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Aim: The Genetic Absence Epilepsy Rats from Strasbourg (GAERS) are an inbred polygenic model of childhood absence epilepsy (CAE), which, as their non‐epileptic control (NEC) rats, are derived from Wistar rats. While the validity of GAERS in reproducing absence seizures is well established, its use as a model for CAE psychiatric comorbidities has been subject to conflicting findings. Differences in colonies, experimental procedures, and the use of diverse controls from different breeders may account for these disparities. Therefore, in this study, we compared GAERS, NEC, and Wistar bred in the same animal facility with commercially available Wistar (Cm Wistar) as a third control. Methods: We performed hole board (HB) and elevated plus maze (EPM) tests that were analyzed with standard quantitative and T‐pattern analysis in male, age‐matched Cm Wistar and GAERS, NEC, and Wistar, bred under the same conditions, to rule out the influence of different housing factors and provide extra information on the structure of anxiety‐like behavior of GAERS rats. Results: Quantitative analysis showed that GAERS and NEC had similar low anxiety‐like behavior when compared to Cm Wistar but not to Wistar rats, although a higher hole‐focused exploration was revealed in NEC. T‐pattern analysis showed that GAERS, NEC, and Wistar had a similar anxiety status, whereas GAERS and NEC exhibited major differences with Cm Wistar but not Wistar rats. EPM results indicated that GAERS and NEC also have similar low anxiety compared to Cm Wistar and/or Wistar rats. Nevertheless, the analysis of the T‐pattern containing open‐arm entry showed GAERS and Wistar to be less anxious than NEC and Cm Wistar rats. Conclusion: To summarize, comorbid anxiety may not be present in male GAERS rats. This study also highlighted the importance of including a control Wistar group bred under the same conditions when evaluating their behavior, as using Wistar rats from commercial breeders can lead to misleading results. [ABSTRACT FROM AUTHOR]

Despite consensus on some neurophysiological hallmarks of the Parkinsonian state (such as beta) band increase) a single mechanism is unlikely to explain the efficacy of deep brain stimulation (DBS) of the subthalamic nucleus (STN). Most experimental evidence to date correlates with an extreme degree of nigral neurodegeneration and not with different stages of PD progression. It seems inappropriate to combine substantially different patients – newly diagnosed, early fluctuators or advanced dyskinetic individuals – within the same group. An efficacious STN‐DBS imposes a new activity pattern within brain circuits, favouring alpha‐ and gamma‐like neuronal discharge, and restores the thalamo‐cortical transmission pathway through axonal activation. In addition, stimulation via the dorsal contacts of the macro‐electrode may affect cortical activation antidromically. However, basal ganglia (BG) modulation remains cardinal for 'OFF'‐'ON' transition (as revealed by cGMP increase occurring during STN‐DBS in the substantia nigra pars reticulata and internal globus pallidus). New research promises to clarify to what extent STN‐DBS restores striato‐centric bidirectional plasticity, and whether non‐neuronal cellular actions (microglia, neurovascular) play a part. Future studies will assess whether extremely anticipated DBS or lesioning in selected patients are capable of providing neuroprotection to the synuclein‐mediated alterations of synaptic efficiency. This review addresses these open issues through the specific mechanisms prevailing in a given disease stage. In patients undergoing early protocol, alteration in endogenous transmitters and recovery of plasticity are concurrent players. In advanced stages, re‐modulation of endogenous band frequencies, disruption of pathological pattern and/or antidromic cortical activation are, likely, the prominent modes. This manuscript proposes a new perspective in interpreting the efficacy of STN‐DBS in PD patients. The main concept is that the burden of neurodegeneration and PD stage represent the major factors. Whereas rescuing neuroplasticity plus rebalancing of endogenous band frequencies are early players, instead, in advanced PD stages, antidromic impact on cortex and circuitry disruption exert major roles. The understanding of the specific mechanisms prevalent in any given subject is crucial for on‐going trials, either experimenting adaptive DBS or targeting young patients. [ABSTRACT FROM AUTHOR]

