Novelty-suppressed Feeding Test Research Articles

Loureirin C and Xanthoceraside Prevent Abnormal Behaviors Associated with Downregulation of Brain Derived Neurotrophic Factor and AKT/mTOR/CREB Signaling in the Prefrontal Cortex Induced by Chronic Corticosterone Exposure in Mice.

Brain derived neurotrophic factor (BDNF) is one of the most abundant neurotrophic factors, and its deficits are involved in the pathogenesis of major depressive disorders (MDD). Loureirin C (Lou C) is a compound derived from red resin extracted from the stems of Chinese dragon's blood. Xanthoceraside (Xan) is a triterpenoid saponin extracted from the husks of Xanthoceras sorbifolia Bunge. These compounds have neuroprotective effects through upregulation of BDNF. The present study aimed to evaluate whether Lou C and Xan attenuate abnormal behaviors induced by chronic corticosterone (CORT) administration. CORT was administered subcutaneously to mice for 3weeks, and Lou C and Xan, dispensed orally once a day during the last 2weeks of CORT administration. Chronic CORT administration induced abnormal behaviors such as prolonged starting latency in the open field test, decreased social interaction time in the social interaction test and prolonged latency to eat in the novelty suppressed feeding test. Chronic CORT administration decreased the expression levels of BDNF and the phosphorylation of protein kinase B (Akt), mammalian target of rapamycin (mTOR), and the cAMP response element binding protein (CREB) in the prefrontal cortex. Lou C and Xan dose-dependently prevented the abnormal behaviors and decreased the expression levels of BDNF and in phosphorylation of AKT, mTOR, and CREB in the prefrontal cortex of CORT mice. These results suggest that Lou C and Xan could be attractive candidates for pharmacotherapy of MDD at least in part, given their propensity to increase BDNF expression and phosphorylation of AKT, mTOR, and CREB.

Loureirin C and Xanthoceraside Attenuate Depression-Like Behaviors and Expression of Interleukin-17 in the Prefrontal Cortex Induced by Chronic Unpredictable Mild Stress in Mice.

Major depressive disorder (MDD) is the most prevalent and serious psychiatric disease involving inflammation. Loureirin C and Xanthoceraside are extracts of dragon's blood and Xanthoceras sorbifolia Bunge, respectively, which have neuroprotective and anti-inflammatory properties. In this study, we examined whether Loureirin C and Xanthoceraside attenuated depression-like behaviors and inflammation induced by chronic unpredicted mild stress (CUMS) in mice. Adult C57BL/6J mice exposed to CUMS for 4weeks showed depression-like behaviors characterized by hyperactivity in a novel environment, decreased interaction time in the social interaction test, prolongation of eating latency in the novelty suppressed feeding test, and increased immobility in the forced swimming test. CUMS increased the expression of interleukin-17 (IL-17) in the prefrontal cortex (PFC). One week after exposure to CUMS, the mice were treated with Loureirin C (0.64mg/kg) or Xanthoceraside (1.28mg/kg) once a day for 3weeks during CUMS. Loureirin C and Xanthoceraside significantly attenuated CUMS-induced behavioral impairment. Furthermore, both Loureirin C and Xanthoceraside prevented IL-17 expression induced by CUMS in the PFC. This data suggests that Loureirin C and Xanthoceraside have antidepressant-like properties that may be associated with the inhibition of IL-17 expression.

Novel Antidepressant-Like Properties of the Iron Chelator Deferiprone in a Mouse Model of Depression

Depressed individuals who carry the short allele for the serotonin-transporter-linked promotor region of the gene are more vulnerable to stress and have reduced response to first-line antidepressants such as selective serotonin reuptake inhibitors. Since depression severity has been reported to correlate with brain iron levels, the present study aimed to characterise the potential antidepressant properties of the iron chelator deferiprone. Using the serotonin transporter knock-out (5-HTT KO) mouse model, we assessed the behavioural effects of acute deferiprone on the Porsolt swim test (PST) and novelty-suppressed feeding test (NSFT). Brain and blood iron levels were also measured following acute deferiprone. To determine the relevant brain regions activated by deferiprone, we then measured c-Fos expression and applied network-based analyses. We found that deferiprone reduced immobility time in the PST in 5-HTT KO mice and reduced latency to feed in the NSFT in both genotypes, suggesting potential antidepressant-like effects. There was no effect on brain or blood iron levels following deferiprone treatment, potentially indicating an acute iron-independent mechanism. Deferiprone reversed the increase in c-Fos expression induced by swim stress in 5-HTT KO mice in the lateral amygdala. Functional network analyses suggest that hub regions of activity in mice treated with deferiprone include the caudate putamen and prefrontal cortex. The PST-induced increase in network modularity in wild-type mice was not observed in 5-HTT KO mice. Altogether, our data show that the antidepressant-like effects of deferiprone could be acting via an iron-independent mechanism and that these therapeutic effects are underpinned by changes in neuronal activity in the lateral amygdala.

