Transcriptional expression study in the central nervous system of rats: what gene should be used as internal control?

Caloric restriction in mice improves short-term recognition memory and modifies the neuroinflammatory response in the hippocampus of male adult offspring

Restrictive diets (RD) can influence the inflammatory phenotype of dams and their offspring. Thus, this study aimed to evaluate the effects of caloric restriction on the neuroinflammatory profile in the hippocampus and the short-term recognition memory of male offspring from RD-fed dams. Mice dams received standard diet ad libitum (CONT) or restrictive diet (RD; 30% reduction of CONT consumption) during pregnancy and lactation. Male pups were weaned at 21 days and randomly divided into two groups that received CONT or RD; groups were named according to maternal/offspring diets: CONT/CONT, CONT/RD, RD/CONT, and RD/RD. At 90 days old, short-term memory was assessed by the object recognition test (ORT); the inflammatory state of the hippocampus was analyzed by gene expression of sirtuin-1 (Sirt1) and inflammasome Nlrp3; and by protein expression of toll-like receptor-4 (TLR-4) and zonula occludens-1 (ZO-1). Our results showed an improvement in short-term memory in RD-fed offspring. The expression of Sirt1 was higher in RD/CONT compared to CONT/CONT and decreased in RD/RD compared to CONT/RD. Nlrp3 gene expression showed an offspring effect, being decreased in RD-fed mice. TLR-4 expression was higher in RD/CONT compared to CONT/CONT, similarly to ZO-1 expression. However, ZO-1 also showed a maternal diet effect and increased expression in the offspring of RD dams. Our findings demonstrate that caloric restriction improved short-term recognition memory. However, a restrictive diet should be applied with caution; depending on the offspring's diet, it may not benefit the neuroinflammatory phenotype or cognition.

Dietary interventions in mice affect oxidative stress and gene expression of the Prlr and Esr1 in the adipose tissue and hypothalamus of dams and their offspring

Maternal diet is key to the progeny's health since it may impact on the offspring's adult life. In this study, mice dams received standard (CONT), restrictive (RD), or hypercaloric (HD) diets during mating, pregnancy, and lactation. Male offspring of each group of dams also received these diets: CONT, RD, HD. Aiming to evaluate the oxidative stress in the adipose tissue, reactive oxygen species (ROS) production, catalase (CAT), and superoxide dismutase (SOD) activities were analyzed in dams and offspring. In the adipose tissue and hypothalamus, gene expression of prolactin (Prlr) and estrogen alpha (Esr1) receptors was performed in dams and offspring. Protein expression of Stat5 was evaluated in the adipose tissue of the offspring from RD-fed dams. HD-fed dams increased triglycerides and leptin serum concentrations, and decreased SOD activity in the adipose tissue. In the offspring's adipose tissue, we observed a maternal diet effect caused by HD, with increased ROS production and SOD and CAT activities. Gene expression of Prlr and Esr1 in the offspring's adipose tissue was decreased due to maternal RD. Mice from HD-fed dams showed higher Stat5 expression compared to the offspring from CONT and RD dams in the adipose tissue. In the hypothalamus, we found decreased expression of Prlr in RD and HD dams, compared to CONT; and a maternal diet effect on Prlr and Esr1 gene expression in the offspring. In conclusion, we can affirm that maternal nutrition impacts the redox state and influences the gene expression of Prlr and Esr1, which are involved in energy metabolism, both peripherally and centrally in the adult life of the female offspring.

Gene expression evaluation of antioxidant enzymes in patients with hepatocellular carcinoma: RT-qPCR and bioinformatic analyses

