Validation of housekeeping genes as an internal control for gene expression studies in the brain of ovariectomized rats treated with tibolone

Alterations of learning and memory are accompanied by alterations in the expression of 5-HT receptors, glucocorticoid receptor and brain-derived neurotrophic factor in different brain regions of an animal model of depression generated by neonatally male treatment with clomipramine in male rats

Depressive illness has been associated with impaired cognitive processes accompanied by reduced neurotrophin levels, especially brain-derived neurotrophic factor (BDNF), and dysfunctions in the hypothalamic-pituitary-adrenal (HPA) axis. In addition, depression is characterized by a decreased functioning of the serotonergic system due to changes in the activity or expression of its receptors including, most significantly, 5-HT1A, 5-HT2A, and 5-HT3 in brain regions that regulate mood, emotions, and memory, such as the prefrontal cortex, hippocampus, and amygdala. In this regard, rats treated with clomipramine (CMI) in the neonatal stage show depression-like behaviors that persist into adulthood; hence, this constitutes an adequate model of depression for exploring various molecular aspects associated with the etiology of this disorder. This, study, then, was designed to analyze the long-term effects of early postnatal exposure to CMI on the expression of 5-HT1A, 5-HT2A, and 5-HT3 receptors, as well as BDNF and GR in the following brain regions: PFC, amygdala, hippocampus, and hypothalamus, which could be related to alterations in memory and learning, as evaluated using the novel object recognition (NOR) and Morris water maze (MWM). Expression of the 5-HT1A, 5-HT2A, and 5-HT3 receptors, BDNF, and the glucocorticoid receptor (GR) was assessed by RT-qPCR in the four aforementioned brain regions, all of which play important roles in the control of memory and mood. Findings show that neonatal treatment with CMI causes alterations in memory and learning, as indicated by alterations in the results of the MWM and NOR tests. Expression of the 5-HT1A receptor increased in the hippocampus, amygdala, and hypothalamus, but decreased in the PFC, while the 5-HT2A and BDNF receptors decreased their expression in the PFC, amygdala, and hippocampus. There was no change in the expression of the 5-HT3 receptor. In addition, expression of GR in the hippocampus and PFC was low, but increased in the hypothalamus. Taken together, these data show that neonatal CMI treatment produces permanent molecular changes in brain regions related to learning and memory that could contribute to explaining the behavioral alterations observed in this model.

Metabolic, neuroendocrine and behavioral effects of social defeat in male and female mice using the chronic non-discriminatory social defeat stress model

Stress-related disorders predominately affect females, yet preclinical models of chronic stress exclusively use males especially in models where social stressors are studied. Here, we implemented a 21-day novel social defeat paradigm in which a female and male C57 intruder are simultaneously placed in the cage of a territorial, resident CD-1 male mouse, and the resident proceeds to attack both intruders. Mice were given access to a regular laboratory diet, high in carbohydrates, and a palatable diet, high in fat. Chronic social defeat stress using this paradigm resulted in increased caloric intake in male and female mice, with the effects being more pronounced in females. We observed sex differences in high fat diet intake in response to stress, which was correlated with higher levels of plasma ghrelin observed in female mice but not male mice. Furthermore, females exposed to chronic stress displayed changes in growth hormone secretatogue receptor (ghsr) and neuropeptide-y (npy) expression in the arcuate nucleus of the hypothalamus, potentially increasing ghrelin sensitivity and inducing changes in diet choice and caloric intake. Behavioral results show that females tended to spend more time interacting during the social interaction test, compared to males who displayed higher vigilance towards the stranger mouse. Overall, our results highlight unique neurometabolic alterations in female mice in response to stress that is not present in male mice and may be important for coping with chronic stress and sustaining reproductive function.

Effect of Environmental Concentration of Carbamazepine on the Behaviour and Gene Expression of Laboratory Rats

Carbamazepine (CBZ), an effective drug for epilepsy and other neurological diseases, and its metabolites are one of the most frequently detected substances in the aquatic environment. Although these are doses of very low concentrations, chronic exposure to them can affect the physiological processes of living organisms. This experiment may clarify if carbamazepine, under an environmental and a therapeutic concentration, can affect the behaviour of higher vertebrates, especially mammals, and gene expressions of Ugt1a6 and Ugt1a7 in the brain compared to the control group without exposure to CBZ. Three groups of thirteen rats were randomly formed, and each group was treated either with carbamazepine 12 mg/kg (therapeutic), carbamazepine 0.1 mg/kg (environmental), or by 10% DMSO solution (control). The memory, anxiety, and social behaviour of the rats were assessed by the test Elevated Plus Maze, the novel object recognition test, and the social chamber paradigm. After testing, they were euthanised and brain tissue samples were collected and analysed for mRNA expression of Ugt1a6 and Ugt1a7 genes. The tests did not show significant differences in the behaviour of the rats between the groups. However, there were significant changes at the gene expression level of Ugt1a7.

