Nitro-oleic acid (NO2-OA) ameliorates erectile dysfunction in a rat model of diabetes mellitus via modulation of fibrosis, inflammation and autophagy.

Background: Inflammation, fibrosis and autophagy represent closely related factors associated with the pathogenesis of diabetes mellitus erectile dysfunction (DMED). In this study, the therapeutic effect of nitro-oleic acid (NO2-OA) in a streptozotocin-induced rat model of DMED was evaluated. Methods: Sixty rats were randomly divided into four groups: control, DMED, DMED + Vehicle and DMED + NO2-OA. DMED was induced by intraperitoneal injection of streptozotocin in male rats. Blood glucose and body weight were measured every 2 weeks. After 4 weeks of NO2-OA treatment, erectile function was measured by electrical stimulation of cavernous nerve (CN). Western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), immunofluorescence and Masson's trichrome staining were used to verify the related factors and protein expression levels. Results: We found that NO2-OA could significantly increase erectile pressure in the corpus cavernosum of DMED rats. Results of western blot, confocal immunofluorescence and qRT-PCR assays revealed that NO2-OA significantly reduced inflammatory factors and the expression of nuclear factor kappa B (NF-κB). In addition, Masson staining results indicated that NO2-OA significantly reduced the display of fibrotic tissue in the corpus cavernosum. These beneficial effects may be related to reductions in the expression of transforming growth factor-ß1 (TGF-ß1) and connective tissue growth factor (CTGF) and the increase in the expression of α-smooth muscle actin (α-SMA). Finally, NO2-OA treatment increased the expression of the autophagy marker, LC3, while P62 was decreased, effects suggesting that one of the underlying mechanisms of NO2-OA may involve an activation of the PI3K/AKT/mTOR pathway to enhance the capacity for autophagy within this tissue. Conclusions: NO2-OA enhances erectile function within a rat model of DMED by inhibiting inflammation and fibrosis along with activating autophagy.

Nitro-oleic acid ameliorates erectile dysfunction in a streptozotocin-induced rat model of diabetes by inhibiting oxidative stress and apoptosis and activating the NO/cGMP pathway.

The major vascular complications associated with diabetes make the management of diabetic mellitus erectile dysfunction (DMED) a challenging endeavor. Notable factors contributing to DMED include oxidative stress, nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway activation, and apoptosis, while nitro-oleic acid (NO2-OA) has been shown to be beneficial in treating these aspects of this condition. We, herein, investigated the effects and possible mechanisms of NO2-OA on erectile function as assessed in a streptozotocin-induced rat model of diabetes. Our results revealed that the erectile function of DMED rats was significantly impaired compared with that of the control group. However, in response to 4 weeks of NO2-OA treatment, there was an improvement in erectile function. The expression of oxidative stress-related indicators was significantly increased and the NO/cGMP pathway was impaired in the DMED group. The expression of proapoptotic factors was increased, while that of antiapoptotic factors was decreased in the DMED group. Moreover, the cell morphology in the cavernous tissue of the DMED group also changed adversely. NO2-OA treatment significantly reversed all these changes observed in the DMED group. In conclusion, NO2-OA treatment partially improved erectile function in DMED rats through mechanisms that included inhibition of oxidative stress, activation of the NO/cGMP pathway, and a reduction in apoptosis.

Stress-induced reduction of Na+/H+ exchanger isoform 1 promotes maladaptation of neuroplasticity and exacerbates depressive behaviors.

Major depression disorder (MDD) is a neuropsychiatric disorder characterized by abnormal neuronal activity in specific brain regions. A factor that is crucial in maintaining normal neuronal functioning is intracellular pH (pHi) homeostasis. In this study, we show that chronic stress, which induces depression-like behaviors in animal models, down-regulates the expression of the hippocampal Na+/H+ exchanger isoform 1, NHE1, a major determinant of pHi in neurons. Knockdown of NHE1 in CA1 hippocampal pyramidal neurons leads to intracellular acidification, promotes dendritic spine loss, lowers excitatory synaptic transmission, and enhances the susceptibility to stress exposure in rats. Moreover, E3 ubiquitin ligase cullin4A may promote ubiquitination and degradation of NHE1 to induce these effects of an unbalanced pHi on synaptic processes. Electrophysiological data further suggest that the abnormal excitability of hippocampal neurons caused by maladaptation of neuroplasticity may be involved in the pathogenesis of this disease. These findings elucidate a mechanism for pHi homeostasis alteration as related to MDD.