Abstract: Aims: Serotonergic (5‐HT) modulation of the lateral habenula (LHb) activity is central in normal and pathologic conditions such as mood disorders. Among the multiple 5‐HT receptors (5‐HTRs) involved, the 5‐HT2CR seems to play a pivotal role. Yet, the role of 5‐HT2ARs in the control of the LHb neuronal activity is completely unknown. Methods: Single‐cell extracellular recording of the LHb neurons was used in rats to study the effect of the general activation and blockade of the 5‐HT2CR and 5‐HT2AR with Ro 60‐0175 and SB242084, TCB‐2 and MDL11939, respectively. The expression of both receptors in the LHb was confirmed using immunohistochemistry. Results: Cumulative doses (5‐640 μg/kg, iv) of Ro 60‐0175 and TCB‐2 affected the activity of 34% and 63% of the LHb recorded neurons, respectively. LHb neurons were either inhibited at low doses or excited at higher doses of the 5‐HT2A/CR agonists. SB242084 or MDL11939 (both at 200 μg/kg, iv) did not modify neuronal firing when injected alone, but reverted the bidirectional effects of Ro 60‐0175 or TCB‐2, respectively. 5‐HT2CRs and 5‐HT2ARs are expressed in less than the 20% of the LHb neurons, and they neither colocalize nor make heterodimers. Strikingly, only 5‐HT2ARs are expressed by the majority of LHb astrocyte cells. Conclusions: Peripheral administration of 5‐HT2AR agonist promotes a heterogeneous pattern of neuronal responses in the LHb, and these effects are more prominent than those induced by the 5‐HT2CR activation. [ABSTRACT FROM AUTHOR]

Summary: Aim: The transgenic D1CT‐7 mouse is one of the best‐characterized animal models of Tourette's syndrome (TS), exhibiting spontaneous tic‐like Head‐Body Twitches (HBT) and deficits in sensorimotor gating. This study is aimed at evaluating the behavioral dynamics of these mutants and their potential relevance to TS. Methods: The behavior of D1CT‐7 and Wild Type littermates was firstly assessed by considering frequencies and durations. To detect recurrent real‐time behavioral sequences, the multivariate T‐pattern analysis was employed. Analyses of transition probabilities among behaviors further provided an overall picture of the behavioral dynamics. Results: T‐patterns and transition matrices revealed in D1CT‐7 mice a clear‐cut hyperactivity compared to controls, with a lower behavioral organization and a marked shift from cautious sniffing toward locomotion. Moreover, the behavioral patterns of the transgenic mice were pervasively disturbed by intrusive tic‐like HBT leading to a marked fragmentation of the behavior. Novel exposure to open field provoked a transient inhibitory control over the disrupting phenotype. Conclusion: The results of this study show that the D1CT‐7 mouse model is subjected to a behavioral fragmentation, with repercussions going beyond the simple tic‐like phenomenon. These phenotypes are strikingly akin to behavioral problems observed in patients with TS and further validate the power of this model in summarizing pivotal behavioral aspects of TS. [ABSTRACT FROM AUTHOR]

Linked Articles: This article is part of a themed section on Updating Neuropathology and Neuropharmacology of Monoaminergic Systems. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v173.13/issuetoc. [ABSTRACT FROM AUTHOR]

Typical absence seizures ( ASs) are nonconvulsive epileptic events which are commonly observed in pediatric and juvenile epilepsies and may be present in adults suffering from other idiopathic generalized epilepsies. Our understanding of the pathophysiological mechanisms of ASs has been greatly advanced by the availability of genetic and pharmacological models, in particular the γ-hydroxybutyrate ( GHB) model which, in recent years, has been extensively used in studies in transgenic mice. GHB is an endogenous brain molecule that upon administration to various species, including humans, induces not only ASs but also a state of sedation/hypnosis. Analysis of the available data clearly indicates that only in the rat does there exist a set of GHB-elicited behavioral and EEG events that can be confidently classified as ASs. Other GHB activities, particularly in mice, appear to be mostly of a sedative/hypnotic nature: thus, their relevance to ASs requires further investigation. At the molecular level, GHB acts as a weak GABA-B agonist, while the existence of a GHB receptor remains elusive. The pre- and postsynaptic actions underlying GHB-elicited ASs have been thoroughly elucidated in thalamus, but little is known about the cellular/network effects of GHB in neocortex, the other brain region involved in the generation of ASs. [ABSTRACT FROM AUTHOR]

Background A considerable body of human and animal experimental evidence links monoaminergic systems and cognition. Monoamine oxidase inhibitors ( MAOIs), being able to enhance monoaminergic transmission and having neuroprotective properties, might represent a promising therapeutic strategy in cognitive impairment in Alzheimer's disease ( AD) and other dementias. Methods The MAO-A and MAO-B inhibition profile of N-(furan-2-ylmethyl)-N-prop-2-yn-1-amine derivates (compounds 1-3) were evaluated by fluorimetric method and their absorption, distribution, metabolism, excretion, and toxicity ( ADMET) properties estimated. The effects of the selected compound 1, N-(furan-2-ylmethyl)-N-methylprop-2-yn-1-amine (F2 MPA), were evaluated on the basic synaptic transmission, long-term potentiation ( LTP), and excitability in the dentate gyrus (DG) of the hippocampus of anesthetized rats. Results F2MPA is a partially reversible inhibitor of hMAO-B, with moderate to good ADMET properties and drug-likeness. Intraperitoneal administration of 1 mg/kg F2MPA greatly enhanced basic synaptic transmission, induced LTP, and potentiated electrically induced LTP in the dentate gyrus. Moreover, F2MPA did not modify seizure threshold of pilocarpine-induced convulsion in CD1 mice. Conclusion Our findings suggest that, the MAO-B inhibitor, F2 MPA improves DG synaptic transmission without triggering pathological hyperexcitability. Therefore, F2 MPA shows promise as a potential cognition-enhancing therapeutic drug. [ABSTRACT FROM AUTHOR]

