Effect of chronic valproic Acid treatment on hepatic gene expression profile in wfs1 knockout mouse

Valproic acid (VPA) is a widely used anticonvulsant and mood-stabilizing drug whose use is often associated with drug-induced weight gain. Treatment with VPA has been shown to upregulate Wfs1 expression in vitro. Aim of the present study was to compare the effect of chronic VPA treatment in wild type (WT) and Wfs1 knockout (KO) mice on hepatic gene expression profile. Wild type, Wfs1 heterozygous, and homozygous mice were treated with VPA for three months (300?mg/kg i.p. daily) and gene expression profiles in liver were evaluated using Affymetrix Mouse GeneChip 1.0?ST array. We identified 42 genes affected by Wfs1 genotype, 10 genes regulated by VPA treatment, and 9 genes whose regulation by VPA was dependent on genotype. Among the genes that were regulated differentially by VPA depending on genotype was peroxisome proliferator-activated receptor delta (Ppard), whose expression was upregulated in response to VPA treatment in WT, but not in Wfs1 KO mice. Thus, regulation of Ppard by VPA is dependent on Wfs1 genotype

Wfs1-deficient mice display altered function of serotonergic system and increased behavioral response to antidepressants

It has been shown that mutations in the WFS1 gene make humans more susceptible to mood disorders. Besides that, mood disorders are associated with alterations in the activity of serotonergic and noradrenergic systems. Therefore, in this study, the effects of imipramine, an inhibitor of serotonin (5-HT) and noradrenaline (NA) reuptake, and paroxetine, a selective inhibitor of 5-HT reuptake, were studied in tests of behavioral despair. The tail suspension test (TST) and forced swimming test (FST) were performed in Wfs1-deficient mice. Simultaneously, gene expression and monoamine metabolism studies were conducted to evaluate changes in 5-HT- and NA-ergic systems of Wfs1-deficient mice. The basal immobility time of Wfs1-deficient mice in TST and FST did not differ from that of their wild-type littermates. However, a significant reduction of immobility time in response to lower doses of imipramine and paroxetine was observed in homozygous Wfs1-deficient mice, but not in their wild-type littermates. In gene expression studies, the levels of 5-HT transporter (SERT) were significantly reduced in the pons of homozygous animals. Monoamine metabolism was assayed separately in the dorsal and ventral striatum of naive mice and mice exposed for 30 min to brightly lit motility boxes. We found that this aversive challenge caused a significant increase in the levels of 5-HT and 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of 5-HT, in the ventral and dorsal striatum of wild-type mice, but not in their homozygous littermates. Taken together, the blunted 5-HT metabolism and reduced levels of SERT are a likely reason for the elevated sensitivity of these mice to the action of imipramine and paroxetine. These changes in the pharmacological and neurochemical phenotype of Wfs1-deficient mice may help to explain the increased susceptibility of Wolfram syndrome patients to depressive states

CB1 receptors and anandamide expression is increased in mesolimbic structure after exposure to cat odour

Endocannabinoid system consists of two receptors (CB1, CB2), their endogeneous ligands and the enzymes responsible for their synthesis and degradation. In our experiment we have exposed rats to cat odour to induce the ethologically relevant anxiety reaction in rats. The elevated zero-maze was also performed to test alterations of the emotional behaviour. The animals were killed and RNA was isolated from different brain regions. cDNA expression of genes involved in synthesis or degradation of endocananbinoids (NAPE-PLD, FAAH, PLC and DAGLa, MGLL and receptor CB1) were analyzed in hippocampus, in amygdala and in mesolimbic structure using quantitative real-time PCR. In control group the highest gene exspression level was in CB1 receptors. The FAAH ekspression was 2, 6 times higher in amygdala compared to mesolimbic structure. The MGLL expression in contrary was 6 times higher in mesolimbic structure compared to amygdala. DAGLa expression was 2 times higher than NAPE-PLD expression and there has been also shown that the level of 2-AG in brain is higher than the level of anandamide. Unexpectedly, there were no significant gene expression changes in amygdala and in hipocampus in these animals exposed to cat-odour compared to the control group rats. Also, no differences of the gene expression were in rats preformed zero-maze compared to the control group. But, we found some gene expression changes in mesolimbic structure. There was higher (1, 4 times) CB1 gene expression level rats exposed to cat odour compared to the control group. Also, the expression of NAPE-PLD was 1, 6 times higher than the control group and the level of FAAH expression was 1, 8 times higher. Therefore, there is possible, that the endocannabionid system is more important in mesolimbic structure and anandamide, but not 2-AG synthesis mediates anxiety-related behaviour