Translational control by ketamine and its implications for comorbid cognitive deficits in depressive disorders.

Ketamine has shown antidepressant effects in patients with major depressive disorder (MDD) resistant to first-line treatments and approved for use in this patient population. Ketamine induces several forms of synaptic plasticity, which are proposed to underlie its antidepressant effects. However, the molecular mechanism of action directly responsible for ketamine's antidepressant effects remains under active investigation. It was recently demonstrated that the effectors of the mammalian target of rapamycin complex 1 (mTORC1) signalling pathway, namely, eukaryotic initiation factor 4E (eIF4E) binding proteins 1 and 2 (4E-BP1 and 4E-BP2), are central in mediating ketamine-induced synaptic plasticity and behavioural antidepressant-like effect. 4E-BPs are a family of messenger ribonucleic acid (mRNA) translation repressors inactivated by mTORC1. We observed that their expression in inhibitory interneurons mediates ketamine's effects in the forced swim and novelty suppressed feeding tests and the long-lasting inhibition of GABAergic neurotransmission in the hippocampus. In addition, another effector pathway that regulates translation elongation downstream of mTORC1, the eukaryotic elongation factor 2 kinase (eEF2K), has been implicated in ketamine's behavioural effects. We will discuss how ketamine's rapid antidepressant effect depends on the activation of neuronal mRNA translation through 4E-BP1/2 and eEF2K. Furthermore, given that these pathways also regulate cognitive functions, we will discuss the evidence of ketamine's effect on cognitive function in MDD. Overall, the data accrued from pre-clinical research have implicated the mRNA translation pathways in treating mood symptoms of MDD. However, it is yet unclear whether the pro-cognitive potential of subanesthetic ketamine in rodents also engages these pathways and whether such an effect is consistently observed in the treatment-resistant MDD population.

Contribution of the Opioid System to the Antidepressant Effects of Fluoxetine

BackgroundSelective serotonin reuptake inhibitors such as fluoxetine have a limited treatment efficacy. The mechanism by which some patients respond to fluoxetine while others do not remains poorly understood, limiting treatment effectiveness. We have found the opioid system to be involved in the responsiveness to fluoxetine treatment in a mouse model for anxiety- and depressive-like behavior. MethodsWe analyzed gene expression changes in the dentate gyrus of mice chronically treated with corticosterone and fluoxetine. After identifying a subset of genes of interest, we studied their expression patterns in relation to treatment responsiveness. We further characterized their expression through in situ hybridization and the analysis of a single-cell RNA sequencing dataset. Finally, we behaviorally tested mu and delta opioid receptor knockout mice in the novelty suppressed feeding test and the forced swim test after chronic corticosterone and fluoxetine treatment. ResultsChronic fluoxetine treatment upregulates proenkephalin expression in the dentate gyrus, and this upregulation is associated with treatment responsiveness. The expression of several of the most significantly upregulated genes, including proenkephalin, is localized to an anatomically and transcriptionally specialized subgroup of mature granule cells in the dentate gyrus. We have also found that the delta opioid receptor contributes to some, but not all, of the behavioral effects of fluoxetine. ConclusionsThese data indicate that the opioid system is involved in the antidepressant effects of fluoxetine, and this effect may be mediated through the upregulation of proenkephalin in a subpopulation of mature granule cells.

The Rapid and Long-Lasting Antidepressant Effects of Iridoid Fraction in Gardenia Jasminoides J.Ellis Are Dependent on Activating PKA-CREB Signaling Pathway.

