Search

We demonstrate that the rate of extracellular signal-related kinase phosphorylation (P-ERK1,2/Total-ERK1,2) in the amygdala is negatively and independently associated with anxiety symptoms in 23 consecutive patients with drug-resistant mesial temporal lobe epilepsy that was surgically treated. In naive Wistar rats, the P-ERK1,2/Total-ERK1,2 ratio in the amygdala correlates negatively with innate anxiety-related behavior on the elevated plus maze (n = 20) but positively with expression of defensive-learned behavior (i.e., freezing) on Pavlovian aversive (fear) conditioning (n = 29). The microinfusion of ERK1/2 inhibitor (FR180204, n = 8-13/group) or MEK inhibitor (U0126, n = 8-9/group) into the basolateral amygdala did not affect anxiety-related behavior but impaired the evocation (anticipation) of conditioned-defensive behavior (n = 9-11/group). In conclusion, the P-ERK1,2/Total-ERK1,2 ratio in the amygdala predicts anxiety in humans and the innate anxiety- and conditioned freezing behaviors in rats. However, the ERK1/2 in the basolateral AMY is only required for the expression of defensive-learned behavior. These results support a dissociate ERK-dependent mechanism in the amygdala between innate anxiety-like responses and the anticipation of learned-defensive behavior. These findings have implications for understanding highly prevalent psychiatric disorders related to the defensive circuit manifested by anxiety and fear. HIGHLIGHTS: The P-ERK1,2/Total-ERK1,2 ratio in the amygdala (AMY) correlates negatively with anxiety symptoms in patients with mesial temporal lobe epilepsy. The P-ERK1,2/Total-ERK1,2 in the amygdala correlates negatively with the anxiety-like behavior and positively with freezing-learned behavior in naive rats. ERK1,2 in the basolateral amygdala is required for learned-defensive but not for the anxiety-like behavior expression in rats., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

The central autonomic network, which is connected to the limbic system structures including the amygdala (AMY) and anterior hippocampus (aHIP), regulates the sympathetic and parasympathetic modulation of visceromotor, neuroendocrine, pain, and behavior manifestations during stress responses. Heart rate variability (HRV) is useful to estimate the cardiac autonomic tone. The levels of phosphorylation on the Ser831 and Ser845 sites of the GluA1 subunit of the AMPAr (P-GluA1-Ser845 and P-GluA1-Ser831) are useful markers of synaptic plasticity. The relation between synaptic plasticity in the human limbic system structures and autonomic regulation in humans is unknown. This study investigated the association between HRV and neurochemistry biomarkers of synaptic plasticity in AMY and aHIP. HRV indices were obtained from the resting state electrocardiogram of patients with drug-resistant mesial temporal lobe epilepsy (MTLE, n = 18) and the levels of P-GluA1-Ser845 and P-GluA1-Ser831 in the AMY and aHIP resected during the epilepsy surgery. A backward stepwise multiple linear regression models were used to analyze the association between HRV and synaptic plasticity biomarkers controlling for imbalances in the distribution of sociodemographic, clinical, neuroimaging, and neurosurgical variables. P-GluA1-Ser845 levels in AMY show a negative association (p < 0.05) with the 3 investigated parasympathetic autonomic HRV indices (SDNN, rMSSD, and HF) predicting 24 to 40% of their variation. The final multiple linear regression models include disease duration and levels of P-GluA1-Ser845 and predict 24 to 56% of cardiac autonomic tone variation (p < 0.01). P-GluA1-Ser845 levels in AMY and aHIP are negatively associated with the resting HRV in MTLE-HS indicating that increased synaptic efficiency in amygdala is associated with a parasympathetic cardiac autonomic tone impairment. The results suggest that specific changes in synaptic plasticity may be involved in the brain-heart axis regulation by the limbic system.

The quantitative analysis of electroencephalogram (qEEG) is a suitable tool for mental fatigue (MF) assessment. Here, we evaluated the effects of MF on behavioral performance and alpha power spectral density (PSD) and the association between early alpha PSD reactivity and long-term behavioral MF impairments. Nineteen right-handed adults (21.21 ± 1.77 years old) had their EEG measured during five blocks of the visual oddball paradigm (~ 60 min). A paired t-test was used to compare first and last block values of cognitive performance and alpha PSD. The sample was divided into high (HAG) and low alpha group (LAG) by early alpha PSD median values. The behavioral performance of the HAG and LAG was compared across the blocks by a two-way ANOVA with repeated measures (groups and blocks). MF impairs general behavioral performance and increases alpha PSD. The HAG presents more behavioral impairment when compared to LAG across the task. Simple linear regression between early alpha PSD and behavioral performance across the task can predict 19 to 39% of variation in general behavior impairment by MF. In conclusion, MF induction impairs general behavioral and increases alpha PSD. The other finding was that higher alpha PSD reactivity is associated to higher long-term behavioral impairments of MF. This work contributes to existing knowledge of MF by providing evidence that the possibility of investigating early electrophysiological biomarkers to predict long-term MF impairments.

