Porsolt Swim Test Research Articles

Paternal immune activation by Poly I:C modulates sperm noncoding RNA profiles and causes transgenerational changes in offspring behavior

Paternal pre-conceptual environmental experiences, such as stress and diet, can affect offspring brain and behavioral phenotypes via epigenetic modifications in sperm. Furthermore, maternal immune activation due to infection during gestation can reprogram offspring behavior and brain functioning in adulthood. However, the effects of paternal pre-conceptual exposure to immune activation on the behavior and physiology of offspring (F1) and grand-offspring (F2) are not currently known. We explored effects of paternal pre-conceptual exposure to viral-like immune activation on F1 and F2 behavioral and physiological phenotypes using a C57BL/6J mouse model. Males were treated with a single injection (intraperitoneal) of the viral mimetic polyinosinic:polycytidylic acid (Poly I:C: 12 mg/kg) then bred with naïve female mice four weeks after the Poly I:C (or 0.9% saline control) injection. The F1 offspring of Poly I:C treated fathers displayed increased depression-like behavior in the Porsolt swim test, an altered stress response in the novelty-suppressed feeding test, and significant transcriptomic changes in their hippocampus. Additionally, the F1 male offspring of Poly I:C treated F0 males showed significantly increased immune responsivity after a Poly I:C immune challenge (12 mg/kg). Furthermore, the F2 male grand-offspring took longer to enter and travelled significantly shorter distances in the light zone of the light/dark box. An analysis of the small noncoding RNA profiles in sperm from Poly I:C treated males and their male offspring revealed significant effects of Poly I:C on the sperm microRNA content at the time of conception and on the sperm PIWI-interacting RNA content of the male offspring. Notably, eight miRNAs with an FDR < 0.05 (miR-141-3p, miR-126b-5p, miR-669o-5p, miR-10b-3p, miR-471-5p, miR-463-5p, miR-148b-3p, and miR-181c-5p) were found to be significantly downregulated in the sperm of Poly I:C treated males. Collectively, we demonstrate that paternal pre-conceptual exposure to a viral immune challenge results in both intergenerational and transgenerational effects on brain and behavior that may be mediated by alterations in the sperm small noncoding RNA content.

Anxiety-like Behavior in Female Sprague Dawley Rats Associated with Cecal Clostridiales.

The relationship between the microbiota profile and exposure to stress is not well understood. Therefore, we used a rat model of unpredictable chronic mild stress (UCMS) to investigate this relationship. Depressive-like behaviors were measured in Female Sprague Dawley rats using the sucrose preference test and the Porsolt swim test. Anxiety-like behaviors were measured with the light-dark box test. Fecal corticosterone, cecal microbiota (composition and organic acids), plasma gut permeability (lipopolysaccharide-binding protein, LBP) and plasma inflammation (12 cytokines) markers were measured. Atypical behaviors were observed in female rats following UCMS, but no depressive-like behaviors were observed. Circulating concentrations of cytokines granulocyte-macrophage colony-stimulating factor and cytokine-induced neutrophil chemoattractant 1 were higher in UCMS-exposed female rats; plasma LBP and cecal organic acid levels remained unchanged. Our results reflect a resilient and adaptive phenotype for female SD rats. The relative abundance of taxa from the Clostridiales order and Desulfovibrionaceae family did, however, correlate both positively and negatively with anxiety-like behaviors and plasma cytokine concentrations, regardless of UCMS exposure, supporting the brain-to-gut influence of mild anxiety with a microbiota profile that may involve inflammatory pathways.

Loss of Tyro3 causes anxiety-relevant behavioural changes in female mice.

