The possible contribution of neuronal nicotinic acetylcholine receptors in depression

Effects of Tobacco Use on the Macrostructure and Microstructure of Sleep in Patients with OSA

Objective

Both tobacco use and obstructive apnea-hypopnea syndrome (OSA) can affect sleep, and it is speculated that tobacco use may further affect the sleep of those with OSA. Our primary objective is to clarify the associations between tobacco use and the macrostructure and microstructure of sleep in patients with OSA.

Methods

This retrospective study encompasses a cohort of 1017 patients who were hospitalized between January 2020 and January 2023 for the investigation of sleep disorders. Rigorous inclusion criteria were applied, and all patients underwent a comprehensive polysomnography (PSG) assessment and completed a Pittsburgh Sleep Quality Index (PSQI) questionnaire.

Results

Patients with OSA who concurrently used tobacco exhibited markedly inferior sleep quality than those who did not. Notably, there was no association between the degree of tobacco dependence and sleep quality. Those with OSA who used tobacco demonstrated a significant prolongation of stage 1 light sleep and a reduction of deep sleep duration (N3). In this group, those who demonstrated poor sleep quality had more pronounced alterations in light sleep stages with prolonged N1 and shortened N2 stages.

Conclusion

Our findings reveal a substantial reduction in sleep quality amongst OSA patients who also use tobacco, compared to those with OSA who do not use tobacco. The rate of poor sleep quality was not linearly associated with the level of tobacco dependence. Tobacco use was associated with alterations in both light and slow wave sleep in those with OSA. Importantly, the effects of tobacco dependence on sleep structure were more pronounced in those with more severe OSA.

Two-part models identifying predictors of cigarette, e-cigarette, and cannabis use and change in use over time among young adults in the US

BACKGROUND AND OBJECTIVES

Limited longitudinal research has examined differential interpersonal and intrapersonal correlates of young adult use and use frequency of cigarettes, e-cigarettes, and cannabis. This study aimed to address these limitations.

METHODS

We analyzed five waves of longitudinal data (2018-2020) among 3006 US young adults (Mage = 24.55, 44% male, 32% sexual minority, ~30% racial/ethnic minority). Two-part latent growth models examined likelihood of past-month cigarette, e-cigarette, and cannabis use (binary part) and days used (continuous part) and identified predictors (depressive symptoms, personality traits, adverse childhood experiences [ACEs], parental use) of baseline use and changes over time.

RESULTS

Regarding baseline past-month use (27% cigarettes, 38% e-cigarettes, 39% cannabis), depressive symptoms, ACEs, and parental substance use predicted use outcomes (i.e., likelihood, frequency) for each product; extraversion predicted cigarette and e-cigarette use outcomes; openness predicted e-cigarette and cannabis use outcomes; conscientiousness negatively predicted cigarette and cannabis use outcomes; and agreeableness negatively predicted cannabis use frequency. Regarding longitudinal changes, conscientiousness predicted accelerated increase of cigarette use frequency at later timepoints; depressive symptoms predicted increases in likelihood of e-cigarette use but the association weakened over time; and parental cannabis use predicted decreased cannabis use frequency but the association weakened over time.

DISCUSSION AND CONCLUSIONS

Young adult substance use interventions should target high-risk subgroups and focus on distinct factors impacting use, including chronic, escalating, and decreasing use.

SCIENTIFIC SIGNIFICANCE

This study advances the literature regarding distinct predictors of different substance use outcomes and provides unique data to inform interventions targeting young adult cigarette, e-cigarette, and cannabis use.

Machine learning models for predicting depression in Korean young employees

Background

The incidence of depression among employees has gradually risen. Previous studies have focused on predicting the risk of depression, but most studies were conducted using basic statistical methods. This study used machine learning algorithms to build models that detect and identify the important factors associated with depression in the workplace.

Methods

A total of 503 employees completed an online survey that included questionnaires on general characteristics, physical health, job-related factors, psychosocial protective, and risk factors in the workplace. The dataset contained 27 predictor variables and one dependent variable which referred to the status of employees (normal or at the risk of depression). The prediction accuracy of three machine learning models using sparse logistic regression, support vector machine, and random forest was compared with the accuracy, precision, sensitivity, specificity, and AUC. Additionally, the important factors identified via sparse logistic regression and random forest.

