). RESULTS: While most of the studied genes were uninfluenced by paroxetine treatment, we could observe a robust downregulation of tryptophan hydroxylase-2 in the brain region where the serotonergic cell bodies reside, that is, the raphe nuclei. p-CPA induced a significant increase in the expression of Htr1b and Htr2a in amygdala and of Htr2c in the striatum and a marked reduction in the expression of Htr6 in prefrontal cortex; it also enhanced the expression of the brain-derived neurotrophic factor (Bdnf) in raphe and hippocampus. CONCLUSION: With some notable exceptions, the expression of most of the studied genes is left unchanged by short-term modulation of extracellular levels of serotonin.

Good news regarding SSRI safety in Danish meta-analysis.

In two previous letters on an selective serotonin reuptake inhibitor (SSRI) meta-analysis conducted by the Copenhagen Trial Unit at Copenhagen University Hospital, we have commented on a large number of errors, almost all of which have tilted the results in an anti-drug direction, that unfortunately mar this publication. While the authors have acknowledged many of these mishaps, and may now be expected to submit an extensive errata list to the journal where their paper was once published, we regretfully note that also their latest contribution to this exchange is surprisingly inaccurate. However, its many shortcomings notwithstanding, their meta-analysis does add to the current literature by confirming that SSRIs do not seem to enhance the risk for suicide or death, and also that these drugs seem to enhance the risk of side effects categorised as serious only in the elderly.

Selective serotonin reuptake inhibition increases noise burst-induced unconditioned and context-conditioned freezing.

OBJECTIVE: Whereas long-term administration of selective serotonin reuptake inhibitors (SSRIs) is effective for the treatment of anxiety disorders, acute administration of these drugs may exert a paradoxical anxiogenic effect. The aim of the present study was to explore the possible effect of an SSRI in situations of unconditioned or limited conditioned fear. METHODS: Male Sprague Dawley rats were administered a single dose of an SSRI, escitalopram, before acquisition or expression of context conditioned fear, where noise bursts were used as the unconditioned stimulus. Freezing was assessed as a measure of unconditioned fear (=the acute response to noise bursts) or conditioned fear (=the response to the context), respectively. RESULTS: Noise bursts elicited an acute increase in freezing but no robust conditioned response 7 days after exposure. Administration of escitalopram before testing exacerbated the freezing response during presentation of the unconditioned stimulus and also unmasked a conditioned response; in contrast, administration of escitalopram prior to acquisition did not influence the conditioned response. CONCLUSION: The data suggest that freezing in rats exposed to a stimulus inducing relatively mild fear may be enhanced by acute pretreatment with an SSRI regardless of whether the freezing displayed by the animals is an acute unconditioned response to the stimulus in question or a conditioned response to the same stimulus.

Effects of selective serotonin reuptake inhibitors on rating-scale-assessed suicidality in adults with depression.

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) have been claimed to elicit or aggravate suicidal ideation. Aims To explore the effect of SSRIs on the suicidality item of the Hamilton Rating Scale for Depression (HRSD). METHOD: We undertook a patient-level mega-analysis of adults with depression participating in industry-sponsored studies of sertraline, paroxetine or citalopram, comparing patients on an SSRI (n = 5681) with those on placebo (n = 2581) with respect to HRSD-rated suicidality. Separate analyses were conducted for young adults (age 18-24; n = 537) and adults (age ≥25; n = 7725). RESULTS: Among adults, the reduction in mean rating of suicidality was larger and the risk for aggravation of suicidality lower in patients receiving an SSRI from week 1 and onwards. In young adults, SSRI treatment neither reduced nor increased suicidality ratings relative to placebo at the end-point. CONCLUSIONS: The net effect of SSRIs on suicidality appears beneficial in people above the age of 24 and neutral in those aged 18-24. Declaration of interest F.H. has received speaker's fees from Servier. E.E. has previously been on the advisory boards and/or received speaker's honoraria and/or research grants from Eli Lilly, GlaxoSmithKline, Servier and Lundbeck.