Screen for genes in periaqueductal grey of male Wistar rats related to reduced exploratory activity in the elevated plus-maze

Aim of a present study was to find genes in the periaqueductal grey (PAG) related to the exploratory behavior in rats. Male Wistar rats were divided according to their exploratory behavior in the elevated plus-maze model of anxiety into two groups: high (non-anxious) and low (anxious) exploratory activity. Differential expression of genes was analyzed using the cDNA representational difference analysis (RDA). Q-RT-PCR was used to confirm most prominent changes and functional annotation of the identified genes was performed to establish pathways related to exploratory behavior of rats. We found different genetic activation related to the exploratory activity of rats. Rats with low exploratory activity showed increase in the intracellular signal transduction and in GABA, vasopressin and adrenergic receptor activities. Functional annotation confirmed significant induction of cAMP system and GTPases in rats with anxious-type behavior. On the other hand, rats with high exploratory activity in the elevated plus-maze (non-anxious type of behavior) had increased activity of genes forming “behavioral fear response” system. These changes were specific to PAG, because they were not found in the cerebellum. In addition, plasma corticosterone levels were significantly higher in rats with non-anxious behavior compared to anxious behavior. Our results show that non-anxious behavior is related to activation of “fear response system” and more intense activation of HPA axis. Possibly it means that this system helps animals to cope with the threatening circumstances. More detailed analysis of this potential “fear response system” is necessary in the further studies for understanding its role in the regulation of emotional behavior

Cat odour induced anxiety in rodents: changes in expression of neuropeptide genes in brain structures

The effect of cat odour exposure was studied on the behaviour and neuropeptide gene expression in rodents. Exposure to the cat odour suppressed the exploratory activity of male Wistar rats in the elevated zero-maze. Treatment with morphine (1 mg/kg) increased the exploratory behaviour of rats in an unfamiliar environment. Previous exposure of animals to the cat odour completely abolished this stimulating action of morphine. Cat odour exposure induced a significant increase in the expression of Pomc1, Oprm1 and Cck genes in the brain structures related to anxiety and motivation. The similar study was also performed in female 129Sv/C57/Bl6 mice. The exposure of wild-type and homozygous CCK2 receptor deficient mice to the cat odour did not reveal substantial differences between the two genotypes. However, the following exposure of mice to the elevated plus-maze established differences as homozygous mice displayed increased exploratory activity in the plus-maze. The cat odour exposure significantly reduced exploratory activity only in homozygous mice. Together with the increased exploratory activity in homozygous mice the expression of Oprm1 gene was elevated in the frontal cortex and mesencephalon. Thus, the reduced anxiety of homozygous mice seems to be related to an increased tone of opioid system in the brain. The exposure of mice to cat odour did not change the gene expression in wild-type mice, whereas in homozygous animals a significantly increased expression of the Mc3r gene in the frontal cortex and temporal lobe, and the Pomc1 gene in the temporal lobe, mesencephalon and mesolimbic area was established. Therefore, it is likely that the increased function of melanocortin system is responsible for the anxiogenic effect of cat odour exposure in homozygous mice. In conclusion, the experiments conducted on rodents demonstrate that the cat odour exposure induced anxiety is accompanied by the compensatory changes in the activity of opioid and melanocortin systems

Cat odour-induced anxiety—a study of the involvement of the endocannabinoid system

Rationale Recent evidence suggests the involvement of the endocannabinoid (EC) system in the regulation of anxiety. Objectives The aim of present work was to study the role of the EC system in cat odour-induced anxiety in rats. Materials and methods Male Wistar rats were exposed to cat odour in home and motility cages. Exposure of rats to elevated zero-maze was used to determine changes in anxiety. Effect of rimonabant (0.3–3 mg/kg), antagonist of CB1 receptors, was studied on cat odour-induced alterations in exploratory behaviour. Real-time PCR was used to determine gene expression levels of EC-related genes in the brain. Results Anxiogenic-like action of cat odour was evident in the elevated zero-maze. Cat odour increased the expression of FAAH, the enzyme responsible for the degradation of anandamide, in the mesolimbic area. By contrast, in the amygdala and periaqueductal grey (PAG) levels of NAPE-PLD, the enzyme related to the synthesis of anandamide, and FAAH were remarkably decreased. Cat odour also decreased the expression of enzymes related to metabolism of 2-archidonoyl-glycerol in the amygdala and PAG. Pre-treatment of rats with rimonabant (0.3–3 mg/kg) reduced the exploratory behaviour of rats, but did not affect cat odour-induced changes. Conclusion Exposure to cat odour induces anxiogenic-like effect on the behaviour in rats. Cat odour also causes moderate increase in expression of EC-related genes in the mesolimbic area, whereas significant down-regulation is established in the amygdala and PAG. Relation of predator odour-induced anxiety to the inhibition of the EC system in the amygdala and PAG is supported by behavioural studies where blockade of CB1 receptors by rimonabant induces anxiogenic-like action

