cAMP/PKA-CREB-BDNF signaling pathway in hippocampus mediates cyclooxygenase 2-induced learning/memory deficits of rats subjected to chronic unpredictable mild stress

URB597 modulates neuroplasticity, neuroinflammatory, and Nrf2/HO-1 signaling pathways in the hippocampus and prefrontal cortex of male and female rats in a stress-induced model of depression

Major depressive disorder is often associated with cognitive impairments, and neuroinflammation is considered a key contributor to the onset of depression. Pharmacological inhibition of fatty acid amide hydrolase (FAAH), which augments endocannabinoid signaling, has emerged as a promising approach to treating depression. The main purpose of this study is to asses the influence of FAAH inhibitor URB597 on inflammatory response and oxidative stress in chronic unpredictable stress (CUS)-induced depressive female and male rats and to explore the underlying molecular mechanisms. Chronically stressed animals showed long-term memory deficits, while URB597 improved memory only in stressed males. URB597 treatment enhanced levels of brain-derived neurotrophic factor (BDNF) in the hippocampus and mPFC of stressed female and male rats and increased phosphorylated calcium/calmodulin-dependent protein kinase II (pCaMKII) levels in the hippocampus and mPFC of CUS males. Additionally, increased phosphorylation of JAK2 and STAT3 in the hippocampus and mPFC of CUS male and female rats, was reduced following URB597 treatment. URB597 decreased the CUS-enhanced iNOS protein expression in the hippocampus and mPFC of both sexes. Furthermore, URB597 normalized CUS-induced reductions in Nrf2 and HO-1 levels in the mPFC of both sexes, with no changes in the hippocampus. Our findings suggest that URB597 may inhibit the CUS-induced neuroinflammatory response by suppressing the pro-inflammatory mediators and the activation of the JAK2/STAT3 signaling in the hippocampus and mPFC of both sexes. URB597 treatment contributed to synaptic plasticity in a sex-specific manner by upregulating brain CaMKII signaling in males. URB597 also exerts neuroprotective effects through region-specific antioxidant properties. These results have implications for sex-specific treatment strategies in stress-related neuropsychiatric disorders.

Exploring the Connection Between BDNF/TrkB and AC/cAMP/PKA/CREB Signaling Pathways: Potential for Neuroprotection and Therapeutic Targets for Neurological Disorders

The BDNF/TrkB and AC/cAMP/PKA/CREB signaling pathways play a vital role in neuroplasticity, neuronal survival, and cognitive functions. This review explores its physiological and pathological implications in neurological disorders, with a focus on neurodegenerative diseases (NDDs) and neuropsychiatric disorders (NPDs). Neurological conditions increasingly burden public health, making understanding the biochemical mechanisms that underpin these diseases critical. BDNF, a neurotrophic factor, binds to the TrkB receptor, activating multiple intracellular signaling cascades that regulate cellular responses essential for neurogenesis, memory, and learning. Dysregulation within this pathway has been linked to various NDDs, as well as NPDs. Key components of the path, including adenylyl cyclase and cyclic AMP, mediate the effects of neurotransmitters and growth factors, influencing downstream targets like PKA and CREB, which are crucial for gene expression and synaptic changes. Furthermore, the review discusses the challenges of targeting this pathway for therapeutic interventions, including receptor isoform diversity, blood-brain barrier penetration, and potential side effects. Future strategies may include the development of selective TrkB modulators, nanoparticle carriers for drug delivery, and innovative gene therapy techniques. Advancing the understanding of this complex signaling network holds promise for effective interventions in treating neurological and psychiatric disorders, ultimately enhancing neuroprotection and cognitive resilience.

Sigma-1 receptor agonist PRE-084 increases BDNF by activating the ERK/CREB pathway to rescue learning and memory impairment caused by type II diabetes

Sigma-1 receptor (Sig-1R) agonists has therapeutic effects in neurological disorders and possesses properties that can reverse cognitive dysfunction. This study investigated the therapeutic efficacy of Sig-1R activation on cognitive dysfunction in streptozotocin (STZ) combined with high fat and high sugar diet (HFD)-induced type 2 diabetic rats. By employing morris water maze (MWM) testing and computed tomography (CT) imaging, we observed that activation of Sig-1R effectively mitigated brain atrophy and cognitive impairment in diabetes-induced cognitive impairment (DCI) rats. Given the fundamental role of intact hippocampal synaptic plasticity in maintaining cognitive function, we investigated the correlation between Sig-1R and Brain-Derived Neurotrophic Factor (BDNF), a well-established neurotrophic factor. And we also analyzed the expression of Postsynaptic density protein-95 (PSD95) protein. Golgi staining, Haematoxylin-eosin (HE) staining, Nissl staining, and immunofluorescence results show that activating Sig-1R can upregulate BDNF expression and reducing synaptic damage in hippocampal neurons. To elucidate the mechanism by which Sig-1R activation leads to increased BDNF levels, we investigated the Extracellular Signal-Regulated Kinase/Cyclic AMP Response Element-Binding Protein(ERK/CREB) protein pathway. In vitro and in vivo, we observed that Sig-1R activates the ERK/CREB signaling pathway, thereby stimulating BDNF release and increased PSD95 expression. Further intervention with BD1047 antagonist and Tropomyosin-Related Kinase B (TrkB) antagonist ANA-12 confirmed our conclusion that Sig-1R activation upregulated p-ERK and p-CREB protein expression, promoted BDNF transcription, the expression of PSD95 protein was up-regulated, reduces synaptic damage in damaged hippocampal neurons, and rescued cognitive impairment in DCI rats.

Hippocampal Apoptosis: Molecular Mechanisms Triggered by Toxic Cannabinoid Exposure: A Narrative Review

Hippocampal apoptosis is increasingly recognized as a significant consequence of toxic cannabinoid exposure, with profound implications for cognitive function and mental health. This narrative review comprehensively examines the molecular mechanisms underlying cannabinoid-induced apoptosis, focusing on the interplay of various bioactive compounds and their effects on neuronal integrity. We begin by discussing the key players in cannabinoid biology, followed by a synthesis of findings from animal and clinical studies that highlight the neurotoxic potential of cannabinoids. Central to our analysis are the roles of neuroinflammation and oxidative stress, which exacerbate neuronal damage and contribute to cell death. The activation of cannabinoid receptors, particularly CB1 and CB2, is scrutinized for its dual role in mediating neuroprotective and neurotoxic effects. We explore calcium dysregulation as a critical mechanism that leads to excitotoxicity, mitochondrial dysfunction, and the activation of pro-apoptotic pathways. Additionally, we address the inhibition of anti-apoptotic proteins, induction of endoplasmic reticulum (ER) stress, and disruption of neurotransmitter systems, all of which further facilitate apoptosis in hippocampal neurons. Alterations in neurotrophic factor levels are also examined, as they play a vital role in neuronal survival and plasticity. Ultimately, this review underscores the multifaceted nature of cannabinoid-induced hippocampal apoptosis and calls for further research to elucidate these complex interactions, aiming to inform clinical practices and public health policies regarding cannabinoid use. The findings presented herein highlight the urgent need for a nuanced understanding of the risks associated with cannabinoid exposure, particularly in vulnerable populations.

Syringa oblata Lindl extract alleviated corticosterone-induced depression via the cAMP/PKA-CREB-BDNF pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Syringa oblata Lindl (ZDX) is a plant in the Oleaceae family that is the primary ingredient in the classic Tibetan medicine AKARU sinensis. The plant's stem is used as a medicine, and Tibetan doctors often use it as a sedative, a use with a history of nearly 100 years. Tibetan medicine mainly uses lilac to treat headache, forgetfulness, insomnia, irritability and other symptoms. Depression is a chronic mental disorder characterized by low mood, cognitive impairments, and physical discomfort, and it has become a significant public health issue. Given the limitations of existing treatments, interest in alternative therapies, including herbal medicines, is increasing.

AIM

To elucidate the mechanism of ZDX extract in the treatment of depression.

MATERIALS AND METHODS

A depression-like mouse model was established via the subcutaneous injection of corticosterone (CORT) into the groin, and a model of PC12 cell injury was established via CORT treatment. The antidepressant effect of the ZDX extract was subsequently evaluated via weight measurements, the sucrose preference test (SPT), the forced swimming test (FST), the open field test(OFT), the tail suspension test (TST), HE staining, Nissl staining and ELISA. Moreover, immunofluorescence staining, qRT‒PCR and Western blotting were used to determine whether ZDX extract can regulate the cAMP/PKA-CREB-BDNF pathway to prevent depression and neuronal apoptosis.

RESULTS

ZDX extract significantly improved depression-like behaviours; inhibited decreases in the protein levels of cAMP, PKA, CREB and BDNF; and increased proliferative activity in the hippocampus and cortex. In addition, in vitro, ZDX extract attenuated CORT-induced injury and apoptosis in hippocampal neurons and inhibited CORT-induced decreases in the mRNA expression levels of cAMP, PKA, CREB and BDNF.

CONCLUSIONS

These findings suggest that ZDX extract has potential as a novel antidepressant therapeutic agent, offering a complementary approach to current treatments by targeting multiple pathways involved in the pathogenesis of depression. Further research is warranted to explore the clinical applications of ZDX extract in the treatment of depression.

Fluoxetine treatment reverses chronic stress-induced promotion on Fk506-binding protein 5 expression and multiple effects on glucocorticoid receptor phosphorylation in the paraventricular nucleus of mice

BACKGROUND

Fluoxetine is widely used as a first-line antidepressant. However, the molecular mechanisms for its antidepressant effects are still not fully understood. Hyperactivation of the hypothalamic-pituitary-adrenal (HPA) axis is a core pathogenic mechanism contributing to depression, and fluoxetine treatment prevents this dysfunction. The glucocorticoid receptor (GR) is a major negative feedback regulator of the HPA axis, while Fk506-binding protein 5 (Fkbp5) is a negative regulator of the GR signaling. Therefore, we examined the effects of fluoxetine on Fkbp5 and the GR signaling in the hypothalamic paraventricular nucleus (PVN) of depressed mice.