Katakam and co-workers have not shown SSRIs to be harmful and ineffective and should stop claiming that they have.

Funded by the Danish state to provide guidance in health-related matters, the Copenhagen Trial Unit (CTU) at Rigshospitalet may cause considerable societal harm if allowing their analyses to be influenced by bias and prejudice rather than rigor and impartiality. This is why we found it worthwhile to comment on a report from the CTU in which the authors invoked analyses marred by numerous errors and methodological mistakes to claim that selective serotonin reuptake inhibitors (SSRIs) are harmful and ineffective. The CTU group has now produced a response to our comment which is on par with their original contribution in terms of bias, misconceptions and mistakes. Our conclusion is that the reputation of the CTU would be best served by the authors asking for retraction of their SSRI paper.

Multiple possible inaccuracies cast doubt on a recent report suggesting selective serotonin reuptake inhibitors to be toxic and ineffective.

According to a systematic review on the use of selective serotonin reuptake inhibitors (SSRIs) in adult depression that was recently published in BMC Psychiatry, the results of which have been widely disseminated in lay media, these drugs increase the risk for serious adverse events (SAEs) while exerting poor antidepressant efficacy. A cursory analysis, however, suggests the analysis of SAEs conducted by the authors to be marred by both methodological inaccuracies and blatant errors. After having corrected for these apparent mistakes, we conducted a sensitivity analysis in which we also accounted for a possible moderating effect of age; while this suggests SSRIs to be safe drugs in the non-elderly, they do confirm what is already known, that is, that they may enhance the risk for SAEs in the old. Given the loose definition of SAE, including also innocuous phenomena, the possible clinical significance of the latter observation, however, remains unclear until the nature and actual impact of the SAEs in question have been clarified. Moreover, with respect to efficacy, we find the paper in BMC Psychiatry misleading: first, the authors seem unaware of the well-established shortcomings associated with the conventional efficacy parameter on which their analysis is based, second, they have included suboptimal SSRI doses and third, they have missed some pivotal trials. Unless there are explanations for the many peculiarities in this paper that have escaped us, and which may be satisfactorily clarified by the authors, it seems important that the conclusions presented in this paper be publicly rectified.

A genetic association study of CSMD1 and CSMD2 with cognitive function.

The complement cascade plays a role in synaptic pruning and synaptic plasticity, which seem to be involved in cognitive functions and psychiatric disorders. Genetic variants in the closely related CSMD1 and CSMD2 genes, which are implicated in complement regulation, are associated with schizophrenia. Since patients with schizophrenia often show cognitive impairments, we tested whether variants in CSMD1 and CSMD2 are also associated with cognitive functions per se. We took a discovery-replication approach, using well-characterized Scandinavian cohorts. A total of 1637 SNPs in CSMD1 and 206 SNPs in CSMD2 were tested for association with cognitive functions in the NCNG sample (Norwegian Cognitive NeuroGenetics; n=670). Replication testing of SNPs with p-value<0.001 (7 in CSMD1 and 3 in CSMD2) was carried out in the TOP sample (Thematically Organized Psychosis; n=1025) and the BETULA sample (Betula Longitudinal Study on aging, memory and dementia; n=1742). Finally, we conducted a meta-analysis of these SNPs using all three samples. The previously identified schizophrenia marker in CSMD1 (SNP rs10503253) was also included. The strongest association was observed between the CSMD1 SNP rs2740931 and performance in immediate episodic memory (p-value=5×10-6, minor allele A, MAF 0.48-0.49, negative direction of effect). This association reached the study-wide significance level (p⩽1.2×10-5). SNP rs10503253 was not significantly associated with cognitive functions in our samples. In conclusion, we studied n=3437 individuals and found evidence that a variant in CSMD1 is associated with cognitive function. Additional studies of larger samples with cognitive phenotypes will be needed to further clarify the role of CSMD1 in cognitive phenotypes in health and disease.

The ACE Gene Is Associated with Late-Life Major Depression and Age at Dementia Onset in a Population-Based Cohort.