Agomelatine rescues lipopolysaccharide-induced neural injury and depression-like behaviors via suppression of the Gαi-2-PKA-ASK1 signaling pathway.

BACKGROUND: Agomelatine has been shown to be effective in the treatment of depression, but the molecular mechanisms underlying its antidepressant effects have yet to be elucidated. Identification of these molecular mechanisms would not only offer new insights into the basis for depression but also provide the foundation for the development of novel treatments for this disorder. METHODS: Intraperitoneal injection of LPS was used to induce depression-like behaviors in rats. The interactions of the 5-HT2C reporter and Gαi-2 were verified by immunoprecipitation or immunofluorescence assay. Inflammatory related proteins, autophagy related proteins and apoptosis markers were verified by immunoblotting or immunofluorescence assay. Finally, electron microscopy analysis was used to observe the synapse and ultrastructural pathology. RESULTS: Here, we found that the capacity for agomelatine to ameliorate depression and anxiety in a lipopolysaccharide (LPS)-induced rat model of depression was associated with an alleviation of neuroinflammation, abnormal autophagy and neuronal apoptosis as well as the promotion of neurogenesis in the hippocampal dentate gyrus (DG) region of these rats. We also found that the 5-HT2C receptor is coupled with G alphai (2) (Gαi-2) protein within hippocampal neurons and, agomelatine, acting as a 5-HT2C receptor antagonist, can up-regulate activity of the Gαi-2-cAMP-PKA pathway. Such events then suppress activation of the apoptosis signal-regulating kinase 1 (ASK1) pathway, a member of the mitogen-activated protein kinase (MAPK) family involved in pathological processes of many diseases. CONCLUSION: Taken together, these results suggest that agomelatine plays a neuroprotective role in regulating neuroinflammation, autophagy disorder and apoptosis in this LPS-induced rat model of depression, effects which are associated with the display of antidepressant behaviors. These findings provide evidence for some of the potential mechanisms for the antidepressant effects of agomelatine.

N-acetylcysteine improves diabetic associated erectile dysfunction in streptozotocin-induced diabetic mice by inhibiting oxidative stress.

Oxidative stress appears to play a role in the pathogenesis of diabetes mellitus erectile dysfunction (DMED). This study aimed to investigate the effect of N-acetylcysteine (NAC) on DMED in streptozotocin-induced diabetic mice and to explore potential mechanisms. In the present study, we show that an erectile dysfunction is present in the streptozotocin-induced mouse model of diabetes as indicated by decreases in intracavernous pressure responses to electro-stimulation as well as from results of the apomorphine test of erectile function. After treatment of NAC, the intracavernous pressure was increased. In these DMED mice, oxidative stress and inflammatory responses were significantly reduced within the cavernous microenvironment, while activity of antioxidant enzymes in this cavernous tissue was enhanced after NAC treatment. These changes protected mitochondrial stress damage and a significant decreased in apoptosis within the cavernous tissue of DMED mice. This appears to involve activation of the nuclear factor erythroid 2-like-2 (Nrf2) signalling pathway, as well as suppression of the mitogen-activated protein kinase (MAPK) p38/ NF-κB pathway within cavernous tissue. In conclusion, NAC can improve erectile function through inhibiting oxidative stress via activating Nrf2 pathways and reducing apoptosis in streptozotocin-induced diabetic mice. NAC might provide a promising therapeutic strategy for individuals with DMED.

Microglia secrete miR-146a-5p-containing exosomes to regulate neurogenesis in depression.

