Dysfunction of calcium/calmodulin/CaM kinase IIα cascades in the medial prefrontal cortex in post-traumatic stress disorder

Medicinal cannabis oil improves anxiety-like and depressive-like behaviors in CCS mice via the BDNF/TRPC6 signaling pathway

BACKGROUND

Post-traumatic stress disorder (PTSD) refers to a chronic impairing psychiatric disorder occurring after exposure to the severe traumatic event. Studies have demonstrated that medicinal cannabis oil plays an important role in neuroprotection, but the mechanism by which it exerts anti-PTSD effects remains unclear.

METHODS

The chronic complex stress (CCS) simulating the conditions of long voyage stress for 4 weeks was used to establish the PTSD mice model. After that, behavioral tests were used to evaluate PTSD-like behaviors in mice. Mouse brain tissue index was detected and hematoxylin-eosin staining was used to assess pathological changes in the hippocampus. The indicators of cell apoptosis and the BDNF/TRPC6 signaling activation in the mice hippocampus were detected by western blotting or real-time quantitative reverse transcription PCR experiments.

RESULTS

We established the PTSD mice model induced by CCS, which exhibited significant PTSD-like phenotypes, including increased anxiety-like and depression-like behaviors. Medicinal cannabis oil treatment significantly ameliorated PTSD-like behaviors and improved brain histomorphological abnormalities in CCS mice. Mechanistically, medicinal cannabis oil reduced CCS-induced cell apoptosis and enhanced the activation of BDNF/TRPC6 signaling pathway.

CONCLUSIONS

We constructed a PTSD model with CCS and medicinal cannabis oil that significantly improved anxiety-like and depressive-like behaviors in CCS mice, which may play an anti-PTSD role by stimulating the BDNF/TRPC6 signaling pathway.

Posttraumatic stress disorder is characterized by functional dysregulation of dermal fibroblasts

Incidence of mental health disorders are rising in modernity, with psychological stress linked to a propensity for developing various chronic diseases due to a relative inability of the body to counter the allostatic load on cellular level. Despite these high rates of comorbidities associated with posttraumatic stress disorder (PTSD), there is still a lack of understanding in terms of the peripheral effects of PTSD on tissue level. Therefore, the purpose of this study was to profile basal dermal fibroblast functional status in PTSD using a wide range of markers involved in the cell-to-cell communication facilitated by fibroblasts. Primary dermal fibroblasts derived from patients diagnosed with PTSD (n = 11) and matched trauma exposed controls (i.e. who did not develop PTSD, n = 10) were cultured using standard techniques. The patients and controls were matched based on age, sex, body-mass index (BMI) and lifestyle. The growth rate, population doubling time, cell surface marker expression (CD31, FNDC5) (flow cytometry), secretome (TIMP-2, MMP-9) (ELISAs), intracellular signalling capacity (Fluo-4 Ca2+ flux) and gene expression (IL-6, IL-10, PTX-3, iNOS, Arg1) were compared between groups. The data illustrated significant PTSD-associated fibroblast conditioning resulting in a blunted signalling capacity. This observation highlights the importance of including tissue-specific investigations in future studies focused on elucidating the association between PTSD and subsequent risk for somatic disease.

Stress-related cellular pathophysiology as a crosstalk risk factor for neurocognitive and psychiatric disorders

In this narrative review, we examine biological processes linking psychological stress and cognition, with a focus on how psychological stress can activate multiple neurobiological mechanisms that drive cognitive decline and behavioral change. First, we describe the general neurobiology of the stress response to define neurocognitive stress reactivity. Second, we review aspects of epigenetic regulation, synaptic transmission, sex hormones, photoperiodic plasticity, and psychoneuroimmunological processes that can contribute to cognitive decline and neuropsychiatric conditions. Third, we explain mechanistic processes linking the stress response and neuropathology. Fourth, we discuss molecular nuances such as an interplay between kinases and proteins, as well as differential role of sex hormones, that can increase vulnerability to cognitive and emotional dysregulation following stress. Finally, we explicate several testable hypotheses for stress, neurocognitive, and neuropsychiatric research. Together, this work highlights how stress processes alter neurophysiology on multiple levels to increase individuals' risk for neurocognitive and psychiatric disorders, and points toward novel therapeutic targets for mitigating these effects. The resulting models can thus advance dementia and mental health research, and translational neuroscience, with an eye toward clinical application in cognitive and behavioral neurology, and psychiatry.

