Protein pCREB Research Articles

Increased SIRT3 Expression and Antioxidant Defense under Hyperglycemic Conditions in HepG2 Cells.

Hyperglycemia exacerbates the production of mitochondrial reactive oxygen species and this contributes to a variety of pathological conditions. Sirtuin 3 (SIRT3) has been shown to play a role in decreasing oxidative stress and improving disease outcomes by regulating antioxidant defense. Our understanding of molecular events during oxidative stress under chronic hyperglycemia in the liver is limited. We postulated that SIRT3 may play a role in antioxidant defense under hyperglycemic conditions in HepG2 cells. Cell viability was determined in HepG2 and human embryonic kidney (HEK) 293 cells cultured in the presence of 5.5 mM glucose (control), 19.9 mM mannitol (osmotic control), 10 mM glucose and 30 mM glucose (hyperglycemic), and nicotinamide (NAM) (10 mM) at 24-hr and 72-hr time points. SIRT3, peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), and cyclic adenosoine monophosphate (cAMP) response element binding protein (pCREB) protein expression were measured via western blotting. Mitochondrial antioxidant enzymes glutathione peroxidase 1 (GPx1), superoxide dismutase 2 (SOD2), and uncoupling protein 2 (UCP2) and mitochondrial DNA (mtDNA) repair enzyme 8-oxoguanine glycosylase (OGG1) were evaluated via quantitative PCR (qPCR). Increased cell viability and protein expression of SIRT3, pCREB, and PGC-1α were observed under hyperglycemic conditions at 24 hr. These were further elevated at the 72-hr time point. We also observed higher fold changes of SIRT3, GPx1, SOD2, UCP2, and OGG1 in the treated groups. Treatment with NAM decreased protein and gene expression of SIRT3, pCREB, PGC-1α, GPx1, SOD2, UCP2, and OGG1 at both time points in the hyperglycemic groups. Our data may allude to the relationship that has been established between SIRT3 and PGC-1α with regard to increased antioxidant defense during oxidative stress. This suggests that SIRT3 may play a role in increasing antioxidant defense and conferring resistance to oxidative stress-induced damage under hyperglycemic conditions in the human hepatoma cell line.

The proliferation effect of rMS on neural stem cells of rats in vitro

Objective To study the mechanism of rats' neural stem cells (NSCs) proliferation in vitro after repetitive magnetic stimulation (rMS). Methods The bilateral hippocampus of neonatal Sprague-Dawley rats (<3 d) was taken out to culture NSCs in vitro. The OD value was evaluated with Cell Counting Kit-8 (cck-8) and cell growth curve was generated. The NSCs cultured were divided into a control group and an rMS group. rMS (3 days, once per day) was applied on p2 NSCs at 10 Hz, 50% machine output and 200 pulses per day. One hour after the last rMS, the cck-8 was used to test the cell proliferation, and the western blotting was applied to detect the protein expression of c-fos and p-CREB. Results The nestin fluorescent staining of p2 neurospheres was proved to be neural stem cells. The growth curve indicated that their viability reached the peak on the third day. The OD value in the rMS group (0.309±0.043) showed a significant difference (P<0.05) after rMS compared with the control group (0.256±0.043). So did the c-fos and p-CREB protein expression between the two groups (P<0.01). Conclusion The rMS at 10 Hz can promote rats' NSCs proliferation in vitro, which may be related to the increased expression of p-CREB and c-fos after rMS. Key words: Repetitive magnetic stimulation; Rats; Neural stem cells; Cell proliferation

Phosphodiesterase sequence variants may predispose to prostate cancer.

We hypothesized that mutations that inactivate phosphodiesterase (PDE) activity and lead to increased cAMP and cyclic guanosine monophosphate levels may be associated with prostate cancer (PCa). We sequenced the entire PDE coding sequences in the DNA of 16 biopsy samples from PCa patients. Novel mutations were confirmed in the somatic or germline state by Sanger sequencing. Data were then compared to the 1000 Genome Project. PDE, CREB and pCREB protein expression was also studied in all samples, in both normal and abnormal tissue, by immunofluorescence. We identified three previously described PDE sequence variants that were significantly more frequent in PCa. Four novel sequence variations, one each in the PDE4B,PDE6C, PDE7B and PDE10A genes, respectively, were also found in the PCa samples. Interestingly, PDE10A and PDE4B novel variants that were present in 19 and 6% of the patients were found in the tumor tissue only. In patients carrying PDE defects, there was pCREB accumulation (P<0.001), and an increase of the pCREB:CREB ratio (patients 0.97±0.03; controls 0.52±0.03; P-value <0.001) by immunohistochemical analysis. We conclude that PDE sequence variants may play a role in the predisposition and/or progression to PCa at the germline and/or somatic state respectively.