METHODS

Mice were exposed to chronic social defeat stress (CSDS), chronic unpredictable mild stress (CUMS), or chronic restraint stress (CRS) with or without fluoxetine treatment (intraperitoneally injected, 20 mg/kg) and examined for changes in depression-like behaviors and HPA axis activity as well as Fkbp5 expression and GR phosphorylation in the PVN. We then examined if adeno-associated virus (AAV)-mediated Fkbp5 overexpression in the PVN affected the antidepressant actions of fluoxetine in mice.

RESULTS

Fluoxetine treatment significantly mitigated CSDS-, CUMS-, and CRS-induced depression-like behaviors and HPA axis hyperactivity in mice. Subsequent western blotting analyses showed that fluoxetine treatment fully reversed not only chronic stress-induced upregulation of Fkbp5 and CRH but also chronic stress-induced increase in Ser203 phosphorylation and decrease in Ser211 and Ser234 phosphorylation in GR in the PVN. Moreover, quantitative real-time reverse transcription PCR (qRT-PCR) analyses revealed that the enhanced mRNA levels of Fkbp5 and CRH in PVN neurons of mice subjected to CSDS/CUMS/CRS were also notably reversed by fluoxetine administration. Conversely, Fkbp5 overexpression in the PVN significantly eliminated the antidepressant effects of fluoxetine in mice without affecting their locomotor activity.

CONCLUSION

These results together suggest that fluoxetine treatment reverses chronic stress-induced promotion on Fkbp5 expression and multiple effects on GR phosphorylation in the PVN of mice.

SIGNIFICANCE STATEMENT

The selective serotonin reuptake inhibitor fluoxetine (sold as Prozac) is a widely used treatment for depression, but the full spectrum of therapeutic mechanisms is still debated. Recent evidence suggests that these therapeutic mechanisms include suppression of chronic stress-activated hypothalamus-pituitary-adrenal (HPA) axis. The current study presents the first in vivo evidence showing that suppression of HPA axis hyperactivity by fluoxetine treatment involves reversal of glucocorticoid receptor (GR) phosphorylation via modulation of the GR negative regulator Fk506-binding protein 5 (Fkbp5) in the hypothalamic paraventricular nucleus (PVN). Fluoxetine treatment not only inhibited chronic stress-induced depression-like behaviors and HPA axis hyperactivity but also reversed Fkbp5 upregulation and GR phosphorylation changes in the PVN, while adeno-associated virus (AAV)-based Fkbp5 overexpression in the PVN eliminated the antidepressant effects of fluoxetine. These findings may expand our understanding of the pharmacological effects of fluoxetine, and further identify Fkbp5 as a possible target for novel antidepressants.

Evaluation of the Influence of Tanacetum vulgare Extract on Cognitive Functions and Hippocampal BDNF Expression

Tanacetum vulgare L. has been traditionally applied as a remedy for headaches, rheumatism, digestion, respiratory and neurological problems, and other medical conditions. However, the literature data on its effects on cognitive function are scarce. The aim of the present work was to evaluate the effects of two doses of T. vulgare alcohol extract on cognitive functions, hippocampal brain-derived neurotrophic factor (BDNF) expression, and organ toxicity in rats. Rats were treated with T. vulgare 200 mg/kg (TV 200) and 1000 mg/kg (TV 1000) for 28 days. After one week of pre-treatment, the animals were subjected to a series of tests. We found that in the active avoidance test, only TV 200 improved learning and memory, while in the passive avoidance test, both doses facilitated these processes. In addition, the two doses enhanced spatial memory. In the elevated plus maze test, only the higher dose of TV 1000 resulted in anxiolytic-like behavior. Both doses of the extract significantly increased the hippocampal expression of BDNF. We suggest that increased neurotrophic factor expression could be one of the important mechanisms underlying the cognition-enhancing effects of T. vulgare extract.

Role of SIRT1 in Potentially Toxic Trace Elements (Lead, Fluoride, Aluminum and Cadmium) Associated Neurodevelopmental Toxicity

The formation of the central nervous system is a meticulously planned and intricate process. Any modification to this process has the potential to disrupt the structure and operation of the brain, which could result in deficiencies in neurological growth. When neurotoxic substances are present during the early stages of development, they can be exceptionally dangerous. Prenatally, the immature brain is extremely vulnerable and is therefore at high risk in pregnant women associated with occupational exposures. Lead, fluoride, aluminum, and cadmium are examples of possibly toxic trace elements that have been identified as an environmental concern in the aetiology of a number of neurological and neurodegenerative illnesses. SIRT1, a member of the sirtuin family has received most attention for its potential neuroprotective properties. SIRT1 is an intriguing therapeutic target since it demonstrates important functions to increase neurogenesis and cellular lifespan by modulating multiple pathways. It promotes axonal extension, neurite growth, and dendritic branching during the development of neurons. Additionally, it contributes to neurogenesis, synaptic plasticity, memory development, and neuroprotection. This review summarizes the possible role of SIRT1 signalling pathway in potentially toxic trace elements -induced neurodevelopmental toxicity, highlighting some molecular pathways such as mitochondrial biogenesis, CREB/BDNF and PGC-1α/NRF1/TFAM.

Semen Cuscutae flavonoids activated the cAMP-PKA-CREB-BDNF pathway and exerted an antidepressant effect in mice

Background

Semen Cuscutae flavonoids (SCFs) constitute a class of metabolites of Semen Cuscutae, a botanical drug that was recently found to have an anti-depression effect. This study aimed to evaluate the anti-depression effects of SCFs in chronic unpredictable mild stress (CUMS)-induced mice and to interrogate the underlying mechanisms.

Materials and methods

The CUMS mice were used for assessing the effects of SCFs treatments on depression. Mice were randomly divided into five groups. Four groups were subjected to the CUMS induction and concomitantly administered orally with either the vehicle or with a high-, medium-, and low-dose of SCFs, once per day for 4 weeks. One group was kept untreated as a control. The mice were then assessed for their statuses of a number of depression-related parameters, including body weight, food intake, sucrose preference test (SPT), open field test (OFT), tail suspension test (TST), and forced swim test (FST). In addition, a day after the completion of these tests, biopsies from the hippocampus were harvested and used to perform metabolomics by HPLC-MS/MS and to assess the levels of cAMP by ELISA and the levels of PKA, CREB, p-CREB, and BDNF by Western blot analyses.

Results

SCFs resulted in significant increases in both body weight and food intake and in the amelioration of the depressive-like behaviors in CUMS mice. A high-dose SCFs treatment led to significant alterations in 72 metabolites, of which 26 were identified as potential biomarkers for the SCFs treatment. These metabolites are associated with lipid, amino acid, and nucleotide metabolism. Among 26 metabolites, cAMP was positively correlated with body weight, SPT, OFT-total distance, and OFT-central residence time, while negatively correlated with immobility time in TST and FST, linking a change in cAMP with the SCFs treatment and the significant improvement in depressive symptoms in CUMS mice. Further analyses revealed that the levels of cAMP, PKA, CREB, p-CREB, and BDNF were reduced in the hippocampus of CUMS mice but were all increased following the SCFs treatments.

Conclusion

SCFs could ameliorate hippocampal metabolic disturbances and depressive behaviors and cause the activation of the cAMP-PKA-CREB-BDNF signaling pathway in the hippocampus of CUMS mice.

The Effect of Psilocybe cubensis on Spatial Memory and BDNF Expression in Male Rats Exposed to Chronic Unpredictable Mild Stress

Psilocybin-containing mushrooms, commonly known as magic mushrooms, drastically affect mental processing, cognitive functioning, and the mood state. In the present study, we investigated the effect of the Psilocybe cubensis extract on spatial memory and the brain-derived neurotrophic factor (BDNF) in rats exposed to chronic unpredictable mild stress (CUMS). The duration of CUMS was 4 weeks. Spatial learning and memory were measured using the Morris water maze apparatus. The Psilocybe cubensis extract was intraperitoneally injected (20 mg/kg) in different time periods: 5 min before training, 24 h before training, 48 h before training, 5 min after training, and 5 min before the probe test. Results showed that CUMS impaired spatial learning and memory, and decreased BDNF in the hippocampus. Psilocybe cubensis (24 and 48 h before training) restored spatial learning, while (48 h before training) restored spatial memory impairment in CUMS rats. Psilocybe cubensis (24 and 48 h before training) increased BDNF in CUMS rats. Psilocybe cubensis administrations (expect 48 h before training) impaired spatial learning and memory and decreased BDNF levels in controls. In conclusion, we suggested that Psilocybe cubensis may be beneficial for the improvement of memory deficits induced by CUMS, while the time of injection seems to be an important factor in its final effect.

Dopamine and D1 receptor in hippocampal dentate gyrus involved in chronic stress-induced alteration of spatial learning and memory in rats

There is increasing evidence that chronic stress (CS), which occurs when the body is exposed to prolonged stressors, significantly impairs learning and memory. Dopamine (DA) plays a critical role in learning and memory in the hippocampus through the activation of D1-like receptors (D1R). However, the specific roles of DA and D1R in the hippocampal dentate gyrus (DG), particularly in CS-induced changes in spatial learning and memory, are not well understood. In this study, we established a CS rat model through the random application of various stressors. We assessed spatial learning and memory using the Morris water maze (MWM) and measured DA concentration and the amplitude of field excitatory postsynaptic potentials (fEPSP) in the DG during the MWM test in freely moving rats. We also examined the involvement of D1R in spatial learning and memory by microinjecting its antagonist (SCH23390) into the DG, and then analyzed the expressions of phosphorylated (p-) Ca2+/calmodulin-dependent protein kinase II (CaMKII), protein kinase A (PKA), and cAMP-response element binding protein (CREB) in the DG using Western blot. During the MWM test, compared with the control group, the escape latency was increased, and the percentage of distance in target quadrant and the number of platform crossings were decreased, in addition, the increase of fEPSP amplitude in the DG was significantly attenuated in CS group. In the control group, the DA concentration in the DG was significantly increased during the MWM test, and this response was enhanced in the CS group. Microinjection of SCH23390 into the DG significantly improved the spatial learning and memory impairments in CS rats, and reversed the inhibitory effect of CS on increase of fEPSP amplitude in the DG during the MWM test. Furthermore, SCH23390 partially reversed the inhibitory effects of CS on the expressions of p-CaMKII, p-PKA, and p-CREB in the DG. Our findings suggest that overactivation of the DA-D1R system in the hippocampal DG impairs spatial learning and memory and related synaptic plasticity in CS rats via downregulation of PKA-CREB signaling pathway.