Time-course analysis of frontal gene expression profiles in the rat model of posttraumatic stress disorder and a comparison with the conditioned fear model

Posttraumatic stress disorder (PTSD) is a complex disorder that involves physiological, emotional, and cognitive dysregulation that may occur after exposure to a life-threatening event. In contrast with the condition of learned fear with resilience to extinction, abnormal fear with impaired fear extinction and exaggeration are considered crucial factors for the pathological development of PTSD. The prefrontal cortex (mPFC) is considered a critical region of top-down control in fear regulation, which involves the modulation of fear expression and extinction. The pathological course of PTSD is usually chronic and persistent; a number of studies have indicated temporal progression in gene expression and phenotypes may be involved in PTSD pathology. In the current study, we use a well-established modified single-prolonged stress (SPS&FS) rat model to feature PTSD-like phenotypes and compared it with a footshock fear conditioning model (FS model); we collected the frontal tissue after extreme stress exposure or fear conditioning and extracted RNA for transcriptome-level gene sequencing. We compared the genetic profiling of the mPFC at early (<2 h after solely FS or SPS&FS exposure) and late (7 days after solely FS or SPS&FS exposure) stages in these two models. First, we identified temporal differences in the expressional patterns between these two models and found pathways such as protein synthesis factor eukaryotic initiation factor 2 (EIF2), transcription factor NF-E2-related factor 2 (NRF2)-mediated oxidative stress response, and acute phase responding signaling enriched in the early stage in both models with significant p-values. Furthermore, in the late stage, the sirtuin signaling pathway was enriched in both models; other pathways such as STAT3, cAMP, lipid metabolism, Gα signaling, and increased fear were especially enriched in the late stage of the SPS&FS model. However, pathways such as VDR/RXR, GP6, and PPAR signaling were activated significantly in the FS model's late stage. Last, the network analysis revealed the temporal dynamics of psychological disorder, the endocrine system, and also genes related to increased fear in the two models. This study could help elucidate the genetic temporal alteration and stage-specific pathways in these two models, as well as a better understanding of the transcriptome-level differences between them.

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.

The effects of orexin-A and orexin receptors on anxiety- and depression-related behaviors in a male rat model of post-traumatic stress disorder

Orexin neurons play an important role in stress-related mental disorders including post-traumatic stress disorder (PTSD). Anxiety- and depression-related symptoms commonly occur in combination with PTSD. However, the role of the orexin system in mediating alterations in these affective symptoms remains unclear. The medial prefrontal cortex (mPFC) is implicated in both cognitive and emotional processing. In the present study, we investigated anxiety- and depression-related behavioral changes using the elevated plus maze, the sucrose preference test, and the open field test in male rats with single prolonged stress (SPS) induced-PTSD. The expression of orexin-A in the hypothalamus and orexin receptors (OX1R and OX2R) in the mPFC was detected and quantified by immunohistochemistry, western blotting, and real-time polymerase chain reaction. We found that the SPS rats exhibited enhanced levels of anxiety, reduced exploratory activities, and anhedonia. Furthermore, SPS resulted in reductions in the expression of orexin-A in the hypothalamus and the increased the expression of OX1R in the mPFC. The intracerebroventricular administration of orexin-A alleviated behavioral changes in SPS rats and partly restored the increased levels of OX1R in the mPFC. These results suggest that the orexin system plays a role in the anxiety- and depression-related symptoms observed in PTSD.