White-matter brain abnormalities have been found across a variety of psychiatric disorders. The extent of white matter pathology is proposed to be predictive of the severity of anxiety disorders. However, it is still unknown whether disruptions of white matter integrity precede, and are sufficient to give rise to, the behavioural symptoms. Interestingly, mood disturbances feature prominently in central demyelinating diseases such as multiple sclerosis. It is unclear whether the greater frequency of neuropsychiatric symptoms is linked to underlying neuropathology. In this study, we characterised male and female Tyro3 knockout (KO) mice using a variety of behavioural paradigms. Anxiety-related behaviours were assessed with the elevated-plus maze and light-dark box. Fear memory processing was assessed using fear conditioning and extinction paradigms. Finally, we assessed immobility time in the Porsolt swim test as a measure of depression-related behavioural despair. Surprisingly, loss of Tyro3 did not lead to manifestation of major shifts in baseline behaviour. We noted significant differences in habituation to novel environments and post-conditioning freezing levels of female Tyro3 KO mice, which are consistent with the female bias in anxiety disorders and could be indicative of maladaptive stress-responses. This study has demonstrated that white matter pathology related to a loss of Tyro3 is associated with pro-anxiety behavioural responses of female mice. Future studies could probe their contribution to increased risk for neuropsychiatric disorders when combined with stressful triggering events.

Novel Antidepressant-Like Properties of the Iron Chelator Deferiprone in a Mouse Model of Depression

Depressed individuals who carry the short allele for the serotonin-transporter-linked promotor region of the gene are more vulnerable to stress and have reduced response to first-line antidepressants such as selective serotonin reuptake inhibitors. Since depression severity has been reported to correlate with brain iron levels, the present study aimed to characterise the potential antidepressant properties of the iron chelator deferiprone. Using the serotonin transporter knock-out (5-HTT KO) mouse model, we assessed the behavioural effects of acute deferiprone on the Porsolt swim test (PST) and novelty-suppressed feeding test (NSFT). Brain and blood iron levels were also measured following acute deferiprone. To determine the relevant brain regions activated by deferiprone, we then measured c-Fos expression and applied network-based analyses. We found that deferiprone reduced immobility time in the PST in 5-HTT KO mice and reduced latency to feed in the NSFT in both genotypes, suggesting potential antidepressant-like effects. There was no effect on brain or blood iron levels following deferiprone treatment, potentially indicating an acute iron-independent mechanism. Deferiprone reversed the increase in c-Fos expression induced by swim stress in 5-HTT KO mice in the lateral amygdala. Functional network analyses suggest that hub regions of activity in mice treated with deferiprone include the caudate putamen and prefrontal cortex. The PST-induced increase in network modularity in wild-type mice was not observed in 5-HTT KO mice. Altogether, our data show that the antidepressant-like effects of deferiprone could be acting via an iron-independent mechanism and that these therapeutic effects are underpinned by changes in neuronal activity in the lateral amygdala.

Changes in the psychoemotional state under the influence of derivatives of neuroactive amino acids of rats after chronic alcohol intoxication

To study an effect of neuroactive amino acids derivatives glufimet and mefargin on the psychoemotional state of rats after chronic alcohol intoxication (CAI). The study was carried out on 10-month-old female Wistar rats. CAI was modeled by replacing drinking water with a 10% solution of ethyl alcohol sweetened with sucrose (50 g/l) for 6 months. Animals (age - 16 months) were divided into groups at the end of alcoholization: 1 (n=15) - intact group - rats without CAI; 2 (n=14) - control - females after CAI; 3 (n=11), 4 (n=14), 5 (n=11) and 6 (n=10) - experimental - females after CAI who received the GABA derivative mefargin (25 mg/kg), the glutamic acid derivative glufimet (29 mg/kg) and comparison drugs phenotropil (25 mg/kg) and heptral (100 mg/kg), respectively. Substances were administered to rats after 6 months of alcoholization intraperitoneally once a day for 14 days, the intact and control groups received physiological saline. The psychoemotional state of the animals was studied in the «Open field» test, «Elevated plus maze» test, «Marble burying» test and the Porsolt swim test after the treatment. In animals of the control group, an increase in anxiety was noted, as evidenced by a greater number of boluses in the Open Field test (3.43±0.56 vs. 1.47±0.39) compared to the intact group (p<0.05), short duration of stay in open arms (26.07±3.47 vs. 68.67±10.08) and fewer hangings from them (3.07±0.25 vs. 6.67±0.79) in the «Elevated plus maze» test. Rats after CAI buried more balls (8.79±1.15 versus 2.73±0.71, p<0.05), which indicated that they had compulsive behavior. In addition, females of the control group were observed to be depressed, as evidenced by a long period of immobilization in the Porsolt swim test (2.36±0.41 versus 0.87±0.31, p<0.05). Mefargin, glufimet, phenotropil and heptral restricted anxiety and manifestations of obsessive-compulsive disorder in females subjected to alcoholism (p<0.05). The antidepressant effect was observed in animals treated with phenotropil and heptral after CAI (p<0.05).

