cAMP Response Element-binding Protein Levels Research Articles

Activation of CREB-BDNF Pathway in Pyramidal Neurons in the Hippocampus Improves the Neurological Outcome of Mice with Ischemic Stroke.

Cerebral ischemia is characterized by several pathological reaction evolving over time. Hyperactivation of glutamatergic neurons is the main factor leading to excitotoxicity which potentiates oxidative stress and triggers the mechanisms of neural apoptosis after cerebral ischemia. However, it is unclear whether glutamate in the ventral hippocampal Cornus Ammonis 1 (vCA1) acts a part in neurological deficits, pain perception, anxiety, and depression induced by ischemic stroke. We investigated the effects of chemogenetic inhibition or activation of vCA1 pyramidal neurons which are mainly glutamatergic neurons on sequelae induced by cerebral ischemia. Our results revealed that inhibition of vCA1 pyramidal neurons by chemogenetics alleviated neurological deficits, pain perception, anxiety, and depression caused by cerebral ischemia in mice, but activation of vCA1 pyramidal neurons had limited effects. Moreover, we found that stroke was accompanied by decreased levels of cAMP-response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in vCA1, which are modulated by glutamate. In this study, overexpression of CREB protein in pyramidal neurons in vCA1 by AAV virus significantly upregulated the content of BDNF and ameliorated the dysfunction induced by ischemic stroke. Our results demonstrated activation of the CREB-BDNF pathway in vCA1 pyramidal neurons significantly improved neurological deficits, pain perception, anxiety, and depression induced by ischemic stroke.

The effect of electroacupuncture on regulating pain and depression-like behaviors induced by chronic neuropathic pain.

Recently, the role of electroacupuncture (EA) in chronic neuropathic pain has been widely reported. However, its specific mechanisms and ability to mitigate depression-like behaviors induced by chronic pain remains unclear. This study aims to determine the analgesic and antidepressant effect of EA. The mechanical threshold sensory and hot plate tests were employed to measure mechanical hyperalgesia and thermal allodynia. The open filed test (OFT) and tail suspension test (TST) were used to observe depressive behavior in chronic constrictive injury (CCI) mice. In addition, the 5-hydroxytryptamine (5-HT) and brain-derived neuropathic factor (BDNF) levels in the anterior cingulate cortex (ACC) and spinal cord were assessed using enzyme-linked immunosorbent assay (ELISA). The protein levels of cAMP-response element-binding protein (CREB) and BDNF in the ACC were analyzed by western blotting. Our results demonstrated that EA treatment could increase the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) values. Also, EA improved the CCI-induced depression-like behaviors, and significantly reversed the down-regulation of BDNF and 5-HT expression in the ACC and spinal cord after CCI. Furthermore, EA regulated the level of CREB in the ACCs and spinal cords of mice. These results suggested that the analgesic and antidepressant effect of EA is achieved through regulating CREB-5-HT/BDNF signaling pathway in the ACCs and spinal cords of mice.

Layer-by-layer self-assembly polyelectrolytes loaded with cyclic adenosine monophosphate enhances the osteo/odontogenic differentiation of stem cells from apical papilla.

Cyclic adenosine monophosphate (cAMP) is a second messenger involved in the dental regeneration. However, efficient long-lasting delivery of cAMP that is sufficient to mimic the in vivo microenvironment remains a major challenge. Here, cAMP was loaded in stem cells from apical papilla (SCAPs) using layer-by-layer self-assembly with gelatin and alginate polyelectrolytes (LBL-cAMP-SCAPs). LBL-cAMP-SCAPs expressed cAMP and increased the phosphorylation level of cAMP-response element-binding protein (CREB) which were evaluated by immunofluorescence and western blotting (WB). Enzyme-linked immunosorbent assay (ELISA) demonstrated that a sustained release of cAMP and vascular endothelial growth factor (VEGF) were present up to 14 days. Scanning electron microscopy (SEM) found LBL-coated SCAPs exhibited a spheroid-like morphology. CCK8 and live/dead staining showed that LBL treatment had no significant effect on cell proliferation and viability. LBL-cAMP-SCAPs enhanced mineralized nodule formation and up-regulated the mRNA levels of the osteogenesis-related genes, as well as related transcription factor-2 protein level which were revealed by Alizarin red staining, RT-PCR and WB, respectively. In conclusion, LBL self-assembly loaded with cAMP promoted the osteo/odontogenic differentiation of SCAPs, thereby providing a potential strategy for bioactive molecular delivery in dental regeneration.