Results

All machine learning models demonstrated similar results, with the lowest accuracy obtained from sparse logistic regression and support vector machine (86.8%) and the highest accuracy from random forest (88.7%). The important factors identified in this study were gender, physical health, job, psychosocial protective factors, and psychosocial risk and protective factors in the workplace.

Discussion

The results of this study indicated the potential of machine learning models to accurately predict the risk of depression among employees. The identified factors that influence the risk of depression can contribute to the development of intelligent mental healthcare systems that can detect early signs of depressive symptoms in the workplace.

Impact of smoking intensities on sleep quality in young Saudi males: a comparative study

This study aimed to compare various components of sleep quality between cigarette smokers of various intensities and non-smokers in young Saudi males. In total, 73 healthy male participants (31 smokers and 42 non-smokers) aged 17-33 years were recruited over three months (August 2018 to October 2018). All participants completed the Pittsburgh Sleep Quality Index (PSQI) questionnaire. The smokers were then divided into three groups, according to their Smoking Index* (SI) (Cigarettes Per Day (CPD) X Years of Tobacco Use), into mild, moderate, and heavy smokers. The PSQI was significantly higher in heavy smokers than in mild smokers (P=0.022) or non-smokers (p=0.013). A significant positive correlation was observed between the PSQI and the smoking index (p=0.005). Sleep duration was significantly longer in heavy smokers compared to mild (p=0.032) and nonsmokers (p=0.047). Sleep disturbance was significantly higher in moderate than nonsmokers (p=0.035) and moderate than mild smokers (p=0.028). Sleep latency was significantly longer in heavy than nonsmokers (p=0.011). Daytime dysfunction was significantly higher in moderate than mild smokers (p=0.041). Habitual sleep efficiency was significantly greater in moderate than in either mild (p=0.013) or nonsmokers (p=0.021). The use of sleep medication was significantly higher in moderate than nonsmokers (p=0.041). The findings suggest that poorer sleep quality is positively associated with smoking intensity among young Saudi males. Considering the importance of sleep quality for well-being and health, these results suggest exploring how improving sleep quality could inform future smoking cessation interventions.

Does Smoking Affect OSA? What about Smoking Cessation?

The connection between smoking and Obstructive sleep apnea (OSA) is not yet clear. There are studies that have confirmed the effect of smoking on sleep disordered breathing, whereas others did not. Nicotine affects sleep, as smokers have prolonged total sleep and REM latency, reduced sleep efficiency, total sleep time, and slow wave sleep. Smoking cessation has been related with impaired sleep. The health consequences of cigarette smoking are well documented, but the effect of smoking cessation on OSA has not been extensively studied. Smoking cessation should improve OSA as upper airway oedema may reduce, but there is limited data to support this hypothesis. The impact of smoking cessation pharmacotherapy on OSA has been studied, especially for nicotine replacement therapy (NRT). However, there are limited data on other smoking cessation medications as bupropion, varenicline, nortriptyline, clonidine, and cytisine. The aim of this review was to explore the current evidence on the association between smoking and OSA, to evaluate if smoking cessation affects OSA, and to investigate the possible effects of different pharmacologic strategies offered for smoking cessation on OSA.

Gender differences in the associations between tobacco smoke exposure and depressive symptoms among U.S. adults: NHANES 2007-2018

BACKGROUND

Findings concerning gender differences in the associations between tobacco smoke exposure (TSE) and depression are inconsistent. This study aimed to investigate the gender-specific associations between active and passive TSE with depressive symptoms in a large, nationally representative sample of U.S. adults.

METHODS

Data were from 27,175 adults aged ≥20 years in the 2007-2018 National Health and Nutrition Examination Survey (NHANES). Depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9). Multivariable logistic regression was used to adjust for possible confounders. Whether the TSE-depression relationships may differ by age, race/ethnicity, socioeconomic status, body mass index (BMI), and self-reported health status was examined.

RESULTS

After adjustment for lifestyle- and health-related variables, no significant associations between active (OR, 1.16 [95% CI, 0.87-1.55]) and passive TSE (OR, 0.84 [95% CI, 0.59-1.19]) and depressive symptoms were found among men. Among women, active TSE was associated with depressive symptoms (OR, 1.90 [95% CI, 1.51-2.39]), while the association for passive TSE was nonsignificant (OR, 1.11 [95% CI, 0.91-1.34]) after adjusting for lifestyle- and health-related variables. Interaction and subgroup analyses showed that self-reported health status could modify the relationship between passive TSE and depressive symptoms among women. Furthermore, a dose-response relationship between serum cotinine and depressive symptoms was found in women, but not in men.

