Hypidone Hydrochloride (YL-0919) Produces a Fast-Onset Reversal of the Behavioral and Synaptic Deficits Caused by Chronic Stress Exposure

Pre- and Post-Synaptic protein in the major depressive Disorder: From neurobiology to therapeutic targets

Major depressive disorder (MDD) has demonstrated its negative impact on various aspects of the lives of those affected. Although several therapies have been developed over the years, it remains a challenge for mental health professionals. Thus, understanding the pathophysiology of MDD is necessary to improve existing treatment options or seek new therapeutic alternatives. Clinical and preclinical studies in animal models of depression have shown the involvement of synaptic plasticity in both the development of MDD and the response to available drugs. However, synaptic plasticity involves a cascade of events, including the action of presynaptic proteins such as synaptophysin and synapsins and postsynaptic proteins such as postsynaptic density-95 (PSD-95). Additionally, several factors can negatively impact the process of spinogenesis/neurogenesis, which are related to many outcomes, including MDD. Thus, this narrative review aims to deepen the understanding of the involvement of synaptic formations and their components in the pathophysiology and treatment of MDD.

AKT and MAPK signaling pathways in hippocampus reveals the pathogenesis of depression in four stress-induced models

Major depressive disorder (MDD) is a highly heterogeneous psychiatric disorder. The pathogenesis of MDD remained unclear, and it may be associated with exposure to different stressors. Most previous studies have focused on molecular changes in a single stress-induced depression model, which limited the identification of the pathogenesis of MDD. The depressive-like behaviors were induced by four well-validated stress models in rats, including chronic unpredictable mild stress, learned helplessness stress, chronic restraint stress and social defeat stress. We applied proteomic and metabolomic to investigate molecular changes in the hippocampus of those four models and revealed 529 proteins and 98 metabolites. Ingenuity Pathways Analysis (IPA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified differentially regulated canonical pathways, and then we presented a schematic model that simulates AKT and MAPK signaling pathways network and their interactions and revealed the cascade reactions. Further, the western blot confirmed that p-AKT, p-ERK12, GluA1, p-MEK1, p-MEK2, p-P38, Syn1, and TrkB, which were changed in at least one depression model. Importantly, p-AKT, p-ERK12, p-MEK1 and p-P38 were identified as common alterations in four depression models. The molecular level changes caused by different stressors may be dramatically different, and even opposite, between four depression models. However, the different molecular alterations converge on a common AKT and MAPK molecular pathway. Further studies of these pathways could contribute to a better understanding of the pathogenesis of depression, with the ultimate goal of helping to develop or select more effective treatment strategies for MDD.

Essential role of microglia in the fast antidepressant action of ketamine and hypidone hydrochloride (YL-0919)

Introduction: Intracerebral microglia play a vital role in mediating central immune response, neuronal repair and synaptic pruning, but its precise role and mechanism in fast action of antidepressants have remained unknown. In this study, we identified that the microglia contributed to the rapid action of antidepressants ketamine and YL-0919. Methods: The depletion of microglia was achieved with the diet containing the colony-stimulating factor 1 receptor (CSF1R) inhibitor PLX5622 in mice. The tail suspension test (TST), forced swimming test (FST) and novelty suppressed feeding test (NSFT) were employed to evaluate the rapid acting antidepressant behavior of ketamine and YL-0919 in the microglia depletion model. The number of microglia in the prefrontal cortex (PFC) was assayed by the immunofluorescence staining. The expressions of synaptic proteins (synapsin-1, PSD-95, GluA1) and brain-derived neurotrophic factor (BDNF) in the PFC were tested by Western blot. Results: The immobility duration in FST and the latency to feed in NSFT were shortened 24 h after an intraperitoneal (i.p.) injection of ketamine (10 mg/kg). The microglial depletion of PLX3397 blocked the rapid antidepressant-like effect of ketamine in mice. In addition, the immobility time in TST and FST as well as latency to feed in NSFT were reduced 24 h after the intragastric (i.g.) administration of YL-0919 (2.5 mg/kg), and the rapid antidepressant effect of YL-0919 was also blocked by the microglial depletion using PLX5622. About 92% of microglia in the prefrontal cortex was depleted in PLX5622 diet-fed mice, while both ketamine and YL-0919 promoted proliferation on the remaining microglia. YL-0919 significantly increased the protein expressions of synapsin-1, PSD-95, GluA1 and BDNF in the PFC, all of which could be blocked by PLX5622. Conclusion: These results suggested the microglia underlying the rapid antidepressant-like effect of ketamine and YL-0919, and microglia would likely constitute in the rapid enhancing impact of synaptic plasticity in the prefrontal cortex by YL-0919.

Astrocytes underlie a faster-onset antidepressant effect of hypidone hydrochloride (YL-0919)

Introduction: Major depression disorder (MDD) is a common and potentially life-threatening mental illness; however, data on its pathogenesis and effective therapeutic measures are lacking. Pathological changes in astrocytes play a pivotal role in MDD. While hypidone hydrochloride (YL-0919), an independently developed antidepressant, has shown rapid action with low side effects, its underlying astrocyte-specific mechanisms remain unclear.