Fat-1 expression enhance hippocampal memory in scopolamine-induced amnesia

Omega-3 polyunsaturated fatty acids (PUFA) are critical for optimal brain health and are involved in psychiatric and neurological ailments. Here, we report the effects of higher endogenous omega-3 PUFA on memory impairment in the hippocampus by studying mice with transgenic expression of the fat-1 gene that converts omega-6 to omega-3 PUFA. We performed Y-maze and passive avoidance tests to evaluate the memory function of fat-1 mice treated with scopolamine. Fat-1 mice showed induced alternation in the Y-maze test and increased latency in the passive avoidance test. The effects of scopolamine on hippocampal neurogenesis were confirmed by increases in the number of Ki-67- and DCX-positive cells in the fat-1 mice. Western blotting revealed increased brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP response element-binding protein levels, and lower scopolamine-induced apoptosis based on the cleaved-caspase 3 protein level in fat-1 mice. These findings suggest that higher endogenous omega-3 PUFA prevented granular cell loss, increased BDNF signaling, and decreased apoptosis signaling in scopolamine-treated fat-1 mice. These processes may underlie granular cell survival and suggest potential therapeutic targets for memory impairment.

Shikimic acid, a mannose bioisostere, promotes hair growth with the induction of anagen hair cycle

Shikimic acid (SA) has recently been found to be a major component of plant stem cells. The exact effects of SA on human hair follicles (HFs) is unknown. The purpose of this study was to examine the effects of SA on hair growth. We investigated the effect of SA on an in vivo C57BL/6 mouse model. We examined the expression of mannose receptor (MR), which is a known receptor of SA, in human HFs and the effect of SA on human dermal papilla cells (hDPCs), outer root sheath cells (hORSCs), and on ex vivo human hair organ culture. SA significantly prolonged anagen hair growth in the in vivo mouse model. We confirmed expression of the MR in human HFs, and that SA increased the proliferation of hDPCs and hORSCs. It was found that SA enhanced hair shaft elongation in an ex vivo human hair organ culture. SA treatment of hDPCs led to increased c-myc, hepatocyte growth factor, keratinocyte growth factor and vascular endothelial growth factor levels and upregulation of p38 MAPK and cAMP response element-binding protein levels. Our results show that SA promotes hair growth and may serve as a new therapeutic agent in the treatment of alopecia.

CRTC2 Is a Key Mediator of Amino Acid-Induced Milk Fat Synthesis in Mammary Epithelial Cells.

Amino acids can stimulate milk fat synthesis, but the underlying molecular mechanism is still largely unknown. In this study, we studied the regulatory role and corresponding molecular mechanism of cAMP response element-binding protein-regulated transcription coactivator 2 (CRTC2) in amino acid-induced milk fat synthesis in mammary epithelial cells. We showed that leucine and methionine stimulated CRTC2 but not p-CRTC2(Ser171) expression and nuclear localization in cow mammary epithelial cells. Knockdown of CRTC2 decreased milk fat synthesis and sterol regulatory element binding protein 1c (SREBP-1c) expression and activation, whereas its overexpression had the opposite effects. Neither knockdown nor overexpression of CRTC2 affected β-casein synthesis and phosphorylation of the machanistic target of rapamycin (mTOR), suggesting that CRTC2 only regulates milk fat synthesis. CRTC2 knockdown abolished the stimulation of leucine and methionine on SREBP-1c expression and activation. Knockdown or overexpression of CRTC2 did not affect the protein level of cAMP-response element-binding protein (CREB) and its phosphorylation but decreased or increased the binding of p-CREB to the promoter of SREBP-1c gene and its mRNA expression, respectively. Mutation of Ser171 of CRTC2 did not alter the stimulation of CRTC2 on SREBP-1c expression and activation, further suggesting that CRTC2 functions in the nucleus. mTOR inhibition by rapamycin totally blocked the stimulation of leucine and methionine on CRTC2 expression. The expression of CRTC2 was dramatically higher in the mouse mammary gland of lactation period, compared with that of the dry and puberty periods, whereas p-CRTC2(Ser171) was not changed, further supporting that CRTC2 is a key transcription coactivator for milk fat synthesis. These results uncover that CRTC2 is a key transcription coactivator of amino acid-stimulated mTOR-mediated milk fat synthesis in mammary epithelial cells.