The use of aminoacid additives in antistress neuroprotective diets

Throughout life, the human body is constantly exposed to stressful factors. The influence of stress reduces the overall state of the body (especially the immune system), reproductive capabilities, performance, memory, and leads to premature aging. Especially affected are people whose professional activities are associated with unfavorable factors (daily duties, psychoemotional overstrains, physical exertion, violation of the diet), which leads to early professional burnout. Therefore, it is necessary to search for substances that increase the body’s resistance to stress and the possibility of using them for preventive purposes. This article presents the results aimed at studying the antistress properties of the N-phenylacetyl-L-prolylglycine compound. The substance was synthesized in the Research Institute of Pharmacology of the Russian Academy of Medical Sciences. The study was conducted on rats with a high level of anxiety of two ages (3 months old, 1.5 years old), since they are the most sensitive to stress influence. For the selection of animals, the following physiological tests were used: the "Porsolt swimming test", the "open field" test. A 30-minute swim at a water temperature of 28-30°C was used as a stress factor. The neuroprotective properties of the aminoacid additive were determined by indicators of peroxidation and activation of the antioxidant system. The content of malondialdehyde and superoxide dismutase, the activity of ceruloplasmin and catalase, the concentration of extra-erythrocyte hemoglobin, the total peroxidase activity was evaluated. The aminoacid additive (N-phenylacetyl-L-prolylglycine) was found to develop neuroprotective properties. In all animals, the use of an aminoacid additive reduces the intensity of the processes of lipid peroxidation and activates the antioxidant systems. However, in young rats the changes in indicators were significantly positive. The results of this study may be the basis for the use of aminoacid additives as functional ingredients with neuroprotective properties in the production of food in the food industry.

The forced swim test: Giving up on behavioral despair (Commentary on Molendijk & de Kloet, 2021).

The forced swim test: Giving up on behavioral despair (Commentary on Molendijk & de Kloet, 2021).

The possibility of using amino acid supplements for stress prevention

Every day, the modern human body is exposed to stress of various etiologies. One of the main effects of long-term stress is to accelerate the rate of premature aging. These processes affect the decrease in working capacity, reproductive capabilities, affect memory, emotions, behavior, vegetative reactions of a person, etc. The influence of unfavorable factors of professional activity (daily duty, psychoemotional overload, physical activity, violation of the diet) leads to early professional burnout. Therefore, it is important to search for and study the mechanisms of action of substances whose use for preventive purposes leads to a stable state of the body to stress. This article presents information on the study of the stress-detecting activity of a Proline-containing compound synthesized at the research Institute of pharmacology of the Russian Academy of medical Sciences. The experiment used male rats with a high level of anxiety of two ages - 3-month-old sexually Mature and 1.5-year-old. The animals were selected based on physiological tests: “Porsolt swimming test”,“open field” test. Stress was simulated by forced 30-minute swimming at a water temperature of 28-30°C. Stress-detecting mechanisms of action of the amino acid compound were evaluated by indicators of the leukocyte formula and the content of biogenic amines. It was found that the development of the strategy of adaptation to the action of a stressful factor (30-minute swimming) depends on age. In young animals, when using an amino acid compound, a hormonal type of activation of the sympathoadrenal system was noted, which is the most effective. The body of 1.5-year-old rats reacted to external influence by activating the sympathoadrenal system along the mediator pathway and entering the depletion phase. The results of this study can be the basis for the use of amino acid compounds as a functional ingredient with a stress-inducing property in the production of food in the food industry.

