Rosiglitazone Mitigates Dexamethasone-Induced Depression in Mice via Modulating Brain Glucose Metabolism and AMPK/mTOR Signaling Pathway

Neuroprotective Effect of Rosuvastatin Calcium Combined with Hyperbaric Oxygen Mediated p38MAPK Pathway in Rats with Leukoaraiosis

This study explored the neuroprotective mechanism of rosuvastatin calcium (RSC) combined with hyperbaric oxygen (HBO) in rats with leukoaraiosis (LA), and its impact on the p38MAPK signaling pathway (SPW). Clean-grade male SD rats were used as subjects, which were assigned into Sham group (SG), LA group (LAG), RSC group (RSCG), HBO group (HBOG), and RSC + HBO group (combination group, CG), 20 rats in each. At 14 d post-modeling, the effects of RSC, HBO, and RSC + HBO treatment on the cognitive function, brain neuronal cell apoptosis, brain tissue matrix metalloproteinases (MMPs) family gene expression, and the status of the p38MAPK SPW in LA rats were analyzed. As against the LAG, the escape latency (EL) was shortened, the count of platform crossings was augmented, the number of brain neuronal cell apoptosis decreased, the relative expression (RE) of brain TIMP-1, MMP-2, MMP-3, and MMP-9 mRNA were reduced (P < 0.05), and the RE of brain cleaved caspase (Cas)-3 and p-p38MAPK proteins were reduced in the RSCG, HBOG, and CG (P < 0.05); As against the RSCG and HBOG, the CG showed more visible improvements in all indicators (P < 0.05). The combination of RSC and HBO can inhibit brain neuronal cell apoptosis and the expression of the MMPs family genes in rats with LA by suppressing the overactivation of the p38MAPK SPW, which is beneficial for the recovery of the rats' cognitive function.

Sleep deprivation activated AMPK/FOXO3a signaling mediates pineal autophagy impairment to reduce melatonin secretion in CUMS + SD rats leading to depression combined with insomnia

This study established an animal model of comorbid depression and insomnia by combining chronic unpredictable mild stress (CUMS) with sleep deprivation (SD). The pathogenesis of comorbid depression and insomnia may be associated with impaired AMPK/FOXO3a signaling, which mediates autophagy inhibition, leading to decreased pineal melatonin secretion. The findings revealed that CUMS + SD rats exhibited more pronounced depression-like behaviors, sleep disorders, increased central oxidative stress, and exacerbated neuroinflammation, accompanied by reduced levels of 5-hydroxytryptophan (5-HT) and melatonin in the pineal gland. Notably, further investigations revealed that impaired mitochondrial autophagy in the pineal gland is closely linked to the significant suppression of AMPK/FOXO3a signaling. The combined intervention of venlafaxine and melatonin effectively ameliorated the impaired mitochondrial autophagy in the pineal gland of CUMS + SD rats and stimulated melatonin secretion. Consequently, the study proposes that dysfunctional mitochondrial autophagy regulated by the AMPK/FOXO3a pathway can influence melatonin secretion, thereby playing a pivotal role in the pathogenesis of depression combined with insomnia.

Caffeic acid differentially modulates behavior and neurochemicals in chronic unpredictable mild stress and dexamethasone induced models of depression