The Protective Effects of Syringic Acid on Bisphenol A-Induced Neurotoxicity Possibly Through AMPK/PGC-1α/Fndc5 and CREB/BDNF Signaling Pathways

Bisphenol A (BPA), an endocrine disruptor, is commonly used to produce epoxy resins and polycarbonate plastics. Continuous exposure to BPA may contribute to the development of diseases in humans and seriously affect their health. Previous research suggests a significant relationship between the increased incidence of neurological diseases and the level of BPA in the living environment. Syringic acid (SA), a natural derivative of gallic acid, has recently considered much attention due to neuromodulator activity and its anti-oxidant, anti-apoptotic, and anti-inflammatory effects. Therefore, in this study, we aimed to investigate the effects of SA on oxidative stress, apoptosis, memory and locomotor disorders, and mitochondrial function, and to identify the mechanisms related to Alzheimer's disease (AD) in the brain of rats receiving high doses of BPA. For this purpose, male Wistar rats received BPA (50, 100, and 200 mg/kg) and SA (50 mg/kg) for 21 days. The results showed that BPA exposure significantly altered the rats' neurobehavioral responses. Additionally, BPA, by increasing the level of ROS, and MDA level, increased the level of oxidative stress while reducing the level of antioxidant enzymes, such as SOD, CAT, GPx, and mitochondrial GSH. The administration of BPA at 200 mg/kg significantly decreased the expression of ERRα, TFAM, irisin, PGC-1α, Bcl-2, and FNDC5, while it increased the expression of TrkB, cytochrome C, caspase 3, and Bax. Moreover, the Western blotting results showed that BPA increased the levels of P-AMPK, GSK3b, p-tau, and Aβ, while it decreased the levels of PKA, P-PKA, Akt, BDNF, CREB, P-CREB, and PI3K. Meanwhile, SA at 50 mg/kg reversed the behavioral, biochemical, and molecular changes induced by high doses of BPA. Overall, BPA could lead to the development of AD by affecting the mitochondria-dependent apoptosis pathway, as well as AMPK/PGC-1α/FNDC5 and CREB/BDNF/TrkB signaling pathways, and finally, by increasing the expression of tau and Aβ proteins. In conclusion, SA, as an antioxidant, significantly reduced the toxicity of BPA.

Ezetimibe protects against Gentamycin-induced ototoxicity in rats by antioxidants, anti-inflammatory mechanisms, and BDNF upregulation

OBJECTIVE

The threat of hearing loss has become a universal reality. Gentamycin (GM) can lead to ototoxicity and may result in permanent hearing loss. This study aimed to elucidate whether the hypolipidemic drug Ezetimibe (EZE) has a possible underlying mechanism for protecting rats from GM-induced ototoxicity.

METHODS AND RESULTS

30 male Wister albino rats were separated into three groups, ten in each group: control, GM, and GM + EZE. At the end of the experiment, rats underwent hearing threshold evaluation via auditory brainstem response (ABR), carotid artery blood flow velocity (CBV), and resistance (CVR) measurement, in addition to a biochemical assessment of serum malondialdehyde (MDA), nitric oxide (NO), catalase (CAT), hemeOxygenase-1 (HO-1), and tumor necrosis factor-α (TNF-α). Also, real-time PCR was employed to quantify the levels of brain-derived neurotrophic factor (BDNF). Cochlea was also studied via histological and immunohistochemical methods. GM revealed a significant increase in CVR, MDA, NO, and TNF-α and a significant decrease in ABR, CBV, CAT, HO-1, and cochlear BDNF expression. EZE supplementation revealed a significant rise in ARB in addition to CBV and a decline in CVR and protected cochlear tissues via antioxidant, anti-inflammatory, and antiapoptotic mechanisms via downregulating Caspase-3 immunoreaction, upregulating proliferating cellular nuclear antigen (PCNA) immunoreaction, and upregulating of the cochlear BDNF expression. Correlations were significantly negative between BDNF and MDA, NO, TNF-α, COX 2, and caspase-3 immunoreaction and significantly positive with CAT, HO-1, and PCNA immunoreaction.

DISCUSSION

EZE can safeguard inner ear tissues from GM via antioxidant, anti-inflammatory, and antiapoptotic mechanisms, as well as upregulation of BDNF mechanisms.

Analysis of the functional role and mRNA expression of GABA B R in the nucleus accumbens of cocaine-addicted rats

BACKGROUND

Drug addiction is a social and medical problem that must be urgently addressed. The nucleus accumbens (NAc) is closely related to addiction-related learning memory, and γ-aminobutyric acid type B receptor (GABA B R) is a potential target for the treatment of drug addiction. However, the role of GABA B R activity levels in the NAc in cocaine addiction is unclear.

METHODS

In this study, we established an animal model of cocaine dependence, modulated the level of GABA B R activity, applied a conditioned place preference assay (CPP) to assess the role of the NAc in reconsolidation of addiction memory, evaluated learning and memory functions by behavioral experiments, examined the expression of GB1, GB2, cyclic adenosine monophosphate response element binding protein (CREB), p-CREB, protein kinase A (PKA), protein kinase (ERK), and Brain-derived neurotrophic factor (BDNF) in the NAc by molecular biology experiments, and screened differentially significantly expressed genes by transcriptome sequencing.

RESULTS

Our study showed that the GABA B receptor agonist baclofen (BLF) had a significant effect on locomotor distance in rats, promoted an increase in GABA levels and significantly inhibited the PKA and ERK1/2/CREB/BDNF signaling pathways. Moreover, transcriptome sequencing showed that GABA B R antagonist intervention identified a total of 21 upregulated mRNAs and 21 downregulated mRNAs. The differentially expressed (DE) mRNA genes were mainly enriched in tyrosine metabolism; however, further study is needed.

CONCLUSION

GABA B R activity in the NAc is involved in the regulation of cocaine addiction and may play an important role through key mRNA pathways.

Emerging phosphodiesterase inhibitors for treatment of neurodegenerative diseases

Neurodegenerative diseases (NDs) cause progressive loss of neuron structure and ultimately lead to neuronal cell death. Since the available drugs show only limited symptomatic relief, NDs are currently considered as incurable. This review will illustrate the principal roles of the signaling systems of cyclic adenosine and guanosine 3',5'-monophosphates (cAMP and cGMP) in the neuronal functions, and summarize expression/activity changes of the associated enzymes in the ND patients, including cyclases, protein kinases, and phosphodiesterases (PDEs). As the sole enzymes hydrolyzing cAMP and cGMP, PDEs are logical targets for modification of neurodegeneration. We will focus on PDE inhibitors and their potentials as disease-modifying therapeutics for the treatment of Alzheimer's disease, Parkinson's disease, and Huntington's disease. For the overlapped but distinct contributions of cAMP and cGMP to NDs, we hypothesize that dual PDE inhibitors, which simultaneously regulate both cAMP and cGMP signaling pathways, may have complementary and synergistic effects on modifying neurodegeneration and thus represent a new direction on the discovery of ND drugs.

Tao-Hong-Si-Wu-Tang Improves the Depressive-like Behaviors in Mice Experiencing Perimenopausal Depression Through Modulating Activity of the Hypothalamic-Pituitary-Adrenal-Ovary Axis and Activating the BDNF-TrkB-CREB Signaling Pathway

Tao-Hong-Si-Wu-Tang (THSWT), a traditional Chinese herbal remedy, is commonly utilized for the treatment of female perimenopausal depression through regulating menstruation, but the mechanism remains unknown. In this study, ICR mice were randomly divided into six groups: low, medium, and high dose of THSWT (0.5, 1.5, and 4.5 g/kg), soy isoflavone (250 mg/kg), ovariectomy group, and control group. All mice, except the control group, had ovaries removed and were exposed to hypoxic stimulation for 28 days to establish a perimenopausal depression mice model. The mice, having unrestricted access to food and water, were administered THSWT treatment for a duration of 14 days. The Western blotting and Enzyme linked immunosorbent assay kits were used to determine protein and hormone levels, respectively. Experimental results showed that THSWT reduced the immobility time of mice from 150.8 s to 104.9 s in the tail suspension test, and it decreased the immobility time of mice from 165.7 s to 119.0 s in the forced swimming test, outperforming the results obtained with soy isoflavones. In addition, THSWT upregulated the protein expression of follicle-stimulating hormone receptor and downregulated the protein expression of corticotropin-releasing hormone-receptor 1 in the hippocampus. Compared with the oophorectomized group, treatment with THSWT decreased the levels of corticosterone and adrenocorticotropic hormone in serum by 173.7 and 23.4 ng/mL, respectively. These findings showed that THSWT could stimulate the perimenopausal nerve tissue and regulate the level of serum hormones in mice. THSWT exhibited promising potential as a viable alternative drug for hormone treatment of perimenopause in clinical use.