Methods: In our study, mice were exposed to chronic restraint stress (CRS) for 14 days or concomitantly administered YL-0919/fluoxetine. Behavioral tests were applied to evaluate the depression model; immunofluorescence and immunohistochemistry staining were used to explore morphological changes in astrocytes; astrocyte-specific RNA sequencing (RNA-Seq) analysis was performed to capture transcriptome wide alterations; and ATP and oxygen consumption rate (OCR) levels of primary astrocytes were measured, followed by YL-0919 incubation to appraise the alteration of energy metabolism and mitochondrial oxidative phosphorylation (OXPHOS).

Results: YL-0919 alleviated CRS-induced depressive-like behaviors faster than fluoxetine and attenuated the number and morphologic deficits in the astrocytes of depressed mice. The changes of gene expression profile in astrocytes after CRS were partially reversed by YL-0919. Moreover, YL-0919 improved astrocyte energy metabolism and mitochondrial OXPHOS in astrocytes.

Conclusion: Our results provide evidence that YL-0919 exerted a faster-onset antidepressant effect on CRS-mice possibly via astrocyte structural remodeling and mitochondria functional restoration.

Antidepressive Effect of Natural Products and Their Derivatives Targeting BDNF-TrkB in Gut-Brain Axis

Modern neurological approaches enable detailed studies on the pathophysiology and treatment of depression. An imbalance in the microbiota-gut-brain axis contributes to the pathogenesis of depression. This extensive review aimed to elucidate the antidepressive effects of brain-derived neurotrophic factor (BDNF)-targeting therapeutic natural products and their derivatives on the gut-brain axis. This information could facilitate the development of novel antidepressant drugs. BDNF is crucial for neuronal genesis, growth, differentiation, survival, plasticity, and synaptic transmission. Signaling via BDNF and its receptor tropomyosin receptor kinase B (TrkB) plays a vital role in the etiopathogenesis of depression and the therapeutic mechanism of antidepressants. This comprehensive review provides information to researchers and scientists for the identification of novel therapeutic approaches for neuropsychiatric disorders, especially depression and stress. Future research should aim to determine the possible causative role of BDNF-TrkB in the gut-brain axis in depression, which will require further animal and clinical research as well as the development of analytical approaches.

The effects of Vilazodone, YL-0919 and Vortioxetine in hemiparkinsonian rats

Parkinson's disease is a neurodegenerative disease often characterized by motor deficits and most commonly treated with dopamine replacement therapy. Despite its benefits, chronic use of L-DOPA results in abnormal involuntary movements known as L-DOPA-induced dyskinesia. Growing evidence shows that with burgeoning dopamine cell loss, neuroplasticity in the serotonin system leads to the development of L-DOPA-induced dyskinesia through the unregulated uptake, conversion, and release of L-DOPA-derived dopamine into the striatum. Previous studies have shown that coincident 5-HT_1A agonism and serotonin transporter inhibition may have anti-dyskinetic potential. Despite this, few studies have explicitly focused on targeting both 5-HT_1A and the serotonin transporter. The present study compares the 5-HT compounds Vilazodone, YL-0919, and Vortioxetine which purportedly work as simultaneous 5-HT_1A receptor agonists and SERT blockers. To do so, adult female Sprague Dawley rats were rendered hemiparkinsonian and treated daily for two weeks with L-DOPA to produce stable dyskinesia. The abnormal involuntary movements and forehand adjusting step tests were utilized as measurements for L-DOPA-induced dyskinesia and motor performance in a within-subjects design. Lesion efficacy was determined by analysis of striatal monoamines via high-performance liquid chromatography. Compounds selective for 5-HT_1A/SERT target sites including Vilazodone and Vortioxetine significantly reduced L-DOPA-induced dyskinesia without compromising L-DOPA pro-motor efficacy. In contrast, YL-0919 failed to reduce L-DOPA-induced dyskinesia, with no effects on L-DOPA-related improvements. Collectively, this work supports pharmacological targeting of 5-HT_1A/SERT to reduce L-DOPA-induced dyskinesia. Additionally, this further provides evidence for Vilazodone and Vortioxetine, FDA-approved compounds, as potential adjunct therapeutics for L-DOPA-induced dyskinesia management in Parkinson's patients.

New monoamine antidepressant, hypidone hydrochloride (YL-0919), enhances the excitability of medial prefrontal cortex in mice via a neural disinhibition mechanism