Lag periods of therapeutic efficacy cause poor compliance of patients, which has made solutions for rapid antidepressants the most urgent need in the depression study field at present. We have identified through our previous studies the rapid antidepressant effects of the traditional herb Gardenia jasminoides J.Ellis [Rubiaceae] (GJ) and its standardized fractions. Through screening different fractions of GJ, we decided to place our focus on the iridoid fraction of GJ (GJ-IF). Methods: 1. Tail suspension test (TST), forced swimming test (FST), and novelty suppressed-feeding test (NSFT) were performed in sequence on mice after GJ-IF administration. 2. Mice in the model group were under chronic unpredictable mild stress (CUMS) for 3 w. After GJ-IF treatment, mice were placed in an open field test (OFT), Sucrose preference test (SPT), NSFT, TST, and FST. 3. Western Blot was performed to examine the expression of brain-derived neurotrophic factor (BDNF), Synapsin 1, cyclic-AMP dependent protein kinase A (PKA), phosphorylated cyclic-AMP responsive element-binding protein (p-CREB), and cAMP response element-binding protein (CREB). 4. Mice in the test group were administrated with GJ-IF after intraperitoneal injection of PKA blocker H89. Results: 1. GJ-IF treatment significantly reduced the immobility time of TST at 1 d and FST at 26 h. 2. GJ-IF reversed the deficits induced by 3 w CUMS in SPT, TST, FST, and NSFT at 1 d and 26 h. The antidepressant effects of a single dose of iridoid fraction could also last for at least 14 d. 3. The results of molecule studies suggested that a single dose of GJ-IF activated p-CREB at 2 h and the PKA-CREB pathway at 1 d. The expression of BDNF did not significantly change from 30 min to 1 d after GJ-IF administration. 4. Blockade of PKA-CREB signaling pathway reversed the antidepressant effects of GJ-IF at 1 d, but not 30 min and 2 h. Conclusion: GJ-IF is the crucial component in the rapid antidepressant of GJ. Rapid and sustained antidepressant effects of GJ-IF were dependent on activating the PKA-CREB signaling pathway.

Rapid-Onset Antidepressant-Like Effect of Nelumbinis semen in Social Hierarchy Stress Model of Depression.

Depression is a disease with increasing prevalence worldwide, and it is necessary to develop a therapeutic agent with better efficacy than existing antidepressant drugs. Antidepressants that act on the glutamatergic nervous system, such as ketamine, have a rapid-onset antidepressant effect and are effective against treatment-resistant depression. However, because of the addictive potential of ketamine, alternative substances without psychological side effects are recommended. In particular, many natural compounds have been tested for their antidepressant effects. The antidepressant effects of Nelumbinis semen (NS) have been tested in many studies, along with the various actions of NS on the glutamatergic system. Thus, it was expected that NS might have a rapid-onset antidepressant effect. To test the antidepressant potential, despair and anhedonic behaviors were measured after administering NS to mice exposed to social hierarchy stress (SHS), and biochemical changes in the prefrontal cortex and hippocampus were analyzed. NS reduced despair-like responses in the forced swim test and tail suspension test. Mice exposed to SHS showed depression-like responses such as increased despair, reduced hedonia, and an anxiety-like response in the novelty suppressed feeding test. NS, but not fluoxetine, improved those depression-like behaviors after acute treatment, and NBQX, an AMPA receptor blocker, inhibited the antidepressant-like effects of NS. The antidepressant-like effect of NS was related to enhanced phosphorylation of mTOR in the prefrontal cortex and dephosphorylation of GluR1 S845 in the hippocampus. Since NS has shown antidepressant-like potential in a preclinical model, it may be considered as a candidate for the development of antidepressants in the future.

Beneficial effects of prolonged 2-phenylethyl alcohol inhalation on chronic distress-induced anxio-depressive-like phenotype in female mice

Chronic distress-induced hypothalamic-pituitary-adrenal axis deregulations have been associated with the development of neuropsychiatric disorders such as anxiety and depression. Currently available drugs treating such pathological conditions have limited efficacy and diverse side effects, revealing the need of new safer strategies. Aromatic plant-based compounds are largely used in herbal medicine due to their therapeutic properties on mood, physiology, and general well-being. The purpose of this study was to investigate the effects of 2-phenylethyl alcohol (PEA), one of the pharmacologically active constituents of rose essential oil, on chronic corticosterone (CORT)-induced behavioral and neurobiological changes in female mice. Animals followed a prolonged PEA inhalation exposure (30 min per day) for 15 consecutive days prior to behavioral evaluation with open-field, forced swim and novelty-suppressed feeding tests. CORT treatment induced an anxio-depressive-like phenotype, evidenced by a reduced locomotor activity in the open-field, and an increased latency to feed in the novelty-suppressed feeding paradigms. To elucidate the neural correlates of our behavioral results, immunohistochemistry was further performed to provide a global map of neural activity based on cerebral cFos expression. The altered feeding behavior was accompanied by a significant decrease in the number of cFos-positive cells in the olfactory bulb, and altered functional brain connectivity as shown by cross-correlation-based network analysis. CORT-induced behavioral and neurobiological alterations were reversed by prolonged PEA inhalation, suggesting a therapeutic action that allows regulating the activity of neural circuits involved in sensory, emotional and feeding behaviors. These findings might contribute to better understand the therapeutic potential of PEA on anxio-depressive symptoms.