Antidepressant activity of fluoxetine in the zinc deficiency model in rats involves the NMDA receptor complex

The zinc deficiency animal model of depression has been proposed; however, it has not been validated in a detailed manner. We have recently shown that depression-like behavior induced by dietary zinc restriction is associated with up-regulation of hippocampal N-methyl-d-aspartate receptor (NMDAR). Here we examined the effects of chronic administration of a selective serotonin reuptake inhibitor, fluoxetine (FLX), on behavioral and biochemical alterations (within NMDAR signaling pathway) induced by zinc deficiency. Male Sprague Dawley rats were fed a zinc adequate diet (ZnA, 50mg Zn/kg) or a zinc deficient diet (ZnD, 3mg Zn/kg) for 4 weeks. Then, FLX treatment (10mg/kg, i.p.) begun. Following 2 weeks of FLX administration the behavior of the rats was examined in the forced swim test (FST) and the spontaneous locomotor activity test. Twenty four hours later tissue was harvested. The proteins of NMDAR (GluN1, GluN2A and GluN2B) or AMPAR (GluA1) subunits, p-CREB and BDNF in the hippocampus (Western blot) and serum zinc level (TXRF) were examined. Depression-like behavior induced by ZnD in the FST was sensitive to chronic treatment with FLX. ZnD increased levels of GluN1, GluN2A, GluN2B and decreased pS485-GluA1, p-CREB and BDNF proteins. Administration of FLX counteracted the zinc restriction-induced changes in serum zinc level and hippocampal GluN1, GluN2A, GluN2B and p-CREB but not BDNF or pS845-GluA1 protein levels. This finding adds new evidence to the predictive validity of the proposed zinc deficiency model of depression. Antidepressant-like activity of FLX in the zinc deficiency model is associated with NMDAR complex.

The effects of willed movement on the extracellular signal-regulated kinase and cAMP response element binding protein pathway following focal cerebral ischemia

Objective To explore the effects of willed movement on neurological performance and the extracellular signal-regulated kinase (ERK) and cAMP response element binding protein (CREB) pathway in rats following focal cerebral ischemia. Methods Reversible middle cerebral artery occlusion was induced in 144 male Sprague-Dawley rats using intraluminal sutures, and they were randomly divided into a control group, a swimming exercise group, an environment modification group, and a willed movement group. The observation time points were at 7, 15 and 30 days after reperfusion. A behavioral test was performed to evaluate any neurological deficiency. Reverse transcription PCR (RT-PCR) and immunofluorescence were used to detect the ERK and CREB responses in terms of mRNA and phosphorylated ERK (pERK) and phosphorylated CREB (pCREB) protein in the peri-ischemic brain tissue. Results The climbing frequency of the willed movement group was significantly higher than that of the environment modification group. Three days after reperfusion the neurological deficit scores of all groups began to decrease, and that of the willed movement group had decreased significantly more than in the other three groups at all time points. ERK/CREB mRNA and pERK and pCREB protein expression were dramatically up-regulated in the willed movement group at 7, 15 and 30 days after reperfusion, significantly more than in the other three groups. Conclusions Willed movement may promote motor recovery by up-regulating and activating the ERK/CREB pathway following focal cerebral ischemia. Key words: Brain ischemia; Exercise therapy; Willed movement; Signal pathways

Cognitive Improvement Induced by Environment Enrichment in Chronic Cerebral Hypoperfusion Rats: a Result of Upregulated Endogenous Neuroprotection?