Behavioral and neuroendocrine responses following threatening situations promote the release of corticosterone, which is known to modulate trauma-related learning and memory process. However, it remains unknown whether the aversive learning generated by interoceptive fear conditioning is affected by glucocorticoid modulation. Therefore, the present study aimed to investigate the role of dexamethasone suppression in encoding and expression of pentylenetetrazole-induced olfactory fear conditioning (OFC) and in contextual second-order conditioning promoted by the conditioned odor. Adult male Long-Evans rats were treated with dexamethasone 60 min before the encoding or the expression in both OFC and contextual second-order conditioning. Dexamethasone treatment impaired encoding and expression of the OFC, but failed to impair encoding and expression of the contextual second-order conditioning. Altogether, our results show that although OFC and thereafter contextual second-order conditioning may allow the study of traumatic memories, each order of conditioning seems to present specific features related to their pharmacological modulation. These findings highlight the importance of addressing the role of neuromodulatory systems in first-order and second-order conditioning to gain a better understanding of these phenomena and support future therapies related to traumatic memories.

Excessive mental workload represent a critical risk factor for workplace accidents. Heart rate variability (HRV) is a non-invasive low cost electrophysiological autonomic biomarker related to emotional and cognitive regulation. Several studies report that mental overload impairs parasympathetic-mediated HRV indices (e.g. rMSSD). However, the influence of resting state HRV as a predictor of long-term mental workload impairments remains unknown. Thirty participants (22 males; 8 females) had their HRV measured (5-min period) before performing the number search task. After the task, the mental load was accessed by the NASA-TLX questionnaire. A simple linear regression model between HRV and NASA-TLX dimensions showed that resting state rMSSD is associated to physical demand (ND-2, R 2  = 0.143, p = 0.03) and frustration level (ND-6, R 2  = 0.175, p = 0.02) dimensions of mental workload. The comparison between 1 and 5-min epochs suggests that regression models remain reliable even using the ultra-short term HRV (< 1 min) recording values (R 2 values from 0.11 to 0.15 for ND-2 and R 2 values from 0.16 to 0.19 for ND-6). These results suggest that resting state HRV is associated to long-term effects of mental workload on physical and emotional demands. In addition, the ultra-short term HRV indices remains reliable to assess ND-2 and ND-6 dimensions of mental workload when compared to gold-standard time interval (> 5 min). The resting state cardiac autonomic tone assessment optimizes the physiological approach with a quick, non-invasive and low-cost assessment that can provide insights about mental load adjustments to prevent work-related accidents.

Fear is a conscious state caused by exposure to real or imagined threats that trigger stress responses that affect the body and brain, particularly limbic structures. A sub-group of patients with mesial temporal lobe epilepsy related to hippocampus sclerosis (MTLE-HS) have seizures with fear, which is called ictal fear (IF), due to epileptic activity within the brain defensive survival circuit structures. Synaptic transmission efficacy can be bi-directionally modified through potentiation (long-term potentiation (LTP)) or depression (long-term depression (LTD)) as well as the phosphorylation state of Ser831 and Ser845 sites at the GluA1 subunit of the glutamate AMPA receptors, which has been characterized as a critical event for this synaptic plasticity. In this study, GluA1 levels and the phosphorylation at Ser845 and Ser831 in the amygdala (AMY), anterior hippocampus (aHIP) and middle gyrus of temporal neocortex (CX) were determined with western blots and compared between MTLE-HS patients who were showing (n = 06) or not showing (n = 25) IF. Patients with IF had an 11% decrease of AMY levels of the GluA1 subunit (p = 0.05) and a 21.5% decrease of aHIP levels of P-GluA1-Ser845 (p = 0.009) compared to patients not showing IF. The observed associations were not related to imbalances in the distribution of other concomitant types of aura, demographic, clinical or neurosurgical variables. The lower levels of P-GluA1-Ser845 in the aHIP of patients with IF were not related to changes in the levels of the serine/threonine-protein phosphatase PP1-alpha catalytic subunit or protein kinase A activation. Taken together, the GluA1 subunit levels in AMY and P-GluA1-Ser845 levels in the aHIP show an overall accuracy of 89.3% (specificity 95.5% and sensitivity 66.7%) to predict the presence of IF. AMY levels of the GluA1 subunit and aHIP levels of P-GluA1-Ser845 were not associated with the psychiatric diagnosis and symptoms of patients. Taken together with previous findings in MTLE-HS patients with IF who were evaluated by stereotactic implanted depth electrodes, we speculate our findings are consistent with the hypothesis that AMY is not a centre of fear but together with other sub-cortical and cortical structures integrates the defensive circuit that detect and respond to threats. This is the first report to address neuroplasticity features in human limbic structures connected to the defensive survival circuits, which has implications for the comprehension of highly prevalent psychiatric disorders and symptoms.