CONCLUSIONS

This study suggests a stronger TSE-depression association in women than in men. Understanding these gender-specific patterns and identifying the potential moderators of such relationships will enable better targeting of public health interventions.

Association Between Second-hand Smoke Exposure and Depressive Symptoms Among Japanese Adults: A Cross-sectional Study

Background

Second-hand smoke exposure has been associated with poor mental health. However, among Japanese adults, little is known about the association between second-hand smoking and depressive symptoms. We examined this association in a cross-sectional study among a Japanese general adult population sample.

Methods

Japanese adults were recruited from the Japan Multi-Institutional Collaborative Cohort Study in the Okazaki area between 2012 and 2017. Second-hand smoke exposure and smoking status were assessed using a self-administered questionnaire. Based on their frequency of exposure to second-hand smoke, non-smokers and smokers were categorized as “almost never,” “sometimes,” and “almost every day”. Depressive symptoms were defined by a Kessler 6 score ≥5 points. We performed a multivariable Poisson regression analysis to obtain adjusted prevalence ratios (PRs) and 95% confidence intervals (CIs) for depressive symptoms.

Results

Overall, 5,121 participants (4,547 non-smokers and 574 smokers) were included whose mean age was 63.6 (standard deviation [SD], 10.3) years for non-smokers and 59.33 (SD, 10.2) years for smokers. The association between second-hand smoking and depressive symptoms was significant among non-smokers, but not among smokers. Among non-smokers, PRs compared with “almost never” were 1.25 (95% CI, 1.09–1.42) for “sometimes” and 1.41 (95% CI, 1.09–1.84) for “almost every day” (P for trend <0.001); among smokers, PRs compared with “almost never” were 1.30 (95% CI, 0.82–2.06) for “sometimes” and 1.44 (95% CI, 0.90–2.33) for “almost every day” (P for trend = 0.144).

Conclusions

Second-hand smoking and depressive symptoms were associated among non-smokers. Our findings indicate the importance of tobacco smoke control for mental health.

Relationship Between Secondhand Smoke Exposure and Depressive Symptoms: A Systematic Review and Dose⁻Response Meta-Analysis

Previous studies have suggested an association between secondhand smoke (SHS) exposure and risk of depressive symptoms. However, it remains unclear whether there is a dose-response relationship. The effect estimates were pooled using fixed-effect or random-effect models based on homogeneity analysis. The dose-response meta-analysis was performed by linear and non-linear regression. Subgroup analyses were conducted to explore the possible sources of heterogeneity. Twenty-four studies were included in this meta-analysis. SHS exposure was significantly associated with increased odds of depressive symptoms (odds ratio (OR) = 1.32, 95% confidence interval (CI) 1.25-1.39). For SHS exposure expressed as an ordinal variable, the dose-response meta-analysis revealed a monotonically increasing relationship between SHS exposure and depressive symptoms. A similar dose-response relationship was observed for SHS exposure expressed as a continuous variable (OR = 1.57, 95% CI = 1.26-1.87). Our findings suggest that SHS exposure is associated with increasing odds of depressive symptoms in a dose-response manner.

Human brain imaging of nicotinic acetylcholine α4β2* receptors using [18 F]Nifene: Selectivity, functional activity, toxicity, aging effects, gender effects, and extrathalamic pathways