Role of hippocampal and prefrontal cortical cholinergic transmission in combination therapy valproate and cannabidiol in memory consolidation in rats: involvement of CREB- BDNF signaling pathways

PURPOSE

Cognitive disorders are associated with valproate and drugs used to treat neuropsychological diseases. Cannabidiol (CBD) has beneficial effects on cognitive function. This study examined the effects of co-administration of CBD and valproate on memory consolidation, cholinergic transmission, and cyclic AMP response element-binding protein (CREB)-brain-derived neurotrophic factor (BDNF) signaling pathway in the prefrontal cortex (PFC) and hippocampus (HPC).

METHODS

One-trial, step-through inhibitory test was used to evaluate memory consolidation in rats. The intra-CA1 injection of physostigmine and atropine was performed to assess the role of cholinergic transmission in this co-administration. Phosphorylated CREB (p-CREB)/CREB ratio and BDNF levels in the PFC and HPC were evaluated.

RESULTS

Post-training intraperitoneal (i.p.) valproate injection reduced memory consolidation; however, post-training co-administration of CBD with valproate ameliorated memory impairment induced by valproate. Post-training intra-CA1 injection of physostigmine at the ineffective doses in memory consolidation (0.5 and 1 µg/rat), plus injection of 10 mg/kg of CBD as an ineffective dose, improved memory loss induced by valproate, which was associated with BDNF and p-CREB level enhancement in the PFC and HPC. Conversely, post-training intra-CA1 injection of ineffective doses of atropine (1 and 2 µg/rat) reduced the positive effects of injection of CBD at a dose of 20 mg/kg on valproate-induced memory loss associated with BDNF and p-CREB level reduction in the PFC and HPC.

CONCLUSION

The results indicated a beneficial interplay between valproate and CBD in the process of memory consolidation, which probably creates this interaction through the BDNF-CREB signaling pathways in the cholinergic transmission of the PFC and HPC regions.

Niuhuang Qingxin Wan ameliorates depressive-like behaviors and improves hippocampal neurogenesis through modulating TrkB/ERK/CREB signaling pathway in chronic restraint stress or corticosterone challenge mice

Introduction: Chronic stress-associated hormonal imbalance impairs hippocampal neurogenesis, contributing to depressive and anxiety behaviors. Targeting neurogenesis is thus a promising antidepressant therapeutic strategy. Niuhuang Qingxin Wan (NHQXW) is an herbal formula for mental disorders in Traditional Chinese Medicine (TCM) practice, but its anti-depressant efficacies and mechanisms remain unverified. Methods: In the present study, we tested the hypothesis that NHQXW could ameliorate depressive-like behaviors and improve hippocampal neurogenesis by modulating the TrkB/ERK/CREB signaling pathway by utilizing two depression mouse models including a chronic restraint stress (CRS) mouse model and a chronic corticosterone (CORT) stress (CCS) induced mouse model. The depression-like mouse models were orally treated with NHQXW whereas fluoxetine was used as the positive control group. We evaluated the effects of NHQXW on depressive- and anxiety-like behaviors and determined the effects of NHQXW on inducing hippocampal neurogenesis. Results: NHQXW treatment significantly ameliorated depressive-like behaviors in those chronic stress mouse models. NHQXW significantly improved hippocampal neurogenesis in the CRS mice and CCS mice. The potential neurogenic mechanism of NHQXW was identified by regulating the expression levels of BDNF, TrkB, p-ERK (T202/T204), p-MEK1/2 (S217/221), and p-CREB (S133) in the hippocampus area of the CCS mice. NHQXW revealed its antidepressant and neurogenic effects that were similar to fluoxetine. Moreover, NHQXW treatment revealed long-term effects on preventing withdrawal-associated rebound symptoms in the CCS mice. Furthermore, in a bioactivity-guided quality control study, liquiritin was identified as one of the bioactive compounds of NHQXW with the bioactivities of neurogenesis-promoting effects. Discussion: Taken together, NHQXW could be a promising TCM formula to attenuate depressive- and anxiety-like behaviors against chronic stress and depression. The underlying anti-depressant mechanisms could be correlated with its neurogenic activities by stimulating the TrkB/ERK/CREB signaling pathway.

Energy metabolism and behavioral parameters in female mice subjected to obesity and offspring deprivation stress

This study aimed to evaluate the behavioral and energy metabolism parameters in female mice subjected to obesity and offspring deprivation (OD) stress. Eighty female Swiss mice, 40 days old, were weighed and divided into two groups: Control group (control diet, n = 40) and Obese group (high-fat diet, n = 40), for induction of the animal model of obesity, the protocol was based on the consumption of a high-fat diet and lasted 8 weeks. Subsequently, the females were subjected to pregnancy, after the birth of the offspring, were divided again into the following groups (n = 20): Control non-deprived (ND), Control + OD, Obese ND, and Obese + OD, for induction of the stress protocol by OD. After the offspring were 21 days old, weaning was performed and the dams were subjected to behavioral tests. The animals were humanely sacrificed, the brain was removed, and brain structures were isolated to assess energy metabolism. Both obesity and OD led to anhedonia in the dams. It was shown that the structures most affected by obesity and OD are the hypothalamus and hippocampus, as evidenced by the mitochondrial dysfunction found in these structures. When analyzing the groups separately, it was observed that OD led to more pronounced mitochondrial damage; however, the association of obesity with OD, as well as obesity alone, also generated damage. Thus, it is concluded that obesity and OD lead to anhedonia in animals and to mitochondrial dysfunction in the hypothalamus and hippocampus, which may lead to losses in feeding control and cognition of the dams.

The Role of BDNF as a Biomarker in Cognitive and Sensory Neurodegeneration

Brain-derived neurotrophic factor (BDNF) has a crucial function in the central nervous system and in sensory structures including olfactory and auditory systems. Many studies have highlighted the protective effects of BDNF in the brain, showing how it can promote neuronal growth and survival and modulate synaptic plasticity. On the other hand, conflicting data about BDNF expression and functions in the cochlear and in olfactory structures have been reported. Several clinical and experimental research studies showed alterations in BDNF levels in neurodegenerative diseases affecting the central and peripheral nervous system, suggesting that BDNF can be a promising biomarker in most neurodegenerative conditions, including Alzheimer's disease, shearing loss, or olfactory impairment. Here, we summarize current research concerning BDNF functions in brain and in sensory domains (olfaction and hearing), focusing on the effects of the BDNF/TrkB signalling pathway activation in both physiological and pathological conditions. Finally, we review significant studies highlighting the possibility to target BDNF as a biomarker in early diagnosis of sensory and cognitive neurodegeneration, opening new opportunities to develop effective therapeutic strategies aimed to counteract neurodegeneration.

Curculigoside rescues hippocampal synaptic deficits elicited by PTSD through activating cAMP-PKA signaling

Chronic traumatic stress results in various psychiatric disorders, especially posttraumatic stress disorder (PTSD). Previous study demonstrated that curculigoside (CUR) a component of Rhizoma Curculiginis prevented fear extinction and stress-induced depression-like behaviors. However, its effects on PTSD and the mechanisms are still not completely clear. In this study, we observed typical PTSD-like phenotypes, synaptic deficit, and reduction of BDNF/TrkB signaling pathway in mice receiving modified single prolonged stress and electrical stimulation (SPS&S). By contrast, systemic administration of CUR blocked PTSD-like phenotypes and synaptic deficits, including reduction of BDNF/TrkB signaling pathway, GluA1 and Arc expression. Importantly, CUR reversed the impairment of PKA signaling pathway elicited by PTSD. We further confirmed that the effects of CUR on synaptic function were through PKA signaling pathway, as H-89, an inhibitor of PKA blocked the effect of CUR on behavioral changes and BDNF/TrkB signaling pathway. Thereafter, we verified that CUR on synaptic function were through PKA pathway using direct intracerebral injection of CUR and H-89. Direct intracerebral injection of CUR activated PKA/CREB/BDNF/TrkB, which was blocked by H-89. Additionally, the docking results showed high binding energies of CUR with A2AR, AC, PRKACA, and PRKAR1A, which might indicate that CUR functions through regulating PKA signaling pathway. In conclusion, CUR prevented the behavioral changes and hippocampal synaptic deficits elicited by PTSD through activating cAMP-PKA signaling.

Echinacoside exerts antidepressant-like effects through enhancing BDNF-CREB pathway and inhibiting neuroinflammation via regulating microglia M1/M2 polarization and JAK1/STAT3 pathway

The present study was performed to investigate the antidepressant effect of echinacoside (ECH) using chronic unpredictable mild stress (CUMS) induced depression mice and lipopolysaccharide (LPS)-stimulated N9 microglial cells. CUMS treatment was performed on C57BL/6 mice for 28 days, followed by gavaging with different doses of echinacoside (15 and 60 mg/kg) for 21 consecutive days. Sucrose preference test (SPT), open field test (OFT), tail suspension test (TST), and forced swimming test (FST) were measured to assess the effects of echinacoside on CUMS-Induced Depressive-Like Behaviors. After that, the pathological changes of hippocampus were determined by Hematoxylin and eosin (HE) staining and Nissl staining; the neurotransmitters, pro-inflammatory cytokines and indoleamine 2,3-dioxygenase (IDO) levels, and the hypothalamic-pituitary-adrenal (HPA) axis activity were determined by enzyme linked immunosorbent assay (ELISA); Iba 1were evaluated by Immunofluorescence assay; Key protein expression levels of CREB/BDNF signal pathway were measured by western blotting. Subsequently, N9 cells were stimulated with 1 μg/ml LPS to induce N9 microglia activation, and were treated with 5-20 μM of echinacoside for 24 h. After that, the levels of NO, interleukin (IL)-1β, IL-6, tumor necrosis factor alpha (TNF-α), IL-4, IL-10, and transforming growth factor beta (TGF-β) in N9 cell culture supernatants were measured by enzyme-linked immunosorbent assay (ELISA) kits; morphology and Iba 1 expression level were observed by high-content screening assay; the M1 markers of CD11b, CD86 and M2 markers of CD206 were analyzed by imaging flow cytometry. Results show that treatment with echinacoside reversed CUMS-increased immobility time in OFT, TST, FST and reversed CUMS-reduced sucrose preference in SPT. In addition, echinacoside reduced the levels of pro-inflammatory cytokines and Iba 1. Moreover, echinacoside significantly increased p-CREB/CREB ratio and BDNF level in hippocampus. Furthermore, echinacoside reduced the secretion of inflammatory factors and inhibited microglia M1 polarization in N9 cells. In conclusion, echinacoside may be beneficial for the treatment of depression diseases through regulating the microglia balance by inhibiting the polarization of microglia to M1 phenotype, and improving hippocampal neurogenesis by the CREB-BDNF signaling pathway.