Any condition leading to chronic liver disease is a potential oncogenic agent for hepatocellular carcinoma (HCC). Alterations in the expression of antioxidant enzymes could alter the redox balance. Our aim was to evaluate the expression of the genes GPX1, GPX4, SEP15, SELENOP, SOD1, SOD2, GSR, CAT, and NFE2L2 in patients with HCC. Differential gene expression analysis was performed using RNA-Seq data from the TCGA and GTEx databases, and RT-qPCR data from HCC patient samples. Bioinformatic analysis revealed significant differential expression in most genes. GPX4 expression was significantly increased (p=0.02), while SOD2 expression was significantly decreased (p=0.04) in experimental data. In TCGA samples, alpha-fetoprotein levels (mg/dL) were negatively correlated with the expression of SEP15 (p<0.001), SELENOP (p<0.001), SOD1 (p<0.001), SOD2 (p<0.001), CAT (p<0.001), and NFE2L2 (p=0.004). Alpha-fetoprotein levels were positively correlated with the expression of GPX4 (p=0.02) and SELENOP (p=0.01) in the experimental data. Low expression of GPX1 (p=0.006), GPX4 (p=0.01), SELENOP (p=0.006), SOD1 (p=0.007), CAT (p<0.001), and NFE2L2 (p<0.001), and higher levels of GSR, were associated with low overall survival at 12 months. These results suggest a significant role for these antioxidant enzymes in HCC pathogenesis and severity.

The combination of hprt and gapdh is the best compound reference genes in the fetal rat hippocampus

Hippocampus, as an important organ of central memory storage and spatial orientation, has been studied increasingly in recent years. The expression of reference genes in the hippocampus of adult rats, which are commonly used in the quantitative real-time polymerase chain reaction (qRT-PCR), is unstable in the fetal hippocampus and may not be suitable for the fetal period. Therefore, this study intends to screen and determine the optimal compound reference genes in the fetal rat hippocampus. Based on the literature, we selected five housekeeping genes (HKGs), including glyceraldehyde 3-phosphate dehydrogenase (gapdh), actin beta (β-actin), hypoxanthine phosphoribosyltransferase (hprt), 18s ribosomal RNA (18s rRNA), and cyclophilin B (cypB). We analyzed the expression of them under physiological conditions in the fetal rat hippocampus using BestKeeper, GeNorm, and NormFinder, to select the most stable compound reference genes. Furthermore, to verify the stability of the compound reference genes, we analyzed the expression of reference genes in the fetal rat hippocampus under the pathological model of prenatal dexamethasone exposure (PDE). Finally, we evaluated the accuracy of compound reference genes through detecting the expression of fetal rat hippocampal brain-derived neurotrophic factor (BDNF) under PDE model. This study determined that the combination of gapdh and hprt was the most stable and suitable compound reference genes in the fetal rat hippocampus. There was no significant difference between male and female fetal rats. We provided the support of accurate and reliable reference genes for the further study of diseases related to the fetal hippocampus.

Restriction and hyperlipidic diets during pregnancy, lactation and adult life modified the expression of dopaminergic system related genes both in female mice and their adult offspring

The neurocircuitry underlying hunger, satiety, motivation to eat and food reward is complex, however a lot of mechanisms are still unknown. Two main cerebral areas are responsible for controlling feeding through hunger and food reward: the hypothalamus (HPT) and the ventral tegmental area (VTA), respectively. The dopaminergic system modulates both these areas and is essential to control food ingestion. Therefore, we aim to evaluate the effects of restrictive and hyperlipidic diets during pregnancy, lactation and during adult life of the offspring, on the expression of dopaminergic system genes in VTA and HPT of mice dams and their adult male offspring. We also measured diets' effect in locomotor activity in the open field (OF) test. Female mice were divided into control (CONT), restriction (RD) and hyperlipidic (HD) dietary groups, and mated with isogenic male mice. On the 9th postpartum day (PPD), dams were tested in the OF, and on the 22nd PPD cerebral areas were collected. After weaning, the offspring also were divided into one of three diet groups, independently of the diets provided to their dams. In the 80th PPD, the offspring was tested in the OF, and at 100th PPD, VTA and HPT were collected. Gene expression was analyzed by quantitative reverse transcription real-time polymerase chain reaction. The correlation between gene expression and locomotor activity was also assessed. In dams' VTA, both diets upregulated the expression of Th, Slc6a3/Dat1, Drd1 and Drd2 genes. In opposition, in the offspring the maternal diet was associated with a reduction in Th and Ddc gene expression. In the HPT, mice dams that received restriction or hyperlipidic diets had increased Th mRNA levels, but reduced the expression of Drd4 gene. The offspring diet had no effect on the expression of the studied genes in their adult lives. Both diets increased mice dam's locomotion in the OF, however none of them altered the offspring locomotor activity. We detected a positive correlation between the duration of total locomotion in the OF and Slc6a3/Dat1 gene expression in VTA of mice dams. In the HPT, a negative correlation of locomotion and Drd4 mRNA levels, and a positive correlation with Th gene expression was observed. Our results show that restriction and hyperlipidic diets alter mice dams' locomotor activity in the OF and modify the expression of dopaminergic system genes in VTA and HPT of mice dams and in VTA of the offspring.