Sex-divergent long-term effects of single prolonged stress in adult rats

Single prolonged stress (SPS) is an experimental model that recapitulates in rodents some of the core symptoms of post-traumatic stress disorder (PTSD). Although women have a two-fold greater risk to develop PTSD, most preclinical studies have been carried out in males. Furthermore, the long-term effects of behavioral alterations induced by SPS have been rarely investigated. Here, we evaluated the long-term effects of SPS on PTSD-relevant behavioral domains in rats and whether these effects were sex-dependent. To this aim, separate cohorts of male and female adult rats were subjected to SPS and, 30 days later, long-term effects were assessed. We found that SPS exposure reduced locomotor activity in both sexes in an open field task. Males only showed increased anxiety-like behavior in the elevated plus maze and marble burying tests, enhanced acoustic startle response and impaired spatial memory retention while females were unaffected. SPS exposure did not alter auditory fear memory dynamics in males, but it did alter extinction retrieval in females. We provide the first evidence that SPS reproduces long-term emotional alterations in male, but not in female, rats which were observed 30 days following trauma exposure, thus resembling some of the hallmark symptoms of PTSD. Furthermore, our results show for the first time a long-term SPS-induced alteration of cued fear extinction in females. Our findings are relevant to future research on trauma-related disorders and may help develop sex-specific interventions to treat PTSD.

The PPM1F gene moderates the association between PTSD and cortical thickness

BACKGROUND

Evidence suggests that single nucleotide polymorphisms (SNPs) in genes involved in serotonergic signaling and stress response pathways moderate associations between PTSD and cortical thickness. This study examined a genetic regulator of these pathways, the PPM1F gene, which has also been implicated in mechanisms of stress responding and is differentially expressed in individuals with comorbid PTSD and depression compared to controls.

METHODS

Drawing from a sample of 240 white non-Hispanic trauma-exposed veterans, we tested 18 SNPs spanning the PPM1F gene for association with PTSD and cortical thickness.

RESULTS

Analyses revealed six PPM1F SNPs that moderated associations between PTSD symptom severity and cortical thickness of bilateral superior frontal and orbitofrontal regions as well as the right pars triangularis (all corrected p's < 0.05) such that greater PTSD severity was related to reduced cortical thickness as a function of genotype. A whole-cortex vertex-wise analysis using the most associated SNP (rs9610608) revealed this effect to be localized to a cluster in the right superior frontal gyrus (cluster-corrected p < 0.02).

LIMITATIONS

Limitations of this study include the small sample size and that the sample was all-white, non-Hispanic predominately male veterans.

CONCLUSIONS

These results extend prior work linking PPM1F to PTSD and suggest that variants in this gene may have bearing on the neural integrity of the prefrontal cortex (PFC).

Adolescent Nicotine Exposure Induces Dysregulation of Mesocorticolimbic Activity States and Depressive and Anxiety-like Prefrontal Cortical Molecular Phenotypes Persisting into Adulthood

Considerable evidence demonstrates strong comorbidity between nicotine dependence and mood and anxiety disorders. Nevertheless, the neurobiological mechanisms linking adolescent nicotine exposure to mood and anxiety disorders are not known. Disturbances in the mesocorticolimbic dopamine (DA) system, comprising the prefrontal cortex (PFC), ventral tegmental area (VTA), and nucleus accumbens (NAc), are correlates of mood and anxiety-related symptoms and this circuitry is strongly influenced by acute or chronic nicotine exposure. Using a combination of behavioral pharmacology, in vivo neuronal electrophysiology and molecular analyses, we examined and compared the effects of chronic nicotine exposure in rats during adolescence versus adulthood to characterize the mechanisms by which adolescent nicotine may selectively confer increased risk of developing mood and anxiety-related symptoms in later life. We report that exposure to nicotine, selectively during adolescence, induces profound and long-lasting neuronal, molecular and behavioral disturbances involving PFC DA D1R and downstream extracellular-signal-related kinase 1-2 (ERK 1-2) signaling. Remarkably, adolescent nicotine induced a persistent state of hyperactive DA activity in the ventral tegmental area (VTA) concomitant with hyperactive neuronal activity states in the PFC. Our findings identify several unique neuronal and molecular biomarkers that may serve as functional risk mechanisms for the long-lasting neuropsychiatric effects of adolescent smoking behaviors.