Adolescent alcohol exposure epigenetically regulates CREB signaling in the adult amygdala

Binge alcohol drinking in adolescence leads to increased risk for alcohol use and other psychiatric disorders in adulthood. The transcription factor cAMP-response element binding (CREB) protein is involved in the neuronal response to adult ethanol exposure, but its role in the enduring effects of adolescent alcohol exposure in adulthood is unknown. We exposed male rats to adolescent intermittent ethanol (AIE) or saline (AIS) during post-natal days 28–41 and evaluated the epigenetic regulation of CREB dynamics in the adult amygdala. A subset of these adult rats was exposed to an acute ethanol challenge. AIE decreased CREB, phosphorylated CREB, CREB-binding protein (CBP) and p300 protein levels in adult amygdaloid brain structures. AIE exposure also causes deficits in Creb1, Cbp, and p300 mRNA expression in the amygdala of AIE adult rats which are normalized after acute ethanol exposure. Interestingly, occupancy of acetylated histone H3K9/14 proteins at specific locations in the Creb1, Cbp, and p300 gene promoter regions was decreased in the amygdala of AIE adult rats and was normalized by acute ethanol exposure. These results suggest that AIE exposure epigenetically reduces CREB and other related transcriptional activators in the amygdala in adulthood that may be associated with the behavioral effects of adolescent alcohol exposure.

P.1.018 - The impact of selective CREB deletion in serotonergic neurons on the effects of fluoxetine administration and antidepressive behaviour

The majority of current antidepressant therapies is based on the enhancement of monoaminergic transmission observed directly after drug administration, yet alleviation of depressive symptoms occurs weeks later. Therefore, the mechanism of molecular changes arising during chronic antidepressant treatment is intensively researched. Many studies have pointed to an important role of cAMP response element binding (CREB) protein in the mechanism of antidepressant drug action, however the data are inconclusive. Generally, an increase of CREB level or activity after chronic antidepressant treatment was postulated, but in other studies opposite effects were observed [1]. Moreover, CREB-deficient animals show antidepressant-like phenotype. However, the feedback from knock-out studies could have been disturbed by cAMP response element modulator (CREM) upregulation occurring upon CREB loss [2], which was not taken into consideration. In our studies we investigated the role of CREB in the mechanism of antidepressant treatment using novel, inducible transgenic mouse model lacking CREB selectively in serotonergic neurons [3], maintained in CREM-deficient background (Creb1TPH2CreERT2Crem-/- mice). The animals have been phenotypically characterized showing no impairments in their basal behavior. However, single Creb1TPH2CreERT2 mutants of both sexes presented drug-resistant phenotype in tail suspension test after fluoxetine treatment, whereas male but not female double mutants (Creb1TPH2CreERT2Crem-/-) reacted to the drug similar to control animals [4]. The aim of current studies was to assess the molecular changes induced by chronic fluoxetine (10 mg/kg i.p., 21 days, 1x daily) treatment in hippocampus and prefrontal cortex (PFC). Animals were sacrificed 24h after last injection and the brain structures were collected. Assessment of mRNA expression for Creb1 and Bdnf genes was measured by RT-PCR using TaqMan probes. The levels of phosphorylated CREB, total CREB and BDNF proteins were studied using Western Blot. The results were analyzed using two-way ANOVA, followed by Fisher’s LSD test. We observed no effect in mRNA expression of Creb1 and Bdnf genes in control animals after fluoxetine treatment, nor in any of studied mutants. Moreover, no changes in phosphorylation of CREB or total CREB protein were visible in any of studied group. On the other hand, BDNF protein was strongly increased in response to drug in hippocampus of control males and females (by 212% and 120%, respectively), and in PFC of control females only (by 47%). Both treated and non-treated Creb1TPH2CreERT2 single mutant mice did not show any changes in BDNF in both studied brain structures; the result was significantly different from the effect observed in control animals after fluoxetine administration. Creb1TPH2CreERT2Crem-/- double mutants presented only non-significant tendency of increased BDNF protein level in hippocampus (both males and females) and PFC (females only). Despite the absence of any effect in CREB mRNA or protein levels observed in both mutant lines, the BDNF upregulation in fluoxetine-treated control mice suggests increased activity of CREB in hippocampus after antidepressant treatment as observed by other investigators [5]. Lack of molecular or behavioral changes after fluoxetine treatment in Creb1TPH2CreERT2 single mutant animals suggests that compensatory role of CREM upregulation in the inducible line may have different effects from that observed previously in constitutive CREB knockouts.