Validation of the Reference Genes for Expression Analysis in the Hippocampus after Transient Ischemia/Reperfusion Injury in Gerbil Brain

Transient brain ischemia in gerbils is a common model to study the mechanisms of neuronal changes in the hippocampus. In cornu ammonnis 2-3, dentate gyrus (CA2-3,DG) regions of the hippocampus, neurons are resistant to 5-min ischemia/reperfusion (I/R) insult, while cornu ammonnis 1 (CA1) is found to be I/R-vulnerable. The quantitative polymerase chain reaction (qRT-PCR) is widely used to study the expression of genes involved in these phenomena. It requires stable and reliable genes for normalization, which is crucial for comparable and reproducible analyses of expression changes of the genes of interest. The aim of this study was to determine the best housekeeping gene for the I/R gerbil model in two parts of the hippocampus in controls and at 3, 48, and 72 h after recanalization. We selected and tested six reference genes frequently used in central nervous system studies: Gapdh, Actb, 18S rRNA, Hprt1, Hmbs, Ywhaz, and additionally Bud23, using RefFinder, a comprehensive tool based on four commonly used algorithms: delta cycle threshold (Ct), BestKeeper, NormFinder, and geNorm, while Hprt1 and Hmbs were the most stable ones in CA2-3,DG. Hmbs was the most stable in the whole hippocampal formation. This indicates that the general use of Hmbs, especially in combination with Gapdh, a highly expressed reference gene, seems to be suitable for qRT-PCR normalization in all hippocampal regions in this model.

NR4A1 inhibits the epithelial–mesenchymal transition of hepatic stellate cells: Involvement of TGF-β–Smad2/3/4–ZEB signaling

This study aimed to examine whether nuclear receptor 4a1 (NR4A1) is involved in inhibiting hepatic stellate cell (HSC) activation and liver fibrosis through the epithelial–mesenchymal transition (EMT). HSC-T6 cells were divided into the control group, the acetaldehyde (200 μM, an EMT activator) group, and the NR4A1 activation group (Cytosporone B; 1 μM). The expression levels of the epithelial marker E-cadherin, the mesenchymal markers fibronectin (FN), vimentin, smooth muscle alpha-actin (α-SMA), and fibroblast-specific protein 1 (FSP-1), and the components of the transforming growth factor (TGF)-β pathway were detected by real-time polymerase chain reaction and western blotting. Compared with the control group, E-cadherin in the acetaldehyde group was downregulated, whereas FN, FSP-1, vimentin, α-SMA, and COL1A1/COL1A2 were upregulated (P < 0.05). Compared with the acetaldehyde group, NR4A1 agonist upregulated E-cadherin and downregulated FN, FSP-1, vimentin, α-SMA, and COL1A1/COL1A2 (P < 0.05). After acetaldehyde stimulation, TGF-β, Smad2/3/4, and zinc finger E-box-binding homeobox (ZEB) were upregulated, while Smad7 mRNA levels were downregulated (all P < 0.05). Compared with acetaldehyde alone, NR4A1 agonist increased Smad7 mRNA levels and reduced TGF-β, Smad2/3/4, and ZEB mRNA levels (all P < 0.05). NR4A1 activation suppresses acetaldehyde-induced EMT, as shown by epithelial and mesenchymal marker expression. The inhibition of the TGF-β–Smad2/3/4–ZEB signaling during HSC activation might be involved.

Validation of housekeeping genes as internal controls for gene expression studies on biofilm formation in Bacillus velezensis

Bacillus velezensis is an important bacterium widely applied in agriculture and industry, and biofilms play critical roles in its environmental tolerance. The appropriate choice of reference genes is essential for key gene expression studies. Multiple internal control genes were selected and validated from the 21 housekeeping genes of B. velezensis by expression stability evaluation during biofilm formation and were used to study the expression of key genes involved in the process. The results showed that pyk, gyrA, recA, and gyrB were stably expressed, and the expression of pyk was the most stable during biofilm formation. A pair of two genes, pyk and gyrA, provided high-quality data when used as internal controls, and the combination of three genes, pyk, gyrA, and recA, was even better. The expression levels of pyk, gyrA, and recA approximated those of five key genes, abrB, epsD, kinC, sinR, and tasA, in biofilm formation, meeting the requirements of ideal internal control genes. The expression patterns of 5 key genes were studied with 16S, pyk, the pair of 2 genes, pyk and gyrA, and the combination of 3 genes, pyk, gyrA, and recA, as internal controls during the biofilm formation process. The results proved that pyk was a suitable internal control, as were the pair of 2 genes, pyk and gyrA, and the combination of 3 genes, pyk, gyrA, and recA. This study provided genes and gene combinations which were validated as suitable internal controls for gene expression studies, especially those on the mechanism of biofilm formation in B. velezensis or even other Bacillus spp. KEY POINTS: • Reference genes is necessary for gene expression study in biofilm formation of Bacillus velezensis • Pyk and 2 gene combinations were selected and validated from 21 common used genes • Expression of key genes in biofilm formation was normalized with the selected internal controls.