PERK signalling pathway mediates single prolonged stress-induced dysfunction of medial prefrontal cortex neurons

Post-traumatic stress disorder (PTSD) is characterized with abnormal learning and memory. Impairments in learning and memory are closely associated with apoptosis in the medial prefrontal cortex (mPFC). We previously examined the endoplasmic reticulum (ER) stress was involved in the apoptosis in the mPFC of PTSD. The PERK pathway plays the important role in the ER stress-induced apoptosis. The aim of the present study was to explore the role of PERK pathway in neuronal apoptosis in the mPFC of rat models of PTSD. We used the single prolonged stress (SPS) to mimic PTSD in rats and studied the effects of the PERK pathway in mPFC. Learning and memory behavior were examined by Morris water maze and novel object recognition tests. Apoptosis in mPFC was detected by TUNEL staining. Our results showed decreased learning memory and increased apoptosis of mPFC neurons in rats exposed to SPS. SPS exposure upregulate mRNA expressions of PERK, p-PERK, eIF2α, p-eIF2α, nuclear ATF4 and C/EBP-homologous protein (CHOP) in mPFC neurons, but the protein levels of these molecules showed difference in magnitude and time course. GSK2606414 (an antagonist of PERK) treatment successfully reversed the above changes. These results suggested that the PERK pathway mediated SPS-induced neural apoptosis in the mPFC. These findings will be helpful in understanding mPFC-related pathogenesis of PTSD.

Effects of calcium-dependent molecular chaperones and endoplasmic reticulum in the amygdala in rats under single‑prolonged stress

The purpose of the present study was to investigate the role of endoplasmic reticulum (ER)‑resident molecular chaperone proteins to identify whether these proteins were involved in post‑traumatic stress disorder (PTSD). The present study detected changes of calreticulin (CRT), calnexin (CNX) and ERp57 in the amygdala of rats, which may with aim of providing a novel insight into the modulation effect of amygdala in PTSD. Single‑prolonged stress (SPS) was applied to create the models of PTSD in rats. The expression levels of CRT, CNX and ERp57 were examined using immunohistochemistry or immunofluorescence, western blot analysis and reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). The results showed that SPS induced significant changes in CRT, CNX and ERp57 expression levels. Furthermore, the expression levels of CRT, CNX and ERp57 were significantly upregulated when compared to that in the control group after SPS exposure by western blot analysis (P<0.05). RT‑qPCR analysis supported these results, indicating an upregulation of mRNA expression level. Taken together, the present findings suggest that SPS may induce changes to the expression of CRT, CNX and ERp57 in the amygdala of rats. The present study provides an insight into the effects of ER‑resident molecular chaperones in the amygdala participating in PTSD, and provides the experimental basis and a mechanism for the pathophysiology of PTSD.

Using the Single Prolonged Stress Model to Examine the Pathophysiology of PTSD

The endurance of memories of emotionally arousing events serves the adaptive role of minimizing future exposure to danger and reinforcing rewarding behaviors. However, following a traumatic event, a subset of individuals suffers from persistent pathological symptoms such as those seen in posttraumatic stress disorder (PTSD). Despite the availability of pharmacological treatments and evidence-based cognitive behavioral therapy, a considerable number of PTSD patients do not respond to the treatment, or show partial remission and relapse of the symptoms. In controlled laboratory studies, PTSD patients show deficient ability to extinguish conditioned fear. Failure to extinguish learned fear could be responsible for the persistence of PTSD symptoms such as elevated anxiety, arousal, and avoidance. It may also explain the high non-response and dropout rates seen during treatment. Animal models are useful for understanding the pathophysiology of the disorder and the development of new treatments. This review examines studies in a rodent model of PTSD with the goal of identifying behavioral and physiological factors that predispose individuals to PTSD symptoms. Single prolonged stress (SPS) is a frequently used rat model of PTSD that involves exposure to several successive stressors. SPS rats show PTSD-like symptoms, including impaired extinction of conditioned fear. Since its development by the Liberzon lab in 1997, the SPS model has been referred to by more than 200 published papers. Here we consider the findings of these studies and unresolved questions that may be investigated using the model.