Overexpression of the Histone Dimethyltransferase G9a in Nucleus Accumbens Shell Increases Cocaine Self-Administration, Stress-Induced Reinstatement, and Anxiety.

Repeated exposure to cocaine induces lasting epigenetic changes in neurons that promote the development and persistence of addiction. One epigenetic alteration involves reductions in levels of the histone dimethyltransferase G9a in nucleus accumbens (NAc) after chronic cocaine administration. This reduction in G9a may enhance cocaine reward because overexpressing G9a in the NAc decreases cocaine-conditioned place preference. Therefore, we hypothesized that HSV-mediated G9a overexpression in the NAc shell (NAcSh) would attenuate cocaine self-administration (SA) and cocaine-seeking behavior. Instead, we found that G9a overexpression, and the resulting increase in histone 3 lysine 9 dimethylation (H3K9me2), increases sensitivity to cocaine reinforcement and enhances motivation for cocaine in self-administering male rats. Moreover, when G9a overexpression is limited to the initial 15 d of cocaine SA training, it produces an enduring postexpression enhancement in cocaine SA and prolonged (over 5 weeks) increases in reinstatement of cocaine seeking induced by foot-shock stress, but in the absence of continued global elevations in H3K9me2. The increase in stress-induced reinstatement is paralleled by heightened anxiety measures, suggesting that countering the cocaine-induced decreases in endogenous G9a with ectopic G9a overexpression leads to lasting anxiogenic effects. Finally, we found an enduring reduction in phosphorylated cAMP-response element binding protein levels in the NAcSh that could account for the increased anxiety. These data demonstrate a novel role for G9a in promoting comorbid cocaine addiction and anxiety and suggest that increased epigenetic repression of transcription through H3K9 during cocaine use can have long-lasting and unexpected negative consequences on behavior.SIGNIFICANCE STATEMENT Cocaine addiction is a neuropsychiatric disorder that is detrimental to society and currently has no effective treatments. The difficulty in treating drug addiction is compounded by the high comorbidity with other psychiatric illnesses, including anxiety disorders. Here, we demonstrate that G9a, an epigenetic repressor of gene expression, acting in the nucleus accumbens, a brain reward region, is capable of increasing both addiction- and anxiety-like behaviors in rats. These findings are intriguing because repeated cocaine exposure decreases G9a in this region and thereby enhances expression of certain addiction-promoting genes. However, our results suggest that countering this cocaine-induced decrease in G9a activity actually exacerbates addiction and sensitivity to relapse under stressful situations.

Study of the Role of CREB, BDNF, and VGF Neuropeptide in Long Term Antidepressant Activity of Crocin in the Rat Cerebellum.

Antidepressant activity of crocin, saffron main component, has been established before. Based on previous study, it is suggested that elevation in the levels of BDNF (brain-derived neurotrophic factor), CREB (cAMP response element binding) and VGF neuropeptide could be considered as one probable molecular mechanisms involved in antidepressant activity of long term crocin administration in the rat hippocampus. In this study we further investigated whether the antidepressant activity of crocin in long term administration was associated with alteration in these factors in the rat cerebellum. Crocin (12.5, 25 and 50 mg/kg/day) and imipramine (10 mg/kg/day) were administered interaperitoneally for 21 days to rats. At the end of experiment, animals were sacrificed and cerebellums were dissected. BDNF, VGF, CREB, and phospho-CREB (P-CREB) protein and mRNA levels in the rat cerebellum were evaluated using Western blot and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). In the current study significant increases in mRNA and protein levels of VGF, CREB and (BDNF) in long term crocin treatment were not observed in the rat cerebellum. Although a slight increase was observed in protein level of P-CREB compared to normal saline, but it was not significant. It is concluded that antidepressant activity of crocin might be partially mediated to CREB. Moreover, other factors rather than BDNF and VGF neuropeptides may alter following long term crocin treatment in the cerebellum. To understand the precise mechanism of crocin antidepressant effects in the cerebellum, longer duration of crocin treatment in further studies is recommended.