Environment enrichment (EE) has been demonstrated to improve the cognitive impairment that is induced by chronic cerebral hypoperfusion (CCH), but the underlying mechanism has not yet been elucidated. This study aimed to investigate the role of endogenous neuroprotection in EE-induced cognitive improvement in rats with CCH. Permanent bilateral common carotid artery occlusions (2-vessel occlusions (2VOs)) were performed to induce CCH in male adult Wistar rats. Four weeks after the surgeries, the rats were exposed to enriched environments for 4 weeks (6 h/day). Subsequently, we assessed the effects of EE on cognitive function, brain histone acetylation levels, neuroprotection-related transcription factors (i.e., cAMP response element-binding protein (CREB), phospho-CREB (p-CREB), hypoxia-inducible factor 1 (HIF-1) α, and nuclear regulatory factor 2 (Nrf2)), and oxidative stress and histological changes in the brain. After 2VO, the rats exposed to the EE treatment exhibited increased acetylation of histone 4 and increased p-CREB and Nrf2 protein levels in the brain. HIF-1α levels were increased after 2VO and reduced after EE treatment. The oxidative damage, histopathological changes in the brain, and spatial learning and memory impairments induced by 2VO were subsequently restored after EE treatment. These data indicate that EE promotes the acetylation of histone 4, regulates some neuroprotection-related transcription factors, attenuates oxidative damage, and protects against the histopathological damage to the brain induced by CCH. Together, the effects of EE in CCH rats might contribute to the recovery of spatial learning and memory.

Behavioral and molecular responses to electroconvulsive shock differ between genetic and environmental rat models of depression

Depression׳s causes play a role in individuals׳ different responses to antidepressant treatments, which require advancements. We investigated the mechanisms behind and responses to a highly effective antidepressant treatment, electroconvulsive therapy (ECT), in rat models with different (genetic or environmental) depression causes. Wistar Kyoto (WKY) rats and Wistar rats treated with chronic unpredictable mild stresses (CUMS) were used as genetic and environmental rat models of depression, respectively. The rats underwent electroconvulsive shock (ECS, the animal analog of ECT) or sham ECS. We performed a sucrose preference test, open field test, and Morris water maze to assess behavior. Hippocampal neuron numbers were measured with Nissl stain. Hippocampal BDNF, CREB, and p-CREB proteins were assayed with ELISA or western blotting. The main results showed that ECS impaired WKY rats׳ memories but improved CUMS rats׳ memories. It elevated hippocampal BDNF and CREB proteins only in CUMS rats, while it improved depressive behavior and hippocampal p-CREB protein levels in both rats, with more effective regulations in the CUMS rats. ECS did not change the hippocampal neuron number in both rats. These findings suggest that ECS exerted up-regulating effects on hippocampal BDNF and CREB (and its phosphorylation) in depressed rats, and the environmental model responded better.

Expression of AQP3 protein in hAECs is regulated by Camp-PKA-CREB signalling pathway.

Previous studies by others and our group have demonstrated the expression of AQP3 protein in human chorioamniotic membranes. Here, we investigated whether cyclic adenosine monophosphate (cAMP) up-regulation of aquaporin 3 (AQP3) protein expression in human amniotic epithelial cells (hAECs) is mediated by protein kinase A (PKA) dependent or independent pathway. Cells were treated with various concentrations of Forskolin, SP-cAMP, H-89 at various time intervals or optimal concentration of Forskolin in combination with H-89 in the blocking experiments. Forskolin significantly increased cAMP levels and the expression of PKA, p-CREB and AQP3. SP-cAMP had similar effects. H-89 inhibited PKA, p-CREB and AQP3 protein expression, and attenuated the stimulatory effect of Forskolin. These results show that the AQP3 protein expression in hAECs was regulated by cAMP-PKA-CREB signal pathway. A relatively short biological half life of AQP3 renders its rapid responsiveness to regulation.

Dehydroepiandrosterone-Regulated Testosterone Biosynthesis via Activation of the ERK1/2 Signaling Pathway in Primary Rat Leydig Cells