Recent advances in dopamine D2 receptor ligands in the treatment of neuropsychiatric disorders

Dopamine is a biologically active amine synthesized in the central and peripheral nervous system. This biogenic monoamine acts by activating five types of dopamine receptors (D_1-5 Rs), which belong to the G protein-coupled receptor family. Antagonists and partial agonists of D₂ Rs are used to treat schizophrenia, Parkinson's disease, depression, and anxiety. The typical pharmacophore with high D₂ R affinity comprises four main areas, namely aromatic moiety, cyclic amine, central linker and aromatic/heteroaromatic lipophilic fragment. From the literature reviewed herein, we can conclude that 4-(2,3-dichlorophenyl), 4-(2-methoxyphenyl)-, 4-(benzo[b]thiophen-4-yl)-1-substituted piperazine, and 4-(6-fluorobenzo[d]isoxazol-3-yl)piperidine moieties are critical for high D₂ R affinity. Four to six atoms chains are optimal for D₂ R affinity with 4-butoxyl as the most pronounced one. The bicyclic aromatic/heteroaromatic systems are most frequently occurring as lipophilic appendages to retain high D₂ R affinity. In this review, we provide a thorough overview of the therapeutic potential of D₂ R modulators in the treatment of the aforementioned disorders. In addition, this review summarizes current knowledge about these diseases, with a focus on the dopaminergic pathway underlying these pathologies. Major attention is paid to the structure, function, and pharmacology of novel D₂ R ligands, which have been developed in the last decade (2010-2021), and belong to the 1,4-disubstituted aromatic cyclic amine group. Due to the abundance of data, allosteric D₂ R ligands and D₂ R modulators from patents are not discussed in this review.

The role of Phosphodiesterase-1 and its natural product inhibitors in Alzheimer's disease: A review

Phosphodiesterase-1 (PDE1) is a versatile enzyme that has surprisingly received considerable attention as a possible therapeutic target in Alzheimer's disease (AD) because it maintains the homeostasis of 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic guanosine monophosphate (cGMP) in the brain. 3',5'-cyclic adenosine monophosphate and 3',5'-cyclic guanosine monophosphate are the two key second messengers that regulate a broad range of intracellular processes and neurocognitive functions, specifically memory and cognition, associated with Alzheimer's disease. However, the lack of available selective drugs on the market poses challenges to identifying the beneficial effects of natural products. The present review focuses on Phosphodiesterase-1 and its isoforms, splicing variants, location, distribution, and function; the role of Phosphodiesterase-1 inhibitors in Alzheimer's disease; and the use of vinpocetine and natural products as specific Phosphodiesterase-1 inhibitors. Moreover, it aims to provide ongoing updates, identify research gaps, and present future perspectives. This review indicates the potential role of Phosphodiesterase-1 inhibitors in the treatment of neurodegenerative disorders, such as Alzheimer's disease. Certain clinical trials on the alleviation of Alzheimer's disease in patients are still in progress. Among de novo outcomes, the employment of Phosphodiesterase-1 inhibitors to treat Alzheimer's disease is an important advancement given the absence of particular therapies in the pipeline for this highly prevalent disease. To sum up, Phosphodiesterase-1 inhibition has been specifically proposed as a critical therapeutic approach for Alzheimer's disease. This study provides a comprehensive review on the biological and pharmacological aspects of Phosphodiesterase-1, its role on the Alzheimer's diseases and its significance as Alzheimer's disease therapeutic target in drug discovery from natural products. This review will help clinical trials and scientific research exploring new entities for the treatment and prevention of Alzheimer's disease.

Vinpocetine, a PDE1 modulator, regulates markers of cerebral health, inflammation, and oxidative stress in a rat model of prenatal alcohol-induced experimental attention deficit hyperactivity disorder

Prenatal alcohol exposure (PAE) has been shown to induce symptomatology associated with attention deficit hyperactivity disorder (ADHD) by altering neurodevelopmental trajectories. Phosphodiesterase-1 (PDE1) is expressed centrally and has been used in various experimental brain conditions. We investigated the role of vinpocetine, a PDE1 inhibitor, on behavioral phenotypes and important biochemical deficits associated with a PAE rat model of ADHD. Protein markers of cerebral health (synapsin-IIa, BDNF, and pCREB), inflammation (IL-6, IL-10, and TNF-α), and oxidative stress (TBARS, GSH, and SOD) were analyzed in three brain regions (frontal cortex, striatum, and cerebellum). Hyperactivity, inattention, and anxiety introduced in the offspring due to PAE were assayed using open-field, Y-maze, and elevated plus maze, respectively. Administration of vinpocetine (10 & 20 mg/kg, p.o. [by mouth]) to PAE rat offspring for 4 weeks resulted in improvement of the behavioral profile of the animals. Additionally, levels of protein markers such as synapsin-IIa, BDNF, pCREB, IL-10, SOD, and GSH were found to be significantly increased, with a significant reduction in markers such as TNF-α, IL-6, and TBARS in selected brain regions of vinpocetine-treated animals. Vinpocetine, a selective PDE1 inhibitor, rectified behavioral phenotypes associated with ADHD, possibly by improving cerebral function, reducing brain inflammation, and reducing brain oxidative stress. This study provides preliminary analysis and suggests that the PDE1 enzyme may be an important pharmacological tool to study ADHD as a result of PAE.

Effects of 5.8 GHz microwave on hippocampal synaptic plasticity of rats

OBJECTIVE

5.8 GHz spectrum is gaining more attention in wireless technology. To explore the potential hazards, we investigated the effect of exposure to 5.8 GHz microwave on learning and memory ability of rats. Methods: Morris Water maze (MWM), Novel object recognition (NOR) and Fear conditioning test (FCT) were used to evaluate the ability of spatial and non-spatial memory of rats. The hippocampal morphology, the level of brain injury factors in serum and the mitochondrial membrane potential of hippocampal neurons was examined to evaluate the damage of hippocampal neurons. The density of dendritic spines, the ultrastructure of synapses and the level of PSD95, Synaptophysin, p-CREB and CREB were detected to evaluate the hippocampal synaptic plasticity.

RESULTS

Compared with Sham group, there was no significant difference in the performance of ethology (in MWM, NOR, FCT) in Microwave 2 h group or Microwave 4 h group. The hippocampal morphology, the serum level of brain injury factors and the content of mitochondrial JC-1 monomer in Microwave 2 h group or Microwave 4 h group did not change obviously, compared with Sham group. The density of dendritic spines, the ultrastructure of synapse and the level of PSD95, Synaptophysin, p-CREB and CREB in hippocampus in Microwave 2 h group or Microwave 4 h group did not significantly change, compared with Sham group.

CONCLUSION

Under this experimental condition, exposure to 5.8 GHz microwave could not affect the hippocampal synaptic plasticity of rats.

Regional Differences in BDNF Expression and Behavior as a Function of Sex and Enrichment Type: Oxytocin Matters

The early environment is critical to brain development, but the relative contribution of physical versus social stimulation is unclear. Here, we investigated in male and female rats the response to early physical and social environmental enrichment in relation to oxytocin (OT) and brain-derived neurotrophic factor (BDNF) expression. The findings show that males and females respond differently to prolonged sensorimotor stimulation from postnatal days 21-110 in terms of functional, structural, and molecular changes in the hippocampus versus medial prefrontal cortex (mPFC). Physical enrichment promoted motor and cognitive functions and hippocampal BDNF mRNA and protein expression in both sexes. Combined physical and social enrichment, however, promoted functional and structural gain in females. These changes were accompanied by elevated plasma oxytocin (OT) levels and BDNF mRNA expression in the mPFC, while the hippocampus was not affected. Administration of an OT antagonist in females blocked the beneficial effects of enrichment and led to reduced cortical BDNF signaling. These findings suggest that an OT-based mechanism selectively stimulates a region-specific BDNF response which is dependent on the type of experience.

Alcohol reinstatement after prolonged abstinence from alcohol drinking by female adolescent rats: Roles of cyclooxygenase-2 and the prostaglandin E2 receptor 1

BACKGROUND

Adolescent alcohol misuse is a global problem that can significantly increase the reinstatement of alcohol drinking during re-exposure after abstinence, but the mechanism that causes this increase is unknown. Female adolescents are an understudied population but they are particularly vulnerable to adolescent-onset alcohol abuse. We aimed to determine how adolescent-onset alcohol drinking affects pro-inflammatory mediators endothelin-1 (ET-1), cyclooxygenase-2 (COX-2), and prostaglandin E₂ (PGE₂) in the brain and the role of COX-2 and PGE₂ in EtOH reinstatement in adolescent females.

METHODS

Adolescent female rats were exposed to a 2-bottle choice paradigm of water vs 5% ethanol (EtOH) every other day over a 21 day period. ET-1 and COX-2 proteins were measured in the dorsal striatum (DS) after a 4 week abstinence from EtOH drinking. The COX-2 inhibitor nimesulide was then administered during abstinence prior to an EtOH reinstatement or sucrose preference or to measure PGE₂ content. The PGE₂ receptor 1 (EP₁) antagonist SC-51089 was then administered prior to EtOH reinstatement during which EtOH intake was measured.