Nicotinic acetylcholinergic receptors (nAChR's) have been implicated in several brain disorders, including addiction, Parkinson's disease, Alzheimer's disease and schizophrenia. Here we report in vitro selectivity and functional properties, toxicity in rats, in vivo evaluation in humans, and comparison across species of [¹⁸ F]Nifene, a fast acting PET imaging agent for α4β2* nAChRs. Nifene had subnanomolar affinities for hα2β2 (0.34 nM), hα3β2 (0.80 nM) and hα4β2 (0.83 nM) nAChR but weaker (27-219 nM) for hβ4 nAChR subtypes and 169 nM for hα7 nAChR. In functional assays, Nifene (100 μM) exhibited 14% agonist and >50% antagonist characteristics. In 14-day acute toxicity in rats, the maximum tolerated dose (MTD) and the no observed adverse effect level (NOAEL) were estimated to exceed 40 μg/kg/day (278 μg/m² /day). In human PET studies, [¹⁸ F]Nifene (185 MBq; <0.10 μg) was well tolerated with no adverse effects. Distribution volume ratios (DVR) of [¹⁸ F]Nifene in white matter thalamic radiations were ∼1.6 (anterior) and ∼1.5 (superior longitudinal fasciculus). Habenula known to contain α3β2 nAChR exhibited low levels of [¹⁸ F]Nifene binding while the red nucleus with α2β2 nAChR had DVR ∼1.6-1.7. Females had higher [¹⁸ F]Nifene binding in all brain regions, with thalamus showing >15% than males. No significant aging effect was observed in [¹⁸ F]Nifene binding over 5 decades. In all species (mice, rats, monkeys, and humans) thalamus showed highest [¹⁸ F]Nifene binding with reference region ratios >2 compared to extrathalamic regions. Our findings suggest that [¹⁸ F]Nifene PET may be used to study α4β2* nAChRs in various CNS disorders and for translational research.

Secondhand smoke exposure and mental health in adults: a meta-analysis of cross-sectional studies

PURPOSE

Previous studies assessing secondhand smoke (SHS) and risk of mental health problems have yielded inconsistent results. We performed a meta-analysis to statistically assess the association between SHS exposure, depressive symptoms and psychological distress among adults.

METHODS

A systematically search of Pubmed (1946-2015) and EMBASE (1976-2015) was conducted and supplemented by bibliographies of all retrieved articles to find additional relevant citations. Odds ratios (OR) and associated 95 % confidence interval (CI) of each eligible study were extracted and pooled in our meta-analysis.

RESULTS

A total of 11 studies comprising 86,739 participants met the inclusion criteria. A random-effect model was used in meta-analysis since considerable heterogeneity was expected. Our results indicate that SHS exposure was significantly associated with depressive symptoms (OR 1.60, 95 % CI 1.35-1.90) and psychological distress (OR 1.32, 95 % CI 1.11-1.56).

CONCLUSION

Exposure to SHS among non-smoker is associated with depressive symptoms and psychological distress, emphasizing the significance of reducing SHS exposure at a population level.

Age at smoking initiation and self-rated health among second grade high school boys and girls in Scania, Sweden, a cross-sectional study

BACKGROUND

Smoking is usually initiated early in life and most adult regular smokers have started smoking before 18 years of age. A younger age at smoking initiation is associated with risk taking behaviours and worse health outcomes regarding psychological and somatic conditions, suggested to be caused by exposure during critical developmental periods. The present study aims to investigate self-rated health among second grade high school boys and girls related to age at smoking initiation (<14 years of age and ≥ 14 years of age) among current and former smokers, compared to never smokers.

METHODS

Data was derived from the Scania public health survey among children and adolescents in 2012. The study was cross-sectional with retrospective information about first time cigarette smoking experiences among 3245 boys and 3434 girls in second grade of high school. Self-rated health was assessed with the question "How do you rate your general health". Associations of age at smoking initiation, current smoking status and poor self-rated health were investigated with logistic regression models.

RESULTS

Crude odds ratios of poor self-rated health were increased for all smoking groups compared to never smokers. Former smoking boys and currently smoking girls with early smoking initiation had the highest odds ratios of poor self-rated health, with odds ratios (OR) 2.4 (95 % confidence interval (CI): 1.5-3.7) and OR 2.9 (95 % CI: 2.3-3.6), respectively. After adjustments for sociodemographic factors, health-related behaviours, psychosocial factors, weight and functional disabilities, the results were attenuated, but remained statistically significant regarding former and current smoking boys with early smoking initiation, OR 2.0 (95 % CI: 1.1-3.7) and OR 1.7 (95 % CI: 1.1-2.4) and for current smoking girls with early and later smoking initiation, OR 2.1 (95 % CI: 1.5-2.8) and OR 1.5 (95 % CI: 1.1-2.0).