Molecular Mechanisms of IRE1α-ASK1 Pathway Reactions to Unfolded Protein Response in DRN Neurons of Post-Traumatic Stress Disorder Rats

The goal of this study was to further elucidate the molecular mechanisms of post-traumatic stress disorder (PTSD) pathogenesis and to provide experimental evidence for new drug targets for effective PTSD treatment. Expression changes of IRE1α, ASK1, and other downstream molecules of the IRE1α-ASK1 endoplasmic reticulum stress (ERS) signaling pathway were investigated. JNK, P38, CHOP, Bcl-2, and Bax were analyzed at both protein and mRNA levels of dorsal raphe nucleus (DRN) neurons of PTSD rats. The rat PTSD model was established via the single-prolonged stress (SPS) method. Animals were randomly divided into five groups: a normal control group, a 1-day SPS group, a 4-days SPS group, a 7-day SPS group, and a 14-day SPS group. Spatial memory and learning ability of rats were evaluated subsequent to SPS using the Morris water maze test. Changes of IRE1α expression in the control and SPS groups were detected via immunohistochemistry (IHC). Protein and mRNA expressions of IRE1α, ASK1, JNK, P38, CHOP, Bcl-2, and Bax in the control and SPS groups were detected via Western blot and RT-PCR, respectively. The Morris water maze test revealed significantly longer average escape latencies in all SPS groups compared to the control group. In the spatial probe test, the percentage of time spent in the target quadrant was significantly lower in the SPS groups compared to control. IHC revealed increased positive expression of IRE1α subsequent to SPS challenge, reaching maximal levels on days four and seven (P < 0.01), while significantly decreasing on day 14 (P < 0.01). Western blot and RT-PCR revealed that protein and mRNA expressions of IRE1α, ASK1, JNK, CHOP, and P38 were significantly increased compared to control, peaking on days one, four, and seven post-SPS before returning to previous levels. Compared to control, expressions of Bcl-2 and Bax presented an initial increasing tendency followed by a decrease. A peak of Bcl-2 expression appeared early on day one following SPS, then decreased to a steady level. Bax expression in the SPS groups remained constant during early stages after SPS (days one to three) compared to control; however, expression significantly increased on day four and maintained a high level. In summary, 1) SPS challenge significantly activated the IRE1α-ASK1-JNK and IRE1α-ASK1-P38 apoptosis-signaling pathways in DRN neurons of PTSD rats. This resulted in a cascade of downstream reactions and ultimately apoptosis of DRN neurons. 2) Increased expression of apoptosis-associated molecules Bcl-2 and Bax in DRN neurons following SPS challenge was revealed as a central mechanism, inducing apoptosis of DRN neurons in PTSD rats.

HIV-1 Transgenic Rat Prefrontal Cortex Hyper-Excitability is Enhanced by Cocaine Self-Administration

