Paweł M. Boguszewski

Emotional changes related to age in rats--a behavioral analysis.

The present study investigated age-related differences in the emotional behavior of rats using factor analysis to identify motivational factors influencing spontaneous behavior in open field with illuminated center (OF), plus maze (EPM) and social interactions test. Animals of the same strain, bred under the same conditions, formed two experimental groups: young adults (YA, N=20) tested at the age of 4 months and old rats (OA, N=16) tested at the age of 24 months. The computer video based tracking system EthoVision was used for automated acquisition and analysis of data. The results of each test were analyzed separately for YA and OA by factor analysis. Two main independent factors emerged from the analysis of OF measures-factor 1, which appeared to reflect motor activity, and factor 2, reflecting anxiety. The measures best reflecting motor activity (distance moved in the peripheral zone) and anxiety (time spent in central zone) decreased significantly with age. Factor analysis for EPM measures revealed, in both groups, three independent factors. In YA, factor 1 reflected motor activity, factor 2-anxiety, in OA measures of anxiety loaded on factor 1, measures of activity on factor 2. Factor 3 in both groups appeared to represent a decision making process. The number of entries to the closed arms declined significantly in OA, showing an age related decrease of motor activity. Also, the ratio of open arms entries in relation to the total number of entries decreased in OA, indicating a higher anxiety level. Three independent factors emerged from the analysis of social interaction measures. The pattern of factor loading was different in young and old animals, although the number and time of social interactions did not show age-related differences. In addition to a decrease of motor activity we conclude that old rats also differ from young animals in emotional and social behavior.

The effect of age on the dynamics and the level of c-Fos activation in response to acute restraint in Lewis rats

Recent studies have reported an age-related increase of anxiety in rodents with a concomitant decrease in neuronal activity in some of the key structures of the fear/anxiety circuit. In the present study we present evidence that distinct parts of this circuit are differentially affected by age in Lewis rats. The effect of ageing is observed both at the actual level of neuronal activation and its time-course. While the structures belonging to the HPA axis react with a bigger neuronal activation and almost no change in the shape of dynamics curve in response to restraint, the structures involved in higher processing of emotional cues (amygdala and hippocampus) become deficiently activated with age despite their generally higher basal level of activation.

Age increases anxiety and reactivity of the fear/anxiety circuit in Lewis rats.

A growing body of data indicates that changes in emotional behavior occur with age. Young Lewis rats are known to display hypofunction of the HPA axis. With age the reactivity of this axis is thought to increase with a concomitant rise in anxiety. In the current study, we investigate how and if the pattern of neuronal activation (measured as c-Fos protein expression) in Lewis rat brains changes with age and in response to novel environments differing in aversiveness. We found that distinct parts of the fear/anxiety circuit (i.e., the amygdalar complex, hippocampus and hypothalamus) undergo diverse age-related changes in response to behavioral challenges. While in the hypothalamus an increase in responsivity to mild stressors was observed with age, no such effect was present in the hippocampus. The amygdalar complex (especially the medial and cortical nuclei) on the other hand exhibited an age-dependent decrease in neuronal activation to mild stressors. This was accompanied by a marked increase in anxiety not correlated with a decline in locomotor activity.

Overexpression of STIM1 in neurons in mouse brain improves contextual learning and impairs long-term depression.

STIM1 is an endoplasmic reticulum calcium sensor that is involved in several processes in neurons, including store-operated calcium entry. STIM1 also inhibits voltage-gated calcium channels, such as Cav1.2 and Cav3.1, and is thus considered a multifunctional protein. The aim of this work was to investigate the ways in which transgenic neuronal overexpression of STIM1 in FVB/NJ mice affects animal behavior and the electrophysiological properties of neurons in acute hippocampal slices. We overexpressed STIM1 from the Thy1.2 promoter and verified neuronal expression by quantitative reverse-transcription polymerase chain reaction, Western blot, and immunohistochemistry. Mature primary hippocampal cultures expressed STIM1 but exhibited no changes in calcium homeostasis. Basal synaptic transmission efficiency and short-term plasticity were comparable in slices that were isolated from transgenic mice, similarly as the magnitude of long-term potentiation. However, long-term depression that was induced by the glutamate receptor 1/5 agonist (S)-3,5-dihydroxyphenylglycine was impaired in STIM1 slices. Interestingly, transgenic mice exhibited a decrease in anxiety-like behavior and improvements in contextual learning. In summary, our data indicate that STIM1 overexpression in neurons in the brain perturbs metabotropic glutamate receptor signaling, leading to impairments in long-term depression and alterations in animal behavior. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.