Background: Dehydroepiandrosterone decreases with age and this reduction has been shown to be associated with physical health in human. Some studies have suggested that the effects of DHEA are exerted after it is biotransformed into more biologically-active hormones in peripheral target cells. This study investigated the effects of DHEA on the testosterone biosynthesis and possible signaling pathway mechanism underlying these DHEA effects were also explored in primary rat Leydig cells. Methods: Primary Leydig cells were treated with DHEA and then detected testosterone content by RIA and steroidogenic enzymes, ERK1/2 signal pathway factors protein expression level by Western blot. Results: Incubation of primary Leydig cells with DHEA significantly increased testosterone content and 3β-HSD and 17β-HSD protein expression levels, while aromatase protein expression levels were decreased. Compared with the control group, p-ERK1/2 and p-CREB protein levels were significantly increased in DHEA-treated groups. Testosterone content was significantly decreased in the DHEA-treated group pre-incubated with U0126 (p-ERK1/2 inhibitor). Additionally, the rise in p-ERK1/2, 3β-HSD and 17β-HSD protein levels induced by DHEA was reversed when cells were pre-incubated with U0126. Interestingly, no significant difference was found in aromatase protein expression level in cells pretreated with U0126. Conclusion: These findings demonstrate that (a) exogenous DHEA might preferentially convert to testosterone rather than estradiol due to the up-regulation of 3β-HSD and 17β-HSD protein levels and the down-regulation of aromatase protein level in primary Leydig cells, and (b) the action of DHEA is at least partly associated with the elevation of p-ERK1/2 and p-CREB protein levels.

Monosialotetrahexosylganglioside Inhibits the Expression of p-CREB and NR2B in the Auditory Cortex in Rats with Salicylate-Induced Tinnitus.

This study investigated the effects of monosialotetrahexosylganglioside (GM1) on the expression of N-methyl-D-aspartate receptor subunit 2B (NR2B) and phosphorylated (p)-cyclic AMP response element-binding protein (CREB) in the auditory cortex of rats with tinnitus. Tinnitus-like behavior in rats was tested with the gap prepulse inhibition of acoustic startle paradigm. We then investigated the NR2B mRNA and protein and p-CREB protein levels in the auditory cortex of tinnitus rats compared with normal rats. Rats treated for 4 days with salicylate exhibited tinnitus. NR2B mRNA and protein and p-CREB protein levels were upregulated in these animals, with expression returning to normal levels 14 days after cessation of treatment; baseline levels of NR2B and p-CREB were also restored by GM1 administration. These data suggest that chronic salicylate administration induces tinnitus via upregulation of p-CREB and NR2B expression, and that GM1 can potentially be used to treat tinnitus.

PFOS Disturbs BDNF-ERK-CREB Signalling in Association with Increased MicroRNA-22 in SH-SY5Y Cells.

Perfluorooctane sulfonate (PFOS), a ubiquitous environmental pollutant, is neurotoxic to mammalian species. However, the underlying mechanism of its neurotoxicity was unclear. We hypothesized that PFOS suppresses BDNF expression to produce its neurotoxic effects by inhibiting the ERK-CREB pathway. SH-SY5Y human neuroblastoma cells were exposed to various concentrations of PFOS to examine the role of the BDNF-ERK-CREB signalling pathway in PFOS-induced apoptosis and cytotoxicity. Furthermore, to ascertain the mechanism by which PFOS reduces BDNF signalling, we examined the expression levels of miR-16 and miR-22, which potentially regulate BDNF mRNA translation at the posttranscriptional level. Results indicated that PFOS significantly decreased cell viability and induced apoptosis in SH-SY5Y cells. In addition, BDNF and pERK protein levels decreased after PFOS treatment; however, pCREB protein levels were significantly elevated in PFOS treated groups. TrkB protein expression increased in the 10 μM and 50 μM PFOS groups and significantly decreased in the 100 μM PFOS group. Our results demonstrated that PFOS exposure decreased miR-16 expression and increased miR-22 expression, which may represent a possible mechanism by which PFOS decreases BDNF protein levels. PFOS may inhibit BDNF-ERK-CREB signalling by increasing miR-22 levels, which may, in part, explain the mechanism of PFOS neurotoxicity.