The medial prefrontal cortex (mPFC) is dysregulated in HIV-1-infected humans and the dysregulation is enhanced by cocaine abuse. Understanding mPFC pathophysiology in this comorbid state has been hampered by the dearth of relevant animal models. To help fill this knowledge gap, electrophysiological assessments were made of mPFC pyramidal neurons (PN) from adult male HIV-1 transgenic (Tg) F344 rats (which express seven of the nine HIV-1 toxic proteins) and non-Tg F344 rats that self-administered cocaine for 14 days (COC-SA), as well as saline-yoked controls (SAL-Yoked) and experimentally naive Tg and non-Tg rats. Forebrain slices were harvested and prepared for whole-cell patch-clamp recording, and in treated rats, this occurred after 14-18 days of forced abstinence. Aged-matched rats were used for immunohistochemical detection of the L-channel protein, Cav1.2-α1c. We determined that: (i) the two genotypes acquired the operant task and maintained similar levels of COC-SA, (ii) forced abstinence from COC-SA enhanced mPFC PN excitability in both genotypes, and neurons from Tg rats exhibited the greatest pathophysiology, (iii) neurons from SAL-Yoked Tg rats were more excitable than those from SAL-Yoked non-Tg rats, and in Tg rats (iv) blockade of L-type Ca(2+) channels reduced the enhanced excitability, and (v) Cav1.2-immunoreactivity was increased. These findings provide the first assessment of the mPFC pathophysiology in a rodent model of HIV-1-mediated neuropathology with and without cocaine self-administration. Outcomes reveal an enhanced cortical excitability during chronic exposure to HIV-1 proteins that is excessively exacerbated with cocaine abuse. Such neuropathophysiology may underlie the cognitive dysregulation reported for comorbid humans.

Elevated plasma CaM expression in patients with acute cerebral infarction predicts poor outcomes and is inversely associated with miR-26b expression

BACKGROUND

Calcium overload plays an important role in ischemia/reperfusion injury during ischemic brain damage and is mediated by calmodulin (CaM). However, the understanding of the regulatory mechanisms of CaM expression at the gene level is limited. The expression levels of miR-26b change significantly during ACI, and bioinformatic analyses predict that miR-26b would be a potential regulator of calmodulin (CALM1) mRNA. This study aimed to determine the expression of miR-26b and CaM in the plasma of patients with ACI and investigate the impact of miR-26b on CALM1 expression.

METHODS

CaM and miR-26b expression analyses from the plasma of patients with ACI and normal controls were performed using ELISA and qRT-PCR, respectively. Correlations between CaM, miR-26b, and NIHSS scores were analyzed. Then, miR-26b mimics and inhibitors were transfected into HUVE cell lines via lipofectamine. CALM1 mRNA expression in HUVECs was detected by RT-PCR, and the protein levels were detected by Western blot.

RESULTS

Plasma CaM expression in patients with ACI was significantly higher when compared with normal controls, and miR-26b expression was significantly lower. The plasma levels of CaM and miR-26b were correlated with the NIHSS scores in ACI patients. miR-26b modulated CALM1 in vitro. The transfected miR-26b mimic and inhibitor significantly altered the expression of CALM1/CAM at the mRNA and protein levels in cultured HUVECs.

CONCLUSIONS

CaM might be a potential novel blood marker in patients with ACI. miR-26b targeted CALM1 and affected the expression of CaM at the post-transcriptional level, which likely contributed to the progression of ACI brain injury.

Changes in integrin αv, vinculin and connexin43 in the medial prefrontal cortex in rats under single-prolonged stress

Post‑traumatic stress disorder (PTSD) is a stress‑accociated mental disorder that occurs as a result of exposure to a traumatic event, with characteristic symptoms, including intrusive memories, hyperarousal and avoidance. The medial prefrontal cortex (mPFC) is known to be significantly involved in emotional adjustment, particularly introspection, inhibition of the amygdala and emotional memory. Previous structural neuroimaging studies have revealed that the mPFC of PTSD patients was significantly smaller when compared with that of controls and their emotional adjustment function was weakened. However, the mechanisms that cause such atrophy remain to be elucidated. The aim of the present study was to elucidate the possible mechanisms involved in apoptosis induced by single‑prolonged stress (SPS) in the mPFC of PTSD rats. SPS is an animal model reflective of PTSD. Of the proposed animal models of PTSD, SPS is one that has been shown to be reliably reproducible in patients with PTSD. Wistar rats were sacrificed at 1, 4, 7 and 14 days after exposure to SPS. Apoptotic cells were assessed using electron microscopy and the TUNEL method. Expression of integrin αv, vinculin and connexin43 were detected using immunohistochemistry, western blotting and reverse transcription polymerase chain reaction. The present results demonstrated that apoptotic cells significantly increased in the mPFC of SPS rats, accompanied with changes in expression of integrin αv, vinculin and connexin43. The present results indicated that SPS‑induced apoptosis in the mPFC of PTSD rats and the mitochondrial pathway were involved in the process of SPS‑induced apoptosis.