Effects of Crocin on Spatial Memory Impairment Induced by Hyoscine and Its Effects on BDNF, CREB, and p-CREB Protein and mRNA Levels in Rat Hippocampus

Background: Crocus sativus L., (Iridaceace), known as saffron, is used in traditional medicine for different purposes such asmemory improvment. Crocin is one of the pharmacologically active constituents responsible for many medicinal properties of saffron. Objectives: In this study, the effects of crocin, an active saffron constituent, on hyoscine inducedmemory impairment and its effect onprotein andmRNAtranscript levels of CREB (cAMP response element binding protein), BDNF(brain-derived neurotrophic factor), and phospho-CREB (p-CREB) were investigated in rat hippocampus. Methods: Rats were intraperitoneally treated with crocin (10, 20, and 40 mg/kg), normal saline (1 mL/kg), and rivastigmine (1.5 mg/kg) 30 minutes prior to hyoscine (1 mg/kg) for five days. The effects were studied on spacial learning and memory using Morris water maze. Protein and transcript levels of CREB and BDNF were analyzed using western blotting and qRT PCR methods, respectively. Results: Five days treatment with crocin (20 and 40 mg/kg) and rivastigmine significantly increased the presence of animals in target quadrant in probe trial on the 8th day compared to hyoscine. Crocin (20 mg/Kg) increased significantly BDNF and CREB protein and transcript levels compared to hyoscine. Conclusions: Crocin improved memory impairment induced by hyoscine through reduction of the latency to find the platform in the probe trial in Morris water maze test. Crocin improved memory probably due to the increase of BDNF and CREB protein and transcript levels. © 2017, Jundishapur Journal of Natural Pharmaceutical Products.

Neuron-derived orphan receptor 1 transduces survival signals in neuronal cells in response to hypoxia-induced apoptotic insults.

OBJECT Hypoxia can induce cell death or trigger adaptive mechanisms to guarantee cell survival. Neuron-derived orphan receptor 1 (NOR-1) works as an early-response protein in response to a variety of environmental stresses. In this study, the authors evaluated the roles of NOR-1 in hypoxia-induced neuronal insults. METHODS Neuro-2a cells were exposed to oxygen/glucose deprivation (OGD). Cell viability, cell morphology, cas-pase-3 activity, DNA fragmentation, and cell apoptosis were assayed to determine the mechanisms of OGD-induced neuronal insults. RNA and protein analyses were carried out to evaluate the effects of OGD on expressions of NOR-1, cAMP response element-binding (CREB), and cellular inhibitor of apoptosis protein 2 (cIAP2) genes. Translations of these gene expressions were knocked down using RNA interference. Mice subjected to traumatic brain injury (TBI) and NOR-1 was immunodetected. RESULTS Exposure of neuro-2a cells to OGD decreased cell viability in a time-dependent manner. Additionally, OGD led to cell shrinkage, DNA fragmentation, and cell apoptosis. In parallel, treatment of neuro-2a cells with OGD time dependently increased cellular NOR-1 mRNA and protein expressions. Interestingly, administration of TBI also augmented NOR-1 levels in the impacted regions of mice. As to the mechanism, exposure to OGD increased nuclear levels of the transcription factor CREB protein. Downregulating CREB expression using RNA interference simultaneously inhibited OGD-induced NOR-1 mRNA expression. Also, levels of cIAP2 mRNA and protein in neuro-2a cells were augmented by OGD. After reducing cIAP2 translation, OGD-induced cell death was reduced. Sequentially, application of NOR-1 small interfering RNA to neuro-2a cells significantly inhibited OGD-induced cIAP2 mRNA expression and concurrently alleviated hypoxia-induced alterations in cell viability, caspase-3 activation, DNA damage, and cell apoptosis. CONCLUSIONS This study shows that NOR-1 can transduce survival signals in neuronal cells responsible for hypoxiainduced apoptotic insults through activation of a CREB/cIAP2-dependent mechanism.

Colorectal Carcinogenesis: Connecting K-RAS-Induced Transformation and CREB Activity In Vitro and In Vivo.