Chronic stress followed by social isolation promotes depressive-like behaviour, alters microglial and astrocyte biology and reduces hippocampal neurogenesis in male mice

Unpredictable chronic mild stress (UCMS) is one of the most commonly used, robust and translatable models for studying the neurobiological basis of major depression. Although the model currently has multiple advantages, it does not entirely follow the trajectory of the disorder, whereby depressive symptomology can often present months after exposure to stress. Furthermore, patients with depression are more likely to withdraw in response to their stressful experience, or as a symptom of their depression, and, in turn, this withdrawal/isolation can further exacerbate the stressful experience and the depressive symptomology. Therefore, we investigated the effect(s) of 6 weeks of UCMS followed by another 6 weeks of social isolation (referred to as UCMSI), on behaviour, corticosterone stress responsivity, immune system functioning, and hippocampal neurogenesis, in young adult male mice. We found that UCMSI induced several behavioural changes resembling depression but did not induce peripheral inflammation. However, UCMSI animals showed increased microglial activation in the ventral dentate gyrus (DG) of the hippocampus and astrocyte activation in both the dorsal and ventral DG, with increased GFAP-positive cell immunoreactivity, GFAP-positive cell hypertrophy and process extension, and increased s100β-positive cell density. Moreover, UCMSI animals had significantly reduced neurogenesis in the DG and reduced levels of peripheral vascular endothelial growth factor (VEGF) – a trophic factor produced by astrocytes and that stimulates neurogenesis. Finally, UCMSI mice also had normal baseline corticosterone levels but a smaller increase in corticosterone following acute stress, that is, the Porsolt Swim Test. Our work gives clinically relevant insights into the role that microglial and astrocyte functioning, and hippocampal neurogenesis may play in the context of stress, social isolation and depression, offering a potentially new avenue for therapeutic target.

Differences in the dopaminergic reward system in rats that passively and actively behave in the Porsolt test

The aim of the study was to assess appetitive responses and central dopaminergic neurotransmission in passive and active rats divided according to their immobility time in the Porsolt swim test and exposed to restraint stress. Passive rats had more episodes of appetitive 50-kHz ultrasonic vocalization (USV) during rat encounter after social isolation and spent significantly more time in the amphetamine-associated context in conditioned place preference test, compared to active rats. Restraint stress decreased sucrose preference, but increased appetitive vocalization and reinforced the conditioned place preference only in passive animals that was associated with increased dopamine concentration in the amygdala. Restraint stress increased also the level of Cocaine- and Amphetamine Regulated Transcript (CART) peptide, a neuromodulator linked to dopamine neurotransmission, in the central nucleus of amygdala, while decreasing it the nucleus accumbens shell in passive rats. In the parvocellular region of paraventricular nucleus of the hypothalamus passive animals had a higher expression of CART compared to passive restraint rats and active control rats.The obtained results show that active and passive rats in the Porsolt test differ significantly in response to appetitive stimuli, which can be additionally changed under stress conditions. The underlying mechanisms are probably associated with differences in dopaminergic activity and CART signaling in reward system.