Changes in the glucocorticoid receptor and Ca²⁺/calreticulin-dependent signalling pathway in the medial prefrontal cortex of rats with post-traumatic stress disorder

The glucocorticoid receptor (GR), calreticulin (CRT) and protein kinase C (PKC) have all been implicated in the Ca(2+)-dependent signalling pathway, which plays an important role in the plasticity of the central nervous system, learning and memory. The medial prefrontal cortex (mPFC) is known to be involved in mechanisms of learning and memory. In the present study, single prolonged stress (SPS) was used as an animal model of post-traumatic stress disorder (PTSD). The Morris water maze test was used to detect rats' ability for spatial memory and learning. A fluorescence spectrophotometer was used to measure the concentration of intracellular Ca(2+) in mPFC. Immunohistochemistry, immunofluorescence, western blot and reverse transcription polymerase chain reaction were used to explore changes in GR, CRT and PKC in mPFC of SPS rats. The concentration of Ca(2+) in mPFC was increased in the SPS rats. We found increased intensity of GR and CRT immunoreactivity and increased messenger RNA (mRNA) levels of GR, CRT and PKC in mPFC of the SPS groups, although the degree and time of increase was different among them. The protein levels of cytoplasmic GR, cytoplasmic CRT and cytoplasmic pPKC increased in mPFC of the SPS groups, whereas the protein level of nuclear GR decreased in comparison with the control group. As a conclusion, changed CRT and GR/PKC were involved in the mechanism of SPS-induced dysfunctional mPFC.

Single Prolonged Stress induces ATF6 alpha-dependent Endoplasmic reticulum stress and the apoptotic process in medial Frontal Cortex neurons

BACKGROUND

In our previous researches, we have found that apoptosis was induced in the medial prefrontal cortex (mPFC) of post-traumatic stress disorder (PTSD) rats. Endoplasmic reticulum (ER) stress-induced apoptosis has been implicated in the development of several disorder diseases. The aim of this study was to investigate whether endoplasmic reticulum-related pathway is involved in single-prolonged stress (SPS) induced apoptosis in the mPFC of PTSD rats by examining the expression levels of ATF6 alpha (ATF6α), two important downstream molecular chaperones of ATF6α in the ER stress: Glucose-regulated protein (GRP) 78 and ERP57, and apoptotic factors caspase 12, caspase 9, and caspase 3.

RESULTS

Our results of Morris Water Maze (MWM) test showed that after SPS exposure, a striking increase of the escape latency was observed in SPS rats at day 1 through day 6, and SPS rats had much less time spent in target quadrant compared to control rats ( P < 0.01). And From immunofluorescence assays, we found that there was a gradual increase on the protein expression of ATF6α in response to SPS, which indicated ATF6α was activated by SPS. And additionally, immunohistochemistry assays, western blotting and reverse transcription-polymerase chain reaction (RT-PCR) showed that the immunoreactivity, protein and mRNA expression of GRP78 and ERP57 increased on 1, 4 days, and peaked on 7 days after SPS exposure, which revealed that SPS triggered inductions of GRP78 and ERP57 in the mPFC neurons. Moreover, RT-PCR assays demonstrated that there were up-regulations in the transcripts levels of caspase 12, caspase 9, and caspase 3 in response to SPS, which were according with the proteins changes of these apoptotic factors and indicated that ER stress and the activation of caspases contributed to SPS.