Hypidone hydrochloride (YL-0919) is a novel antidepressant in clinical phase II trial. Previous studies show that YL-0919 is a selective 5-HT (serotonin) reuptake inhibitor, 5-HT_1A receptor partial agonist, and 5-HT₆ receptor agonist, which exerts antidepressant effects in various animal models, but its effects on neural function remain unclear. Medial prefrontal cortex (mPFC), a highly evolved brain region, controls highest order cognitive functions and emotion regulation. In this study we investigated the effects of YL-0919 on the mPFC function, including the changes in neuronal activities using electrophysiological recordings. Extracellular recording (in vivo) showed that chronic administration of YL-0919 significantly increased the spontaneous discharges of mPFC neurons. In mouse mPFC slices, whole-cell recording revealed that perfusion of YL-0919 significantly increased the frequency of sEPSCs, but decreased the frequency of sIPSCs. Then we conducted whole-cell recording in mPFC slices of GAD67-GFP transgenic mice, and demonstrated that YL-0919 significantly inhibited the excitability of GABAergic neurons. In contrast, it did not alter the excitability of pyramidal neurons in mPFC slices of normal mice. Moreover, the inhibition of GABAergic neurons by YL-0919 was prevented by pre-treatment with 5-HT_1A receptor antagonist WAY 100635. Finally, chronic administration of YL-0919 significantly increased the phosphorylation levels of mTOR and GSK-3β in the mPFC as compared with vehicle. Taken together, our results demonstrate that YL-0919 enhances the excitability of mPFC via a disinhibition mechanism to fulfill its rapid antidepressant neural mechanism, which was accomplished by 5-HT_1A receptor-mediated inhibition of inhibitory GABAergic interneurons.

Role of BDNF-mTORC1 Signaling Pathway in Female Depression

Depression is a common psychological and mental disorder, characterized by low mood, slow thinking and low will, and even suicidal tendencies in severe cases. It imposes a huge mental and economic burden on patients and their families, and its prevention and treatment have become an urgent public health problem. It is worth noting that there is a significant gender difference in the incidence of depression. Studies have shown that females are far more likely to suffer from depression than males, confirming a close relationship between estrogen and the onset of depression. Moreover, recent studies suggest that the brain-derived neurotrophic factor- (BDNF-) mammalian target of rapamycin complex-1 (mTORC1) signaling pathway is a crucial target pathway for improving depression and mediates the rapid antidepressant-like effects of various antidepressants. However, it is not clear whether the BDNF-mTORC1 signaling pathway mediates the regulation of female depression and how to regulate female depression. Hence, we focused on the modulation of estrogen-BDNF-mTORC1 signaling in depression and its possible mechanisms in recent years.

The Faster-Onset Antidepressant Effects of Hypidone Hydrochloride (YL-0919) in Monkeys Subjected to Chronic Unpredictable Stress

Given the limited monkey models of depression available to date, as well as the procedural complexity and time investments that they involve, the ability to test the efficacy and time course of antidepressants in monkey models is greatly restricted. The present study attempted to build a simple and feasible monkey model of depression with chronic unpredictable stress (CUS) and evaluate the antidepressant effect and onset time of fluoxetine hydrochloride (FLX) and the new drug hypidone hydrochloride (YL-0919), a potent and selective 5-HT reuptake inhibitor, 5-HT_1A receptor partial agonist and 5-HT₆ receptor full agonist. Female cynomolgus monkeys with low social status in their colonies were selected and subjected to CUS for 8 weeks by means of food and water deprivation, space restriction, loud noise, strobe light, and intimidation with fake snakes. Huddling, self-clasping, locomotion and environmental exploration were monitored to evaluate behavioral changes. In addition, the window-opening test was used to evaluate the exploratory interest of the monkeys. The present results revealed that CUS-exposed monkeys displayed significant depression-like behaviors, including significant decreases in exploratory interest, locomotion, and exploration as well as significant increases in huddling and self-clasping behavior and the level of fecal cortisol after 8 weeks of CUS. Treatment with FLX (2.4 mg/kg, i. g.) or YL-0919 (1.2 mg/kg, i. g.) markedly reversed the depression-like behaviors caused by CUS, producing significant antidepressant effects. YL-0919 (once daily for 9 days) had a faster-onset antidepressant effect, compared with FLX (once daily for 17 days). In summary, the present study first established a CUS model using female cynomolgus monkeys with low social status and then successfully evaluated the onset time of 5-HTergic antidepressants. The results suggested that monkeys exposed to CUS displayed significant depression-like behaviors, and both FLX and YL-0919 produced antidepressant effects in this model. Moreover, YL-0919 appeared to act faster than FLX. The present study provides a promising prospect for the evaluation of fast-onset antidepressant drugs based on a CUS monkey model.

Rapid anti-depressant-like effects of ketamine and other candidates: Molecular and cellular mechanisms

Major depressive disorder takes at least 3 weeks for clinical anti‐depressants, such as serotonin selective reuptake inhibitors, to take effect, and only one‐third of patients remit. Ketamine, a kind of anaesthetic, can alleviate symptoms of major depressive disorder patients in a short time and is reported to be effective to treatment‐resistant depression patients. The rapid and strong anti‐depressant‐like effects of ketamine cause wide concern. In addition to ketamine, caloric restriction and sleep deprivation also elicit similar rapid anti‐depressant‐like effects. However, mechanisms about the rapid anti‐depressant‐like effects remain unclear. Elucidating the mechanisms of rapid anti‐depressant effects is the key to finding new therapeutic targets and developing therapeutic patterns. Therefore, in this review we summarize potential molecular and cellular mechanisms of rapid anti‐depressant‐like effects based on the pre‐clinical and clinical evidence, trying to provide new insight into future therapy.