RESULTS

EtOH drinking significantly increased ET-1 by 33.8 ± 8.9% and COX-2 by 71.4 ± 24.3% in the DS. Treatment with nimesulide during abstinence attenuated EtOH intake during reinstatement after prolonged abstinence by 40.3 ± 12.4% compared to saline controls. Adolescent EtOH drinking and abstinence increased PGE₂ 150.5 ± 30.9% in the DS and nimesulide attenuated this increase. SC-51089 treatment during abstinence attenuated EtOH reinstatement by 48.1 ± 8.4% compared to DMSO controls.

CONCLUSIONS

These experiments identified a prostaglandin-mediated mechanism that offers a putative pharmacological target to attenuate EtOH reinstatement after adolescent-onset EtOH drinking.

Antidepressant Effects of NSAIDs in Rodent Models of Depression-A Systematic Review

In recent years much focus has been on neuroimmune mechanisms of depression. As a consequence, many preclinical and clinical trials have been performed examining potential antidepressant effects of several anti-inflammatory drugs. The results of such trials have been varied. With the current manuscript we wished to elucidate the effects of non-steroidal anti-inflammatory drugs (NSAIDs) on depressive-like behaviour in rodent models of depression by performing a systematic review of the available literature. We performed a systematic literature search in PubMed for rodent models of depression where NSAIDs were administered and a validated measure of depressive-like behaviour was applied. 858 studies were initially identified and screened using Covidence systematic review software. Of these 36 met the inclusion criteria and were included. The extracted articles contained data from both rat and mouse studies but primarily male animals were used. Several depression models were applied and 17 different NSAIDs were tested for antidepressant effects. Our results suggest that stress models are the best choice when examining antidepressant effects of NSAIDs. Furthermore, we found that rat models provide a more homogenous response than mouse models. Intriguingly, the use of female animals was only reported in three studies and these failed to find antidepressant effects of NSAIDs. This should be explored further. When comparing the different classes of NSAIDs, selective COX-2 inhibitors were shown to provide the most stable antidepressant effect compared to non-selective COX-inhibitors. Suggested mechanisms behind the antidepressant effects were attenuation of neuroinflammation, HPA-axis dysregulation and altered monoamine expression.

Bupleurum chinense DC improves CUMS-induced depressive symptoms in rats through upregulation of the cAMP/PKA/CREB signalling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Bupleurum chinense DC. (B. chinense) is the dried root of B. chinense, belonging to the Umbelliferae family. B. chinense has been reported since ancient times for its effect of soothing the liver and relieving depression. Additionally, its important role in treating depression, depressed mood disorders and anti-inflammation has been proven in previous studies. However, its specific mechanism of action remains unknown.

AIM OF THE STUDY

The key targets and metabolites of the antidepressant effect of B. chinense were investigated based on the cAMP signalling pathway. The study examined the mechanism for the antidepressant effect of B. chinense by target prediction, analysis of related metabolites and potential metabolic pathways.

MATERIALS AND METHODS

A network pharmacology approach was used to predict the antidepressant targets and pathways of B. chinense. A depression rat model was established through the CUMS (chronic unpredictable mild stress) procedure. The depression model was assessed by body weight, sugar-water preference, water maze and enzyme-linked immunosorbent assay (ELISA) indicators (5hydroxytryptamine, etc.). The key metabolic pathways were screened by correlations between metabolites and key targets. Finally, a quantitative analysis of key targets and metabolites was experimentally validated.

RESULTS

B. chinense significantly ameliorated the reduction in body weight, sugar-water preference rate and cognitive performance in the water maze experiment in rats with depression induced by CUMS. ELISA, Western blotting (WB) and reverse transcription-polymerase chain reaction (RT-PCR) assays showed that B. chinense significantly improves the expression of protein kinase cyclic adenylic acid (cAMP)-activated catalytic subunit alpha (PRKACA), cAMP-response element-binding protein (CREB) and cAMP activation in the rat brain induced by CUMS. According to metabolic pathway analysis, B. chinense shows an antidepressant effect primarily by regulating the cAMP metabolic pathway.

CONCLUSION

B. chinense upregulated PRKACA and CREB expression and the level of the key metabolite cAMP in the cAMP/PKA/CREB pathway while reducing the inflammatory response to depression treatment. These new findings support future research on the antidepressant effects of B. chinense.

Prenatal Activation of Glucocorticoid Receptors Induces Memory Impairment in a Sex-Dependent Manner: Role of Cyclooxygenase-2

Prenatal exposure to dexamethasone (DEX) results in long-lasting effects on cognitive functions such as learning and memory impairment. However, the mechanisms underlying these DEX-induced deleterious effects are not well known. Here, we assessed whether cyclooxygenase-2 (COX-2) is involved in the impact of prenatal exposure to DEX on learning and memory during adulthood. Pregnant Sprague-Dawley rats received daily injections of either DEX (0.2 mg/kg; i.p.) or saline from gestation day (GD) 14 until GD21. Gene and protein expression of COX-2, as well as presynaptic (synaptophysin) and postsynaptic (postsynaptic density protein-95) proteins, were monitored in the dorsal and ventral hippocampi of adult male and female offspring. A different cohort of adult male and female rat offspring was given daily injections of either vehicle or a specific COX-2 inhibitor (celecoxib 10 mg/kg, i.p.) for 5 consecutive days and was subsequently subjected to Morris water maze memory test. Prenatal DEX enhanced the expression of COX-2 protein and cox-2 mRNA in the dorsal hippocampus of adult female but not male rats. This enhanced COX-2 expression was associated with reduced expression in pre- and postsynaptic proteins and altered memory acquisition and retention. Administration of COX-2-specific inhibitor alleviated prenatal DEX-induced memory impairment in adult female rats. This study suggests that prenatal activation of glucocorticoid receptors stimulates COX-2 gene and protein expression and impairs hippocampal-dependent spatial memory in female but not male rat offspring. Furthermore, COX-2 selective inhibitors can be used to alleviate the long-lasting deleterious effects of corticosteroid medication during pregnancy.

Naringin Mediates Adult Hippocampal Neurogenesis for Antidepression via Activating CREB Signaling

The brain-derived neurotrophic factor/tropomyosin receptor kinase B/cAMP response element-binding protein (BDNF/TrkB/CREB) signaling pathway is a critical therapeutic target for inducing adult hippocampal neurogenesis and antidepressant therapy. In this study, we tested the hypothesis that naringin, a natural medicinal compound, could promote adult hippocampal neurogenesis and improve depression-like behaviors via regulating the BDNF/TrkB/CREB signaling pathway. We first investigated the effects of naringin on promoting adult hippocampal neurogenesis in both normal and chronic corticosterone (CORT)-induced depressive mice. Under physiological condition, naringin treatment enhanced the proliferation of neural stem/progenitor cells (NSPCs) and accelerated neuronal differentiation. In CORT-induced depression mouse model, naringin treatment promoted neuronal differentiation and maturation of NSPCs for hippocampal neurogenesis. Forced swim test, tail suspension test, and open field test confirmed the antidepressant and anxiolytic effects of naringin. Co-treatment of temozolomide (TMZ), a neurogenic inhibitor, abolished these antidepressant and anxiolytic effects. Meanwhile, naringin treatment increased phosphorylation of cAMP response element binding protein (CREB) but had no effect on the expression of brain-derived neurotrophic factor and phosphorylation of TrkB in the hippocampus of CORT-induced depressive mice. Co-treatment of CREB inhibitor 666-15, rather than TrkB inhibitor Cyc-B, abolished the neurogenesis-promoting and antidepressant effects of naringin. Taken together, naringin has antidepressant and anxiolytic effects, and the underlying mechanisms could be attributed to enhance hippocampal neurogenesis via activating CREB signaling.

Roflumilast Reduces Pathological Symptoms of Sporadic Alzheimer's Disease in Rats Produced by Intracerebroventricular Streptozotocin by Inhibiting NF-κB/BACE-1 Mediated Aβ Production in the Hippocampus and Activating the cAMP/BDNF Signalling Pathway

Alzheimer's disease (AD) is a neurological disease that gradually causes memory loss and cognitive impairment. The intracellular secondary messenger cyclic nucleotide cAMP helps in memory acquisition and consolidation. In several models of AD, increasing their levels using phosphodiesterase (PDE) inhibitors improved cognitive performance and prevent memory loss. Thus, the current investigation was undertaken to investigate the therapeutic potential of the PDE-4 inhibitor roflumilast (RFM) against intracerebroventricular (ICV) streptozotocin (STZ)-induced sporadic AD in rats. STZ (3 mg/kg) was given to rats via the ICV route on the stereotaxic apparatus, followed by RFM (0.51 mg/kg/oral) treatment for 15 days, and donepezil (5 mg/kg/oral) was employed as a reference standard drug. Subsequently, we observed that RFM dramatically increased rats learning and memory capacities as measured by the Morris water maze and a novel object recognition task. RFM enhanced the levels of cAMP and brain-derived neurotrophic factors (BDNFs) while decreasing the expression of nuclear factor kappa B (NF-κB) and glial fibrillary acidic protein (GFAP) in the hippocampus of ICV-STZ-infused rats. RFM was found to significantly reduce ICV-STZ-induced neuroinflammation, amyloidogenesis, oxidative stress cholinergic impairments, GSK-3β, and phosphorylated tau levels in the rat hippocampus. Supporting these, histopathological study using Cresyl violet and Congo red demonstrated that RFM reduced neuronal alterations and Aβ deposition in the hippocampus of AD rats. These findings suggest that RFM could be a promising candidate for the management of AD by inhibiting NF-κB/BACE-1 mediated Aβ production in the hippocampus and activating the cAMP/BDNF signalling pathway.