In the present study authors studied the effect of caffeic acid (CA) in chronic unpredictable mild stress (CUMS) and dexamethasone (DEXA) model of depression. CUMS (21 days) and DEXA (1.5 mg/kg × 21 days) was used for the induction of depression and anxiety related behavior. Locomotor activity was determined using actophotometer. Depression related behavior was determined using tail suspension test (TST) and forced swim test (FST) whereas for the determination of anxiety related behavior elevated plus maze (EPM) test was used. Following behavioral studies, mice were sacrificed by decapitation method. Hippocampus was dissected and was used for the neurochemical assays including 5-HT (serotonin), glutamate, nitrite and gamma-aminobutyric acid (GABA). The results obtained suggested that the CA (25-100 mg/kg, i.p.) did not affect the activity count in CUMS exposed and DEXA treated mice. CA (50 mg/kg) evoked anxiogenic reactions in CUMS model by increasing the hippocampal nitrite and glutamate level while CA (50 mg/kg) exerted anxiolysis in DEXA model by reducing the level of 5-HT. In CUMS model, CA exerted antidepressant like effect by increasing the hippocampal nitric oxide (NO) level, in DEXA model CA exerted antidepressant like effect by reducing the hippocampal glutamate level. CA failed to reverse DEXA mediated nNOS inhibition and therefore decreases hippocampal glutamate level to exert antidepressant like effect. Thus, CA modulate anxiety and depression related neurobehavioral alterations in both CUMS and DEXA models.

Oxidative and Excitatory Neurotoxic Stresses in CRISPR/Cas9-Induced Kynurenine Aminotransferase Knockout Mice: A Novel Model for Despair-Based Depression and Post-Traumatic Stress Disorder

BACKGROUNDS

Memory and emotion are especially vulnerable to psychiatric disorders such as post-traumatic stress disorder (PTSD), which is linked to disruptions in serotonin (5-HT) metabolism. Over 90% of the 5-HT precursor tryptophan (Trp) is metabolized via the Trp-kynurenine (KYN) metabolic pathway, which generates a variety of bioactive molecules. Dysregulation of KYN metabolism, particularly low levels of kynurenic acid (KYNA), appears to be linked to neuropsychiatric disorders. The majority of KYNA is produced by the aadat (kat2) gene-encoded mitochondrial kynurenine aminotransferase (KAT) isotype 2. Little is known about the consequences of deleting the KYN enzyme gene.

METHODS

In CRISPR/Cas9-induced aadat knockout (kat2-/-) mice, we examined the effects on emotion, memory, motor function, Trp and its metabolite levels, enzyme activities in the plasma and urine of 8-week-old males compared to wild-type mice.

RESULTS

Transgenic mice showed more depressive-like behaviors in the forced swim test, but not in the tail suspension, anxiety, or memory tests. They also had fewer center field and corner entries, shorter walking distances, and fewer jumping counts in the open field test. Plasma metabolite levels are generally consistent with those of urine: antioxidant KYNs, 5-hydroxyindoleacetic acid, and indole-3-acetic acid levels were lower; enzyme activities in KATs, kynureninase, and monoamine oxidase/aldehyde dehydrogenase were lower, but kynurenine 3-monooxygenase was higher; and oxidative stress and excitotoxicity indices were higher. Transgenic mice displayed depression-like behavior in a learned helplessness model, emotional indifference, and motor deficits, coupled with a decrease in KYNA, a shift of Trp metabolism toward the KYN-3-hydroxykynurenine pathway, and a partial decrease in the gut microbial Trp-indole pathway metabolite.

CONCLUSIONS

This is the first evidence that deleting the aadat gene induces depression-like behaviors uniquely linked to experiences of despair, which appear to be associated with excitatory neurotoxic and oxidative stresses. This may lead to the development of a double-hit preclinical model in despair-based depression, a better understanding of these complex conditions, and more effective therapeutic strategies by elucidating the relationship between Trp metabolism and PTSD pathogenesis.

Empagliflozin ameliorates olfactory bulbectomy-induced depression by mitigating oxidative stress and possible involvement of brain derived neurotrophic factor in diabetic rats