The cholinergic system is one of the most important neurotransmitter systems in the brain with key roles in autonomic control and the regulation of cognitive and emotional responses. However, the precise mechanism by which the cholinergic system influences behaviour is unclear. Adult hippocampal neurogenesis (AHN) is a potential mediator in this context based on evidence, which has identified this process as putative mechanism of antidepressant action. More recently, post-transcriptional regulation by microRNAs is another candidate mechanism based on its involvement in the regulation of AHN and neurotransmission. Taking into account this background, we evaluated the behavioural effects of a non-convulsant dose of pilocarpine - a non-selective muscarinic receptor (mAChR) agonist - in adult Wistar rats. Furthermore, we quantified the expression of different microRNAs implicated in the regulation of AHN. Our results suggests that pilocarpine treatment increases AHN in the granular cell layer but also induced ectopic neurogenesis. Pilocarpine treatment reduced immobility time in forced swimming test but did not affect fear conditioning response, sucrose preference or novelty supressed feeding behaviour. In addition, treatment with pilocarpine down-regulated the expression of 6 microRNAs implicated in the regulation of neurotrophin signalling and axon guidance pathways. Therefore, we suggest that the low-dose stimulation of the cholinergic system is sufficient to alter AHN of rats through post-transcriptional mechanisms, which might contribute to long-lasting behavioural effects., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objectives: Sleepiness and cognitive impairment are common symptoms observed in patients with epilepsy. We investigate whether self-reported sleepiness is associated with cognitive performance in patients with refractory mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). Seventy-one consecutive patients with MTLE-HS were evaluated with the Stanford Sleepiness Scale (SSS) before neuropsychological evaluation. Their mean SSS scores were compared with controls. Each cognitive test was compared between patients with (SSS ≥ 3) or without sleepiness (SSS < 3). Imbalances were controlled by regression analysis. Patients reported a significantly higher degree of sleepiness than controls (p < 0.0001). After multiple linear regression analysis, only one test (RAVLT total) remained associated with self-reported sleepiness., Conclusion: Self-reported sleepiness was significantly higher in MTLE-HS patients than controls, but did not affect their cognitive performance. If confirmed in other populations, our results may have implications for decision making about sleepiness screening in neuropsychological settings.

Background: Recent studies have reported that Heart Rate Variability (HRV) indices remain reliable even during recordings shorter than 5 min, suggesting the ultra-short recording method as a valuable tool for autonomic assessment. However, the minimum time-epoch to obtain a reliable record for all HRV domains (time, frequency, and Poincare geometric measures), as well as the effect of respiratory rate on the reliability of these indices remains unknown., Methods: Twenty volunteers had their HRV recorded in a seated position during spontaneous and controlled respiratory rhythms. HRV intervals with 1, 2, and 3 min were correlated with the gold standard period (6-min duration) and the mean values of all indices were compared in the two respiratory rhythm conditions., Results: rMSSD and SD1 were more reliable for recordings with ultra-short duration at all time intervals (r values from 0.764 to 0.950, p < 0.05) for spontaneous breathing condition, whereas the other indices require longer recording time to obtain reliable values. The controlled breathing rhythm evokes stronger r values for time domain indices (r values from 0.83 to 0.99, p < 0.05 for rMSSD), but impairs the mean values replicability of domains across most time intervals. Although the use of standardized breathing increases the correlations coefficients, all HRV indices showed an increase in mean values (t values from 3.79 to 14.94, p < 0.001) except the RR and HF that presented a decrease (t = 4.14 and 5.96, p < 0.0001)., Conclusion: Our results indicate that proper ultra-short-term recording method can provide a quick and reliable source of cardiac autonomic nervous system assessment., (© 2018 Wiley Periodicals, Inc.)

Interictal hypometabolism is commonly measured by 18-fluoro-deoxyglucose Positron Emission Tomography (FDG-PET) in the temporal lobe of patients with mesial temporal lobe epilepsy (MTLE-HS). Left temporal lobe interictal FDG-PET hypometabolism has been associated with verbal memory impairment, while right temporal lobe FDG-PET hypometabolism is associated with nonverbal memory impairment. The biochemical mechanisms involved in these findings remain unknown. In comparison to healthy controls (n=21), surgically treated patients with MTLE-HS (n=32, left side=17) had significant lower scores in the Rey Auditory Verbal Learning Test (RAVLT retention and delayed), Logical Memory II (LMII), Boston Naming test (BNT), Letter Fluency and Category Fluency. We investigated whether enzymatic activities of the mitochondrial enzymes Complex I (C I), Complex II (C II), Complex IV (C IV) and Succinate Dehydrogenase (SDH) from the resected samples of the middle temporal neocortex (mTCx), amygdala (AMY) and hippocampus (HIP) were associated with performance in the RAVLT, LMII, BNT and fluency tests of our patients. After controlling for the side of hippocampus sclerosis, years of education, disease duration, antiepileptic treatment and seizure outcome after surgery, no independent associations were observed between the cognitive test scores and the analyzed mitochondrial enzymatic activities (p>0.37). Results indicate that memory and language impairment observed in MTLE-HS patients are not strongly associated with the levels of mitochondrial CI, CII, SDH and C IV enzymatic activities in the temporal lobe structures ipsilateral to the HS lesion., (Copyright © 2017 Elsevier B.V. All rights reserved.)