High Fat Diet Impacts Gut Microbiome Differently in Male and Female Sprague Dawley Rats

Obesity has increased during the last couple of decades and is strongly related to cardiovascular disease, hyperlipidemia, diabetes, and neurological disorders, such as depression, which tend to be more prevalent in women. A high fat diet (HFD) is associated with negative effects on the gut microbiome, including increased Firmicutes/Bacteriodetes ratio (F/B ratio) which may affect the integrity of the intestinal barrier. Gut microbiome transplants from male to female rats have been shown to decrease diabetes type 1 in females, suggesting sex differences in the gut microbiome. Previous studies in our lab have shown that Sprague Dawley male rats fed with a HFD showed a depressive‐like behavior and also a decrease of tight junction proteins in the gut suggesting gut permeability. However, it is not clear whether the effects of a HFD on the microbiome are based on gender differences.AIMTo ascertain whether the administration of a HFD will affect differently the gut microbiome in males and females.METHODSThere were four groups of Sprague Dawley rats (n=12/group): Female Low‐Fat Diet (FLFD), Female High Fat Diet (FHFD), Male Low‐Fat Diet (MLFD), Male High Fat Diet (MHFD). Female and male postnatal rats were fed with a LFD (10% fat) for 6 weeks. Then, half of each group were transferred to a HFD (60% fat) for 8 weeks. We measured absolute weight daily, and rats were tested for depressive like syndrome in a porsolt swim test one day before sacrifice. Fat and feces were collected from all animals to assess differences in the gut microbiome.RESULTSRats showed no differences in absolute weight nor in percent weight gain in either group, however, MHFD showed an increase of epidydimal fat tissue compared to MLFD. FHFD group showed a significant increase in immobility compared with the FLFD group suggesting depressive like syndrome (p&lt;0.05). Measurement of depressive like syndrome in males was limited by their size and did not reach significance. In gut microbiome, MHFD showed a significant increase in the F/B ratio compared with the MLFD, however, in females there were no significant differences. Females on a high‐fat diet had a significant increase in Proteobacteria compared to FLFD (p&lt;0.05). In contrast MHFD showed a significant increase in Verrucomicrobia compared with the MLFD (p&lt;0.05).CONCLUSIONSA HFD affects the gut microbiome of males and females differently. The significance of this study is that sex differences may be a potential factor in how a HFD might contribute towards various pathophysiological conditions via differing effects on the gut microbiome.Support or Funding InformationSupported by NIGMS/INBRE P20 GM103475‐14 and RCMI G12 MD007579This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Antidepressant-Like Actions of Inhibitors of Poly(ADP-Ribose) Polymerase in Rodent Models.

BackgroundMany patients suffering from depressive disorders are refractory to treatment with currently available antidepressant medications, while many more exhibit only a partial response. These factors drive research to discover new pharmacological approaches to treat depression. Numerous studies demonstrate evidence of inflammation and elevated oxidative stress in major depression. Recently, major depression has been shown to be associated with elevated levels of DNA oxidation in brain cells, accompanied by increased gene expression of the nuclear base excision repair enzyme, poly(ADP-ribose) polymerase-1. Given these findings and evidence that drugs that inhibit poly(ADP-ribose) polymerase-1 activity have antiinflammatory and neuroprotective properties, the present study was undertaken to examine the potential antidepressant properties of poly(ADP-ribose) polymerase inhibitors.MethodsTwo rodent models, the Porsolt swim test and repeated exposure to psychological stressors, were used to test the poly(ADP-ribose) polymerase inhibitor, 3-aminobenzamide, for potential antidepressant activity. Another poly(ADP-ribose) polymerase inhibitor, 5-aminoisoquinolinone, was also tested.ResultsPoly(ADP-ribose) polymerase inhibitors produced antidepressant-like effects in the Porsolt swim test, decreasing immobility time, and increasing latency to immobility, similar to the effects of fluoxetine. In addition, 3-aminobenzamide treatment increased sucrose preference and social interaction times relative to vehicle-treated control rats following repeated exposure to combined social defeat and unpredictable stress, mediating effects similar to fluoxetine treatment.ConclusionsThe poly(ADP-ribose) polymerase inhibitors 3-aminobenzamide and 5-aminoisoquinolinone exhibit antidepressant-like activity in 2 rodent stress models and uncover poly(ADP-ribose) polymerase as a unique molecular target for the potential development of a novel class of antidepressants.

