The Serotonin 1A (5-HT1A) Receptor as a Pharmacological Target in Depression

Development progress of drugs for bipolar disorder: 75 Years after lithium proved effective

Bipolar disorder, a psychiatric condition identified by significant mood changes and a considerable genetic connection with schizophrenia, needs continuous and extensive management due to its common onset in adolescence and significant impact on psychosocial activities. While traditional mood stabilizers continue to be widely used, the pursuit of more effective treatments remains ongoing, with the current research targeting various stages of the disorder. This study provides a thorough examination of new pharmacological treatments for bipolar disorder, which are currently in Phase II and Phase III clinical trials up to 22 April 2024. A systematic search was conducted using the NIH National Library of Medicine, focusing on both repurposed and innovative drugs now in advanced stages of testing. The study identifies several promising therapeutic agents, including those intended for severe mood disorders with suicidal tendencies, and others aimed at treating mood-related neuroinflammation. Drugs that enhance dopamine stabilization and those that act on serotonin receptor activities were found notable. We also explored the strategic repurposing of already existing medications for broader therapeutic uses and looked into the potential of new formulations designed for the immediate management of symptoms. Our analysis highlights two main strategies for tackling bipolar disorder: finding new uses for existing drugs and developing new medications with unique actions. This approach shows continuous improvement in drug treatments, helping patients manage their condition better and addressing the complicated nature of bipolar disorder.

Correlation between physical exercise levels, depressive symptoms, and sleep quality in college students: Evidence from electroencephalography

BACKGROUND

In recent years, depression has increasingly become a major global public health issue. Among its common physical symptoms, sleep disturbances are prevalent in individuals with depression and are considered a risk factor for the progression of the disorder. Poor sleep quality may be a significant contributor to depression among college students. However, the EEG indicators that are commonly associated with depressive symptoms and sleep quality, as well as the effects of physical exercise on these EEG indicators, remain unclear.

PURPOSE

This study aims to explore the relationship between physical activity levels, depressive symptoms, and sleep quality among college students, based on resting-state electroencephalography (EEG) data in a cross-sectional study.

METHODS

A total of 342 college students were recruited to assess physical activity levels, depressive symptoms, sleep quality, and EEG data. Pearson correlation coefficients were used to evaluate the relationships among these variables, and the PROCESS macro (Model 4) for SPSS was applied to examine the mediating role of sleep quality in the relationship between physical activity levels and depressive symptoms, with mediation effects tested using the bootstrap method.

RESULTS

A significant difference was observed in the Pittsburgh Sleep Quality Index (PSQI) total scores between students with and without depressive symptoms (T = 9.746, P < 0.001). Students with depressive symptoms showed poorer sleep quality across various dimensions, including sleep duration, sleep onset latency, sleep disturbances, and daytime dysfunction. Depression symptom were positively correlated with Sleep Quality (r = 0.547, P < 0.001), indicating that higher depression symptoms are associated with poorer sleep quality. Correlations between depressive symptoms and EEG power values revealed significant associations with theta and beta2 frequencies in multiple brain regions (P < 0.05). Physical exercise showed a significant negative correlation with Sleep Quality scores (r = -0.158, P = 0.004), and with sleep duration (r = -0.141, P = 0.011) and daytime dysfunction (r = -0.142, P = 0.010). Additionally, physical exercise was negatively correlated with theta band power at F8 (P < 0.05). Mediation analysis demonstrated that physical exercise has a direct effect on depressive symptoms (β = -0.123, 95 % CI = -0.287 to -0.069) and an indirect effect through improved sleep quality (β = -0.074, 95 % CI = -0.089 to -0.016), accounting for 60.16 % and 40.65 % of the total effect, respectively.

CONCLUSION

These findings provide a theoretical basis for developing precise exercise intervention programs to improve depressive symptoms and sleep quality among college students. The results indicate that moderate physical activity can help alleviate depressive symptoms and improve sleep quality, thereby enhancing the overall health of college students.

Investigation of Cissus populnea as a Potential Therapeutic Agent for Erectile Dysfunction