Enhancing neurogenesis within the hippocampal dentate gyrus (DG) is critical for maintaining brain development and function in many neurological diseases. However, the neural mechanisms underlying neurogenesis in depression remain unclear. Here, we show that microglia transfer a microglia-enriched microRNA, miR-146a-5p, via secreting exosomes to inhibit neurogenesis in depression. Overexpression of miR-146a-5p in hippocampal DG suppresses neurogenesis and spontaneous discharge of excitatory neurons by directly targeting Krüppel-like factor 4 (KLF4). Downregulation of miR-146a-5p expression ameliorates adult neurogenesis deficits in DG regions and depression-like behaviors in rats. Intriguingly, circular RNA ANKS1B acts as a miRNA sequester for miR-146a-5p to mediate post-transcriptional regulation of KLF4 expression. Collectively, these results indicate that miR-146a-5p can function as a critical factor regulating neurogenesis under conditions of pathological processes resulting from depression and suggest that microglial exosomes generate new crosstalk channels between glial cells and neurons.

MicroRNA-204-5p reduction in rat hippocampus contributes to stress-induced pathology via targeting RGS12 signaling pathway.

BACKGROUND: Neuroinflammation occupies a pivotal position in the pathogenesis of most nervous system diseases, including depression. However, the underlying molecular mechanisms of neuroinflammation associated with neuronal injury in depression remain largely uncharacterized. Therefore, identifying potential molecular mechanisms and therapeutic targets would serve to better understand the progression of this condition. METHODS: Chronic unpredictable stress (CUS) was used to induce depression-like behaviors in rats. RNA-sequencing was used to detect the differentially expressed microRNAs. Stereotactic injection of AAV virus to overexpress or knockdown the miR-204-5p. The oxidative markers and inflammatory related proteins were verified by immunoblotting or immunofluorescence assay. The oxidative stress enzyme and products were verified using enzyme-linked assay kit. Electron microscopy analysis was used to observe the synapse and ultrastructural pathology. Finally, electrophysiological recording was used to analyze the synaptic transmission. RESULTS: Here, we found that the expression of miR-204-5p within the hippocampal dentate gyrus (DG) region of rats was significantly down-regulated after chronic unpredicted stress (CUS), accompanied with the oxidative stress-induced neuronal damage within DG region of these rats. In contrast, overexpression of miR-204-5p within the DG region of CUS rats alleviated oxidative stress and neuroinflammation by directly targeting the regulator of G protein signaling 12 (RGS12), effects which were accompanied with amelioration of depressive-like behaviors in these CUS rats. In addition, down-regulation of miR-204-5p induced neuronal deterioration in DG regions and depressive-like behaviors in rats. CONCLUSION: Taken together, these results suggest that miR-204-5p plays a key role in regulating oxidative stress damage in CUS-induced pathological processes of depression. Such findings provide evidence of the involvement of miR-204-5p in mechanisms underlying oxidative stress associated with depressive phenotype.

Prophylactic treatment of curcumin in a rat model of depression by attenuating hippocampal synaptic loss.

Curcumin is a polyphenol substance considered to be effective in the treatment of a number of neurodegenerative diseases. However, details regarding the exact mechanisms for the protective effects of curcumin in neuropsychiatric disorders, like depression, remain unknown. In the pathogenesis of major depressive disorder (MDD) it appears that dysregulation of oxidative stress and immune systems, particularly within the hippocampal region, may play a critical role. Here, we show that pre-treatment with curcumin (40 mg kg-1) alleviates depression-like behaviors in a LPS-induced rat model of depression, effects which were accompanied with suppression of oxidative stress and inflammation and an inhibition of neuronal apoptosis in the hippocampal CA1 region, and results from ultramicrostructure electrophysiological experiments revealed that the curcumin pre-treatment significantly prevented excessive synaptic loss and enhanced synaptic functioning in this LPS-induced rat model. In addition, curcumin attenuated the increases in levels of miR-146a-5p and decreases in the expression of p-ERK signaling that would normally occur within CA1 regions of these depressed rats. Taken together, these results demonstrated that curcumin exerts neuroprotective and antidepressant activities by suppressing oxidative stress, neural inflammation and their related effects upon synaptic dysregulation. One of the mechanisms for these beneficial effects of curcumin appears to involve the miR-146a-5p/ERK signaling pathway within the hippocampal CA1 region. These findings not only elucidated some of the mechanisms underlying the neuroprotective/antidepressant effects of curcumin, but also suggested a role of curcumin as a potential therapeutic strategy for depression.