Oncogenic transformation is often associated with an increased expression of the cAMP response element binding (CREB) transcription factor controlling the expression of genes involved in cell proliferation, cell cycle, apoptosis, and tumor development, but a link between K-RAS(V12)-induced transformation and CREB has not yet been determined. Therefore, the constitutive and/or inhibitor-regulated mRNA and protein expression of CREB and signal transduction components and growth properties of parental fibroblasts, K-RAS(V12)-transformed counterparts, shCREB K-RAS(V12) transfectants and human colon carcinoma cells were determined. Increased CREB transcript and protein levels accompanied by an enhanced CREB activity was detected in K-RAS(V12)-transformed murine fibroblasts and K-RAS(V12)-mutated human tumor cells, which is dependent on the MAPK/MEK, PI3K, and/or PKC signal transduction. Immunohistochemical (IHC) staining of colorectal carcinoma lesions and murine tumors, with known KRAS gene mutation status, using antibodies specific for CREB and phospho-CREB, revealed a mechanistic link between CREB expression and K-RAS(V12)-mutated colorectal carcinoma lesions when compared with control tissues. Silencing of CREB by shRNA and/or treatment with a CREB inhibitor (KG-501) reverted the neoplastic phenotype of K-RAS(V12) transformants as demonstrated by a more fibroblast-like morphology, enhanced apoptosis sensitivity, increased doubling time, decreased migration, invasion and anchorage-independent growth, reduced tumorigenesis, and enhanced immunogenicity in vivo. The impaired shCREB-mediated invasion of K-RAS(V12) transformants was accompanied by a transcriptional downregulation of different matrix metalloproteinases (MMP) coupled with their reduced enzymatic activity. CREB plays a key role in the K-RAS(V12)-mediated neoplastic phenotype and represents a suitable therapeutic target for murine and human K-RAS(V12)-induced tumors.

AIP inactivation leads to pituitary tumorigenesis through defective Gαi-cAMP signaling

The aryl hydrocarbon receptor interacting protein (AIP) is a tumor-suppressor gene underlying the pituitary adenoma predisposition. Thus far, the exact molecular mechanisms by which inactivated AIP exerts its tumor-promoting action have been unclear. To better understand the role of AIP in pituitary tumorigenesis, we performed gene expression microarray analysis to examine changes between Aip wild-type and knockout mouse embryonic fibroblast (MEF) cell lines. Transcriptional analyses implied that Aip deficiency causes a dysfunction in cyclic adenosine monophosphate (cAMP) signaling, as well as impairments in signaling cascades associated with developmental and immune-inflammatory responses. In vitro experiments showed that AIP deficiency increases intracellular cAMP concentrations in both MEF and murine pituitary adenoma cell lines. Based on knockdown of various G protein α subunits, we concluded that AIP deficiency leads to elevated cAMP concentrations through defective Gαi-2 and Gαi-3 proteins that normally inhibit cAMP synthesis. Furthermore, immunostaining of Gαi-2 revealed that AIP deficiency is associated with a clear reduction in Gαi-2 protein expression levels in human and mouse growth hormone (GH)-secreting pituitary adenomas, thus indicating defective Gαi signaling in these tumors. By contrast, all prolactin-secreting tumors showed prominent Gαi-2 protein levels, irrespective of Aip mutation status. We additionally observed reduced expression of phosphorylated extracellular signal-regulated kinases 1/2 and cAMP response element-binding protein levels in mouse and human AIP-deficient somatotropinomas. This study implies for the first time that a failure to inhibit cAMP synthesis through dysfunctional Gαi signaling underlies the development of GH-secreting pituitary adenomas in AIP mutation carriers.

Activation of Spinal GABAB Receptors Normalizes N‐methyl‐D‐Aspartate Receptor in Diabetic Neuropathy

N‐methyl‐D‐Aspartate receptor (NMDAR) is increased, while GABAB receptor is decreased in the spinal cord dorsal horn in diabetic neuropathy. In this study, we determined the interaction of NMDAR and GABAB receptors in streptozotocin (STZ)‐induced diabetic neuropathy. The paw withdrawal threshold (PWT) was significantly lower in STZ‐treated rats than in saline‐treated rats. Intrathecal baclofen significantly increased the PWT in STZ‐treated rats, an effect that is abolished by pre‐administration of GABAB receptor specific antagonist CGP55845. Spinal NR2B protein and mRNA expression levels were significantly higher in STZ‐treated rats than in saline‐treated rats. Intrathecal baclofen significantly reduced the NR2B protein and mRNA expression levels in STZ‐treated rats. Intrathecal administration of CGP55845 eliminated baclofen‐induced reduction of protein and mRNA levels in STZ‐treated rats. In addition, the phosphorylated cAMP response element‐binding (CREB) protein levels was significantly higher in spinal cord dorsal horn in STZ‐treated rats. Intrathecal baclofen significantly decreased phosphorylated CREB protein levels in STZ‐treated rats, an effect could be blocked by CGP55845. These data suggest that activation of GABAB receptors in the spinal cord dorsal horn suppresses NMDA receptor expression in diabetic neuropathic pain.