CONCLUSION

Boys and girls in second grade of high school with early smoking initiation reported poorer self-rated health than later initiators and never smokers. Poorer self-rated health persisted also after smoking cessation among early initiating boys. Further studies are needed to understand the adverse health effects associated with timing of smoking initiation.

The role of glutamatergic, GABA-ergic, and cholinergic receptors in depression and antidepressant-like effect

Depression is one of the most common mental disorders and social issue worldwide. Although there are many antidepressants available, the effectiveness of the therapy is still a serious issue. Moreover, there are many limitations of currently used antidepressants, including slow onset of action, numerous side effects, or the fact that many patients do not respond adequately to the treatment. Therefore, scientists are searching for new compounds with different mechanisms of action. Numerous data indicate the important role of glutamatergic, GABA-ergic, and cholinergic receptors in the pathomechanism of major depressive disorder. This review presents the role of glutamatergic, GABA-ergic, and cholinergic receptors in depression and antidepressant-like effect.

Anxiolytic- and antidepressant-like effects of the methadone metabolite 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline (EMDP)

The enhancement of GABAergic and monoaminergic neurotransmission has been the mainstay of pharmacotherapy and the focus of drug-discovery for anxiety and depressive disorders for several decades. However, the significant limitations of drugs used for these disorders underscores the need for novel therapeutic targets. Neuronal nicotinic acetylcholine receptors (nAChRs) may represent one such target. For example, mecamylamine, a non-competitive antagonist of nAChRs, displays positive effects in preclinical tests for anxiolytic and antidepressant activity in rodents. In addition, nicotine elicits similar effects in rodent models, possibly by receptor desensitization. Previous studies (Xiao et al., 2001) have identified two metabolites of methadone, EMDP (2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline) and EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine), which are considered to be inactive at opiate receptors, as relatively potent noncompetitive channel blockers of rat α3β4 nAChRs. Here, we show that these compounds are likewise highly effective blockers of human α3β4 and α4β2 nAChRs. Moreover, we show that they display relatively low affinity for opiate binding sites labeled by [(3)H]-naloxone. We then evaluated these compounds in rats and mice in preclinical behavioral models predictive of potential anxiolytic and antidepressant efficacy. We found that EMDP, but not EDDP, displayed robust effects predictive of anxiolytic and antidepressant efficacy without significant effects on locomotor activity. Moreover, EMDP at behaviorally active doses, unlike mecamylamine, did not produce eyelid ptosis, suggesting it may produce fewer autonomic side effects than mecamylamine. Thus, the methadone metabolite EMDP may represent a novel therapeutic avenue for the treatment of some affective disorders.

Translational Research on Nicotine Dependence

Nicotine dependence is a chronic, relapsing disorder with complex biological mechanisms underlying the motivational basis for this behavior. Although more than 70 % of current smokers express a desire to quit, most relapse within one year, underscoring the need for novel treatments. A key focus of translational research models addressing nicotine dependence has been on cross-validation of human and animal models in order to improve the predictive value of medication screening paradigms. In this chapter, we review several lines of research highlighting the utility of cross-validation models in elucidating the biological underpinnings of nicotine reward and reinforcement, identifying factors which may influence individual response to treatment, and facilitating rapid translation of findings to practice.

Neurobiology of chronic mild stress: parallels to major depression

The chronic mild (or unpredictable/variable) stress (CMS) model was developed as an animal model of depression more than 20 years ago. The foundation of this model was that following long-term exposure to a series of mild, but unpredictable stressors, animals would develop a state of impaired reward salience that was akin to the anhedonia observed in major depressive disorder. In the time since its inception, this model has also been used for a variety of studies examining neurobiological variables that are associated with depression, despite the fact that this model has never been critically examined to validate that the neurobiological changes induced by CMS are parallel to those documented in depressive disorder. The aim of the current review is to summarize the current state of knowledge regarding the effects of chronic mild stress on neurobiological variables, such as neurochemistry, neurochemical receptor expression and functionality, neurotrophin expression and cellular plasticity. These findings are then compared to those of clinical research examining common variables in populations with depressive disorders to determine if the changes observed following chronic mild stress are in fact consistent with those observed in major depression. We conclude that the chronic mild stress paradigm: (1) evokes an array of neurobiological changes that mirror those seen in depressive disorders and (2) may be a suitable tool to investigate novel systems that could be disturbed in depression, and thus aid in the development of novel targets for the treatment of depression.