Lipin1 Alleviates Autophagy Disorder in Sciatic Nerve and Improves Diabetic Peripheral Neuropathy.

Diabetic peripheral neuropathy (DPN) is a chronic complication of diabetes, and its neural mechanisms underlying the pathogenesis remain unclear. Autophagy plays an important role in neurodegenerative diseases and nerve tissue injury. Lipin1 is a phosphatidic acid phosphatase enzyme that converts phosphatidic acid (PA) into diacylglycerol (DAG), a precursor of triacylglycerol and phospholipids which plays an important role in maintaining normal peripheral nerve conduction function. However, whether Lipin1 involved in the pathogenesis of DPN via regulation of autophagy is not elucidated. Here, we show that the Lipin1 expression was downregulated in streptozotocin (STZ)-induced DPN rat model. Interestingly, STZ prevented DAG synthesis, and resulted in autophagic hyperactivity, effects which may increase the apoptosis of Schwann cells and lead to demyelination in sciatic nerve in DPN rats. More importantly, upregulation of lipin1 in the DPN rats ameliorated autophagy disorders and pathological changes of the sciatic nerve, which associated with the increase of the motor nerve conductive velocity (MNCV) in DPN rats. In contrast, knockdown of lipin1 exacerbates neuronal abnormalities and facilitates the genesis of DPN phenotypes in rats. In addition, overexpression of lipin1 in RSC96 cells also significantly decreased the autophagic hyperactivity and apoptosis induced by hyperglycemia. These results suggest that lipin1 may exert neuroprotection within the sciatic nerve anomalies and may serve as a potential therapeutic target for the treatment of DPN.

MicroRNA-26a-3p rescues depression-like behaviors in male rats via preventing hippocampal neuronal anomalies.

Depression is a neuropsychiatric disease associated with neuronal anomalies within specific brain regions. In the present study, we screened microRNA (miRNA) expression profiles in the dentate gyrus (DG) of the hippocampus and found that miR-26a-3p was markedly downregulated in a rat model of depression, whereas upregulation of miR-26a-3p within DG regions rescued the neuronal deterioration and depression-like phenotypes resulting from stress exposure, effects that appear to be mediated by the PTEN pathway. The knockdown of miR-26a-3p in DG regions of normal control rats induced depression-like behaviors, effects that were accompanied by activation of the PTEN/PI3K/Akt signaling pathway and neuronal deterioration via suppression of autophagy, impairments in synaptic plasticity, and promotion of neuronal apoptosis. In conclusion, these results suggest that miR-26a-3p deficits within the hippocampal DG mediated the neuronal anomalies contributing to the display of depression-like behaviors. This miRNA may serve as a potential therapeutic target for the treatment of depression.

Neuroprotective effects of microRNA-211-5p on chronic stress-induced neuronal apoptosis and depression-like behaviours.

Findings from recent studies have revealed that microRNAs (miRNAs) are related to numerous neurological disorders. However, whether miRNAs regulate neuronal anomalies involved in the pathogenesis of depression remain unclear. In the present study, we screened miRNA expression profiles in the CA1 hippocampus of a rat model of depression and found that a specific miRNA, microRNA-211-5p, was significantly down-regulated in depressed rats. When miR-211-5p was up-regulated in these rats, neuronal apoptosis within the CA1 area was suppressed, effects which were accompanied with an amelioration of depression-like behaviours in these rats. These neuroprotective effects of miR-211-5p in depressed rats appear to result through suppression of the Dyrk1A/ASK1/JNK signalling pathway within the CA1 area. In further support of this proposal are the findings that knock-down of miR-211-5p within the CA1 area of normal rats activated the Dyrk1A/ASK1/JNK pathway, resulting in the promotion of neuronal apoptosis and display of depression-like behaviours in these rats. Taken together, these results demonstrate that deficits in miR-211-5p contribute to neuronal apoptosis and thus depression-like behaviours in rats. Therefore, the miR-211-5p/Dyrk1A pathway may be critically involved in the pathogenesis of depression and serve as a potential therapeutic target for the treatment of depression.