(1) Objectives: Epilepsy disorder is likely to increase with aging, leading to an increased incidence of comorbidities and mortality. In spite of that, there is a lack of information regarding this issue and little knowledge of cognitive and emotional responses in aging subjects following epileptogenesis. We investigated whether and how aging distress epilepsy-related behavioral and biochemical outcomes are associated with cognition and emotion. (2) Methods: Young and middle-aged Wistar rats (3 or 12 months old) were treated with pentylenetetrazol (PTZ, 35 mg/kg) and injected on alternated days for 20 (young rats) and 32 days (middle-aged rats). Kindling was reached after two consecutive stages 4 plus one stage 5 or 6 in Racine scale. Control and kindled rats were evaluated in the elevated plus-maze (EPM) and object-recognition tests and their hippocampus was collected 24 h later for mitogen-activated protein kinases (MAPK) dosage. (3) Results: Middle-aged rats presented a higher resistance to develop kindling, with a decrease in the seizure severity index observed following the 4th and 9th PTZ injections. Middle-aged rats displayed an increased duration of the first myoclonic seizure and an increased latency to the first generalized seizure when compared to younger rats. The induction of kindling did not impair the animals' performance (regardless of age) in the object-recognition task and the EPM test as well as it did not alter the hippocampal levels of MAPKs. (4) Significance: Our findings reveal that, despite age-related differences during epileptogenesis, middle-aged rats evaluated after kindling performed similarly during discriminative learning and emotional tasks in comparison to young animals, with no alteration of hippocampal MAPKs. Additional investigation must be carried out to explore the electrophysiological mechanisms underlying these responses, as well as the long-term effects displayed after kindling., Competing Interests: The authors declare no conflict of interest.

The potential efficacy of cannabinoid receptor ligands for the treatment of epilepsy remains controversial; cannabis components that act via cannabinoid type 1 (CB1) receptors produce anticonvulsant effects in animal models despite treatment with the CB receptor agonist reliably inducing convulsions in various species. Moreover, the potential role of cannabinoid receptor type 2 (CB2) to modulate seizures remains under-investigated. This study assessed the effects of the selective CB2 receptor agonist, AM1241, on pentylenetetrazole (PTZ)-induced seizures in rats. A stereotactically placed guide cannula was surgically implanted into the right lateral ventricle in adult Wistar rats which, 5-6days later, received an acute intracerebroventricular (i.c.v.) microinfusion of AM1241 (0.01, 1 or 10μg/2μl or vehicle) 5min before intraperitoneal (i.p.) injection of PTZ (70mg/kg). Rats were observed for 30min and the seizure severity behavior measured using a modified Racine's scale. Additional groups of rats were pretreated with a single low dose of the selective CB2 receptor antagonist, AM630 (dose 1mg/kg; i.p.), or vehicle, 30min prior to i.c.v. microinfusion of AM1241 (1μg/2μl). AM1241 administration significantly increased tonic-clonic seizure incidence and severity while also decreasing the onset of generalized seizures (AM1241 1 and 10μg/2μl). Pretreatment with AM630 prevented the proconvulsant effects of AM1241. This study shows, for the first time, that selective activation of CB2 receptors can increase generalized seizure susceptibility and suggests that pathological hyperexcitability phenomena can be differentially regulated by targeting CB1 and CB2 receptors., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Neuropeptides have an important role in several psychiatric conditions. Among them, neuropeptide Y (NPY) seems to be essential to modulate some features of stress-related disorders. Post-traumatic stress disorder (PTSD), characterized by inappropriate fear generalization to safe situations may be modulated by NPY manipulation since this neuropeptide is involved in the promotion of coping with stress. Experimentally, coping strategies have been obtained after exposure in enriched environment (EE) rather than standard one. Thus, in the present study we aimed to assess whether short-term EE situation and NPY-Y1 receptor (Y1r) modulation may affect the extinction of contextual fear conditioning, an experimental approach to PTSD. Here we show that EE-rats have the contextual fear extinction facilitated, and this facilitation was reverted by central infusion of BIBO3304, a nonpeptide Y1r antagonist. In addition, protein analysis revealed an upregulation of hippocampal Y1r in conditioned EE-rats, but no changes were observed in EE-rats that were not conditioned. Our results demonstrated that protective properties of EE on fear extinction can be regulated, at least in part, by activation of NPY-signaling through Y1r within hippocampus, an area that plays a major role in contextual memories. Overall, the activation of Y1r is important to promote better and faster perception of self-location (context), and to reduce fear generalization in rats exposed to EE., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Extensive evidence indicates the influence of the cholinergic system on emotional processing. Previous findings provided new insights into the underlying mechanisms of long-term anxiety, showing that rats injected with a single systemic dose of pilocarpine--a muscarinic receptor (mAChR) agonist--displayed persistent anxiogenic-like responses when evaluated in different behavioral tests and time-points (24 h up to 3 months later). Herein, we investigated whether the pilocarpine-induced long-term anxiogenesis modulates the HPA axis function and the putative involvement of NMDA receptors (NMDARs) following mAChRs activation. Accordingly, adult male Wistar rats presented anxiogenic-like behavior in the elevated plus-maze (EPM) after 24 h or 1 month of pilocarpine injection (150 mg/kg, i.p.). In these animals, mAChR activation disrupted HPA axis function inducing a long-term increase of corticosterone release associated with a reduced expression of hippocampal GRs, as well as consistently decreased NMDAR subunits expression. Furthermore, in another group of rats injected with memantine--an NMDARs antagonist (4 mg/kg, i.p.)--prior to pilocarpine, we found inhibition of anxiogenic-like behaviors in the EPM but no further alterations in the pilocarpine-induced NMDARs downregulation. Our data provide evidence that behavioral anxiogenesis induced by mAChR activation effectively yields short- and long-term alterations in hippocampal NMDARs expression associated with impairment of hippocampal inhibitory regulation of HPA axis activity. This is a novel mechanism associated with anxiety-like responses in rats, which comprise a putative target to future translational studies.