Inhibitory effect of lithium on nucleotide hydrolysis and acetylcholinesterase activity in zebrafish (Danio rerio) brain

Lithium has been used as an effective antimanic drug in humans and it is well known for its effects on neuropsychiatric disorders and neuronal communication. ATP and adenosine are important signaling molecules, and most nerves release ATP as a fast co-transmitter together with classical neurotransmitters such as acetylcholine. In this study, we evaluated the in vitro and in vivo effects of lithium on acetylcholinesterase and ectonucleotidase activities in zebrafish brain. There was a significant inhibition of ADP hydrolysis after in vivo exposure to lithium at 5 and 10 mg/l (27.6% and 29% inhibition, respectively), whereas an inhibitory effect was observed for AMP hydrolysis only at 10 mg/l (30%). Lithium treatment in vivo also significantly decreased the acetylcholinesterase activity at 10 mg/l (21.9%). The mRNA transcript levels of the genes encoding for these enzymes were unchanged after exposure to 5 and 10 mg/l lithium chloride. In order to directly evaluate the action of lithium on enzyme activities, we tested the in vitro effect of lithium at concentrations ranging from 1 to 1000 μM. There were no significant changes in zebrafish brain ectonucleotidase and acetylcholinesterase activities at all concentrations tested in vitro. Our findings show that lithium treatment can alter ectonucleotidase and acetylcholinesterase activities, which may regulate extracellular nucleotide, nucleoside, and acetylcholine levels. These data suggest that cholinergic and purinergic signaling may be targets of the pharmacological effects induced by this compound.

Chronic nicotine treatment differentially modifies acute nicotine and alcohol actions on GABA(A) and glutamate receptors in hippocampal brain slices

BACKGROUND AND PURPOSE

Tobacco and alcohol are often co-abused producing interactive effects in the brain. Although nicotine enhances memory while ethanol impairs it, variable cognitive changes have been reported from concomitant use. This study was designed to determine how nicotine and alcohol interact at synaptic sites to modulate neuronal processes.

EXPERIMENTAL APPROACH

Acute effects of nicotine, ethanol, and both drugs on synaptic excitatory glutamatergic and inhibitory GABAergic transmission were measured using whole-cell recording in hippocampal CA1 pyramidal neurons from brain slices of mice on control or nicotine-containing diets.

KEY RESULTS

Acute nicotine (50 nM) enhanced both GABAergic and glutamatergic synaptic transmission; potentiated GABA(A) receptor currents via activation of α7* and α4β2* nAChRs, and increased N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor currents through α7* receptors. While ethanol (80 mM) also increased GABA(A) currents, it inhibited NMDA currents. Although ethanol had no effect on AMPA currents, it blocked nicotine-induced increases in NMDA and AMPA currents. Following chronic nicotine treatment, acute nicotine or ethanol did not affect NMDA currents, while the effects of GABAergic responses were not altered.

CONCLUSIONS AND IMPLICATIONS

Acute ethanol ingestion selectively attenuated nicotine enhancement of excitatory glutamatergic NMDA and AMPA receptor function, suggesting an overall reduction in excitatory output from the hippocampus. It also indicated that ethanol could decrease the beneficial effects of nicotine on memory performance. In addition, chronic nicotine treatment produced tolerance to the effects of nicotine and cross-tolerance to the effects of ethanol on glutamatergic activity, leading to a potential increase in the use of these drugs.

Novel drugs and therapeutic targets for severe mood disorders

Monoaminergic-based drugs remain the primary focus of pharmaceutical industry drug discovery efforts for mood disorders, despite serious limitations regarding their ability to achieve remission. The quest for novel therapies for unipolar depression and bipolar disorder has generally centered on two complementary approaches: (1) understanding the presumed therapeutically relevant biochemical targets of currently available medications, and using that knowledge to design new drugs directed at both direct biochemical targets and downstream targets that are regulated by chronic drug administration; and (2) developing pathophysiological models of the illness to design therapeutics to attenuate or prevent those pathological processes. This review describes several promising drugs and drug targets for mood disorders using one or both of these approaches. Agents interacting with non-catecholamine neurotransmitter systems with particular promise for unipolar and bipolar depression include excitatory amino acid neurotransmitter modulators (eg, riluzole, N-methyl-D-aspartate antagonists, and AMPA receptor potentiators) and neuropeptide antagonists (targeting corticotropin releasing factor-1 and neurokinin receptors). Potential antidepressant and mood-stabilizing agents targeting common intracellular pathways of known monoaminergic agents and lithium/mood stabilizers are also reviewed, such as neurotrophic factors, extracellular receptor-coupled kinase (ERK) mitogen-activated protein (MAP) kinase and the bcl-2 family of proteins, and inhibitors of phosphodiesterase, glycogen synthase kinase-3, and protein kinase C. A major thrust of drug discovery in mood disorders will continue efforts to identify agents with rapid and sustained onsets of action (such as intravenous administration of ketamine), as well as identify drugs used routinely in non-psychiatric diseases for their antidepressant and mood-stabilizing properties.