Region and context-specific intracellular responses associated with cocaine-induced conditioned place preference expression

The development and maintenance of cocaine addiction depend heavily on learned reward-environment associations that can induce drug-seeking behavior and relapse. Understanding the mechanisms underlying these cue-induced conditioned responses is important for relapse prevention. To test whether intracellular responses measured after cocaine conditioned place preference (CPP) expression are context-dependent, we re-exposed cocaine-treated rats (drug-free) to an environment previously paired with cocaine or saline, 24h after the CPP test. After 8days of cocaine CPP training with one of two cocaine doses (5mg/kg or 20mg/kg, i.p.), CPP was expressed only after conditioning with the higher cocaine dose. In CPP expressing rats, locomotor responses after re-exposure to the cocaine-chamber were greater than in rats re-exposed to the saline-paired chamber. Nucleus Accumbens (NAc) phosphorylated ERK (pERK) levels were increased after re-exposure to the cocaine-paired, but not the saline-paired chamber, regardless of whether or not CPP behavior was expressed. Caudate Putamen (CPu) pERK and FosB protein levels increased after re-exposure to the cocaine chamber only after conditioning with the higher cocaine dose. Conversely, the higher cocaine dose, independent of environment, resulted in increased NAc FosB, ΔFosB and phosphorylated CREB (pCREB) protein levels compared to those conditioned with 5mg/kg cocaine (non-CPP-expressing). Our results suggest that NAc ERK phosphorylation may be involved with retrieving the contextual information of a cocaine-association, without necessarily motivating the expression of CPP behavior. Additionally, we show distinct patterns of intracellular responses in the NAc and CPu indicating a region-specific role for pERK/pCREB/FosB intracellular signaling in the retrieval of cocaine-context associations.

The β-amyloid precursor protein analog P165 improves impaired insulin signal transduction in type 2 diabetic rats.

This study was performed to understand whether P165 improves learning and memory by restoring insulin action using a diabetes mellitus (DM) rat model. A total of 34 male Sprague-Dawley rats were randomly divided into four groups: control group (n = 8), DM group (n = 8), DM group treated with a low dose of P165 (n = 9), and DM group treated with a high dose of P165 (n = 9). After 8 weeks of treatment, the animals were killed and the expression of insulin signaling-related proteins was examined in the hippocampus by Western blot and immunohistochemical staining. Administration of P165 in diabetic rats did not induce a significant effect on the fasting blood glucose level. The expression of IR, IRS-1, AKT, p-CREB, and Bcl-2 proteins was significantly enhanced in the hippocampus in diabetic rats. Treatment of diabetic rats with P165 at both low and high doses significantly attenuated the expression levels of these proteins. Moreover, immunohistochemistry staining showed that IR, IRS-1, AKT, p-CREB, and Bcl-2 were abundantly expressed in the CA1 region of the hippocampus. The number of cells positively stained for the above proteins was significantly higher in diabetic tissues compared to control tissues, whereas P165 treatments induced a significant reduction in the expression of these proteins. The expression of IR, IRS-1, AKT, p-CREB, and Bcl-2 was enhanced in DM rats, and administration of P165 normalized the expression of these molecules, suggesting that P165 can improve impaired insulin signal transduction.

Zinc deficiency in rats is associated with up-regulation of hippocampal NMDA receptor.

Data indicated that zinc deficiency may contribute to the development of depression; however changes induced by zinc deficiency are not fully described. In the present paper we tested whether the dietary zinc restriction in rats causes alterations in N-methyl-D-aspartate receptor (NMDAR) subunits in brain regions that are relevant to depression. Male Sprague Dawley rats were fed a zinc adequate diet (ZnA, 50 mg Zn/kg) or a zinc deficient diet (ZnD, 3 mg Zn/kg) for 4 or 6weeks. Then, the behavior of the rats was examined in the forced swim test, sucrose intake test and social interaction test. Western blot assays were used to study the alterations in NMDAR subunits GluN2A and GluN2B and proteins associated with NMDAR signaling in the hippocampus (Hp) and prefrontal cortex (PFC). Following 4 or 6 weeks of zinc restriction, behavioral despair, anhedonia and a reduction of social behavior occurred in rats with concomitant increased expression of GluN2A and GluN2B and decreased expression of the PSD-95, p-CREB and BDNF protein levels in the Hp. The up-regulation of GluN2A protein was also found in the PFC, but only after prolonged (6 weeks) zinc deprivation. The procedure of zinc restriction in rats causes behavioral changes that share some similarities to the pathophysiology of depression. Obtained data indicated that depressive-like behavior induced by zinc deficiency is associated with the changes in NMDAR signaling pathway.