Tenuifolin ameliorates chronic restraint stress-induced cognitive impairment in C57BL/6J mice

The general consensus is that stress affects the central nervous system and can lead to cognitive problems. The root of Polygala tenuifolia (P. tenuifolia) is a well-known traditional Chinese medicine used for improving brain function. Tenuifolin (TEN) is the major constituent of P. tenuifolia and has a promising neuroprotective property. The purpose of this study was to investigate the alleviating effect of TEN on cognitive impairment induced by chronic restraint stress (CRS) and its mechanism. Our results showed that CRS exposure resulted in impaired cognitive performance in C57BL/6J mice, as indicated by decreased responses in Y-maze, novel objects recognition, and step-through passive avoidance tests. TEN treated daily orally (10 and 20 mg/kg) for 30 days reversed these behavior changes. Meanwhile, TEN could significantly regulate interleukin (IL)-6 and IL-10 levels in the hippocampus. TEN inhibited the toll-like receptor 4/nuclear factor-kappa B-mediated inflammation, as well as adrenocorticotropic hormone and corticosterone levels in serum. Most importantly, we found that TEN also upregulated the expressions of brain-derived neurotrophic factor, tropomyosin kinase B, glucocorticoid receptor, glutamate receptor 1, and synapse-associated proteins. Collectively, these data suggest that TEN has a potential improvement effect on memory loss caused by CRS.

GPR68 Improves Nerve Damage and Myelination in an Immature Rat Model Induced by Sevoflurane Anesthesia by Activating cAMP/CREB to Mediate BDNF

Ovarian cancer G-protein-coupled receptor 1 (OGR1, also known as GPR68) is a member of proton-sensing G-protein-coupled receptors, involved in cardiovascular physiology, tumor biology, and asthma, and exerts a neuroprotective effect against brain ischemia. The effects of GPR68 on anesthesia-induced nerve damage and myelination were investigated in this study. First, 2-day old postnatal rats were exposed to 4.9% sevoflurane for 2 h. Data from hematoxylin and eosin staining and Nissl staining showed that sevoflurane induced pathological changes in the hippocampus with a reduced number of neurons. GPR68 was downregulated in the hippocampus of sevoflurane-induced rats. Second, sevoflurane-induced rats were injected with adeno-associated virus (AAV)-mediated overexpression of GPR68, and overexpression of GPR68 ameliorated sevoflurane-induced pathological changes, enhanced the number of neurons, and improved the learning and memory function. Moreover, overexpression of GPR68 increased the number of BrdU-positive and Olig2-positive cells and enhanced protein expression of Olig2 in sevoflurane-induced rats. Third, the number of myelin basic protein (MBP) positive cells and protein expression of MBP in sevoflurane-induced rats were also enhanced by injection with AAV-GPR68. Overexpression of GPR68 attenuated sevoflurane-induced neuronal apoptosis and oxidative stress in rats. Lastly, overexpression of GPR68 upregulated protein expression of the brain-derived neurotrophic factor (BDNF) by increasing cAMP and phosphorylated cAMP response element-binding protein (CREB). In conclusion, GPR68 alleviated sevoflurane-induced nerve damage and myelination through BDNF-mediated activation of the cAMP/CREB pathway.

Role of CRF and the hypothalamic-pituitary-adrenal axis in stroke: revisiting temporal considerations and targeting a new generation of therapeutics

Ischaemic neurovascular stroke represents a leading cause of death in the developed world. Preclinical and human epidemiological evidence implicates the corticotropin-releasing factor (CRF) family of neuropeptides as mediators of acute neurovascular injury pathology. Preclinical investigations of the role of CRF, CRF receptors and CRF-dependent activation of the hypothalamic-pituitary-adrenal (HPA) axis have pointed toward a tissue-specific and temporal relationship between activation of these pathways and physiological outcomes. Based on the literature, the major phases of ischaemic stroke aetiology may be separated into an acute phase in which CRF and anti-inflammatory stress signalling are beneficial and a chronic phase in which these contribute to neural degeneration, toxicity and apoptotic signalling. Significant gaps in knowledge remain regarding the pathway, temporality and systemic impact of CRF signalling and stress biology in neurovascular injury progression. Heterogeneity among experimental designs poses a challenge to defining the apparent reciprocal relationship between neurological injury and stress metabolism. Despite these challenges, it is our opinion that the elucidated temporality may be best matched with an antibody against CRF with a half-life of days to weeks as opposed to minutes to hours as with small-molecule CRF receptor antagonists. This state-of-the-art review will take a multipronged approach to explore the expected potential benefit of a CRF antibody by modulating CRF and corticotropin-releasing factor receptor 1 signalling, glucocorticoids and autonomic nervous system activity. Additionally, this review compares the modulation of CRF and HPA axis activity in neuropsychiatric diseases and their counterpart outcomes post-stroke and assess lessons learned from antibody therapies in neurodegenerative diseases.

Ionic Channels as Potential Targets for the Treatment of Autism Spectrum Disorder: A Review

Autism spectrum disorder (ASD) is a neurological condition that directly affects brain functions and can culminate in delayed intellectual development, problems in verbal communication, difficulties in social interaction, and stereotyped behaviors. Its etiology reveals a genetic basis that can be strongly influenced by socio-environmental factors. Ion channels controlled by ligand voltage-activated calcium, sodium, and potassium channels may play important roles in modulating sensory and cognitive responses, and their dysfunctions may be closely associated with neurodevelopmental disorders such as ASD. This is due to ionic flow, which is of paramount importance to maintaining physiological conditions in the central nervous system and triggers action potentials, gene expression, and cell signaling. However, since ASD is a multifactorial disease, treatment is directed only to secondary symptoms. Therefore, this research aims to gather evidence concerning the principal pathophysiological mechanisms involving ion channels in order to recognize their importance as therapeutic targets for the treatment of central and secondary ASD symptoms.

Blockade of adenosine A2A receptor alleviates cognitive dysfunction after chronic exposure to intermittent hypoxia in mice

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is widely known for its multiple systems damage, especially neurocognitive deficits in children. Since their discovery, adenosine A_2A receptors (A_2ARs) have been considered as key elements in signaling pathways mediating neurodegenerative diseases such as Huntington's and Alzheimer's, as well as cognitive function regulation. Herein, we investigated A_2AR role in cognitive impairment induced by chronic intermittent hypoxia (CIH). Mice were exposed to CIH 7 h every day for 4 weeks, and intraperitoneally injected with A_2AR agonist CGS21680 or A_2AR antagonist SCH58261 half an hour before IH exposure daily. The 8-arm radial arm maze was utilized to assess spatial memory after CIH exposures.To validate findings using pharmacology, the impact of intermittent hypoxia was investigated in A_2AR knockout mice. CIH-induced memory dysfunction was manifested by increased error rates in the radial arm maze test. The behavioral changes were associated with hippocampal pathology, neuronal apoptosis, and synaptic plasticity impairment. The stimulation of adenosine A_2AR exacerbated memory impairment with more serious neuropathological damage, attenuated long-term potentiation (LTP), syntaxin down-regulation, and increased BDNF protein. Moreover, apoptosis-promoting protein cleaved caspase-3 was upregulated while anti-apoptotic protein Bcl-2 was downregulated. Consistent with these findings, A_2AR inhibition with SCH58261 and A_2AR deletion exhibited the opposite result. Overall, these findings suggest that A_2AR plays a critical role in CIH-induced impairment of learning and memory by accelerating hippocampal neuronal apoptosis and reducing synaptic plasticity. Blockade of adenosine A_2A receptor alleviates cognitive dysfunction after chronic exposure to intermittent hypoxia in mice.

Repeated exposure to sevoflurane in neonatal rats impairs cognition in adulthood via the PKA-CREB-BDNF signaling pathway

Sevoflurane (Sev) anesthesia is widely used in pediatrics due to its low blood-gas partition coefficient and lack of pungency. However, Sev treatment may lead to cognitive dysfunction in later life. The current study administered Sev to neonatal rats to investigate the effects of Sev treatment on cognitive performance in adulthood. In total, 6-day-old rats received 3% Sev for 2 h daily for 3 consecutive days. The cognitive function of rats in adulthood was evaluated in 56-day-old rats by Morris water maze test. The hippocampal neuron morphology was observed by Nissl staining. Hippocampal brain-derived neurotrophic factor (BDNF) levels were measured by ELISA. The protein expression of protein kinase A (PKA), cAMP response element binding protein (CREB), phosphorylated-CREB (p-CREB) and BDNF in hippocampus were assessed by western blotting. The water maze results demonstrated that neonatal treatment with Sev resulted in a significant impairment of cognition in 56-day-old adult rats. Behavioral analysis revealed that Sev treatment increased latency to first pass the platform and decreased residence in target quadrants and across platform frequency compared with the control group in Morris water maze tests. Furthermore, compared with the control group, neonatal exposure to Sev reduced the number of neurons and the concentration of BDNF in the hippocampus, a brain region important for learning and memory. Additionally, Sev significantly decreased the expression of PKA, p-CREB, BDNF and the p-CREB/CREB ratio. Treatment with bucladesine, a selective PKA agonist, partially reversed the deleterious effects of Sev. In summary, the results indicated that PKA-CREB-BDNF signaling served an important role in the cognitive decline caused by neonatal exposure to Sev.

Cilostazol attenuated prenatal valproic acid-induced behavioural and biochemical deficits in a rat model of autism spectrum disorder

OBJECTIVES

Autism spectrum disorder (ASD) is categorized as a neurodevelopmental disorder, presenting with a variety of aetiological and phenotypical features. Inhibiting the enzyme phosphodiesterase-3 (PDE3) with cilostazol is known to produce beneficial effects in several brain disorders. The pharmacological outcome of cilostazol administration was investigated in prenatal valproic acid (VPA)-induced ASD deficits in albino Wistar rats.