In vivo measurement of nicotinic acetylcholine receptors with [18F]norchloro-fluoro-homoepibatidine

Functional changes of nicotinic acetylcholine receptors (nAChR) are important during age-related neuronal degeneration. Recent studies demonstrate the applicability of the nAChR ligand 2-[(18)F]F-A-85380 for neuroimaging of patients with dementias. However, its binding kinetics demands a 7-h acquisition time limiting its practicality for clinical PET studies. Thus, the authors developed [(18)F]norchloro-fluoro-homoepibatidine ([(18)F]NCFHEB) for nAChR imaging. The kinetics of the two enantiomers of [(18)F]NCFHEB were compared with 2-[(18)F]F-A85380 in porcine brain to evaluate their potential for human neuroimaging. Twenty-four juvenile female pigs were studied with PET using [(18)F]NCFHEB. Nine animals received an additional i.v. injection (1 mg/kg) of the nAChR agonist A81418 before radiotracer administration followed by infusion (2 mg/kg/7h) thereafter. Several compartment models were applied for quantification. (-)- and (+)-[(18)F]NCFHEB showed a twofold to threefold higher brain uptake than 2-[(18)F]F-A-85380. All three radiotracers displayed spatially heterogeneous binding kinetics in regions with high, moderate, or low specific binding. The equilibrium of specific binding of (-)-[(18)F]NCFHEB was reached earlier than that of (+)-[(18)F]NCFHEB or 2-[(18)F]F-A85380. Continuous administration of the nAChR agonist A81418 inhibited the specific binding of (-)- and (+)-[(18)F]NCFHEB but not of 2-[(18)F]F-A85380. The peripheral metabolism of (+)-[(18)F]NCFHEB proceeded somewhat slower than that of the other radiotracers. Both enantiomers of [(18)F]NCFHEB are appropriate radiotracers for neuroimaging of nAChR in pigs. Their binding profile in vivo appears to be more selective than that of 2-[(18)F]F-A85380. (-)-[(18)F]NCFHEB offers a faster equilibrium of specific binding than 2-[(18)F]F-A85380.

No evidence for association between 19 cholinergic genes and bipolar disorder

Cholinergic dysfunction has been proposed for the pathogenesis of bipolar disorder (BD), and we have therefore performed a systematic association study of cholinergic system genes in BD (including schizoaffective disorder bipolar type). We genotyped 93 single nucleotide polymorphisms (SNPs) in 19 genes (CHAT, CHRM1-5, CHRNA1-7, CHRNA9, CHRNA10, and CHRNB1-4) in two series of samples: the National Institute of Mental Health (NIMH) Genetics Initiative pedigrees with 474 samples from 152 families, and the Clinical Neurogenetics (CNG) pedigrees with 83 samples from 22 multiplex families. Sib-transmission/disequilibrium test (sib_TDT) analysis showed nominally significant transmission bias for four SNPs (CHRNA2: rs7017417, P = 0.024; CHRNA5: rs514743, P = 0.031; CHRNB1: rs2302762, P = 0.049; CHRNB4: rs1948, P = 0.031). Haploview analyses showed nominally significant transmission bias of several haplotypes in CHRNA2, CHRNA7, CHRNB1, and CHRNB4, respectively. However, none of these associations reached gene-wide significance after correction by permutation. Alcohol dependence (including alcohol abuse) was not a significant covariate in the present genetic association analysis. Thus, it is unlikely that these 19 cholinergic genes play a major role in the pre-disposition to BD in these pedigrees.