Eco-HAB as a fully automated and ecologically relevant assessment of social impairments in mouse models of autism

Eco-HAB is an open source, RFID-based system for automated measurement and analysis of social preference and in-cohort sociability in mice. The system closely follows murine ethology. It requires no contact between a human experimenter and tested animals, overcoming the confounding factors that lead to irreproducible assessment of murine social behavior between laboratories. In Eco-HAB, group-housed animals live in a spacious, four-compartment apparatus with shadowed areas and narrow tunnels, resembling natural burrows. Eco-HAB allows for assessment of the tendency of mice to voluntarily spend time together in ethologically relevant mouse group sizes. Custom-made software for automated tracking, data extraction, and analysis enables quick evaluation of social impairments. The developed protocols and standardized behavioral measures demonstrate high replicability. Unlike classic three-chambered sociability tests, Eco-HAB provides measurements of spontaneous, ecologically relevant social behaviors in group-housed animals. Results are obtained faster, with less manpower, and without confounding factors. DOI: http://dx.doi.org/10.7554/eLife.19532.001

N-acetyl cysteine does not modify the sensitization of the rewarding effect of amphetamine as assessed with frequency-modulated 50-kHz vocalization in the rat.

A satisfactory pharmacological cure for addictions to psychostimulants has not yet been developed. Because of the well-known role of changes in the corticoaccumbal and corticostriatal glutamatergic system(s) in drug seeking and relapses in psychostimulant addiction, much hope is presently linked to the use of agents that restore glutamate homeostasis. In this regard, one of the most promising agents is N-acetyl cysteine, which has been shown to reverse some changes in neuroplasticity associated with psychostimulant addiction/dependence. In this study, we used the enhancement of locomotor activity and the induction of frequency-modulated 50-kHz ultrasonic vocalization (FM 50-kHz USV) to test the possible stimulant properties of N-acetyl cysteine itself in various experimental settings (acute and subchronic administration in amphetamine-naïve and amphetamine-pretreated rats) and the capacity of N-acetyl cysteine to attenuate both the rewarding effects of amphetamine and the behavioral sensitization to this stimulant in rats showing considerable differences in their susceptibility to the FM 50-kHz USV sensitization. Our data showed no stimulant properties of N-acetyl cysteine and no acute effect of the drug on the rewarding properties of amphetamine. Moreover, no effect of N-acetyl cysteine on the pre-existing sensitization of the FM 50-kHz USV and locomotor activity responses to amphetamine were observed, independent of the susceptibility of the rats to the FM 50-kHz USV sensitization. Hence, N-acetyl cysteine seems to be ineffective at reversing the neurobiological changes underlying the sensitization of these responses to amphetamine in rats.

Pramipexole and Fingolimod exert neuroprotection in a mouse model of Parkinson's disease by activation of sphingosine kinase 1 and Akt kinase

&NA; Parkinsons disease (PD) is one of the most severe neurodegenerative diseases with unknown pathogenesis and currently unsuccessful therapies. Recently, neuroprotection via sphingosine‐1‐phosphate (S1P)‐dependent signalling has become a promising target for the treatment of neurodegenerative disorders. Our previous study demonstrated down‐regulation and inhibition of the S1P‐synthesizing enzyme sphingosine kinase 1 (SPHK1) in a PD cellular model. Moreover, we have previously identified a neuroprotective effect of fingolimod (FTY720), a first S1P receptor modulator utilized in the clinic. This study focused on the effects of FTY720 and the dopamine D2/D3 receptor agonist pramipexole (PPX) in a PD mouse model, induced by administration of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP). Administration of FTY720, similar to PPX, abolished an observed loss of tyrosine hydroxylase (TH) immunoreactivity in MPTP‐lesioned brain regions. Moreover, significant changes in SPHK1 expression/activity in MPTP‐lesioned mouse midbrain were identified. PPX, but not FTY720 treatment, significantly protected against these alterations. Both drugs activate another pro‐survival enzyme, Akt kinase, which is a crucial protein downstream of S1PR(s). FTY720 increased BAD protein phosphorylation and in this way may protect mitochondria against the BAD‐induced apoptotic signalling pathway. Both FTY720 and PPX enhanced the locomotor activity of PD mice in the rotarod tests. Our data suggest a neuroprotective role for FTY720 related to the S1PR/Akt kinase signalling pathways as a beneficial treatment target in planning new PD therapeutic options. Moreover, our findings have shed new light on a neuroprotective mechanism of PPX action associated with SPHK1 activation, which provides an opportunity for evaluating multi‐target (SPHK1/S1P/S1PR) effects in the context of PD. Graphical abstract AbbreviationsMPTP/MPP + ‐ 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine/1‐methyl‐4‐phenylpiridinum; PD ‐ Parkinsons Disease; ROS ‐ reactive oxygen species; SPHK1 ‐ sphingosine kinase 1; S1P ‐ sphingosine‐1‐phosphate; S1P1‐5 ‐ sphingosine‐1‐phosphate receptors; red arrows – the pro‐apoptotic pathways; green arrows ‐ the pro‐survival pathways. Figure. No caption available. HighlightsSphingosine kinase 1 (SPHK1) expression/activity are decreased in PD mouse model.Pramipexole (PPX) reversed a reduction in SPHK1 activity in MPTP‐lesioned mice.Fingolimod (FTY720) exerts a neuroprotective effect in PD mouse model in Akt‐dependent manner.FTY720 and PPX improved locomotor activity in PD mice.