Depressive-like behavior is elevated among offspring of parents exposed to dim light at night prior to mating

Rates of major depressive disorder (MDD) have steadily increased over the past 50 years. Many factors have been implicated in the etiology of depressive disorders and environmental influences are being increasingly recognized. The increase in depression rates has coincided with increased artificial nighttime lighting. Exposure to light at night (LAN) has been associated with increased depressive-like behavior in rodents and decreased mood in humans. However, relatively little is known on the multigenerational effects of dLAN on affect. In this study, we exposed adult male and female Siberian hamsters (Phodopus sungorus) to either DARK (0lx) or dim LAN (5lx) for 9 weeks, then paired animals in a full factorial design; all animals were thereafter housed in dark nights. Offspring were gestated and reared in dark nights, then tested in adulthood for depressive-like behaviors and hippocampal expression of glucocorticoid (GR) and melatonin (MT1) receptor expression. Maternal exposure to dLAN decreased sucrose preference, time to first float bout in the Porsolt swim test, and GR expression in the hippocampus. Paternal exposure to dLAN increased time spent floating, and increased hippocampal GR expression. Overall, our results suggest that chronic exposure of parents to light at night has multigenerational effects on offspring depressive-like behavior. If these results pertain to humans, then our data suggest that LAN may contribute to the rapidly rising rates of major depressive disorder in industrialized and developing countries.

Interaction of Cocaine- and Amphetamine-regulated Transcript and Neuropeptide Y on Behavior in the Central Nervous System.

In the central nervous system, cocaine- and amphetamine-regulated transcript (CART) 55-102 peptide is localized in areas, such as the ventral tegmental area, amygdala, hypothalamus, and hippocampus, where emotional activity is regulated. Studies on the effects of the intracerebroventricular (ICV) administration of CART peptide on behavior remain limited. The findings from these studies suggest that this neuropeptide has anxiogenic-like effects. In the central nervous system, neuropeptide Y (NPY) has similar localization as CART. Previous behavioral studies have demonstrated that the ICV administration of NPY has anxiolytic-like effects. In our study, we established five experimental groups of male Wistar rats to study the competitive effects of NPY and CART peptide. These groups were sham (n=10), CART (n=10), NPY (n=10), CART-NPY (n=10), and NPY-CART (n=10). The open field test, elevated plus maze test, and Porsolt swim test were performed for behavioral analyses. Moreover, the rats were decapitated after the behavioral tests, and the amount of these two peptide in their brains was quantified. Our study revealed that the ICV administration of CART peptide is anxiogenic and inhibits animals undergoing learned helplessness in the Porsolt swim test. When we evaluated the results of our study with respect to NPY, we observed its anxiolytic-like effects; in the Porsolt swim test, although it reduced the duration of immobilization, it did not affect the period of struggle. Our results revealed that during the competitive interaction of these two peptides, anxiogenic CART peptide suppressed the anxiolytic effects of NPY.

Forebrain-Specific Loss of BMPRII in Mice Reduces Anxiety and Increases Object Exploration.

To investigate the role of Bone Morphogenic Protein Receptor Type II (BMPRII) in learning, memory, and exploratory behavior in mice, a tissue-specific knockout of BMPRII in the post-natal hippocampus and forebrain was generated. We found that BMPRII mutant mice had normal spatial learning and memory in the Morris water maze, but showed significantly reduced swimming speeds with increased floating behavior. Further analysis using the Porsolt Swim Test to investigate behavioral despair did not reveal any differences in immobility between mutants and controls. In the Elevated Plus Maze, BMPRII mutants and Smad4 mutants showed reduced anxiety, while in exploratory tests, BMPRII mutants showed more interest in object exploration. These results suggest that loss of BMPRII in the mouse hippocampus and forebrain does not disrupt spatial learning and memory encoding, but instead impacts exploratory and anxiety-related behaviors.