Proteomic analysis of male rat nucleus accumbens, dorsal hippocampus and amygdala on conditioned place aversion induced by morphine withdrawal

Addiction is characterized by compulsive drug seeking and taking behavior, which is thought to result from persistent neuroadaptations, encoded by changes of gene expression. We previously demonstrated that the changes in synaptic plasticity were required for the formation of aversive memories associated with morphine withdrawal. However, the proteins involved in synaptic plasticity and aversive memory formation have not been well explored. In the present study, we employed a two-dimensional gel electrophoresis (2-DE)-based proteomic technique to detect the changes of protein expression in the nucleus accumbens, amygdala and dorsal hippocampus of the rats that had developed conditioned morphine withdrawal. We found that twenty-three proteins were significantly altered in the amygdala and dorsal hippocampus after conditioned morphine withdrawal. These proteins can be classified into multiple categories, such as energy metabolism, signal transduction, synaptic transmission, cytoskeletal proteins, chaperones, and protein metabolism according to their biological functions. Eight proteins related to synaptic plasticity were further confirmed by western blot analysis. It is very likely that these identified proteins may contribute to conditioned morphine withdrawal-induced neural plasticity and aversive memory formation. Thus, our work will help understand the potential mechanism associated with generation of drug withdrawal memories.

Effects of Ectoine on Behavior and Candidate Genes Expression in ICV-STZ Rat Model of Sporadic Alzheimer's Disease

Purpose: Alzheimer's disease (AD) is pathologically defined by the presence of amyloid plaques and tangles in the brain, therefore, any drug or compound with potential effect on lowering amyloid plaques, could be noticed for AD management especially in the primary phases of the disease. Ectoine constitutes a group of small molecule chaperones (SMCs). SMCs inhibit proteins and other changeable macromolecular structures misfolding from environmental stresses. Ectoine has been reported successfully prohibit insulin amyloid formation in vitro. Methods: We selected eight genes, DAXX, NFκβ, VEGF, PSEN1, MTAP2, SYP, MAPK3 and TNFα genes which had previously showed significant differential expression in Alzheimer human brain and STZ- rat model. We considered the neuroprotective efficacy by comparing the expression of candidate genes levels in the hippocampus of rat model of Sopradic Alzheimer's disease (SAD), using qPCR in compound-treated and control groups as well as therapeutic effects at learning and memory levels by using Morris Water Maze (MWM) test. Results: Our results showed significant down-regulation of Syp, Mapk3 and Tnfα and up-regulation of Vegf in rat's hippocampus after treatment with ectoine comparing to the STZ-induced group. In MWM, there was no significant change in swimming distance and time for finding the hidden platform in treated comparing to STZ-induced group. In addition, it wasn't seen significant change in compound-treated comparing to STZ-induced and control groups in memory level. Conclusion: It seems this compound may have significant effect on expression level of some AD- related genes but not on clinical levels.

Effects of Herbal Compound (IMOD) on Behavior and Expression of Alzheimer's Disease Related Genes in Streptozotocin-Rat Model of Sporadic Alzheimer's Disease

Purpose: Sporadic Alzheimer’s disease (AD) accounts for over 95% of cases. Possible mechanisms of AD such as inflammation and oxidative stresses in the brain motivate researchers to follow many therapies which would be effective, especially in the early stages of the disease. IMOD, the herbal extract of R. Canina, T. Vulgare and U. Dioica plant species enriched with selenium, has anti-inflammatory, immunoregulatory and protective effects against oxidative stress.