IGF-1 release in the medial prefrontal cortex mediates the rapid and sustained antidepressant-like actions of ketamine

Ketamine, an N-methyl-D-aspartate receptor antagonist, exerts rapid and sustained antidepressant actions. Preclinical studies demonstrated that the release of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor in the medial prefrontal cortex (mPFC) is essential for the antidepressant-like effects of ketamine. However, the role of other neurotrophic factors in the antidepressant-like effects of ketamine has not been fully investigated. Since the intra-mPFC infusion of insulin-like growth factor 1 (IGF-1) reportedly produced antidepressant-like effects, the present study examined the role of endogenous intra-mPFC IGF-1 signaling in the antidepressant-like actions of ketamine. In vivo microdialysis showed that ketamine (10 and 30 mg/kg) significantly increased extracellular IGF-1 levels in the mPFC of male C57BL/6J mice for at least 5 h. Infusion of an IGF-1 neutralizing antibody (nAb; 160 ng/side) into the mPFC 15 min before or 2 h after ketamine injection blocked the antidepressant-like effects of ketamine in three different behavioral paradigms (forced swim, female urine sniffing, and novelty-suppressed feeding tests were conducted 1, 3 and 4 days post-ketamine, respectively). The ketamine-like antidepressant-like actions of the intra-mPFC infusion of BDNF (100 ng/side) and IGF-1 (50 ng/side) respectively were not blocked by co-infused IGF-1 nAb and BDNF nAb (200 ng/side). Moreover, intra-mPFC infusion of IGF-1 nAb 2 h post-ketamine blocked the antidepressant-like effects of ketamine in a murine lipopolysaccharide (LPS)-induced depression model. Intra-mPFC IGF-1 infusion also produced antidepressant-like effects in the LPS-challenged mice via mechanistic target of rapamycin complex 1 activation. These results suggest that persistent release of IGF-1, independently of BDNF, in the mPFC is essential for the antidepressant-like actions of ketamine.

Endocannabinoid regulation of behavior in response to negative affective states associated with alcohol abstinence

Alcohol use disorder (AUD) is characterized by elevated levels of alcohol intake followed by negative affective states when individuals halt alcohol consumption. In individuals suffering from AUD, alcohol taking and seeking is often hypothesized to be motivated by negative reinforcement, where individuals continue consuming alcohol in order to avoid the negative affective states that are triggered by abstinence. Females are particularly vulnerable to the effects of AUD and are more likely to drink to regulate this negative affect produced by abstinence. The endogenous cannabinoid (eCB) signaling system is heavily implicated in the mediation of both reward and reinforcement, and alcohol consumption has been shown to be positively correlated with release of the eCB ligand 2‐arachidonoylglycerol (2‐AG) within the reward neurocircuitry. Taking this into consideration, we took a multifaceted approach to investigate the mechanisms by which individuals avoid negative affective symptoms associated with prolonged alcohol abstinence, one of the leading causes of relapse. Using a mouse model of chronic alcohol consumption followed by prolonged forced abstinence (CDFA) and pharmacological enhancement of eCB with JZL184, we were able to examine how altered eCB signaling can affect how females respond to avoid negative outcomes. First, by using negative reinforcement operant conditioning, we show that increased eCB signaling via a single injection of JZL184 causes an increase in acquisition rate as compared to ethanol‐treated and control animals. After reaching acquisition, a difference in behavioral pattern is noted; when given the chance to either escape or avoid the foot shock, JZL‐treated animals consistently chose to escape the shock rather than fully avoid it, possibly indicating a reduced sensitivity to the aversive stimulus. Next, when comparing latency to first bite in the novelty‐suppressed feeding test (NSFT), a common protocol used to measure depression and anxiety, with acquisition rate, we found that, in ethanol‐treated animals, decreased latency to eat is negatively correlated with days to acquisition. Moreover, we are able to reverse this effect with a single dose of JZL184. Together, these data indicate that a single dose of JZL184 has the ability to cause long‐lasting effects on the eCB signaling system and, consequently, the reward circuitry. Moving forward it will be critical to directly link these effects between reinforcement learning and reward processing in order to develop a pharmacological intervention to reduce the negative affective states following alcohol abstinence.