Hippocampal miR-211-5p regulates neurogenesis and depression-like behaviors in the rat.

Emerging evidence has shown that microRNAs (miRNAs) contribute to the pathogenesis of depression, a potentially life-threatening and disabling mental disorder caused by the interaction of genetic and environmental factors. However, the specific miRNAs and their underlying molecular mechanisms as involved in the pathogenesis and development of depression remain largely unknown. In the present study, we screened miRNA expression profiles and found that miR-211-5p was significantly down-regulated within the dentate gyrus (DG) hippocampus in the chronic unpredictable mild stress (CUMS) induced rat model of depression. Deficits in miR-211-5p were accompanied with reductions in neurogenesis and increased apoptosis in these CUMS rats. In contrast, an up-regulation of miR-211-5p within the DG area in CUMS rats promoted neuronal neurogenesis, reduced neuronal apoptosis via suppression of the Dyrk1A/STAT3 signaling pathway and relieved depression-like behaviors in these CUMS rats. In rats subjected to a knock-down of miR-211-5p in the DG there was an increase in neuronal apoptosis and a decrease in neuronal regeneration, effects which were accompanied with an induction of depression-like behaviors. Taken together, the results of our study reveal that altered levels of miR-211-5p in the hippocampal DG area exert a significant impact on neurogenesis, apoptosis and thus depression-like behaviors in rats. These findings suggest that the miR-211-5p/Dyrk1A pathway plays an important role in the pathogenesis of depression and may serve as a potential therapeutic target for the treatment of depression.

N-Acetylcysteine Rescues Hippocampal Oxidative Stress-Induced Neuronal Injury via Suppression of p38/JNK Signaling in Depressed Rats.

Progression of neuronal deterioration within specific brain regions is considered as one of the principal bases for the development of major depressive disorders. Therefore, protects and promotes the maintaining of normal structure and function of neurons might be a potential therapeutic strategy in the treatment of depression. Here, we report that the antioxidant, N-acetylcysteine (NAC), inhibited neuronal injury through its capacity to reduce oxidative stress and exerted antidepressant effects. Specifically, we show that antioxidant enzyme activity was significantly decreased in the hippocampal CA1 region of depressive rats, while treatment with NAC (300 mg/kg, i.p.) produced neuroprotective effects against mitochondrial oxidative stress injuries and oxidative DNA damage in CA1 neurons of these rats. Moreover, NAC treatment alleviated neuronal injury resulting from neuroinflammation and apoptosis in depressed rats, effects that were associated with reductions in dendritic spine atrophy, and synapse deficits. These effects appear to involve a down-regulation of p38 mitogen-activated protein kinase (MAPK)-JNK signaling along with an up-regulation of ERK signaling within the hippocampal CA1 region. Moreover, this NAC treatment significantly ameliorated depression-like behaviors as indicated by performance in the sucrose preference and forced swim tests (FST). Taken together, these results reveal the potential involvement of oxidative stress in the generation of depression. And, the antidepressant-like effects exerted by NAC may involve reductions in this oxidative stress that can result in neuronal deterioration. Such neuroprotective effects of NAC may indicate a potential therapeutic strategy for the treatment of stress-related depression.

Ginsenoside-Rg1 Rescues Stress-Induced Depression-Like Behaviors via Suppression of Oxidative Stress and Neural Inflammation in Rats.