Empagliflozin, a sodium-glucose co-transporter 2 (SGLT2) inhibitor, has recently reported to prevent the depression in chronic animal model. The present study aimed to explore the antidepressant potential of empagliflozin using a neuroinflammation-mediated depression involving the olfactory bulbectomy (OBX) model in diabetic rats. A low dose of streptozotocin was injected to induce diabetes in all group of animals. Following the confirmation of hyperglycemia, OBX surgery was performed. Post-surgery, the drug treatments were administered orally for 14 consecutive days. The study evaluated the effects of daily oral administration of empagliflozin at doses of 5 and 10 mg/kg, alongside metformin (200 mg/kg) and clomipramine (50 mg/kg), on OBX-induced behavioral depression in rats. Separate sham and vehicle control groups were also maintained. Behavioral parameters in open field, forced swim test, elevated plus maze and splash test were recorded on 28th day. Results showed that empagliflozin, at the higher dose, significantly enhanced behavioral outcomes, evidenced by increased distance travelled, greater open arm entries, and reduced immobility, alongside a notable reduction in grooming time. Moreover, empagliflozin significantly restored the antioxidants level specifically Glutathione (GSH) and Catalase (CAT) in OBX insulted rat brain and decreased Lipid peroxidase (LPO). Notably, molecular docking study demonstrated a good binding affinity of empagliflozin for Brain-Derived Neurotrophic Factor (BDNF), suggesting that its antidepressant effects may be mediated through the modulation of the BDNF pathway. These findings support the potential therapeutic application of empagliflozin for depression, particularly in cases associated with neuroinflammation and oxidative stress.

Babesia duncani Pyruvate Kinase Inhibitor Screening and Identification of Key Active Amino Acid Residues

Babesia duncani (B. duncani), a protozoan parasite prevalent in North America, is a significant threat for human health. Given the regulatory role of pyruvate kinase I (PyK I) in glycolytic metabolism flux and ATP generation, PyK I has been considered the target for drug intervention for a long time. In this study, B. duncani PyK I (BdPyK I) was successfully cloned, expressed, and purified. Polyclonal antibodies were confirmed to recognize the native BdPyK I protein (56 kDa) using Western blotting. AlphaFold software predicted the three-dimensional structure of BdPyK I, and molecular docking with small molecules was conducted to identify potential binding sites of inhibitor on BdPyK I. Moreover, inhibitory effects of six inhibitors (tannic acid, apigenin, shikonin, PKM2 inhibitor, rosiglitazone, and pioglitazone) on BdPyK I were examined under the optimal enzymatic conditions of 3 mM PEP and 3 mM ADP, and significant activity reduction was found. Enzyme kinetics and growth inhibition assays further confirmed the reliability of these inhibitors, with PKM2 inhibitor, tannic acid, and apigenin exhibiting the highest selectivity index as specific inhibitors for B. duncani. Subsequently, key amino acid residues were mutated in both BdPyK I and Homo sapiens pyruvate kinase I (HPyK I), and two differential amino acid residues (isoleucine and phenylalanine) were identified between HPyK I and BdPyK I through PyK activity detection experiments. These findings lay foundation for understanding the role of PyK I in the growth and development of B. duncani, providing insights for babesiosis prevention and drug development.

Liraglutide and Naringenin relieve depressive symptoms in mice by enhancing Neurogenesis and reducing inflammation

Depression is a debilitating mental disease that negatively impacts individuals' lives and society. Novel hypotheses have been recently proposed to improve our understanding of depression pathogenesis. Impaired neuroplasticity and upregulated neuro-inflammation add-on to the disturbance in monoamine neurotransmitters and therefore require novel anti-depressants to target them simultaneously. Recent reports demonstrate the antidepressant effect of the anti-diabetic drug liraglutide. Similarly, the natural flavonoid naringenin has shown both anti-diabetic and anti-depressant effects. However, the neuro-pharmacological mechanisms underlying their actions remain understudied. The study aims to evaluate the antidepressant effects and neuroprotective mechanisms of liraglutide, naringenin or a combination of both. Depression was induced in mice by administering dexamethasone (32 mcg/kg) for seven consecutive days. Liraglutide (200 mcg/kg), naringenin (50 mg/kg) and a combination of both were administered either simultaneously or after induction of depression for twenty-eight days. Behavioral and molecular assays were used to assess the progression of depressive symptoms and biomarkers. Liraglutide and naringenin alone or in combination alleviated the depressive behavior in mice, manifested by decrease in anxiety, anhedonia, and despair. Mechanistically, liraglutide and naringenin improved neurogenesis, decreased neuroinflammation and comparably restored the monoamines levels to that of the reference drug escitalopram. The drugs protected mice from developing depression when given simultaneously with dexamethasone. Collectively, the results highlight the usability of liraglutide and naringenin in the treatment of depression in mice and emphasize the different pathways that contribute to the pathogenesis of depression.