P.1.g.106 Enhancement of neuroprotective and antiamnesic properties of piracetam by aspirin in rats with experimental chronic hyperglycemia

restriction increased expression of NR2A and NR2B proteins and decreased expression of p-CREB and BDNF proteins in the Hp were observed. The up-regulation of NR2A protein accompanied by a decreased expression of p-CREB and BDNF proteins was also found in the PFC, but only after prolonged (6 weeks) zinc deprivation. Conclusions: The current data show that the increased expression of hippocampal NR2A and NR2B proteins after dietary zinc deprivation is linked to the depressive-like behavior. The altered composition of NMDAR subunits has been observed in experimental models of depression based on stress exposure [2] and in post-mortem tissues of suicide victims who may have suffered from depression [3]. The present data further support the zinc deficiency paradigm as a model of depression. Moreover, it indicates that changes of NMDAR subunits at the protein level in a response to zinc deprivation are complex and vary across brain regions and the course of time.

Propofol prevents electroconvulsive-shock-induced memory impairment through regulation of hippocampal synaptic plasticity in a rat model of depression.

BackgroundAlthough a rapid and efficient psychiatric treatment, electroconvulsive therapy (ECT) induces memory impairment. Modified ECT requires anesthesia for safety purposes. Although traditionally found to exert amnesic effects in general anesthesia, which is an inherent part of modified ECT, some anesthetics have been found to protect against ECT-induced cognitive impairment. However, the mechanisms remain unclear. We investigated the effects of propofol (2,6-diisopropylphenol) on memory in depressed rats undergoing electroconvulsive shock (ECS), the analog of ECT in animals, under anesthesia as well as its mechanisms.MethodsChronic unpredictable mild stresses were adopted to reproduce depression in a rodent model. Rats underwent ECS (or sham ECS) with anesthesia with propofol or normal saline. Behavior was assessed in sucrose preference, open field and Morris water maze tests. Hippocampal long-term potentiation (LTP) was measured using electrophysiological techniques. PSD-95, CREB, and p-CREB protein expression was assayed with Western blotting.ResultsDepression induced memory damage, and downregulated LTP, PSD-95, CREB, and p-CREB; these effects were exacerbated in depressed rats by ECS; propofol did not reverse the depression-induced changes, but when administered in modified ECS, propofol improved memory and reversed the downregulation of LTP and the proteins.ConclusionThese findings suggest that propofol prevents ECS-induced memory impairment, and modified ECS under anesthesia with propofol improves memory in depressed rats, possibly by reversing the excessive changes in hippocampal synaptic plasticity. These observations provide a novel insight into potential targets for optimizing the clinical use of ECT for psychiatric disorders.

Effects of desipramine treatment on stress-induced up-regulation of norepinephrine transporter expression in rat brains.

Many studies demonstrate down-regulation of the norepinephrine transporter (NET) by desipramine (DMI) in vitro and in stress-naive rats. Little is known regarding regulation of the NET in stressed animals. The present study was designed to investigate effects of DMI on the expression of NET and protein kinases in the stress rat. Adult Fischer 344 rats were subjected to chronic social defeat (CSD) for 4 weeks. DMI (10 mg/kg, intraperitoneal (i.p.)) was administered concurrently with CSD or 1 or 2 weeks after cessation of CSD. Sucrose consumption, NET expression, and protein kinases were measured. CSD significantly increased messenger RNA (mRNA) and protein levels of NET in the locus coeruleus, as well as NET protein levels in the hippocampus, frontal cortex, and amygdala. These effects were nearly abolished when DMI was administered concurrently with CSD. CSD-induced up-regulation of NET expression in the locus coeruleus, hippocampus, and amygdala lasted at least 2 weeks after cessation of CSD, an effect that was significantly attenuated by 1 or 2 weeks of DMI treatment starting from cessation of the CSD. Concurrent administration of DMI with CSD did not markedly interfere with CSD-induced decreases in protein levels of protein kinases A and C in these brain regions, but it did reverse the CSD-induced reduction in phosphorylated cAMP response element-binding (pCREB) protein levels in most brain regions. These findings suggest that NET regulation by DMI occurs in both stressed and behaviorally naive rats, and DMI-induced changes in pCREB may be involved.

Cyclic adenosine monophosphate-responsive element-binding protein activation predicts an unfavorable prognosis in patients with hepatocellular carcinoma.