Depression is an inflammatory-related condition, with the progression in neuronal damage resulting in major depression disorder. Ginsenoside-Rg1, a sterol extract from the herb Panax ginseng, has been shown to exert neuroprotective effects upon neurodegeneration disorders. However, whether ginsenoside-Rg1 confers antidepressant-like effects on neuroinflammation as associated with depression, as well as the possible mechanism involved in these neuroprotective effects, is currently unclear. In the present report, we show that treatment with ginsenoside-Rg1 (40 mg/kg, i.p.) significantly ameliorated depressive-like behaviors as induced by chronic unpredictable mild stress (CUMS) in a rat model of depression. Moreover, these CUMS rats treated with ginsenoside-Rg1 showed reductions in the levels of the oxidative stress products and the activity in the antioxidant stress kinase. Furthermore, CUMS rats treated with ginsenoside-Rg1 showed ameliorated neuroinflammation and associated neuronal apoptosis along with a reduction in dendritic spine atrophy and display of depressive behaviors. Taken together, the results of this study suggest that ginsenoside-Rg1 produces antidepressant-like effects in CUMS-exposed rats; and one of the mechanisms for these antidepressant-like effects of ginsenoside-Rg1 appears to involve protection against oxidative stress and thus the neuronal deterioration resulting from inflammatory responses. These findings provide evidence for the therapeutic potential of ginsenoside-Rg1 in the treatment of stress-related depression.

COX-2 inhibition rescues depression-like behaviors via suppressing glial activation, oxidative stress and neuronal apoptosis in rats.

Depression is considered a neuropsychiatric condition which is associated with neuronal injury within specific brain regions. We previously reported that cyclo-oxygenase (COX)-2, a rate-limiting enzyme for prostaglandin E2 (PGE2) synthesis, significantly enhanced depressive-like disorders induced by chronic stress in rats. However, the underlying molecular mechanisms and identification of potential therapeutic targets for preventing neuronal injury associated with depression remain largely uncharacterized. Here, we show that COX-2 inhibition by celecoxib protects against neuronal injury through suppression of oxidative stress and, in this way, mediates its antidepressant effects. COX-2 is highly expressed in the hippocampal dentate gyrus (DG) of rat depression model and its activity is responsible for depression-like behaviors as demonstrated in two independent rat models of depression. Inhibition of COX-2 exerts neuroprotective actions in DG regions, including suppressing neuroinflammatory response, against oxidative stress and neuronal apoptosis, which are the critical risk factors for neuronal injury and pathophysiology of depression. Moreover, the antioxidant, N-acetylcysteine (NAC), significantly attenuates oxidative stress levels and dendritic spine deficiencies resulting from COX-2 overexpression; and, suppression of oxidative stress by NAC also significantly ameliorates depressive behaviors in rats. These findings suggest that selective inhibition of COX-2 ameliorates depression-like behaviors in rat models of depression. This selective inhibition of COX-2 appears to be protective against oxidative stress and neuronal deterioration resulting from chronic stress. Taken together, these findings have potentially important clinical implications with regard to the development of novel therapeutic approaches in the treatment of neuropsychiatric conditions like depression.

Interleukin-6: Its role and mechanisms in rescuing depression-like behaviors in rat models of depression.

Neuronal injury within specific brain regions is considered a critical risk factor in the pathophysiology of depression. However, the underlying mechanisms of this process, and thus the potential for development of novel therapeutic strategies in the treatment of depression, remain largely unknown. Here, we report that Il-6 protects against neuronal anomalies related with depression, in part, by suppressing oxidative stress and consequent autophagic and apoptotic hyperactivity. Specifically, we show that IL-6 is downregulated within the CA1 hippocampus in two animal models of depression and upregulated by antidepressants. Increasing levels of IL-6 in the CA1 region result in pleiotropic protective actions including reductions in oxidative stress and modulation of autophagy, anti-immuno-inflammatory activation and anti-apoptotic effects in CA1 neurons, all of which are associated with the rescue of depression-like behaviors. In contrast, IL-6 downregulation exacerbates neuronal anomalies within the CA1 region and facilitates the genesis of depression phenotypes in rats. Interestingly, in addition to attenuating oxidative damage, the antioxidant, N-acetylcysteine (NAC), is also associated with significantly decreased neuronal deficits and the display of depressive behaviors in rats. These results suggest that IL-6 may exert neuroprotection within CA1 neurons via pleiotropic mechanisms and may serve as a potential therapeutic target for the treatment of depression.