OBJECTIVE: Depression and dementia in the elderly have been suggested to share similar risk factors and pathogenetic background, and recently the authors reported that the APOEɛ4 allele is a risk factor for both disorders in the general population. The aim of the present study was to examine the influence of the well-known polymorphisms rs1799752 in the angiotensin-converting enzyme (ACE) and rs5186 in the angiotensin receptor II type 1 (AGTR1) on late-life depression and dementia in a population-based Swedish cohort of older individuals followed over 12 years. METHODS: In 2000-2001, 900 individuals underwent neuropsychiatric and neuropsychological examinations. Follow-up evaluations were performed in 2005-2006 and 2009-2010, and register data on dementia to 2012 were included. Cross-sectional associations between genotypes/alleles and depression and dementia at baseline and between genotypes/alleles and depression on at least one occasion during the study period and dementia onset to 2012 were investigated. RESULTS: As previously found for rs1799752 in ACE, rs5186 in AGTR1 was associated with dementia at baseline (OR: 3.25 [CI: 1.42-7.06], z = 2.90, p = 0.004). These associations became substantially weaker, or disappeared, when dementia onset to 2012 was included. For rs1799752 this could be explained by a significant association with age at onset (mean: 79.5 [SD: 6.45] years for risk-genotype carriers and 81.7 [SD: 7.12] years for carriers of other genotypes, b = -2.43, t = -2.38, df = 192, p = 0.02). When individuals with major depression on at least one occasion were analyzed, a significant association (OR: 2.14 [95% CI: 1.13-4.20], z = 2.28, p = 0.02), remaining after exclusion of dementia, with rs1799752 in ACE was found. CONCLUSION: In this population-based sample of older individuals, genetic variations in ACE seem to be important both for late-life major depression and dementia.

Fourth consensus of the International Society for Premenstrual Disorders (ISPMD): auditable standards for diagnosis and management of premenstrual disorder.

Whilst professional bodies such as the Royal College and the American College of Obstetricians and Gynecologists have well-established standards for audit of management for most gynaecology disorders, such standards for premenstrual disorders (PMDs) have yet to be developed. The International Society of Premenstrual Disorders (ISPMD) has already published three consensus papers on PMDs covering areas that include definition, classification/quantification, clinical trial design and management (American College Obstetricians and Gynecologists 2011; Brown et al. in Cochrane Database Syst Rev 2:CD001396, 2009; Dickerson et al. in Am Fam Physician 67(8):1743-1752, 2003). In this fourth consensus of ISPMD, we aim to create a set of auditable standards for the clinical management of PMDs. All members of the original ISPMD consensus group were invited to submit one or more auditable standards to be eligible in the inclusion of the consensus. Ninety-five percent of members (18/19) responded with at least one auditable standard. A total of 66 auditable standards were received, which were returned to all group members who then ranked the standards in order of priority, before the results were collated. Proposed standards related to the diagnosis of PMDs identified the importance of obtaining an accurate history, that a symptom diary should be kept for 2 months prior to diagnosis and that symptom reporting demonstrates symptoms in the premenstrual phase of the menstrual cycle and relieved by menstruation. Regarding treatment, the most important standards were the use of selective serotonin reuptake inhibitors (SSRIs) as a first line treatment, an evidence-based approach to treatment and that SSRI side effects are properly explained to patients. A set of comprehensive standards to be used in the diagnosis and treatment of PMD has been established, for which PMD management can be audited against for standardised and improved care.

Differences in Anxiety-Like Behavior within a Batch of Wistar Rats Are Associated with Differences in Serotonergic Transmission, Enhanced by Acute SRI Administration, and Abolished By Serotonin Depletion.