CircDYM ameliorates CUMS mice depressive-like behavior and inhibits hippocampal neurons injury via miR-497a-5p/NR3C1 axis

BackgroundDepression is an important mental disease that threatens human physical and mental health. Circular RNA (circRNA) has been confirmed to be involved in the regulation of depression progression, but the role and mechanism of circDYM in depression progression need to be further explored. MethodsChronic unpredictable mild stress (CUMS) mice model was constructed to assess mice depressive-like behavior using novelty-suppressed feeding test, sucrose preference test, social interaction test, and forced swimming test. The expression of circDYM, microRNA (miR)-497a-5p and glucocorticoid receptor (NR3C1) was measured by quantitative real-time PCR. The protein levels of NR3C1 and apoptosis markers were analyzed by western blot analysis. Hippocampal neurons viability, apoptosis and inflammation were detected by cell counting kit 8 assay, flow cytometry and ELISA assay. Furthermore, RNA interaction was confirmed by dual-luciferase reporter assay, RIP assay and RNA pull-down assay. ResultsOur study showed that circDYM and NR3C1 were downregulated and miR-497a-5p was upregulated in the hippocampus tissues of CUMS mice. Overexpressed circDYM alleviated CUMS mice depressive-like behavior and repressed hippocampal neurons injury. In terms of mechanism, circDYM could upregulate NR3C1 by sponging miR-497a-5p. MiR-497a-5p overexpression reversed the regulation of circDYM on CUMS mice depressive-like behavior and hippocampal neurons injury. In addition, the function of miR-497a-5p overexpression on CUMS mice depressive-like behavior and hippocampal neurons injury also could be reversed by overexpressing NR3C1. ConclusionIn summary, our study confirmed that circDYM could relieve the depressive-like behavior in CUMS mice and hippocampal neurons injury through miR-497a-5p/NR3C1 pathway. These data confirmed that circDYM had an anti-depressive function, which might be a potential target for depression treatment.

Vitamin B6 Antidepressant Effects Are Comparable to Common Antidepressant Drugs in Bacillus-Calmette-Guerin Induced Depression Model in Mice.

Objective: Bacillus-Calmette-Guerin (BCG) inoculation in mice produces an acute period of illness followed by a chronic depressive-like behavior period that lasts for few weeks. The aim was to evaluate vitamin B6 antidepressant effect in comparison with common antidepressants. Method : BCG (0.2 ml/mouse) single dose was intraperitoneally inoculated in male mice. Vitamin B6 (100 mg/kg), fluoxetine, imipramine, or venlafaxine (10 mg/kg each) were intraperitoneally injected for 14 consecutive days following BCG administration. Illness was evaluated following inoculation and depressive-like behaviors were assessed on days 7 and 14. Results: Illness was induced by BCG since mice lost weight and locomotor activity was reduced. Illness was prevented by vitamin B6 similar to antidepressant drugs. Despair was measured by immobility time during the forced swim test and BCG increased it compared to control (193 ± 3s vs 151 ± 7s, P < 0.01) on day 7, and (200 ± 5s vs 147 ± 6s, P < 0.001) on day 14. Vitamin B6, like antidepressants, reduced despair. BCG clearly induced anhedonia evaluated by sucrose preference test (47.5%), and it was soothed by B6 and the antidepressants. Novelty-suppressed feeding test evaluated long term depressive behavior after 14 days. BCG increased the latency to first feeding (222 ± 41s vs control 87 ± 2.6s, P < 0.001) and reduced food consumption per body weight (13 ± 1 mg/g vs control 19 ± 2 mg/g, P < 0.001) while B6 like antidepressants reduced latency and improved food consumption. Conclusion: Vitamin B6 efficiently prevented BCG sickness and depression that was comparable to common antidepressant drugs. Therefore, B6 supplement for preventing depression in high-risk individuals is suggested for further clinical research.

Voluntary physical activity increases maternal care and reduces anxiety- and depression-related behaviours during the postpartum period in mice

A growing body of evidence suggests voluntary physical activity is associated with decreased stress-related disorders such as anxiety- and depression-like behaviours in both humans and rodents. The postpartum period is also a vulnerable transition time for the development of these neurobehavioural disorders in women. This study aimed to determine whether voluntary physical activity during pregnancy and postpartum period can increase maternal care and decrease anxiety- and depression-related behaviours in postpartum dams. To this end, pregnant mice were exposed to running wheel during their gestational and postpartum periods, and then nest building, active nursing, and licking/grooming behaviours were recorded as maternal care. To assess depression and anxiety-related symptoms, several behavioural tests such as the novelty-suppressed feeding test, tail suspension test, sucrose preference test, social interaction test, forced swim test, open field, elevated plus maze, light-dark box, and elevated zero maze were used. To identify the most important mechanisms behind these behavioural alterations, we measured oxytocin, adrenocorticotropic hormone (ACTH) and corticosterone in the serum and serotonin in the brain of postpartum dams. Our findings showed that running wheel significantly increased maternal care, and decreased depression-like behaviour during the postpartum period through increasing serum oxytocin and brain serotonin levels, whereas it decreased anxiety-like behaviour via attenuating the hypothalamic–pituitaryadrenal (HPA) axis activity by measuring ACTH and corticosterone levels in postpartum dams. Overall, this study suggests that voluntary physical activity during pregnancy and the postpartum period might improve maternal care and decrease anxiety and depression-related behaviours in postpartum dams.