Breathing in Parkinsonism in the Rat

Parkinsonism is underlain by dopamine (DA) deficiency in the mid-brain, a neurotransmitter innately involved with respiratory regulation. However, the state of respiration in parkinsonism is an unsettled issue. In this study we seek to determine ventilation and its responses to hypoxia in a reserpine--alpha-methyl-tyrosine model of parkinsonism in the rat. We also attempted to differentiate between the role of discrete brain and carotid body DA stores in the modulation of the hypoxic ventilatory response (HVR). To this end we used domperidone, a peripheral D2 receptor antagonist, and levodopa, a central D2 receptor agonist. The HVRs to acute 12% and 8% hypoxia were studied in a whole body plethysmograph in the same rats before and after the induction of parkinsonic symptoms in conscious rats. We found that resting ventilation and the HVR were distinctly reduced in parkinsonism. The reduction was particularly evident in the peak hypoxic hyperpneic augmentation. Domperidone, which enhanced ventilation in the control healthy condition, failed to reverse the reduced parkinsonic HVR. In contrast, levodopa, which did not appreciably affected ventilation in the healthy condition, caused the parkinsonic HVR to return to and above the baseline healthy level. The findings demonstrate the predominance of a lack of the central DA stimulatory element and minimize the role of carotid body DA in the ventilatory impediment of parkinsonism. In conclusion, the study provides the pathophysiological savvy concerning the respiratory insufficiency of parkinsonism, a sequela which carries a risk of chronically impaired blood oxygenation, which may drive the disease worsening.

Neuropeptide Y Y2 and Y5 receptors as promising targets for neuroprotection in primary neurons exposed to oxygen-glucose deprivation and in transient focal cerebral ischemia in rats

It was postulated that neuropeptide Y (NPY)-ergic system could be involved in the ischemic pathophysiology, however, the role of particular subtypes of NPY receptors (YRs) in neuroprotection against ischemia is still not well known. Therefore, we investigated the effect of NPY and YR ligands using in vitro and in vivo experimental ischemic stroke models. Our in vitro findings showed that NPY (0.5-1μM) and specific agonists of Y2R (0.1-1μM) and Y5R (0.5-1μM) but not that of Y1R produced neuroprotective effects against oxygen-glucose deprivation (OGD)-induced neuronal cell death, being also effective when given 30min after the end of OGD. The neuroprotective effects of Y2R and Y5R agonists were reversed by appropriate antagonists. Neuroprotection mediated by NPY, Y2R and Y5R agonists was accompanied by the inhibition of both OGD-induced calpain activation and glutamate release. Data from in vivo studies demonstrated that Y2R agonist (10μg/6μl; i.c.v.) not only diminished the infarct volume in rats subjected to transient middle cerebral artery occlusion (MCAO) but also improved selected gait parameters in CatWalk behavioral test, being also effective after delayed treatment. Moreover, we found that a Y5R agonist (10μg/6μl; i.c.v.) did not reduce MCAO-evoked brain damage but improved stride length, when it was given 30min after starting the occlusion. In conclusion, our studies indicate that Y5 and especially Y2 receptors may be promising targets for neuroprotection against ischemic damage.

Three-dimensional grammar in the brain: Dissociating the neural correlates of natural sign language and manually coded spoken language.

In several countries natural sign languages were considered inadequate for education. Instead, new sign-supported systems were created, based on the belief that spoken/written language is grammatically superior. One such system called SJM (system językowo-migowy) preserves the grammatical and lexical structure of spoken Polish and since 1960s has been extensively employed in schools and on TV. Nevertheless, the Deaf community avoids using SJM for everyday communication, its preferred language being PJM (polski język migowy), a natural sign language, structurally and grammatically independent of spoken Polish and featuring classifier constructions (CCs). Here, for the first time, we compare, with fMRI method, the neural bases of natural vs. devised communication systems. Deaf signers were presented with three types of signed sentences (SJM and PJM with/without CCs). Consistent with previous findings, PJM with CCs compared to either SJM or PJM without CCs recruited the parietal lobes. The reverse comparison revealed activation in the anterior temporal lobes, suggesting increased semantic combinatory processes in lexical sign comprehension. Finally, PJM compared with SJM engaged left posterior superior temporal gyrus and anterior temporal lobe, areas crucial for sentence-level speech comprehension. We suggest that activity in these two areas reflects greater processing efficiency for naturally evolved sign language.