The epileptogenesis process involves cell signaling events associated with neuroplasticity. The mitogen-activated protein kinases (MAPKs) integrate signals originating from a variety of extracellular stimuli and may regulate cell differentiation, survival, cell death and synaptic plasticity. Here we compared the total and phosphorylated MAPKs (ERK1/2, JNK1/2 and p38(MAPK)) levels in the neocortex and hippocampus of adult Swiss male mice quantified by western blotting analysis 48 h after the last injection of pentylenetetrazole (PTZ), according to the kindling protocol (35 mg/kg, i.p., on alternated days, with a total of eight injections). The total levels of the investigated MAPKs and the phospho-p38(MAPK) in the neocortex and hippocampus were not affected by the PTZ injections. The MAPKs phosphorylation levels remain unaltered in PTZ-treated animals without convulsive seizures. The phospho-JNK2 phosphorylation, but not the phospho-JNK1, was increased in the hippocampus of PTZ-treated animals showing 1-3 days with convulsive seizures, whereas no significant changes were observed in those animals with more than 3 days with convulsive seizures. The phospho-ERK1/2 phosphorylation decreased in the neocortex and increased in the hippocampus of animals with 1-4 days with convulsive seizures and became unaltered in mice that showed convulsive seizures for more than 4 days. These findings indicate that resistance to PTZ kindling is associated with unaltered ERK1/2, JNK1/2 and p38(MAPK) phosphorylation levels in the neocortex and hippocampus. Moreover, when the PTZ kindling-induced epileptogenesis manifests behaviorally, the activation of the different MAPKs sub-families shows a variable and non-linear pattern in the neocortex and hippocampus.

Recent evidence supports a role for the substance P (SP) in the control of anxiety and epilepsy disorders. Aversive stimuli alter SP levels and SP immunoreactivity in limbic regions, suggesting that changes in SP-NK1 receptor signaling may modulate the neuronal excitability involved in seizures and anxiogenesis. The involvement of NK1 receptors of the dorsal hippocampus and lateral septum in the anxiogenic-like effects induced by a single injection of pilocarpine (PILO) was examined in non-convulsive rats evaluated in the elevated plus-maze (EPM). Male Wistar rats were systemically injected with methyl-scopolamine (1mg/kg) followed 30 min later by saline or PILO (350 mg/kg) and only rats that did not present status epilepticus were used. One month later, vehicle or FK888 (100 pmol) - an NK1 receptor antagonist - were infused in the dorsal hippocampus or the lateral septum of the rats and then behaviorally evaluated in the EPM. Previous treatment with PILO decreased the time spent in and the frequency of entries in the open arms of the EPM, besides altering risk-assessment behaviors such as the number of unprotected head-dipping, protected stretch-attend postures and the frequency of open-arms end activity, showing thus a long-lasting anxiogenic-like profile. FK888 did not show any effect per se but inhibited the anxiogenic responses induced by PILO when injected into the dorsal hippocampus, but not into the lateral septum. Our data suggest that SP-NK1 receptor signaling of the dorsal hippocampus is involved in the anxiogenic-like profile induced by PILO in rats evaluated in the EPM test., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The cholinergic system is implicated in emotional regulation. The injection of non-convulsant doses of the muscarinic receptor agonist pilocarpine (PILO) induces long-lasting anxiogenic responses in rats evaluated at different time-points (24h to 3 months). To investigate the underlying mechanisms, rats treated with PILO (150mg/kg) were injected 24h or 1 month later with an anxiolytic (diazepam, 1mg/kg, DZP) or anxiogenic (pentylenetetrazole, 15mg/kg, PTZ) drug and evaluated in the elevated plus-maze (EPM). Prefrontal cortex (PFC) and hippocampal (HIP) electroencephalographic recordings and acetylcolinesterase (AChE) activity were also analyzed after PILO treatment. Anxiogenic responses observed in the EPM 24h or 1 month after PILO treatment (e.g., decreased time spent and number of entries into the open arms of the maze) were blocked by DZP but not affected by PTZ. No epileptiform events were registered in the HIP or PFC at 24h or 1 month after PILO injection, but enhanced theta activity was observed in the HIP. DZP decreased hippocampal theta of PILO-treated rats in contrast with PTZ, which increased this parameter in saline- and PILO-treated rats. The HIP and PFC AChE activity did not change after PILO treatment. Our findings demonstrate that the long-term effects on the emotionality of rats induced by PILO are associated with electrophysiological changes in the HIP and sensitive to pharmacological manipulation of the GABAergic system. The present work may support this new research model of long-lasting anxiety, while also highlighting the muscarinic system as a potential target involved in anxiety disorders., (© 2013 Elsevier B.V. All rights reserved.)

L-DOPA alleviates the motor symptoms of Parkinson's disease, but its long-term use is associated with undesirable dyskinesia. We now tested whether exercise can attenuate this L-DOPA-induced dyskinesia (LID). We tested the effects of exercise on LID in 6-hydroxydopamine hydrochloride-hemiparkinsonian mice. Animals were treated with L-DOPA/benserazide (25/12.5 mg/kg, i.p.) without and with possibility to exercise (running wheel) during 2 weeks. Exercise drastically prevented the development of LID, and its associated aberrant striatal signaling, namely the hyperphosphorylation of dopamine and cAMP-regulated phosphoprotein 32 kDa protein and c-Fos expression. Our results indicate that exercise can partially prevent the development of LID through the normalization of striatopallidal dopaminergic signaling., (Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.)