AimTo investigate the clinical significance of cyclic adenosine monophosphate-responsive element-binding (CREB) and phosphorylated CREB (pCREB) expression in human hepatocellular carcinoma (HCC).Materials and methodsImmunohistochemistry and Western blot analyses were performed to detect the expression and subcellular localizations of CREB and pCREB proteins in 130 pairs of HCC and adjacent nonneoplastic liver tissues.ResultsBoth immunohistochemistry and Western blot analyses showed that the expression levels of CREB and pCREB proteins in HCC tissues were significantly higher than those in the adjacent nonneoplastic liver tissues (both P<0.001). In addition, the combined upregulation of CREB and pCREB proteins (CREB-high/pCREB-high) was significantly associated with serum α-fetoprotein (P=0.02), tumor stage (P<0.001), and tumor grade (P=0.01). Moreover, HCC patients with CREB-high/pCREB-high expression showed shortest 5-year disease-free survival and 5-year overall survival (both P<0.001). Furthermore, the multivariate survival analysis found that the combined upregulation of CREB and pCREB proteins may be an independent unfavorable prognostic factor for both 5-year disease-free survival and 5-year overall survival (both P=0.01) in HCC.ConclusionOur data indicate for the first time that the activation of the CREB protein may be associated with tumor progression in HCC, and may serve as a valuable marker of prognosis for patients with this malignancy.

Caloric restriction can improve learning ability in C57/BL mice via regulation of the insulin-PI3K/Akt signaling pathway

To identify the molecular mechanism underlying improved spatial learning ability of C57/BL mice on a caloric restricted (CR) diet. Seven-week-old male C57/BL mice were randomly divided into three groups: normal control group (NC group, n = 10), high energy group (n = 10), and low energy group (CR group, n = 10). Body mass and levels of blood glucose were measured every 2 weeks over the course of 30 weeks. After 30 weeks, metabolic parameters, serum total cholesterol, and insulin-like growth factor 1 (IGF-1) were measured, and learning and memory ability of animals were tested using the Morris water maze. The expression of insulin signaling pathway-related proteins in the brain tissues also were tested for molecular mechanism. When compared with the NC group, body weight, and levels of serum glucose decreased in the CR group and increased in the high energy group at all time points tested. Average escape latency and swimming distance were lower in the CR group as compared to the control group after 30 weeks. The serum cholesterol level of the high energy group was significantly higher than that of the control group. The expressions of IGF-1, IR, IRS-1, PI3K, Akt/PKB, and p-CREB protein in the CR group were significantly lower and the expressions of PI3K and Akt/PKB protein in the high energy group were significantly lower than those of the control group at post 30 weeks treatment. Our findings demonstrate that the low energy diet may improve hippocampus-dependent spatial learning ability in C57/BL mice, possibly through a regulatory mechanism of the insulin-PI3K/Akt signaling pathway.

The effects of lobeline on nicotine withdrawal-induced depression-like behavior in mice

Evidence suggests that neuronal nicotinic acetylcholine receptor (nAChR) ligand lobeline has antidepressant-like properties. The present study investigated the effects of lobeline on nicotine withdrawal-induced depression-like behavior. Adult C57BL/6J mice were exposed to nicotine (200μg/ml) in drinking solution for 3weeks. During withdrawal, depression-like behavior was measured by the forced swim test (FST). We also determined norepinephrine (NE) levels in the prefrontal cortex (PFC) and hippocampus during nicotine withdrawal. Furthermore, we determined the effects of repeated treatment with lobeline or a selective α4β2 nAChR ligand 3-(pyridine-3́-yl)-cytisine on brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP-responsive element binding (p-CREB) protein expression in the hippocampus. Withdrawal from chronic nicotine increased immobility time in the FST, a measure for depression-like behavior. Pretreatment with lobeline significantly decreased immobility time during nicotine withdrawal. In addition, pretreatment with lobeline attenuated nicotine withdrawal-induced increased NE levels in the PFC and hippocampus. Further, repeated treatment with lobeline or 3-(pyridine-3́-yl)-cytisine decreased immobility time in the FST and reduced withdrawal-induced increased BDNF and p-CREB expression in the hippocampus. Taken together, our results indicate that lobeline attenuated nicotine withdrawal-induced depression-like behavior likely by targeting brain nAChRs, noradrenergic neurotransmission, and/or hippocampal BDNF. Thus, lobeline may have some potential to prevent smoking relapse by counteracting nicotine withdrawal-induced depression in humans.