PI3K-AKT/mTOR Signaling in Psychiatric Disorders: A Valuable Target to Stimulate or Suppress?

Economic development and increased stress have considerably increased the prevalence of psychiatric disorders in recent years, which rank as some of the most prevalent diseases globally. Several factors, including chronic social stress, genetic inheritance, and autogenous diseases, lead to the development and progression of psychiatric disorders. Clinical treatments for psychiatric disorders include psychotherapy, chemotherapy, and electric shock therapy. Although various achievements have been made researching psychiatric disorders, the pathogenesis of these diseases has not been fully understood yet, and serious adverse effects and resistance to antipsychotics are major obstacles to treating patients with psychiatric disorders. Recent studies have shown that the mammalian target of rapamycin (mTOR) is a central signaling hub that functions in nerve growth, synapse formation, and plasticity. The PI3K-AKT/mTOR pathway is a critical target for mediating the rapid antidepressant effects of these pharmacological agents in clinical and preclinical research. Abnormal PI3K-AKT/mTOR signaling is closely associated with the pathogenesis of several neurodevelopmental disorders. In this review, we focused on the role of mTOR signaling and the related aberrant neurogenesis in psychiatric disorders. Elucidating the neurobiology of the PI3K-AKT/mTOR signaling pathway in psychiatric disorders and its actions in response to antidepressants will help us better understand brain development and quickly identify new therapeutic targets for the treatment of these mental illnesses.

Antidepressant pharmacological mechanisms: focusing on the regulation of autophagy

The core symptoms of depression are anhedonia and persistent hopelessness. Selective serotonin reuptake inhibitors (SSRIs) and their related medications are commonly used for clinical treatment, despite their significant adverse effects. Traditional Chinese medicine with its multiple targets, channels, and compounds, exhibit immense potential in treating depression. Autophagy, a vital process in depression pathology, has emerged as a promising target for intervention. This review summarized the pharmacological mechanisms of antidepressants by regulating autophagy. We presented insights from recent studies, discussed current research limitations, and proposed new strategies for basic research and their clinical application in depression.

Therapeutic Investigation of Palm Oil Mill Effluent-Derived Beta-Carotene in Streptozotocin-Induced Diabetic Retinopathy via the Regulation of Blood-Retina Barrier Functions

Diabetic retinopathy (DR) primarily progresses into retinal degeneration caused by microvascular dysfunction. The pathophysiology of DR progression is still uncertain. This study investigates the function of beta-carotene (PBC) originating from palm oil mill effluent in the treatment of diabetes in mice. An intraperitoneal injection of streptozotocin (35 mg/kg) was used to induce diabetes, which was then accelerated by an intravitreal (i.vit.) injection of STZ (20 µL on day 7). PBC (50 and 100 mg/kg) and dexamethasone (DEX: 10 mg/kg) were also administered orally (p.o.) for 21 days. At various time intervals, the optomotor response (OMR) and visual-cue function test (VCFT) responses were evaluated. Biomarkers, such as reduced glutathione (GSH), thiobarbituric acid reactive substances (TBARSs), and catalase activity were determined in retinal tissue samples. DR significantly lowers the spatial frequency threshold (SFT) and time spent in the target quadrant (TSTQ), increases the reaching time in the visual-cue platform (RVCP), lowers retinal GSH and catalase activity levels, and elevates TBARS levels. The treatments of PBC and DEX also ameliorate STZ-induced DR alterations. The potential ameliorative activity of PBC in DR is attributed to its anti-diabetic, anti-oxidative, and control of blood-retinal barrier layer properties.