Repeated Yueju, But Not Fluoxetine, Induced Sustained Antidepressant Activity in a Mouse Model of Chronic Learned Helplessness: Involvement of CaMKII Signaling in the Hippocampus.

Objective Depression is characterized with long disease length, whereas one major disadvantage of current mainstream treatment of depression is a high rate of relapse and recurrence. A sustained antidepressant activity is proposed to facilitate the prevention of relapse/recurrence. Here we compared the long-term antidepressant effect of Yueju, a traditional Chinese medicine formula, and a conventional antidepressant, fluoxetine, as well as revealing the underlying mechanism of long-term antidepressant effect of Yueju. Methods Clinical long-term depression condition was modelled by using chronic learned helplessness (cLH) protocol in ICR strain mice. The short-term and long-term antidepressant effects of drugs were assessed with learned helplessness (LH), tail suspension test (TST), forced swim test (FST), and novelty-suppressed feeding (NSF) test. The expression of PKA, CaMKII signaling, and NR1, the NMDA receptor subunit, in hippocampus was determined. A CaMKII inhibitor (KN-62) was used to assess the role of CaMKII signaling in antidepressant effects of Yueju or fluoxetine. Results In the mice exposed to chronic learned helplessness (cLH) procedure, administration of Yueju or fluoxetine for 3 weeks elicited comparable antidepressant effects, indicated by learned helplessness test, as well as TST and NSF. However, 5 days after termination of the 3-week-long drug administration, only mice previously treated with Yueju still showed the alleviation of depressive-like behaviors. At this time, the downregulation of PKA and p-CaMKII/CaMKII and upregulation of NMDA receptor subunit NR1 in the hippocampus were normalized in animals previously treated with Yueju. In contrast, none of the expressions of these proteins were changed in mice previously treated with fluoxetine. Interestingly, an administration of KN-62 blunted the antidepressant effect of Yueju. Conclusion These findings showed the sustained antidepressant efficacy of chronic treatment with routine dose of Yueju and the CaMKII signaling activation may play a critical role in the sustained antidepressant response.

Effects of electroacupuncture on BNDF/mTORC1 signaling pathway and synaptic plasticity in prefrontal cortex of rats exposed to chronic unpredictable mild stress

To investigate the effects of electroacupuncture (EA) on the expression of related proteins in the brain-derived neurotrophic factor (BDNF)/mammalian target of rapamycin complex 1 (mTORC1) signaling pathway and synapse-associated proteins and the density of dendrite spines in the prefrontal cortex (PFC) of depression model rats, and to reveal the underlying mechanism by which EA regulates the synaptic plasticity to improve depressive symptoms. Thirty-six healthy male Sprague-Dawley (SD) rats were randomly divided into normal group, model group, EA group, and scopolamine (SCOP) group, with 9 in each group. The depression model was established by exposing rats to chronic unpredictable mild stress (CUMS) combined with isolated feeding. Rats in the EA group were treated with EA (2 Hz/100 Hz, 1-1.2 mA) at "Baihui" (GV20), "Yintang" (EX-HN3), "Hegu" (LI4), and "Taichong" (LR3), 20 min each time, once per day, for 14 d, while those in the SCOP group treated with intraperitoneal injection of 25 μg/kg SCOP, once every 16 h, for 14 d. The sucrose preference and feeding latency of rats in each group were observed in the sucrose preference test (SPT) and novelty-suppressed feeding test. The expression levels of proteins in the BDNF/mTORC1 signaling pathway and synapse-associated proteins PSD95, Synapsin Ⅰ, and GluR1 were assayed by Western blot. Golgi-Cox staining was conducted for exploring the total density of dendritic spines on the apical dendrites of layer Ⅴ pyramidal neurons in PFC as well as the densities of mature, immature, and filopodial-like dendritic spines. Compared with the normal group, the model group exhibited significantly decreased sucrose preference (P<0.001), prolonged feeding latency (P<0.001), down-regulated BDNF, mTORC1, phosphorylated mTORC1 (p-mTORC1), PSD95, Synapsin Ⅰ, and GluR1 expression (P<0.001，P<0.01), and diminished total, mature, and immature spine dendritic densities (P<0.001). Compared with the model group, both EA and SCOP remarkably increased the sucrose preference (P<0.001), shortened the feeding latency (P<0.001), up-regulated the BDNF, mTORC1, p-mTORC1, PSD95, Synapsin Ⅰ, and GluR1 expression in PFC(P<0.05，P<0.01，P<0.001), and elevated the total and immature spine dendritic densities (P<0.001,P<0.01). The density of filopodial-like dendritic spine in the EA group was obviously enhanced (P<0.01), whereas the mature dendritic spine density in the SCOP group rose sharply (P<0.001). However, there were no significant differences between the EA group and SCOP group (P>0.05). EA alleviates the depressive symptoms of CUMS model rats possibly by up-regulating the expression of proteins in the BDNF/mTORC1 signaling pathway and synapse-asso-ciated proteins PSD95, Synapsin Ⅰ, and GluR1, increasing the dendritic spine density, and enhancing the synaptic plasticity in PFC.