Anti‐depressant Effects of Aqueous Extract from Acanthopanax senticosus in Mice

In this paper, the anti-depressant effects of Acanthopanax senticosus extract (ASE) were studied using animal models of depression including the forced swimming and tail suspension tests. The anti-depressive mechanism of ASE was explored by monitoring the levels of monoamine neurotransmitters including 5-hydroxytrylamine (5-HT), norepinephrine (NE), and dopamine (DA), as well as cAMP response element-binding (CREB) protein expression in the whole brain of mice following the tail suspension test. Our results showed that intragastric administration of ASE at a dose of 2000 mg/kg for seven days significantly reduced the duration of immobility in both the forced swimming test and the tail suspension test. These results indicate that ASE possesses antidepressant-like properties. Pre-treatment with 2000 mg/kg of ASE for seven days significantly elevated the levels of 5-HT, NE, and DA in the whole brain of mice. Moreover, ASE at doses of 1000 and 2000 mg/kg significantly up-regulated the level of CREB protein. Taken together, these findings suggest that the anti-depressive mechanism of ASE may be mediated via the central monoaminergic neurotransmitter system and CREB protein expression. Therefore, administration of ASE may be beneficial for patients with depressive disorders.

Prunella vulgaris Attenuates Prepulse Inhibition Deficit and Attention Disruption induced by MK‐801 in Mice

Prunella vulgaris var. lilacina is widely distributed in Korea, Japan, China, and Europe, and it has been traditionally used to treat inflammation or hypertension. In the present study, we investigated the effects of the ethanolic extract of the spikes of Prunella vulgaris var. lilacina (EEPV) on dizocilpine (MK-801)-induced schizophrenia-like phenotype behaviors such as the disruption of prepulse inhibition and attention deficits in mice. We also determined the effect of EEPV on MK-801-induced alterations in phosphorylated extracellular signal-regulated kinase, phosphorylated protein kinase B, phospho-glycogen synthase kinase 3-β, and phosphorylated cAMP response element-binding protein levels in the cortex and hippocampus of mice. MK-801-induced prepulse inhibition deficits were ameliorated by the administration of EEPV, as shown in the acoustic startle response test. Furthermore, EEPV attenuated the MK-801-induced attention deficits in the water finding test. We also found that EEPV attenuated the increased phosphorylated extracellular signal-regulated kinase, phosphorylated protein kinase B, or phospho-glycogen synthase kinase 3-β levels induced by MK-801 in the cortex but not in the hippocampus. These results suggest that EEPV could be useful for treating schizophrenia because EEPV ameliorates prepulse inhibition disruption and attention deficits induced by MK-801.

Transducer of regulated CREB-binding proteins (TORCs) transcription and function is impaired in Huntington's disease

Huntington's disease (HD) is an incurable neurological disorder caused by an abnormal glutamine repeat expansion in the huntingtin (Htt) protein. In the present studies, we investigated the role of Transducers of Regulated cAMP response element-binding (CREB) protein activity (TORCs) in HD, since TORCs play an important role in the expression of the transcriptional co-regulator peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), whose expression is impaired in HD. We found significantly decreased TORC1 expression levels in STHdhQ111 cells expressing mutant Htt, in the striatum of NLS-N171-82Q, R6/2 and HdhQ111 HD transgenic mice and in postmortem striatal tissue from HD patients. TORC1 overexpression in wild-type (WT) and Htt striatal cells increased CREB mRNA and protein levels, PGC-1α promoter activity, mRNA expression of the PGC-1α, NRF-1, Tfam and CytC genes, mitochondrial DNA content, mitochondrial activity and mitochondrial membrane potential. TORC1 overexpression also increased the resistance of striatal cells to 3-nitropropionic (3-NP) acid-mediated toxicity. In cultured WT and mutant Htt striatal cells, small hairpin RNA-mediated TORC1 knockdown resulted in decreased PGC-1α expression and increased susceptibility to 3-NP-induced toxicity. Overexpression of PGC-1α partially prevented TORC1 knockdown-mediated increased susceptibility of Htt striatal cells to 3-NP. Specific knockdown of TORC1 in the striatum of NLS-N171-82Q HD transgenic mice induced neurodegeneration. Lastly, knockdown of Htt prevents transcriptional repression of TORC1 and CREB in Htt striatal cells. These findings show that impaired expression and function of TORC1, which results in a reduction in PGC-1α, plays an important role in mitochondrial dysfunction in HD.