P.1.h.041 Effect of fluoxetine and alprazolam on escape response induced by hypoxia

effects on behavior, gene expression and DNA methylation in the hippocampus, particularly of female 5-Htt+/− offspring. To follow up this interaction, in the present study we aim to investigate the role of a PS x 5-Htt interaction in resilience in female wild type (5-Htt+/+) and heterozygous (±) 5-HTT deficient offspring. To this end, we applied the maternal restraint stress paradigm of PS in female 5-Htt+/+ and 5-Htt+/− mice from E13 to E17, three times a day. We then analyzed behavioral parameters related to anxietyand depressive-like behavior as well as hypothalamic– pituitary–adrenal axis function in the adult female offspring. We found that the PS mice spent less time with a conspecific animal in the 3-chamber-sociability test than controls (p = 0.012, 2-factorial ANOVA). Based on the sociability data, we separated 5-Htt+/+ and 5-Htt+/− PS offspring into a ‘normally social’, resilient group, comparable to control animals, and an ‘unsocial’, susceptible group, which showed no preference for spending time with the conspecific animal, in contrast to the control group. Locomotor activity, basal and stress-induced corticosterone levels, anxietylike behavior in the EPM, behavioral despair in the Porsolt swim test and anhedonia in the sucrose preference were analyzed based on the classification in resilient and susceptible groups. While susceptible PS 5-Htt+/+ animals showed less anxiety-like behavior in the elevated plus maze when compared to control 5-Htt+/+ mice (Man-Whitney-U Bonferroni-Holmes corrected p = 0.032), this effect was not found for the 5-Htt+/− genotype animals. On the other hand, susceptible 5-Htt+/− mice showed a trend for increased basal corticosterone levels (Man-Whitney-U BonferroniHolmes corrected p = 0.071), whereas no differences for basal corticosterone were found for 5-Htt+/+ animals. No effects of PS or genotype were observed in the Porsolt swim test and the sucrose preference test. Thus, our findings indicate a modulating role of the 5-Htt genotype on the role of resilience towards PS in female mice. Next on our agenda, we aim to identify the molecular players that are mediating the interaction between PS and the 5-Htt genotype in the context of vulnerability and resilience to PS. For this purpose, gene expression profiles of the hippocampus are currently being analyzed using mRNAseq. Arising candidate genes will then be validated using qPCR and analyzed in regard of DNA methylation and histone modifications.

Behavioral assessment of acute inhibition of system xc (-) in rats.

Gaps in our understanding of glutamatergic signaling may be key obstacles in accurately modeling complex CNS diseases. System xc (-) is an example of a poorly understood component of glutamate homeostasis that has the potential to contribute to CNS diseases. This study aims to determine whether system xc (-) contributes to behaviors used to model features of CNS disease states. In situ hybridization was used to map mRNA expression of xCT throughout the brain. Microdialysis in the prefrontal cortex was used to sample extracellular glutamate levels; HPLC was used to measure extracellular glutamate and tissue glutathione concentrations. Acute administration of sulfasalazine (8-16mg/kg, IP) was used to decrease system xc (-) activity. Behavior was measured using attentional set shifting, elevated plus maze, open-field maze, Porsolt swim test, and social interaction paradigm. The expression of xCT mRNA was detected throughout the brain, with high expression in several structures including the basolateral amygdala and prefrontal cortex. Doses of sulfasalazine that produced a reduction in extracellular glutamate levels were identified and subsequently used in the behavioral experiments. Sulfasalazine impaired performance in attentional set shifting and reduced the amount of time spent in an open arm of an elevated plus maze and the center of an open-field maze without altering behavior in a Porsolt swim test, total distance moved in an open-field maze, or social interaction. The widespread distribution of system xc (-) and involvement in a growing list of behaviors suggests that this form of nonvesicular glutamate release is a key component of excitatory signaling.