Relation between increased anxiety and reduced expression of alpha1 and alpha2 subunits of GABAA receptors in Wfs1-deficient mice

Mutations in the coding region of the WFS1 gene cause Wolfram syndrome, a rare multisystem neurodegenerative disorder of autosomal recessive inheritance. In clinical studies a relation between mutations in the Wfs1 gene and increased susceptibility for mood disorders has been established. According to our previous studies, mice lacking Wfs1 gene displayed increased anxiety in stressful environment. As the GABA-ergic system plays a significant role in the regulation of anxiety, we analyzed the expression of GABA-related genes in the forebrain structures of wild-type and Wfs1-deficient mice. Experimentally naïve Wfs1-deficient animals displayed a significant down-regulation of α1 (Gabra1) and α2 (Gabra2) subunits of GABAA receptors in the temporal lobe and frontal cortex. Exposure of wild-type mice to the elevated plus-maze decreased levels of Gabra1 and Gabra2 genes in the temporal lobe. A similar tendency was also established in the frontal cortex of wild-type animals exposed to behavioral test. In Wfs1-deficient mice the elevated plus-maze exposure did not induce further changes in the expression of Gabra1 and Gabra2 genes. By contrast, the expression of Gad1 and Gad2 genes, enzymes responsible for the synthesis of GABA, was not significantly affected by the exposure of mice to the elevated plus-maze or by the invalidation of Wfs1 gene. Altogether, the present study demonstrates that increased anxiety of Wfs1-deficient mice is probably linked to reduced expression of Gabra1 and Gabra2 genes in the frontal cortex and temporal lobe

Lsamp–/– mice display lower sensitivity to amphetamine and have elevated 5-HT turnover

In mice, the limbic system-associated membrane protein (Lsamp) gene has been implicated in locomotion, anxiety, fear reaction, learning, social behaviour and adaptation. Human data links the LSAMP gene to several psychiatric disorders and completed suicide. Here, we investigated changes in major monoamine systems in mice lacking the Lsamp gene. First, the locomotor and rewarding effects of amphetamine were studied in Lsamp–/– mice and Lsamp+/+ mice. Second, monoamine levels in major brain regions in response to saline and amphetamine injections were measured and, third, the expression levels of dopamine system-related genes in the brain were studied in these mice. Lsamp–/– mice displayed lower sensitivity to amphetamine in the motility box. Likewise, in the place preference test, the rewarding effect of amphetamine was absent in Lsamp–/– mice. In all brain regions studied, Lsamp–/– mice displayed lower serotonin (5-HT) baseline levels, but a greater 5-HT turnover rate, and amphetamine increased the level of 5-HT and lowered 5-HT turnover to a greater extent in Lsamp–/– mice. Finally, Lsamp–/– mice had lower level of dopamine transporter (DAT) mRNA in the mesencephalon. In conclusion, Lsamp-deficiency leads to increased endogenous 5-HT-ergic tone and enhanced 5-HT release in response to amphetamine. Elevated 5-HT function and reduced activity of DAT are the probable reasons for the blunted effects of amphetamine in these mice. Lsamp–/– mice are a promising model to study the neurobiological mechanisms of deviant social behaviour and adaptation impairment observed in many psychiatric disorders

Cat odor exposure induces distinct changes in the exploratory behavior and Wfs1 gene expression in C57Bl/6 and 129Sv mice

129Sv and C57Bl/6 (Bl6) strains are two most widely used inbred mice strains for generation of transgenic animals. The present study confirms the existence of substantial differences in the behavior of these two mice strains. The exploratory behavior of Bl6 mice in a novel environment was significantly higher compared to 129Sv mice. The exposure of mice to cat odor-induced an anxiety-like state in Bl6, but not in 129Sv mice. The levels of Wfs1 gene expression did not differ in the prefrontal cortex, mesolimbic area and temporal lobe of experimentally naive Bl6 and 129Sv mice. However, after cat odor exposure the expression of Wfs1 gene was significantly lower in the mesolimbic area and temporal lobe of Bl6 mice compared to 129Sv strain. Dynamics of Wfs1 gene expression and exploratory behavior suggest that the down-regulation of Wfs1 gene in Bl6 mice might be related to the increased anxiety. Further studies are needed to test the robustness and possible causal relationship of this finding