Cissus populnea (CP) is a plant reported to possess an erection-enhancing ability, though mechanisms remain unclear. Drugs targeting phosphodiesterase 5 (PDE5) inhibition, such as sildenafil, have been employed to treat erectile dysfunction (EDRF), but they are associated with several complications. This study investigated the effect of C. populnea extracts (aqueous and saponin-rich) on the activity and gene expressions of proteins related to erection. PDE5, Nitric oxide synthase (NOS) and androgen receptor (AR) genes were studied using RT-PCR on CP-treated paroxetine-induced ERDF-rats. It also employed Schrödinger suites for investigations such as molecular and induced-fit docking, MMGBSA, ADMET, and QSAR profiling of CP-phytocompounds. C. populnea extracts reduce the activity and downregulate the expression of the PDE5 gene while upregulating the expressions of AR and NOS genes in the ERDF-rats relative to the control group. Five (leading) compounds with induced-fit docking (IFD) scores in kcal/mol, namely, stigmasterol (-638.73), daucosterol (-644.73), furostanol (-639.29), papaverine (-639.03), and capsaicin (-642.88), had better docking scores of -9.936, -9.824, -9.064, -8.863, and -8.736 kcal/mol, respectively, compared with those of sildenafil (-8.611 kcal/mol). They also showed an excellent ADMET profile, satisfying Lipinski's rule of five. The MMGBSA predictions revealed that stigmasterol, daucosterol, papaverine, and capsaicin had binding free energies of -45.29, -59.14, -50.63, and -50.47 kcal/mol, respectively, suggesting that they are significant inhibitors of PDE5. The QSAR model revealed that lead compounds possess good pIC50 values. These results indicate that C. populnea is a more promising possible treatment for controlling EDRF and deserves further research.

Using Precision Medicine to Disentangle Genotype-Phenotype Relationships in Twins with Rett Syndrome: A Case Report

Rett syndrome (RTT) is a paediatric neurodevelopmental disorder spanning four developmental stages. This multi-system disorder offers a unique window to explore genotype-phenotype relationships in a disease model. However, genetic prognosticators of RTT have limited clinical value due to the disorder's heterogeneity on multiple levels. This case report used a precision medicine approach to better understand the clinical phenotype of RTT twins with an identical pathogenic MECP2 mutation and discordant neurodevelopmental profiles. Targeted genotyping, objective physiological monitoring of heart rate variability (HRV) parameters, and clinical severity were assessed in a RTT twin pair (5 years 7 months old) with an identical pathogenic MECP2 mutation. Longitudinal assessment of autonomic HRV parameters was conducted using the Empatica E4 wristband device, and clinical severity was assessed using the RTT-anchored Clinical Global Impression Scale (RTT-CGI) and the Multi-System Profile of Symptoms Scale (MPSS). Genotype data revealed impaired BDNF function for twin A when compared to twin B. Twin A also had poorer autonomic health than twin B, as indicated by lower autonomic metrics (autonomic inflexibility). Hospitalisation, RTT-CGI-S, and MPSS subscale scores were used as measures of clinical severity, and these were worse in twin A. Treatment using buspirone shifted twin A from an inflexible to a flexible autonomic profile. This was mirrored in the MPSS scores, which showed a reduction in autonomic and cardiac symptoms following buspirone treatment. Our findings showed that a combination of a co-occurring rs6265 BDNF polymorphism, and worse autonomic and clinical profiles led to a poorer prognosis for twin A compared to twin B. Buspirone was able to shift a rigid autonomic profile to a more flexible one for twin A and thereby prevent cardiac and autonomic symptoms from worsening. The clinical profile for twin A represents a departure from the disorder trajectory typically observed in RTT and underscores the importance of wider genotype profiling and longitudinal objective physiological monitoring alongside measures of clinical symptoms and severity when assessing genotype-phenotype relationships in RTT patients with identical pathogenic mutations. A precision medicine approach that assesses genetic and physiological risk factors can be extended to other neurodevelopmental disorders to monitor risk when genotype-phenotype relationships are not so obvious.

Targeting Nr2e3 to Modulate Tet2 Expression: Therapeutic Potential for Depression Treatment

Epigenetic mechanisms such as DNA methylation and hydroxymethylation play a significant role in depression. This research has shown that Ten-eleven translocation 2 (Tet2) deficiency prompts depression-like behaviors, but Tet2's transcriptional regulation remains unclear. In the study, bioinformatics is used to identify nuclear receptor subfamily 2 group E member 3 (Nr2e3) as a potential Tet2 regulator. Nr2e3 is found to enhance Tet2's transcriptional activity by binding to its promoter region. Nr2e3 knockdown in mouse hippocampus leads to reduced Tet2 expression, depression-like behaviors, decreased hydroxymethylation of synaptic genes, and downregulation of synaptic proteins like postsynaptic density 95 KDa (PSD95) and N-methy-d-aspartate receptor 1 (NMDAR1). Fewer dendritic spines are also observed. Nr2e3 thus appears to play an antidepressant role under stress. In search of potential treatments, small molecule compounds to increase Nr2e3 expression are screened. Azacyclonal (AZA) is found to enhance the Nr2e3/Tet2 pathway and exhibited antidepressant effects in stressed mice, increasing PSD95 and NMDAR1 expression and dendritic spine density. This study illuminates Tet2's upstream regulatory mechanism, providing a new target for identifying early depression biomarkers and developing treatments.