CONCLUSION

Current data in this study highlight that SPS induced ATF6α-dependent Endoplasmic reticulum stress and ER-related apoptosis in the mPFC neurons, which indicated that the endoplasmic reticulum pathway may be involved in PTSD-induced apoptosis.

Emerging role of CaMKII in neuropsychiatric disease

Although it has been known for decades that hippocampal calcium/calmodulin (CaM)-dependent protein kinase II (CaMKII) plays an essential role in learning and memory consolidation, the roles of CaMKII in other brain regions are only recently being explored in depth. A series of recent studies suggest that CaMKII dysfunction throughout the brain may underlie myriad neuropsychiatric disorders, including drug addiction, schizophrenia, depression, epilepsy, and multiple neurodevelopmental disorders, perhaps through maladaptations in glutamate signaling and neuroplasticity. I review here the structure, function, subcellular localization, and expression patterns of CaMKII isoforms, as well as recent advances demonstrating that disturbances in these properties may contribute to psychiatric disorders.

Effect of glucose-regulated protein 94 and endoplasmic reticulum modulator caspase-12 in medial prefrontal cortex in a rat model of posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is an anxiety disorder caused by a life-threatening traumatic experience, which affects a patient's quality of life and social stability. The objective of this study was to investigate the change of the glucose-regulated protein (GRP) 94 and apoptosis-related caspase-12 expression in medial prefrontal cortex (mPFC) in rats to determine whether endoplasmic reticulum apoptosis pathway plays an important role in single-prolonged stress (SPS), a well-established PTSD animal model, and therefore to provide experimental evidence to reveal PTSD pathogenesis. A total of 120 healthy male Wistar rats were selected for this study, randomly divided into a normal control group and SPS groups of 1, 4, 7, 14, and 28 days. Behavioral studies of the learning and memory capabilities of rats were observed by using Morris water maze. Morphological changes were detected using transmission electron microscopy (TEM). Immunohistochemistry, Western blot, and reverse transcription polymerase chain reaction (RT-PCR) were used to detect the expressions of caspase-12 and GRP94 expressions in mPFC. Our results showed that compared with control groups, after the SPS exposure, the average escape latency was prolonged in place navigation test (P < 0.05), and swimming time in the third quadrant in spatial probe test shortened. The morphological change of mPFC in each SPS group bears typical apoptotic characteristics. The expressions of GRP94 and caspase-12 gradually increased on 1 and 4 days, peaked on 7 days after the SPS exposure, and then decreased. These results suggest that SPS exposure can induce apoptotic neurons and a change of caspase-12 and GRP94 expression in the mPFC, which may be one of the pathogenesis of mPFC abnormal function in PTSD.

Increased neuronal apoptosis in medial prefrontal cortex is accompanied with changes of Bcl-2 and Bax in a rat model of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is an anxiety disorder caused by traumatic experience, which affects a patient's quality of life and social stability. The objective of this study was to determine the apoptosis-related genes B-cell lymphoma 2 (Bcl-2) and BCL2-associated X (Bax) expressions and medial prefrontal cortex (mPFC) neuronal apoptosis after PTSD in rat model and therefore to provide experimental evidence to reveal PTSD pathogenesis. The single-prolonged stress (SPS) method was used to set up the rat PTSD models. Chemiluminescence was used to determine serum corticosterone levels. Neuronal apoptosis was detected using transmission electron microscopy, Hoechst staining, and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Immunohistochemistry, immunofluorescence, RT-PCR, and Western blot were used to detect the expressions of Bcl-2 and Bax protein in mPFC. Our results showed an increased mPFC neuronal apoptosis after SPS stimulation. The number of apoptotic cells peaked on day 7. The expressions of Bcl-2 and Bax peaked on days 4 and 7. The Bcl-2/Bax ratio elevated on days 1 and 4 but decreased markedly on day 7. These results indicated that SPS stimulation increased the number of apoptotic neurons, up-regulated the expressions of Bcl-2 and Bax, and altered the Bcl-2/Bax ratio in the mPFC of PTSD rats.