Sex differences in affective states and association with voluntary ethanol intake in Sprague-Dawley rats.

Alcohol use disorders (AUDs) are a major problem across the USA. While AUD remains a complex human condition, it is difficult to isolate the directionality of anxiety and ethanol (EtOH) drinking from outside influences. The present study sought to investigate the relationship between affective states and EtOH intake using male and female Sprague-Dawley rats. Using complementary tests of anxiety- and depressive-like behavior, we found sex- and test-specific differences in basal affective behavior such that females displayed enhanced anxiety-like behavior in the splash test and males displayed enhanced anxiety-like behavior in the novelty-suppressed feeding test. Although, there were no sex differences in EtOH intake and no correlation between baseline anxiety-like behavior and subsequent EtOH intake, we did find that depressive-like behavior predicted future EtOH intake in female rats only. In addition, we observed an increase in depressive-like behavior is male rats in both the water and EtOH drinking groups (compared to baseline levels). Furthermore, post-drinking anxiety-like behavior, but not depressive-like behavior predicted subsequent EtOH intake in female rats. Lastly, we found a history of EtOH intake decreased pain thresholds in male and female rats, but increased anxiety-like and depressive-like behavior was associated with decreased thermal sensitivity only in EtOH-drinking males. Together, these experiments provide important information on the complex interaction between negative affect and EtOH intake and how these two contexts reciprocally do, or do not, influence each other in a sex-specific manner.

Sex differences in behavioral, cognitive and voluntary ethanol-intake effects in Dexamethasone-induced depression-like state in Wistar rat

The stress response is attached to psychosomatic and psychiatric disorders. Therefore, it is important to comprehend the underlying mechanisms influencing this relationship. Moreover, men and women respond differently to stress–both psychologically and biologically. These differences should be studied to have an enhanced understanding of the gender difference. However, researches shedding light on sex dimorphism implication have historically been insufficient. Based on observations that advocate the inclusion of sex as a biological variable in stress response, the present study was designed to explore sex differences in (i) depressive-like, (ii) anxiety-like behaviors, (iii) cognitive-like performances, and (iv) voluntary ethanol intake (VEI) in Wistar rat submitted to dexamethasone (DEX)-stress simulation. Rats were administered daily with DEX (1.5 mg/kg, s.c., 21 days) or vehicle. Behavior, cognitive, and VEI states of rats were evaluated in the following paradigms: forced swimming test (FST); saccharin preference test (SPT); open field test (OFT); elevated plus-maze test (EPMT); novelty suppressed feeding test (NSFT); spatial learning and memory in Morris water maze test (MWMT); VEI in two-bottle choice paradigm. DEX-treated rats showed a set of depression-like behaviors: increased time of immobility; reduced preference for saccharin consumption; increased anxiety-like behavior; cognitive impairments; and enhanced VEI. Sexual dimorphism was recorded in this study. Females were more impaired in FST, SPT, EPMT, NSFT, and VEI. Results demonstrate that DEX-treatment induced a behavioral alterations related to anxiety-depressive-like state with learning and memory impairments; confirm the facilitatory role of glucocorticoids on VEI and reveal sexual dimorphism in stress response.