Searching for new therapeutic strategies through modulation of glutamatergic transmission using effective neuroprotective agents is essential. Glutamatergic excitotoxicity is a common factor to neurodegenerative diseases and acute events such as cerebral ischemia, traumatic brain injury, and epilepsy. This study aimed to evaluate behavioral and electroencephalographic (EEG) responses of mice cerebral cortex and hippocampus to subconvulsant and convulsant application of NMDA and quinolinic acid (QA), respectively. Moreover, it aimed to evaluate if EEG responses may be related to the neuroprotective effects of NMDA. Mice were preconditioned with NMDA (75 mg/kg, i.p.) and EEG recordings were performed for 30 min. One day later, QA was injected (36.8 nmol/site) and EEG recordings were performed during 10 min. EEG analysis demonstrated NMDA preconditioning promotes spike-wave discharges (SWDs), but it does not display behavioral manifestation of seizures. Animals that were protected by NMDA preconditioning against QA-induced behavioral seizures, presented higher number of SWD after NMDA administration, in comparison to animals preconditioned with NMDA that did display behavioral seizures after QA infusion. No differences were observed in latency for the first seizure or duration of seizures. EEG recordings after QA infusion demonstrated there were no differences in the number of SWD, latency for the first seizure or duration of seizures in animals pretreated with saline or in animals preconditioned by NMDA that received QA. A negative correlation was identified between the number of NMDA-induced SWD and QA-induced seizures severity. These results suggest a higher activation during NMDA preconditioning diminishes mice probability to display behavioral seizures after QA infusion.

Rationale: There is extensive evidence indicating the influence of seizures on emotional responses observed in human and animals, but so far few studies are focusing on the behavioral profile of animals that do not have seizures despite being treated with convulsant agents., Objectives: We aimed to establish the behavioral profile, biochemical, and electrographic features of rats submitted to the pilocarpine model of temporal lobe epilepsy, Methods: Rats treated with pilocarpine (20 to 350 mg/kg, i.p.) that did not develop status epilepticus or spontaneous recurrent seizures were evaluated 1 month later in the elevated plus maze (EPM), T-maze (ETM), open-field (OF), and step-down avoidance tests. Electroencephalographic (EEG), glutamate uptake, and hippocampal neuronal death assays were also performed, Results: Pilocarpine (150 or 350 mg/kg) promoted anxiogenic-like effects in rats evaluated in the EPM, ETM, and OF tests, whereas only the highest dose evoked spike-wave discharges during EEG recordings. Hippocampal theta rhythm was increased by pilocarpine 150 or 350 mg/kg and only the highest dose reduced the L-[(3)H]-glutamate uptake and cell viability on hippocampal slices., Conclusions: Subconvulsant doses of pilocarpine promote long-lasting alterations on neural circuitry, reflected by an increased theta activity in the hippocampus and an anxiety-like profile of rats evaluated 1 month after the treatment which is independent of seizure occurrence and is not related to changes in glutamate uptake or hippocampal damage. These results prompt us to suggest that a systemic administration of subconvulsant doses of pilocarpine could be useful as a new tool to model trait anxiety in rats.