BACKGROUND: The anxiety-reducing effect of long-term administration of serotonin reuptake inhibitors is usually seen only in subjects with anxiety disorders, and such patients are also abnormally inclined to experience a paradoxical anxiety-enhancing effect of acute serotonin reuptake inhibition. These unique responses to serotonin reuptake inhibitors in anxiety-prone subjects suggest, as do genetic association studies, that inter-individual differences in anxiety may be associated with differences in serotonergic transmission. METHODS: The one-third of the animals within a batch of Wistar rats most inclined to spend time on open arms in the elevated plus maze were compared with the one-third most inclined to avoid them with respect to indices of brain serotonergic transmission and how their behavior was influenced by serotonin-modulating drugs. RESULTS: "Anxious" rats displayed higher expression of the tryptophan hydroxylase-2 gene and higher levels of the tryptophan hydroxylase-2 protein in raphe and also higher levels of serotonin in amygdala. Supporting these differences to be important for the behavioral differences, serotonin depletion obtained by the tryptophan hydroxylase-2 inhibitor p-chlorophenylalanine eliminated them by reducing anxiety in "anxious" but not "non-anxious" rats. Acute administration of a serotonin reuptake inhibitor, paroxetine, exerted an anxiety-enhancing effect in "anxious" but not "non-anxious" rats, which was eliminated by long-term pretreatment with another serotonin reuptake inhibitor, escitalopram. CONCLUSIONS: Differences in an anxiogenic impact of serotonin, which is enhanced by acute serotonin reuptake inhibitor administration, may contribute to differences in anxiety-like behavior amongst Wistar rats.

Polymorphisms of dopamine pathway genes NRG1 and LMX1A are associated with cognitive performance in bipolar disorder.

OBJECTIVES: LIM homeobox transcription factor 1, alpha (LMX1A) and neuregulin 1 (NRG1) are susceptibility genes for schizophrenia that have been implicated in the dopaminergic pathway and have been associated with altered cognitive functioning. We hypothesized that single nucleotide polymorphisms (SNPs) in LMX1A and NRG1 would be associated with cognitive functioning in bipolar disorder. METHODS: In total, four SNPs were directly genotyped. Regression models with five aggregated cognitive domains and intelligence quotient (IQ) score were run using risk variants of LMX1A (rs11809911, rs4657412, rs6668493) and NRG1 (rs35753505) as predictors. Models were performed in a clinical sample of patients with bipolar disorder (n = 114) and healthy controls (n = 104). RESULTS: The risk variants of the rs11809911 SNP in LMX1A were negatively associated with IQ score and memory/learning, whereas the risk variants of rs35753505 in NRG1 were positively associated with IQ score (adjusted R(2) = 0.17, Q = 0.006) and memory/learning (adjusted R(2) = 0.24, Q = 0.001). The risk variants of the rs35753505 SNP in NRG1 were positively associated with language (adjusted R(2) = 0.11, Q = 0.006), visuospatial functions (adjusted R(2) = 0.23, Q = 0.001), and attention/speed (adjusted R(2) = 0.25, Q = 0.001). Results could not be replicated in controls. CONCLUSIONS: The risk variants of the rs35753505 SNP were associated with increased performance in several cognitive domains and IQ, whereas the risk variants of the rs11809911 SNP in LMX1A was associated with reduced IQ and memory/learning.

A study of possible associations between single nucleotide polymorphisms in the estrogen receptor 2 gene and female sexual desire.

INTRODUCTION: Female sexual desire and arousal problems have been shown to have a heritable component of moderate size. Previous molecular genetic studies on sexual desire have mainly focused on genes associated with neurotransmitters such as dopamine and serotonin. Nevertheless, there is reason to believe that hormones with more specific functions concerning sexuality could have an impact on sexual desire and arousal. AIM: The aim of the present study was to investigate the possible effects of 17 single nucleotide polymorphisms (SNPs) located in estrogen receptor genes on female sexual desire and subjective and genital arousal (lubrication). Based on previous research, we hypothesized that ESR1 and ESR2 are relevant genes that contribute to female sexual desire and arousal. MAIN OUTCOME MEASURES: The desire, arousal, and lubrication subdomains of the Female Sexual Function Index self-report questionnaire were used. METHODS: The present study involved 2,448 female twins and their sisters aged 18-49 who had submitted saliva samples for genotyping. The participants were a subset from a large-scale, population-based sample. RESULTS: We found nominally significant main effects on sexual desire for three ESR2 -linked SNPs when controlled for anxiety, suggesting that individuals homozygous for the G allele of the rs1271572 SNP, and the A allele of the rs4986938 and rs928554 SNPs had lower levels of sexual desire. The rs4986938 SNP also had a nominally significant effect on lubrication. No effects for any of the SNPs on subjective arousal could be detected. CONCLUSIONS: The number of nominally significant results for SNPs in the ESR2 gene before correcting for multiple testing suggests that further studies on the possible influence of this gene on interindividual variation in female sexual functioning are warranted. In contrast, no support for an involvement of ESR1 was obtained. Our results should be interpreted with caution until replicated in independent, large samples.