Methods: In this study three AD-related genes, DAXX, NFκβ and VEGF, were chosen as candidate to investigate the neuroprotective effect of the extract by comparing their expression levels in the hippocampus of rat model of sporadic AD, using qPCR in the herbal-treated and control groups. The therapeutic effects on learning and memory levels were evaluated by Morris Water Maze (MWM) test.

Results: Gene expression results were indicative of significant up-regulation of Vegf in rat’s hippocampus after treatment with the herbal extract comparing to model group (P-value= 0.001). The MWM results showed significant changes in path length and time for finding the hidden platform in all groups during test and the same change in the treated comparing to the control group in memory level.

Conclusion: It could be concluded that the herbal extract may have significant effect on gene expression but not on behavioral level.

The Impact of Oxytocin Gene Knockout on Sexual Behavior and Gene Expression Related to Neuroendocrine Systems in the Brain of Female Mice

Social relations are built and maintained from the interaction among individuals. The oxytocin (OT), vasopressin (VP), estrogen, dopamine, and their receptors are involved in the modulation of sexual behavior in females. This study aimed to analyze the impact of OT gene knockout (OTKO) on sexual behavior and the gene expression of oxytocin (OTR), estrogen alpha (ERα), estrogen beta (ERβ), vasopressin (V1aR), and dopamine (D2R) receptors in the olfactory bulb (OB), prefrontal cortex (PFC), hippocampus (HPC), and hypothalamus (HPT), as well as in the synthesis of VP in the HPT of female mice. Wild-type (WT) littermates were used for comparisons. The CDNAs were synthesized by polymerase chain reaction and the gene expression was calculated with the 2-ΔΔCt formula. Our results showed that the absence of OT caused an increase in the frequency and duration of non-receptive postures and a decrease in receptive postures in the OTKO. OTKO females showed a significant decrease in the gene expression of OTR in the HPC, V1aR in the HPT, and ERα and ERβ in the PFC. There was no significant difference in the gene expression of D2R of OTKO. However, OTKO showed an increased gene expression of V1aR in the HPC. There is no significant difference in VP mRNA synthesis in the HPT between OTKO and WT. Our findings demonstrate that the absence of OT leads to significant changes in the expression of the studied genes (OTR, ERα, ERβ, V1aR), and these changes may contribute to the decreased sexual behavior observed in OTKO females.

Evaluation of tumor necrosis factor (TNF)-α mRNA expression level and the rs1799964 polymorphism of the TNF-α gene in peripheral mononuclear cells of patients with inflammatory bowel diseases

Crohn's disease (CD) and ulcerative colitis (UC) are types of chronic inflammatory bowel disease (IBD) of which the actual causes remain unknown. Emerging data indicate that alterations in cytokine synthesis may be involved in IBD pathogenesis. The aim of the present study was to determine whether the tumor necrosis factor (TNF)-α mRNA expression level and rs1799964 polymorphism are the genetic susceptibility component of IBD development. The TNF-α mRNA expression level of peripheral blood mononuclear cells (PBMCs) was measured using comparative reverse-transcription quantitative polymerase chain reaction (PCR). Genomic DNA from 201 individuals (CD: n=15; UC: n=86; control subjects: n=100) was analyzed for the presence of the TNF-α-1031 polymorphism by PCR-restriction fragment length polymorphism. An increased TNF-α mRNA expression level was additionally observed in the CC genotype of the -1031 TNF-α gene polymorphism compared with the TC and TT genotypes (P<0.05). Furthermore, the present results revealed that there was no significant difference in the genotype/allele frequencies of the -1031 TNF-α gene polymorphism in Iranian IBD patients. By comparison, the TNF-α mRNA expression level was evaluated in patients with a history of taking medications and demonstrated a significant association in the group that received the 5-ASA + Pred + AZA,5. 5-ASA + Pred + AZA + IFX when compared with the other groups (P<0.05). Thus, these results support the hypothesis that overexpression of the TNF-α gene, which correlated with the CC genotype, may represent a genetic risk factor for Iranian IBD.