Anxiety- and depression-like behavior are correlated with leptin and leptin receptor expression in prefrontal cortex of streptozotocin-induced diabetic rats

Anxiety and depression are common in diabetics. Diabetes also may cause reduced leptin levels in the blood. We investigated the relation between diabetes induced anxiety- and depression-like behavior, and leptin and leptin receptor expression levels in diabetic rats. The anxiety- and depression-like behaviors of rats were assessed 4 weeks after intraperitoneal injection of streptozotocin. Diabetic rats exhibited greater anxiety-like behavior; they spent more time in closed branches of the elevated plus maze test and less time in the center cells of the open field arena. Increased depression-like behavior was observed in diabetic rats using the Porsolt swim test. Prefrontal cortex (PFC), blood leptin levels and PFC neuron numbers were decreased, and leptin receptor expression and apoptosis were increased in diabetic rats. Blood corticosterone levels also were increased in diabetic rats. These results indicate that reduction of leptin up-regulates leptin receptor expression and may affect PFC neurons, which eventually triggers anxiety- and depression-like behaviors in diabetic rats.

2691 – Bilateral transection of the chorda tympani and lingual nerves increased anxiety- and depression-like behaviors in rats

Sensory information plays an important role to determine psycho-emotional behaviors of individuals. In this study, we have examined psycho-emotional behaviors of rats after disrupting the oral sensory relay to brain with bilateral transection of the chorda tympami and lingual nerve (LNX). LNX rats are expected to lose their sensory information from the anterior two thirds of the tongue. Two weeks after the nerve transections or sham operations, rats were subjected to behavioral sessions to examine anxiety- and depression-like behaviors, and the brain monoamine levels were analyzed by high-performance liquid chromatography. Initial weight loss after the surgery was bigger in LNX rats and this effect remained during the whole experimental period, although daily food intake per 100 g body weight became greater in LNX rats. Ambulatory activity was decreased, anxiety-related behaviors during the activity test increased, time spent in the open arms during elevated plus maze test decreased, and immobility duration during Porsolt swim test increased in LNX rats compared with sham rats. LNX rats showed anhedonia with decreased sucrose consumption compared to sham rats. Serotonin levels in the hippocampus were decreased in LNX rats compared with sham rats. Results suggest that disruption of oral sensory relay to brain may lead to the development of depression- and anxiety-related disorders, and decreased serotonergic activity in the hippocampus play a role in its underlying mechanism. Supported by the NRF (2010-0003642) funded by MOEST

Sustained expression of brain-derived neurotrophic factor is required for maintenance of dendritic spines and normal behavior

Brain-derived neurotrophic factor (BDNF) plays important roles in the development, maintenance, and plasticity of the mammalian forebrain. These functions include regulation of neuronal maturation and survival, axonal and dendritic arborization, synaptic efficacy, and modulation of complex behaviors including depression and spatial learning. Although analysis of mutant mice has helped establish essential developmental functions for BDNF, its requirement in the adult is less well documented. We have studied late-onset forebrain-specific BDNF knockout (CaMK-BDNFKO) mice, in which BDNF is lost primarily from the cortex and hippocampus in early adulthood, well after BDNF expression has begun in these structures. We found that although CaMK-BDNFKO mice grew at a normal rate and can survive more than a year, they had smaller brains than wild-type siblings. The CaMK-BDNFKO mice had generally normal behavior in tests for ataxia and anxiety, but displayed reduced spatial learning ability in the Morris water task and increased depression in the Porsolt swim test. These behavioral deficits were very similar to those we previously described in an early-onset forebrain-specific BDNF knockout. To identify an anatomical correlate of the abnormal behavior, we quantified dendritic spines in cortical neurons. The spine density of CaMK-BDNFKO mice was normal at P35, but by P84, there was a 30% reduction in spine density. The strong similarities we find between early- and late-onset BDNF knockouts suggest that BDNF signaling is required continuously in the CNS for the maintenance of some forebrain circuitry also affected by developmental BDNF depletion.