Estrogen receptor-α expression in neuronal cells affects bone mass.

It has generally been assumed that bone mass is controlled by endocrine mechanisms and the local bone environment. Recent findings demonstrate that central pathways are involved in the regulation of bone mass. Estrogen is involved in the regulation of bone homeostasis and the CNS is also a target for estrogen actions. The aim of this study was to investigate in vivo the role of central estrogen receptor-α (ERα) expression for bone mass. Nestin-Cre mice were crossed with ERα(flox) mice to generate mice lacking ERα expression specifically in nervous tissue (nestin-ERα(-/-)). Bone mineral density was increased in both the trabecular and cortical bone compartments in nestin-ERα(-/-) mice compared with controls. Femoral bone strength was increased in nestin-ERα(-/-) mice, as demonstrated by increased stiffness and maximal load of failure. The high bone mass phenotype in nestin-ERα(-/-) mice was mainly caused by increased bone formation. Serum leptin levels were elevated as a result of increased leptin expression in white adipose tissue (WAT) and slightly increased amount of WAT in nestin-ERα(-/-) mice. Leptin receptor mRNA levels were reduced in the hypothalamus but not in bone. In conclusion, inactivation of central ERα signaling results in increased bone mass, demonstrating that the balance between peripheral stimulatory and central inhibitory ERα actions is important for the regulation of bone mass. We propose that the increased bone mass in nestin-ERα(-/-) mice is mediated via decreased central leptin sensitivity and thereby increased secretion of leptin from WAT, which, in turn, results in increased peripheral leptin-induced bone formation.

Motor Efficacy of Subcutaneous DIZ102, Intravenous DIZ101 or Intestinal Levodopa/Carbidopa Infusion.

BACKGROUND: It has been suggested that carbidopa at high blood concentrations may counter the therapeutic effect of levodopa in Parkinson's disease by entering the brain and blocking central levodopa conversion to dopamine. We previously demonstrated equivalent plasma levodopa concentration in patients with Parkinson's disease during 16 h of (1) intravenous carbidopa/levodopa (DIZ101) infusion, (2) subcutaneous carbidopa/levodopa (DIZ102) infusion or (3) intestinal carbidopa/levodopa gel infusion. Plasma levels of carbidopa were however approximately four times higher with DIZ101 and DIZ102 than with LCIG, and higher than those usually observed with oral levodopa/carbidopa. OBJECTIVES: To investigate if high carbidopa blood concentrations obtained with parenteral levodopa/carbidopa (ratio 8:1) counter the effect of levodopa on motor symptoms. METHODS: Eighteen patients with advanced Parkinson's disease were administered DIZ101, DIZ102, and intestinal levodopa/carbidopa gel for 16 h on different days in randomized order. Video recordings of a subset of the motor examination in the Unified Parkinson's Disease Rating Scale (UPDRS) were evaluated by raters blinded for treatment and time. Motor function was also measured using a wrist-worn device monitoring bradykinesia, dyskinesia, and tremor (Parkinson KinetiGraph). RESULTS: There was no tendency for poorer levodopa effect with DIZ101 or DIZ102 as compared to LCIG. CONCLUSION: Although DIZ101 or DIZ102 causes approximately four times higher plasma carbidopa levels than LCIG, patients responded equally well to all treatments. The results do not indicate that high plasma carbidopa levels hamper the motor efficacy of levodopa.