Phase 1, placebo-controlled, single ascending dose trial to evaluate the safety, pharmacokinetics and effect on altered states of consciousness of intranasal BPL-003 (5-methoxy-N,N-dimethyltryptamine benzoate) in healthy participants

AIMS

To investigate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of BPL-003, a novel intranasal benzoate salt formulation of 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), in healthy participants.

METHODS

In all, 44 psychedelic-naïve participants enrolled in the double-blind, placebo-controlled single ascending dose study (1-12 mg BPL-003). Concentrations of 5-MeO-DMT and its pharmacologically active metabolite, bufotenine, were determined in plasma and urine. PD endpoints included subjective drug intensity (SDI) rating, the Mystical Experience Questionnaire (MEQ-30) and the Ego Dissolution Inventory (EDI).

RESULTS

BPL-003 was well tolerated at doses up to 12 mg. There were no serious adverse events (AEs), and most AEs were mild; the most common being nasal discomfort, nausea, headache and vomiting. 5-MeO-DMT was rapidly absorbed and eliminated; the median time to peak plasma concentration was approximately 8-10 min and the mean terminal elimination half-life was <27 min. 5-MeO-DMT systemic exposure increased approximately dose-proportionally, while plasma bufotenine concentrations and urinary excretion of 5-MeO-DMT and bufotenine were negligible. The intensity of the SDI ratings was associated with plasma 5-MeO-DMT concentrations. MEQ-30 and EDI scores generally increased with the BPL-003 dose; 60% of participants had a 'complete mystical experience' at 10 and 12 mg doses. Profound and highly emotional consciousness-altering effects were observed with BPL-003, with a rapid onset and short-lasting duration.

CONCLUSION

The novel intranasal formulation of BPL-003 was well tolerated with dose-proportional increases in PK and PD effects. The short duration of action and induction of mystical experiences suggest clinical potential, warranting further trials.

CLINICAL TRIAL REGISTRATION

NCT05347849.

Development of heterocyclic-based frameworks as potential scaffold of 5-HT1A receptor agonist and future perspectives: A review

As a subtype of the 5-hydroxytryptamine (5-HT) receptor, 5-HT1A receptors are involved in the pathological process of psychiatric disorders and is an important target for antidepressants. The research groups focus on these area have tried to design novel compounds to alleviate depression by targeting 5-HT1A receptor. The heterocyclic structures is an important scaffold to enhance the antidepressant activity of ligands, including piperazine, piperidine, benzothiazole, and pyrrolidone. The current review highlights the function and significance of nitrogen-based heterocyclics 5-HT1AR represented by piperazine, piperidine, benzothiazole, and pyrrolidone in the development of antidepressant.

St. John's wort extract Ze 117 alters the membrane fluidity of C6 glioma cells by influencing cellular cholesterol metabolism

Chronic stress is associated with major depressive disorder (MDD). Increased glucocorticoid levels caused by uncontrolled release through the hypothalamic‒pituitary‒adrenal (HPA) axis can cause changes in the lipid content of the cellular plasma membrane. These changes are suspected to be involved in the development of depressive disorders. St. John's wort extract (SJW) Ze 117 has long been used as an alternative to synthetic antidepressants. Part of its effect may be due to an effect on the cellular lipid composition and thus on the properties of plasma membranes and receptor systems embedded therein. In this study, we investigated the effect of Ze 117 on that of dexamethasone and simvastatin. Dexamethasone increases the fluidity of C6 cell plasma membranes. This effect is counteracted by administration of Ze 117. Here we demonstrate that this is not due to a change in C16:1/16:0 and C18:1/18:0 ratios in C6 cell fatty acids. On the other hand, Ze 117 increased the cellular cholesterol content by 42.5%, whereas dexamethasone reduced cholesterol levels similarly to simvastatin. Lowering cholesterol levels by dexamethasone or simvastatin resulted in decreased β-arrestin 2 recruitment to the 5-HT1a receptor. This effect was counterbalanced by Ze 117, whereas the SJW extract had little effect on β-arrestin 2 recruitment in non-stressed cells. Taken together, in C6 cells, Ze 117 induces changes in membrane fluidity through its effect on cellular cholesterol metabolism rather than by affecting fatty acid saturation. This effect is reflected in an altered signal transduction of the 5-HT1a receptor under Ze 117 administration. The current in vitro results support the hypothesis that Ze 117 addresses relevant parts of the cellular lipid metabolism, possibly explaining some of the antidepressant actions of Ze 117.