METHODS

Cilostazol was administered in two doses (30/60 mg/kg) to male rats born of females administered with VPA on gestational day 12. Behavioural assays on locomotion (open field), social interaction, repetitive behaviour (y-maze) and anxiety (elevated plus maze) were performed in all groups. Further, biochemical assessments of markers associated with neuronal function (BDNF, pCREB), inflammation (TNF-α, IL-6, IL-10) and oxidative stress were carried out in frontal cortex, hippocampus, striatum and cerebellum.

KEY FINDINGS

The cilostazol regimen, attenuated prenatal VPA exposure associated hyperlocomotion, social interaction deficits, repetitive behavior, and anxiety. Further, biochemical markers such as BDNF, pCREB, IL-10 and GSH were found to be significantly increased contrary to markers such as TNF-α, IL-6 and TBARS in the assessed brain regions.

CONCLUSIONS

Cilostazol rectified core behavioural traits while producing significant changes to biochemistry in the brain, suggesting benefits of cilostazol administration in experimental models of ASD.

Vinpocetine amended prenatal valproic acid induced features of ASD possibly by altering markers of neuronal function, inflammation, and oxidative stress

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with complex etiology and phenotypes. Phosphodiesterase-1 (PDE1) inhibitors are known to provide benefits in various brain conditions manifesting similar behavioral phenotypes. The pharmacological consequences of vinpocetine administration a PDE1 inhibitor in prenatal-valproic acid (pre-VPA) induced ASD related behavioral phenotypes (social behavior deficits, repetitive behavior, anxiety, hyperlocomotion, and nociception) was assessed. Also, effects on important biochemical markers of neuronal function (DCX-neurogenesis, BDNF-neuronal survival, synapsin-IIa-synaptic transmission, pCREB-neuronal transcription factor), inflammation (interleukin [IL]-6, IL-10, and TNF-α) and oxidative stress (thiobarbituric acid reactive substance [TBARS] and glutathione (GSH) were studied in important brain areas (frontal cortex, cerebral cortex, hippocampus, and striatum). Further, neuronal cell viability was determined in dentate gyrus using Nissl staining. Pre-VPA administration resulted into impaired behavior, brain biochemistry, and neuronal cell viability. Administration of vinpocetine resulted in improvements of pre-VPA impaired social behavior, repetitive behavior, anxiety, locomotion, and nociception. Also, vinpocetine resulted in a significant increase in the levels of BDNF, synapsin-IIa, DCX, pCREB/CREB, IL-10, and GSH along with significant decrease in TNF-α, IL-6, TBARS, number of pyknotic and chromatolytic cells in different brain areas of pre-VPA group. Finally, high association between behavioral parameters and biochemical parameters was observed upon Pearson's correlation analysis. Vinpocetine, a PDE1 inhibitor rectified important behavioral phenotypes related with ASD, possibly by improving neuronal function, brain inflammation and brain oxidative stress. Thus, PDE1 may be a possible target for further understanding ASD. LAY SUMMARY: ASD is a brain developmental disorder with a wide array of genetic and environmental factors. Many targets have been identified till date, but a clinical treatment is still afar. The results of this study indicate that vinpocetine administration resulted in amelioration of ASD associated symptomatology in rats, prenatally exposed to VPA. Our research adds a widely expressed brain enzyme PDE1, as a possible novel pharmacological target and opens-up a new line of enquiry for ASD treatment.

Resveratrol improved hippocampal neurogenesis following lead exposure in rats through activation of SIRT1 signaling

Lead (Pb) poses a potential environmental risk factor for cognitive dysfunction during early life and childhood. Resveratrol is considered a promising antioxidant with respect to the prevention of cognitive deficits and act as a potent SIRT1 agonist. Herein, this study aims to investigate the profile of neurogenesis markers following Pb exposure and to determine the regulatory role of resveratrol in this process. We confirmed firstly the protective effects of resveratrol against Pb-induced impairments of hippocampal neurogenesis in Male SD rats. Pb exposure early in life caused the altered expression of Ki-67, NeuN, caspase-3 and SIRT1 signaling, thereby resulting in spatial cognitive impairment of adolescent rats. As expected, resveratrol reduced cognitive damage and promoted neurogenesis in Pb-induced injury by regulation of SIRT1 pathway. Collectively, our study establishes the efficacy of resveratrol as a neuroprotective agent and provides a strong rationale for further studies on SIRT1-mediated mechanisms of neuroprotective functions.

Ginsenoside Re protects against chronic restraint stress-induced cognitive deficits through regulation of NLRP3 and Nrf2 pathways in mice

Exposure to chronic stress negatively affects the development of cognition, characterized by learning and memory decline. Ginsenoside Re (GRe), an active compound derived from Panax ginseng, exhibited neuroprotective activity in various neurological diseases. In this study, the protective effect of GRe on chronic restraint stress (CRS)-induced memory deficit was investigated. The mice were experienced 35 days of the CRS induction. The GRe was administered daily orally (10, 20, or 40 mg/kg) during the next 3 weeks stress session and the behavior test period. The CRS-induced memory impairment mice were subjected to behavioral tasks, such as the Y-maze, novel objects recognition, and step-through passive avoidance tests. Nissl staining was used to examine the neuron numbers. The levels of antioxidant enzymes, malondialdehyde, and proinflammatory factor were determined by kits and ELISA assays. The expressions of brain-derived neurotrophic factor (BDNF), NOD-like receptor protein 3 (NLRP3), nuclear factor erythroid-2 related factor 2 (Nrf2) and synapse-associated proteins (synaptophysin, SYP, and postsynaptic density 95, PSD95) were measured by Western blotting. Behavioral assessments indicated that GRe could ameliorate the cognitive impairment of CRS-induced mice, as indicated by increased responses in Y-maze (p < .05), novel objects recognition (p < .01), and step-through passive avoidance tests (p < .01). In addition, GRe treatment significantly decreased the neuronal loss in CRS mice in histological examination. Moreover, chronic GRe treatment significantly ameliorated the down-regulated the expressions of BDNF, Nrf2, heme oxygenase (HO)-1, SYP, and PSD95, as well as up-regulated NLRP3, the adaptor protein ASC, and Caspase-1 protein expression in the hippocampus of CRS-treated mice. Taken together, these findings suggest that GRe has a potential therapeutic effect on memory impairment in C57BL/6J mice exposed to CRS paradigm.

Biased agonism in drug discovery: Is there a future for biased 5-HT1A receptor agonists in the treatment of neuropsychiatric diseases?

Serotonin (5-HT) is one of the fundamental neurotransmitters that contribute to the information essential for an organism's normal, physiological function. Serotonin acts centrally and systemically. The 5-HT_1A receptor is the most widespread serotonin receptor, and participates in many brain-related disorders, including anxiety, depression, and cognitive impairments. The 5-HT_1A receptor can activate several different biochemical pathways and signals through both G protein-dependent and G protein-independent pathways. Preclinical experiments indicate that distinct signaling pathways in specific brain regions may be crucial for antidepressant-like, anxiolytic-like, and procognitive responses. Therefore, the development of new ligands that selectively target a particular signaling pathway(s) could open new possibilities for more effective and safer pharmacotherapy. This review discusses the current state of preclinical studies focusing on the concept of functional selectivity (biased agonism) regarding the 5-HT_1A receptor and its role in antidepressant-like, anxiolytic-like, and procognitive regulation. Such work highlights not only the differential effects of targeted autoreceptors, vs. heteroreceptors, but also the importance of targeting specific downstream intracellular signaling processes, thereby enhancing favorable over unfavorable signaling activation.

An Integrative Pharmacology-Based Strategy to Uncover the Mechanism of Xiong-Pi-Fang in Treating Coronary Heart Disease with Depression

Objectives: This study aimed to explore the mechanism of Xiong-Pi-Fang (XPF) in the treatment of coronary heart disease (CHD) with depression by an integrative strategy combining serum pharmacochemistry, network pharmacology analysis, and experimental validation. Methods: An ultrahigh performance liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (UPLC-Q-TOF/MS) method was constructed to identify compounds in rat serum after oral administration of XPF, and a component-target network was established using Cytoscape, between the targets of XPF ingredients and CHD with depression. Furthermore, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed to deduce the mechanism of XPF in treating CHD with depression. Finally, in a chronic unpredictable mild stress (CUMS)-and isoproterenol (ISO)-induced rat model, TUNEL was used to detect the apoptosis index of the myocardium and hippocampus, ELISA and western blot were used to detect the predicted hub targets, namely AngII, 5-HT, cAMP, PKA, CREB, BDNF, Bcl-2, Bax, Cyt-c, and caspase-3. Results: We identified 51 compounds in rat serum after oral administration of XPF, which mainly included phenolic acids, saponins, and flavonoids. Network pharmacology analysis revealed that XPF may regulate targets, such as ACE2, HTR1A, HTR2A, AKT1, PKIA, CREB1, BDNF, BCL2, BAX, CASP3, cAMP signaling pathway, and cell apoptosis process in the treatment of CHD with depression. ELISA analysis showed that XPF decreased Ang-II content in the circulation and central nervous system, inhibited 5-HT levels in peripheral circulation, and increased 5-HT content in the central nervous system and cAMP content in the myocardia and hippocampus. Meanwhile, western blot analysis indicated that XPF could upregulate the expression levels of PKA, CREB, and BDNF both in the myocardia and hippocampus. TUNEL staining indicated that the apoptosis index of myocardial and hippocampal cells increased in CUMS-and ISO-induced CHD in rats under depression, and XPF could increase the expression of Bcl-2, inhibit the expression of Bax, Cyt-c, and caspase-3, and rectify the injury of the hippocampus and myocardium, which exerted antidepressant and antimyocardial ischemia effects. Conclusion: Our study proposed an integrated strategy, combining serum pharmacochemistry and network pharmacology to investigate the mechanisms of XPF in treating CHD with depression. The mechanism of XPF in treating CHD with depression may be related to the activation of the cAMP signaling pathway and the inhibition of the apoptosis.