&amp;lt;i&amp;gt;Khaya grandifololia&amp;lt;/i&amp;gt; Improves Cognition and Prevents Scopolamine-Induced Impairment of Brain Functions by Activating the Cholinergic and Antioxidant Systems in Rats

Alzheimer’s disease (AD) is a multifactorial, progressive neurodegenerative disorder with dementia and persistent impairment of cognitive functions as the main clinical characteristics. Although signs of progress are being made in developing AD therapy, there is no effective drug capable of stopping and/or slowing down the progression of the disease. We have previously indicated in an in vitro setting of AD that <i>Khaya grandifololia</i> (KG) crude extract possesses antioxidant, anti-inflammatory, and neuroprotective activities. In the current work, we have evaluated the activity of KG hydroethanolic (KG-HE) extract in preventing cognitive impairment and promoting memory improvement in vivo. Results from behavioral tests indicated a significant improvement in memory performance and a delay in depression-like behavior upon treatment of rats with KG-HE extract (5, 25, and 50 mg/kg) or donepezil (1 mg/kg) as standard. Because scopolamine (1 mg/kg) impaired cognitive performance in the tail suspension test, Morris Water Maze test, and Novelty Suppressed Feeding Test, KG-HE extract (5, 25, and 50 mg/kg) or donepezil (1 mg/kg) treatment prevented scopolamine-induced performance impairment. Moreover, both KG-HE extract (5, 25, and 50 mg/kg) and donepezil (1 mg/kg) prevented the scopolamine-induced cognitive impairment by inhibiting the acetylcholinesterase activity. In addition, the brain parameters of stress oxidation (SOD, CAT, and GSH) reduced by scopolamine treatment were regulated by the administration of KG-HE extract or the standard drug donepezil. An increase in the MDA level and the phosphatase activity both in the serum and brain due to scopolamine treatment was restored by the administration of KG-HE extract or donepezil. Taken together, these results suggest that KG-HE extract improves cognition and relieves the scopolamine-induced cognitive impairment via activation of the cholinergic and anti-oxidation systems in rats.

Therapeutic effect of Thymoquinone on behavioural response to UCMS and neuroinflammation in hippocampus and amygdala in BALB/c mice model.

Major depressive disorder is the leading cause of disability worldwide. The corticolimbic system plays a critical role in the emotional and cognitive aspects of major depressive disorder. Owing to the unsatisfactory efficacy of conventional antidepressants, there is a need to explore novel therapies. The current study aimed to explore the antidepressant potential of thymoquinone, a natural compound with anti-inflammatory activity, and propose its underlying mechanism of action in the unpredictable chronic mild stress (UCMS) mouse model. Coat state, forced swim test, elevated plus maze test, novelty suppressed feeding test and social interaction test were performed to quantify the behavioural shift induced by UCMS and the effect of thymoquinone and fluoxetine treatment. In addition, messenger RNA (mRNA) expression levels of inflammatory cytokines (IL-1β, IL-6 and TNF-α) and BDNF and NeuN were analysed by a quantitative real-time polymerase chain reaction in the hippocampus and amygdala of experimental and control groups. UCMS significantly deteriorated coat state. Thymoquinone reinstated the resignation behaviour and latency to feed affected by UCMS. UCMS induced an increase in inflammatory cytokines (IL-1β, IL-6 and TNF-α) in the hippocampus and amygdala, which was decreased by thymoquinone. UCMS caused an increase in BDNF and NeuN mRNA levels in the amygdala while a decrease in the hippocampus. This opposite effect on BDNF was also compensated by thymoquinone; however, thymoquinone did not significantly change Ki67 and NeuN mRNA levels in the hippocampus. Thymoquinone restored the behavioural changes induced by UCMS. In addition, the antidepressant effect of thymoquinone is in line with changes in inflammatory parameters and changes in BDNF in the hippocampus and amygdala.

Exposure to single prolonged stress fails to induce anxiety-like behavior in mice

Single prolonged stress (SPS) is a well-established and most frequently used rat model to induce post-traumatic stress disorder (PTSD)-like symptoms, which helps to understand the neurobiological mechanisms as well as developing novel therapeutic strategies for PTSD. However, whether such stress model works efficiently in mice remains unknown. In the present study, we established a mouse SPS (mSPS) model by exposing C57BL/6J mice to a series of multimodal stressors on a single day, then the anxiety-like behavior was measured by open-field test, elevated plus maze test, dark-light box, and novelty-suppressed feeding test. Our results showed that mSPS had no significant effect on the anxiety-like behavior in mice after different days of recovery. The expression of the glucocorticoid receptor and brain-derived neurotrophic factor (BDNF), two proteins that highly associated with stress-related behaviors, also remained unaltered in both the amygdala and hippocampus. By contrast, the protein levels of NR2A and NR2B, two main subunits of the <i>N</i>-methyl-D-aspartate receptor (NMDAR), was reduced in the hippocampus, but not amygdala. In conclusion, our results indicate that mSPS may not be an efficient mouse model to explore the pathophysiology of PTSD-related anxiety-like behavior.