Central injections of serotonin (5-HT) produce hyperdipsic and hypnogenic behavioral effects that are correlated to decreased Fos-immunorreactivity of 5-HT neurons in free-feeding pigeons. We herein (1) probed the role of 5-HT(1A) receptors on the 5-HT- or 8-OH-DPAT-evoked postprandial behaviors and (2) described the sleep-waking states (waking, W; drowsiness, D; slow-wave sleep, SWS; rapid-eye movement sleep, REMS) and sleep architecture of free-feeding pigeons after these treatments. Latency, frequency and duration of feeding, drinking, preening, exploratory and sleep-like behaviors (SLB) were examined after intracerebroventricular (ICV) injections of 5-HT (0, 50 or 150 nmol) or 8-OH-DPAT (DPAT, 0 or 30 nmol) in pigeons pretreated with the 5-HT(1A) antagonist WAY100635 (WAY, 0, 0.1, 0.3 or 1 nmol). Additionally, the acute (1h) waking-sleep-related electrographic activity in the hippocampus (HP) was examined after ICV injections of 5-HT (150 or 300 nmol) or DPAT (30 or 60 nmol) in pigeons pretreated with WAY (0 or 1 nmol). 5-HT and DPAT acutely increased drinking and then sleep: all doses of WAY attenuated the 5-HT (50 nmol) -induced dipsogenic effect, but left unchanged the effects of the 150 nmol 5-HT dose. The WAY 0.1 nmol dose blocked the SLB induced by the 5-HT 50 nmol dose. Given before the vehicle (VEH) injections, WAY does not affect water or food intake, but increased the SLB duration at all doses. DPAT injections increased feeding, drinking and SLB. All the WAY doses attenuated the DPAT-induced drinking and feeding responses, and the WAY 0.1 and 0.3 nmol doses reduced DPAT-induced SLB. DPAT or 5-HT injections decreased the duration of electrographically-determined waking, increased the durations of D and induced the emergence of SWS and REMS states indistinguishable from the hippocampal EEG associated with spontaneous sleep, as judged from visual and spectral analysis. WAY (1 nmol) increased SWS and D, and potentiated the 5-HT- and DPAT-induced SWS. These data suggest that 5-HT-induced drinking depends on the activation of presynaptic 5-HT(1A) receptors, while 5-HT(1A) autoreceptor activation contributes to the 5-HT-induced sleep. 5-HT-induced drinking and sleep behaviors may thus be provoked by a 5-HT(1A)-evoked, rebound-like reduction in central 5-HTergic activity. These data also indicate that an ongoing, tonic and inhibitory influence of central 5-HT circuits may participate in the control of feeding, drinking and rest behaviors in pigeons during the wake, nibbling diurnal state. These mechanisms appear to be comparable to those found in mammals, suggesting that they may represent a conserved, plesiomorphic functional trait of the amniotes brain., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Central injections of serotonin (5-HT) in food-deprived/refed pigeons evoke a sequence of hypophagic, hyperdipsic and sleep-like responses that resemble the postprandial behavioral sequence. Fasting-refeeding procedures affect sleep and drinking behaviors "per se". Here, we describe the behavioral profile and long-term food/water intake following intracerebroventricular (ICV) injections of 5-HT (50, 150, 300 nmol/2 μl) in free-feeding/drinking pigeons. The patterns of Fos activity (Fos+) in serotonergic (immunoreactive to tryptophan hydroxylase, TPH+) neurons after these treatments were also examined. 5-HT ICV injections evoked vehement drinking within 15 min, followed by an intense sleep. These effects did not extend beyond the first hour after treatment. 5-HT failed to affect feeding behavior consistently. The density of double-stained (Fos+/TPH+) cells was examined in 6 brainstem areas of pigeons treated with 5-HT (5-HTW) or vehicle. Another group received 5-HT and remained without access to water during 2h after treatment (5-HTØ). In the pontine raphe, Fos+ density correlated positively to sleep, and increased in both the 5-HTW and 5-HTØ animals. In the n. linearis caudalis, Fos+ and Fos+/TPH+ labeling was negatively correlated to sleep and was reduced in 5-HTØ animals. In the A8 region, Fos+/TPH+ labeling was reduced in 5-HTW and 5-HTØ animals, was positively correlated to food intake and negatively correlated to sleep. These data indicate that hyperdipsic and hypnogenic effects of ICV 5-HT in pigeons may result from the inhibition of a tonic activity of serotonergic neurons, which is possibly relevant to the control of postprandial behaviors, and that these relationships are shared functional traits of the serotonergic circuits in amniotes., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Rationale: Behavioral consequences of convulsive episodes are well documented, but less attention was paid to changes that occur in response to subconvulsant doses of drugs., Objectives: We investigated short- and long-term effects of a single systemic injection of a subconvulsant dose of pilocarpine on the behavior of rats as evaluated in the elevated plus maze., Methods and Results: Pilocarpine induced an anxiogenic-like profile 24 h later, and this effect persisted for up to 3 months (% of time spent on open arms at 24 h, control = 35.47 ± 3.23; pilocarpine 150 = 8.2 ± 2.6; 3 months, control = 31.9 ± 5.5; pilocarpine 150 = 9.3 ± 4.9). Temporary inactivation of fimbria-fornix with lidocaine 4% promoted an anxiolytic-like effect per se, suggesting a tonic control of this pathway on the modulation of anxiety-related behaviors. Lidocaine also reduced the anxiogenic-like profile of animals tested 1 month after pilocarpine treatment (% of time spent on open arms, saline + phosphate-buffered saline (PBS) = 31.7 + 3.7; saline + lidocaine = 54.4 + 4.7; pilocarpine + PBS = 10.3 + 4.1; pilocarpine + lidocaine = 40.1 + 9.1). To determine whether the anxiogenic-like effect was mediated by septal region or by direct hippocampal projections to the diencephalon, the neural transmission of post-commissural fornix was blocked, and a similar reduction in the anxiogenic-like effect of pilocarpine was observed., Conclusions: Our findings suggest that a single systemic injection of pilocarpine may induce long-lasting anxiogenic-like behavior in rats, an effect that appears to be mediated, in part, through a direct path from hippocampus to medial hypothalamic sites involved in fear responses.

The distribution of tryptophan hydroxylase (TPH)-containing perikarya and processes in the brainstem and diencephalon of the pigeon (Columba livia) were investigated using single-labeling chromogenic and double-labeling fluorescence immunohistochemical methods for TPH and 5-HT. TPH-immunoreactive (TPH-ir) perikarya were seen extending from the caudal medulla to mid-hypothalamic levels, located in brainstem regions previously described as containing 5-HT-ir somata. Brainstem TPH-ir cell clusters (the midline raphe, and the dorsolateral and ventrolateral serotonergic cell groups) and the circumventricular cerebrospinal fluid-contacting neurons in the taenia choroidea (in the caudal brainstem), recessus infundibuli and paraventricular organ (in the hypothalamus) were shown to co-express 5-HT immunoreactivity. However, heavily labeled TPH-ir cell clusters were observed in the nucleus premamillaris (PMM), in the stratum cellulare internum (SCI), in the nucleus paraventricularis magnocellularis (PVN) and in the medial border of the nucleus dorsomedialis anterior thalami (DMA). Double-labeling experiments indicated that none of these medial hypothalamic TPH-ir cells were immunoreactive to 5-HT. These cells correspond to dopamine- and melatonin-containing neurons previously found in the avian hypothalamus, and appear to be comparable to the mammalian TPH-ir hypothalamic A11-A13 catecholaminergic somata, suggesting that they may be a conserved attribute in the amniote medial hypothalamus.