Hippocampal CA1 ßCaMKII mediates neuroinflammatory responses via COX-2/PGE2 signaling pathways in depression.

BACKGROUND: Neuroinflammation has recently emerged as a critical risk factor in the pathophysiology of depression. However, the underlying molecular mechanisms and the development of novel therapeutic strategies as means to target these inflammatory pathways for use in the treatment of depression remain unresolved. In the present study, we aimed to investigate the molecular events of neuroinflammation as related to its induction of depression-like behaviors. METHODS: Chronic unpredictable mild stress (CUMS) or lipopolysaccharide (LPS) was used to induce depression-like behaviors in rats. The inflammatory factors and related proteins were verified by RT-PCR, immunoblotting, and immunofluorescence assay. In vivo intracerebral injection of adenovirus-associated virus (AAV) in rats was used to overexpress or block the function of the ß form of the calcium/calmodulin-dependent protein kinase type II (ßCaMKII). In vivo intracerebroventricular injection of SB203580 was used to block p38 mitogen-activated protein kinase (MAPK). Finally, the prostaglandin E2 (PGE2) concentration was verified by using enzyme-linked assay kit. RESULTS: The expression of cyclo-oxygenase (COX)-2, which is responsible for production of the pro-inflammatory factor PGE2 and thus glial activation, was increased in the CA1 hippocampus in a rat model of depression. Further, the ßCaMKII in CA1 was significantly upregulated in depressed rats, while antidepressant treatment downregulated this kinase. Overexpression of ßCaMKII via infusion of a constructed AAV-ßCaMKII into the CA1 region resulted in phosphorylation of the p38 MAPK and the activating transcription factor 2 (ATF2). These effects were accompanied by an enhanced activity of the COX-2/PGE2 pathway and effectively induced core symptoms of depression. Conversely, knockdown of ßCaMKII within the CA1 region reversed these inflammation-related biochemical parameters and significantly rescued depression symptoms. CONCLUSION: These results demonstrate that ßCaMKII can act as a critical regulator in depression via activating neuroinflammatory pathways within the CA1 region. Moreover, this study provides new perspectives on molecular targets and drug therapies for future investigation in the treatment of depression.

Neuroprotective Effects of Ginsenoside-Rg1 Against Depression-Like Behaviors via Suppressing Glial Activation, Synaptic Deficits, and Neuronal Apoptosis in Rats.

Depression is considered a neuropsychiatric disease associated with various neuronal changes within specific brain regions. We previously reported that ginsenoside-Rg1, a potential neuroprotective agent extracted from ginseng, significantly alleviated depressive-like disorders induced by chronic stress in rats. However, the mechanisms by which ginsenoside-Rg1 exerts its neuroprotective effects in depression remain largely uncharacterized. In the present study we confirm that ginsenoside-Rg1 significantly prevented the antidepressant-like effects in a rat model of chronic unpredictable mild stress (CUMS) and report on some of the underlying mechanisms associated with this effect. Specifically, we found that chronic pretreatment with ginsenoside-Rg1 prior to stress exposure significantly suppressed inflammatory pathway activity via alleviating the overexpression of proinflammatory cytokines and the activation of microglia and astrocytes. These effects were accompanied with an attenuation of dendritic spine and synaptic deficits as associated with an upregulation of synaptic-related proteins in the ventral medial prefrontal cortex (vmPFC). In addition, ginsenoside-Rg1 inhibited neuronal apoptosis induced by CUMS exposure, increased Bcl-2 expression and decreased cleaved Caspase-3 and Caspase-9 expression within the vmPFC region. Furthermore, ginsenoside-Rg1 could increase the nuclear factor erythroid 2-related factor (Nrf2) expression and inhibit p38 mitogen-activated protein kinase (p-p38 MAPK) and nuclear factor κB (NF-κB) p65 subunit activation within the vmPFC. Taken together, these results suggest that the neuroprotective effects of ginsenoside-Rg1, which may assume the antidepressant-like effect in this animal model of depression, appears to result from amelioration of a CUMS-dependent neuronal deterioration within the vmPFC. Moreover, they also provide support for the therapeutic potential of ginsenoside-Rg1 in the treatment of stress-related mental disorders.