The administration of olanzapine and fluoxetine has synergistic effects on intracellular survival pathways in the rat brain

Recently, several studies have emerged suggesting a role of the intracellular survival pathways in the treatment of mood disorders. In addition, the beneficial effects of using a combination of antipsychotics and antidepressants have been shown. With this in mind, we evaluated the effects of the acute administration of fluoxetine (FLX), olanzapine (OLZ) and the combination of fluoxetine/olanzapine on the brain-derived-neurotrophic factor (BDNF), cAMP response element-binding (CREB), Protein Kinase B (PKB, Akt), B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated death promoter (BAD) in the rat brain. Adult Wistar rats received an acute injection of OLZ (3 or 6 mg/kg) and/or FLX (12.5 or 25 mg/kg), and were evaluated for Akt, BDNF, CREB, Bcl-2 and BAD protein levels in the prefrontal cortex, hippocampus and striatum. Our results showed that treatment with FLX and OLZ alone or in combination increased the Akt, CREB, BDNF, Bcl-2 and BAD levels in the prefrontal cortex, hippocampus and striatum. However, the combination of FLX and OLZ at high doses was associated with a greater increase in the levels of Akt in the prefrontal cortex, and did not have an effect on the levels of BAD in any of the brain areas that we evaluated. Finally, these findings further support the hypothesis that treatment with FLX and OLZ alone or in combination exert neuroprotective effects, and that intracellular survival pathways could be involved in the therapeutic effects of combining antipsychotic and antidepressant drugs in mood disorders.

Curcumin prevents corticosterone‐induced neurotoxicity and abnormalities of neuroplasticity via 5‐HT receptor pathway

Curcumin, a major active component of Curcuma longa, possesses antioxidant and neuroprotective activities. The present study explores the mechanisms underlying the neuroprotective effect of curcumin against corticosterone and its relation to 5-hydroxy tryptamine (5-HT) receptors. Exposure of cortical neurons to corticosterone results in decreased mRNA levels for three 5-HT receptor subtypes, 5-HT(1A), 5-HT(2A) and 5-HT(4), but 5-HT(1B,) 5-HT(2B), 5-HT(2C), 5-HT(6) and 5-HT(7) receptors remain unchanged. Pre-treatment with curcumin reversed this effect on mRNA for the 5-HT(1A) and 5-HT(4) receptors, but not for the 5-HT(2A) receptor. Moreover, curcumin exerted a neuroprotective effect against corticosterone-induced neuronal death. This observed effect of curcumin was partially blocked by either 5-HT(1A) receptor antagonist p-MPPI or 5-HT(4) receptor antagonist RS 39604 alone; whereas, the simultaneous application of both antagonists completely reversed the effect. Curcumin was also found to regulate corticosterone-induced morphological changes such as increases in soma size, dendritic branching and dendritic spine density, as well as elevate synaptophysin expression in cortical neurons. p-MPPI and RS 39604 reversed the effect of curcumin-induced change in neuronal morphology and synaptophysin expression of corticosterone-treated neurons. In addition, an increase in cyclic adenosine monophosphate (cAMP) level was observed after curcumin treatment, which was further prevented by RS 39604, but not by p-MPPI. However, curcumin-induced elevation in protein kinase A activity and phosphorylation of cAMP response element-binding protein levels were inhibited by both p-MPPI and RS 39604. These findings suggest that the neuroprotection and modulation of neuroplasticity exhibited by curcumin might be mediated, at least in part, via the 5-HT receptor-cAMP-PKA-CREB signal pathway.