The effects of systemic injections of the 5HT(1A) receptor agonist 8-OH-DPAT on the spontaneous ingestive, maintenance, locomotor and sleep-like behaviours, and the sleep/waking-related hippocampal electrographic activity were investigated in pigeons. 8-OH-DPAT (0.06, 0.2, 0.6 or 2.0mg/kg) was found to dose-dependently reduce food and water intake, acutely (in the first 3h) and 24h after treatment, during both low-activity morning hours (starting at 10:00 h) and high-activity evening hours (starting at 14:00 h). Automated 24h records of food and water intake indicated that hypophagic effects can last up to 18 h after injection. Duration and incidence of sleep-like postures increased at all doses, in both morning and afternoon. These effects were associated with decreases in exploratory and preening activities. The 8-OH-DPAT-induced hypnogenic, hypophagic and hypodipsic effects tended to be more intense in the morning than in the afternoon-trials. Pretreatment with WAY 100635 (a 5-HT(1A) antagonist; 0.6 mg/kg) eliminated all of these 8-OH-DPAT-induced effects. WAY 100635 failed to affect feeding when injected alone, but decreased frequency of sleep-like responses and increased the latency to the first sleep-like episode. Hippocampal EEG tracings after 8-OH-DPAT injections (0.6 or 2.0mg/kg) indicated that the hypnogenic effects are associated with a specific increase in the frequency and duration of slow wave sleep. Power density analysis of the hippocampal EEG failed to show differences between 8-OH-DPAT-induced sleep and the sleep occurring after vehicle injections, indicating that it may be electrographically similar to diurnal sleep episodes in the pigeon. These data suggest that while 5-HT(1a) receptor-mediated mechanisms play crucial roles in ingestive and sleep/waking behaviours in mammals and birds, their action upon these states shows substantial inter-taxon variance.

In the present study, the acute behavioral and ingestive effects of ICV injections of mammalian orexin-A (ORXA; vehicle, 0.2, 0.6 or 2 nmol) and of orexin-B (ORXB; vehicle, 0.2, 0.6 or 2 nmol), as well as possible long-term effects (through 24 h of continuous intake monitoring after 0.6 nmol of ORXA or ORXB) of these treatments in food/water intake and in blood levels of metabolic fuels (free fatty acids and glucose, after 0.2 or 0.6 nmol of ORXA) were examined in adult male pigeons. Both ORXA and ORXB treatments failed to produce acute (1-3 h) or long-term effects on feeding and drinking behaviors, and did not change blood free fatty acids and glucose 15 and 30 min after treatments, as compared to vehicle-treated animals. However, ORXA (but not ORXB) treatments evoked a dose-related, intense increase in exploratory behaviors, associated to reduced time spent in alert immobility and sleep-typical postures. These data substantiate the lack of orexigenic effects of ORXs in avian species, and suggest that an important role in vigilance control may represent a conserved functional attribute of orexinergic circuits in vertebrates.

Rationale: Polygala sabulosa, a folk medicine, presents dihydrostyryl-2-pyrones (DST) and styryl-2-pyrones (STY), compounds structurally similar to kavalactones. Our previous study showed that the ethyl acetate fraction (EA) and these constituents present anxiolytic-like, hypno-sedative, and anticonvulsant effects in mice., Objectives: This study investigated the role of benzodiazepine binding site (BDZ-bs) in the central effects of either EA or three DST (1, 2, and 3) and three STY (4, 5, and 7), using in vivo and in vitro assays., Methods and Results: In the elevated plus-maze (EPM), flumazenil (FMZ), a BDZ antagonist, partially blocked the anxiolytic-like effect of DST-3 or STY-4 and STY-7, but not DST-1. Using electroencephalogram (EEG), EA protected against pentylenetetrazole (PTZ)-induced convulsion in rats, an effect partially blocked by FMZ, suggesting the participation of the BDZ-bs in this action. EA also protected against the maximal electroshock (MES)-induced convulsions in mice, a profile distinct from diazepam (DZP). DST and STY compounds inhibited the [(3)H]-flunitrazepam ([(3)H]-FNZ) binding to BDZ-bs in rat cortical synaptosomes with K (i) higher than 100 microM (DST-1), 41.7 microM (DST-2), 35.8 microM (DST-3), 90.3 microM (STY-4), 31.0 microM (STY-5) and 70.0 microM (STY-7). In the saturation assay, DST-3 and STY-7 competitively inhibited the binding of [(3)H]-FNZ to BDZ-bs with a significant decrease in apparent affinity (K (d)) and no change in maximal binding (B (max))., Conclusions: The present data support a partial BDZ-bs mediation of the anxiolytic-like and anticonvulsant effects of EA of P. sabulosa and its main isolated constituents, DST and STY.