Curcumin Protects Against Chronic Stress-induced Dysregulation of Neuroplasticity and Depression-like Behaviors via Suppressing IL-1ß Pathway in Rats.

Accumulating evidence has accrued demonstrating that inflammatory processes in the central nervous system (CNS) are associated with various neurological disorders including depression. However, whether inflammation-mediated neuronal damage is involved in depression-like behaviors induced by chronic stress and, in particular, whether suppression of inflammation could then serve as a potential strategy in depression therapy remains largely unknown. The present study aimed to investigate the neuronal mechanisms and signaling pathways through which inflammation results in neuronal deterioration in a rat model of depression and thus identify agents with potential roles as antidepressant treatments. Our results showed that chronic unpredictable mild stress (CUMS) exposure induced microglia activation and overexpression of the cytokines interleukin-1ß (IL-1ß), interleukin-6 (IL-6), and tumor necrosis factor-a (TNF-α) within the medial prefrontal cortex (mPFC), effects which were paralleled with neuronal structural changes. In contrast, chronic administration of either IL-1ß or nuclear factor κB (NF-κB) antagonists significantly ameliorated this dysregulation of neuronal structure and biochemical parameters such as SSH1 and phospho-cofilin within the mPFC, as well as the display of depression-like behaviors induced by CUMS exposure. More importantly, pretreatment with curcumin (40 mg/kg, i.p., 5 weeks), produced antidepressant-like actions and repressed the inflammatory responses and neuronal structural abnormalities. These findings reveal some of the molecular neuroinflammation pathways associated with depression and suggest new avenues of investigation for the development of potential antidepressant therapies in the treatment of inflammation-related neuronal deterioration in this disorder.

Ginsenoside Rg1 Prevents Chronic Stress-Induced Depression-Like Behaviors and Neuronal Structural Plasticity in Rats.

BACKGROUND/AIMS: Ginsenoside Rg1 has been demonstrated to exhibit neuroprotective effects in various studies. This study aimed to investigate the neuronal mechanisms underlying the neuroprotective and antidepressant-like effects of ginsenoside Rg1 in a rat model of depression. METHODS: Chronic unpredictable mild stress was used to induce depression-like behaviors in rats. Transmission electron microscopy was used to observe neuronal synapses within the basolateral amygdala (BLA). The expression of microRNA (miR)-134 in the BLA was verified by real-time quantitative PCR. Finally, the synaptic plasticity-associated proteins CAMP-response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) were detected by immunoblotting. RESULTS: Results showed that chronic stress effectively induced depression-like behaviors in rats, which were associated with significant ultrastructural changes within BLA neurons. Moreover, chronic stress decreased the expression of miR-134 in the BLA, which was accompanied by decreased phosphorylation of CREB and decreased expression of BDNF. Remarkably, chronic administration of ginsenoside Rg1 (40 mg/kg, i.p., 5 weeks) significantly ameliorated the neuronal structural abnormalities and biochemical changes induced by chronic stress, as well as preventing depression-like behaviors in these rats. CONCLUSION: Results suggested that ginsenoside Rg1 may exhibit neuroprotection and antidepressant-like effects by activating the CREB-BDNF system within the BLA in this rat model of depression. Amelioration of depression-like behaviors by ginsenoside Rg1 appears to involve modulation of the synapse-associated factor miR-134 within the BLA. Therefore, these findings demonstrate some of the neuronal mechanisms associated with depression and the therapeutic potential of ginsenoside Rg1 for use in the treatment of depression in clinical trials.