The Effects of Melilotus officinalis Extract on Expression of Daxx, Nfkb and Vegf Genes in the Streptozotocin-Induced Rat Model of Sporadic Alzheimer's Disease

BACKGROUND

Possible mechanisms of Alzheimer Disease (AD) such as inflammation and oxidative stresses in the brain led us to investigate potential AD therapeutics of Melilotus officinalis, an herbal extract, with possible role as an anti-inflammatory and anti-oxidant agent. Among different genes which had important role in Sporadic AD (SAD), three genes including DAXX, NFkB and VEGF have shown significant statistical diversity in the brains of Alzheimer patients.

METHODS

These genes were chosen to be investigated for neuroprotective effects of the extract by comparing the expression level in the hippocampus of Sporadic AD (SAD) rat model using quantitative polymerase chain reaction (qPCR) in the treated and untreated groups. In addition, therapeutic effects at the behavioral, learning and memory level by Morris Water Maze (MWM) test were investigated.

RESULTS

The results represented significant decreased expression in Daxx, Nfkb and Vegf genes in the SAD rat's model treated with the herbal extract compared to the Streptozotocin-induced (STZ-induced) rats. Furthermore, no significant changes were seen in swimming distance and time for finding the hidden platform in the herbal-treated compared to the STZ-induced group. In memory level, no significant changes were observed among treated and untreated groups.

CONCLUSION

It seems that the herbal extract may have significant effect on Alzheimer-related gene expression changes but not on clinical levels.

Neuroprotective Effects of Herbal Extract (Rosa canina, Tanacetum vulgare and Urtica dioica) on Rat Model of Sporadic Alzheimer's Disease

BACKGROUND

Sporadic Alzheimer's Disease (SAD) is caused by genetic risk factors, aging and oxidative stresses. The herbal extract of Rosa canina (R. canina), Tanacetum vulgare (T. vulgare) and Urtica dioica (U. dioica) has a beneficial role in aging, as an anti-inflammatory and anti-oxidative agent. In this study, the neuroprotective effects of this herbal extract in the rat model of SAD was investigated.

METHODS

The rats were divided into control, sham, model, herbal extract -treated and ethanol-treated groups. Drug interventions were started on the 21(st) day after modeling and each treatment group was given the drugs by intraperitoneal (I.P.) route for 21 days. The expression levels of the five important genes for pathogenesis of SAD including Syp, Psen1, Mapk3, Map2 and Tnf-α were measured by qPCR between the hippocampi of SAD model which were treated by this herbal extract and control groups. The Morris Water Maze was adapted to test spatial learning and memory ability of the rats.

RESULTS

Treatment of the rat model of SAD with herbal extract induced a significant change in expression of Syp (p=0.001) and Psen1 (p=0.029). In Morris Water Maze, significant changes in spatial learning seen in the rat model group were improved in herbal-treated group.

CONCLUSION

This herbal extract could have anti-dementia properties and improve spatial learning and memory in SAD rat model.

With Reference to Reference Genes: A Systematic Review of Endogenous Controls in Gene Expression Studies

The choice of reference genes that are stably expressed amongst treatment groups is a crucial step in real-time quantitative PCR gene expression studies. Recent guidelines have specified that a minimum of two validated reference genes should be used for normalisation. However, a quantitative review of the literature showed that the average number of reference genes used across all studies was 1.2. Thus, the vast majority of studies continue to use a single gene, with β-actin (ACTB) and/or glyceraldehyde 3-phosphate dehydrogenase (GAPDH) being commonly selected in studies of vertebrate gene expression. Few studies (15%) tested a panel of potential reference genes for stability of expression before using them to normalise data. Amongst studies specifically testing reference gene stability, few found ACTB or GAPDH to be optimal, whereby these genes were significantly less likely to be chosen when larger panels of potential reference genes were screened. Fewer reference genes were tested for stability in non-model organisms, presumably owing to a dearth of available primers in less well characterised species. Furthermore, the experimental conditions under which real-time quantitative PCR analyses were conducted had a large influence on the choice of reference genes, whereby different studies of rat brain tissue showed different reference genes to be the most stable. These results highlight the importance of validating the choice of normalising reference genes before conducting gene expression studies.