Effect of Short Photoperiod on Behavior and Brain Plasticity in Mice Differing in Predisposition to Catalepsy: The Role of BDNF and Serotonin System

Seasonal affective disorder is characterized by depression during fall/winter as a result of shorter daylight. Catalepsy is a syndrome of some grave mental diseases. Both the neurotransmitter serotonin (5-HT) and brain-derived neurotrophic factor (BDNF) are involved in the pathophysiological mechanisms underlying catalepsy and depressive disorders. The aim was to compare the response of behavior and brain plasticity to photoperiod alterations in catalepsy-resistant C57BL/6J and catalepsy-prone CBA/Lac male mice. Mice of both strains were exposed for six weeks to standard-day (14 h light/10 h darkness) or short-day (4 h light/20 h darkness) conditions. Short photoperiod increased depressive-like behavior in both strains. Only treated CBA/Lac mice demonstrated increased cataleptic immobility, decreased brain 5-HT level, and the expression of Tph2 gene encoding the key enzyme for 5-HT biosynthesis. Mice of both strains maintained under short-day conditions, compared to those under standard-day conditions, showed a region-specific decrease in the brain transcription of the Htr1a, Htr4, and Htr7 genes. After a short photoperiod exposure, the mRNA levels of the BDNF-related genes were reduced in CBA/Lac mice and were increased in the C57BL/6J mice. Thus, the predisposition to catalepsy considerably influences the photoperiodic changes in neuroplasticity, wherein both C57BL/6J and CBA/Lac mice can serve as a powerful tool for investigating the link between seasons and mood.

A psychometric evaluation of the 16-item PHQ-ADS concomitant anxiety and depression scale in the UK biobank using item response theory

BACKGROUND

The Patient Health Questionnaire Anxiety and Depression Scale (PHQ-ADS) provides a reliable and valid measure of concomitant depression and anxiety. However, research on its psychometric efficiency and optimal scale length using item-response theory (IRT) has not been reported. This study aimed to optimize the length of the PHQ-ADS scale without losing information by discarding items that were a poor fit to the IRT model.

METHODS

The UK Biobank is a large cohort study designed to investigate risk factors for a broad range of disease. PHQ-ADS data were available from n = 152,826 participants (age = 55.87 years; SD = 7.73; 56.4 % female), 30.4 % of the entire UK Biobank sample. Psychometric properties of the PHQ-ADS were investigated using a 2-parameter IRT and Mokken analysis. Item statistics included discrimination, difficulty and Loevinger H coefficients of monotonicity.

RESULTS

In the entire 16-item scale, item discrimination ranged from 1.40 to 4.22, with the item 'worrying' showing the highest level of discrimination and the item 'sleep disturbance' showing the lowest. Mokken analysis showed that the 16-item PHQ-ADS scale could be reduced to a 7-item scale without loss of test information. The reduced scale comprised mainly items measuring cognitive-affective symptoms of anxiety/depression, whereas items measuring somatic symptoms were discarded. The revised scale showed high discrimination and scalability.

LIMITATIONS

Findings are limited by the use of cross-sectional data that only included the baseline online questionnaire, but not other waves.

CONCLUSIONS

IRT is a useful technique for scale reductions which serve the clinical and epidemiological need to optimize screening questionnaires to reduce redundancy and maximize information. A reduced-item 7-item PHQ-ADS scale reduces the response burden on participants in epidemiological research settings, without loss of information.

Gepirone Extended-Release: First Approval

Gepirone HCL extended-release (gepirone ER; EXXUA™), an oral, selective serotonin (5HT)1A receptor agonist formulated for once-daily administration, has been developed by Fabre-Kramer Pharmaceuticals, Inc. for the treatment of psychiatric disorders, including major depressive disorder (MDD). In September 2023, gepirone ER was approved in the USA for the treatment of adults with MDD. This article summarizes the milestones in the development of gepirone ER leading to this first approval for the treatment of adults with MDD.

Functional Dimerization of Serotonin Receptors: Role in Health and Depressive Disorders

Understanding the neurobiological underpinnings of depressive disorder constitutes a pressing challenge in the fields of psychiatry and neurobiology. Depression represents one of the most prevalent forms of mental and behavioral disorders globally. Alterations in dimerization capacity can influence the functional characteristics of serotonin receptors and may constitute a contributing factor to the onset of depressive disorders. The objective of this review is to consolidate the current understanding of interactions within the 5-HT receptor family and between 5-HT receptors and members of other receptor families. Furthermore, it aims to elucidate the role of such complexes in depressive disorders and delineate the mechanisms through which antidepressants exert their effects.

Tryptamines and Mental Health: Activating the 5-HT Receptor for Therapeutic Potential

Tryptamines, a class of 3-aminoethyl-indoles that activate the serotonin receptor, show potential for novel mental health treatments. The FDA has granted "breakthrough therapy designation" to psilocybin and MDMA for treatment-resistant depression, major depressive disorder, and post-traumatic stress disorder, sparking global research efforts. Various clinical trials are currently investigating the therapeutic value of psilocybin for several mental health disorders. Results thus far indicate significant improvements in patient-reported outcomes via reductions in experiential avoidance. These advancements highlight a promising future for tryptamines in mental health therapy.