Cortistatin ( CST)-14, a neuropeptide that is structurally and functionally related to somatostatin-14 ( SRIF) binds all five somatostatin receptor subtypes (sst1-sst5). Using in vivo microdialysis and telemetry-based electroencephalographic recordings, we provide the first experimental evidence for anticonvulsive effects of CST-14 in a pilocarpine-induced seizure model in rats and mice and for the involvement of sst2 and sst3 receptors in these anticonvulsant actions of CST-14. Both receptor subtypes are required for the anticonvulsant effects of CST-14 given that co-perfusion of a selective sst2 antagonist (cyanamid15486) or a selective sst3 antagonist ( SST3- ODN-8) reversed anticonvulsant effect of CST-14, and this, independently of each other. Next, as the ghrelin receptor has been proposed as a target for the biological effects of CST-14, we used ghrelin receptor knockout mice and their wild type littermates to study the involvement of this receptor in the anticonvulsive actions of CST-14. Our results show a significant decrease in seizure duration in both genotypes when CST-14 treated mice were compared with corresponding control animals receiving only pilocarpine. In addition, this CST-14-induced decrease was comparable in both genotypes. We here thus provide the first evidence that ghrelin receptors are not involved in mediating anticonvulsant actions of CST-14 in vivo. [ABSTRACT FROM AUTHOR]

Aims Serotonin (5- HT) neurons mediate the ectopic release of dopamine ( DA) induced by l- DOPA in the Parkinsonian brain. We hypothesized that the participation of noradrenalin transporters ( NET) in the clearance of DA may account for the lower effect of l- DOPA in extrastriatal regions compared with the striatum. Methods Using a multisite intracerebral microdialysis approach, we tested the influence of the pharmacological blockade of NET and/or the destruction of noradrenalin ( NE) fibers on DA and 5- HT release in the striatum, hippocampus ( HIPP), substantia nigra pars reticulata ( SNr) and prefrontal cortex ( PFC) of 6-hydroxydopamine-lesioned rats. Results l- DOPA (12 mg/kg, i.p.) increased DA extracellular levels to a lesser extent in the SNr, PFC and HIPP compared with the striatum. The NET blockers desipramine (10 mg/kg, i.p.) and reboxetine (3 mg/kg, i.p.) potentiated l- DOPA effect in the PFC, SNr and HIPP but not in the striatum. The NE neurotoxin N-(2-chloroethyl)- N-ethyl-2-bromobenzylamine (50 mg/kg, i.p. 1 week before dialysis experiment) potentiated l- DOPA effect in the SNr and HIPP. 5- HT extracellular levels were enhanced only when l- DOPA was combined to NET blockers. Conclusion Noradrenalin neurons are indirectly involved in the mechanism of action of l- DOPA in part through the heterologous reuptake of DA in extrastriatal regions. [ABSTRACT FROM AUTHOR]

Oligodendrocytes ( OLs), the myelin-forming cells of the central nervous system, form a functional unit with axons and play a crucial role in axonal integrity. An episode of hypoxia-ischemia causes rapid and severe damage to these particularly vulnerable cells via multiple pathways such as overactivation of glutamate and ATP receptors, oxidative stress, and disruption of mitochondrial function. The cardinal effect of OL pathology is demyelination and dysmyelination, and this has profound effects on axonal function, transport, structure, metabolism, and survival. The OL is a primary target of ischemia in adult-onset stroke and especially in periventricular leukomalacia and should be considered as a primary therapeutic target in these conditions. More emphasis is needed on therapeutic strategies that target OLs, myelin, and their receptors, as these have the potential to significantly attenuate white matter injury and to establish functional recovery of white matter after stroke. In this review, we will summarize recent progress on the role of OLs in white matter ischemic injury and the current and emerging principles that form the basis for protective strategies against OL death. [ABSTRACT FROM AUTHOR]

Aims Substantial evidence indicates that 5- HT2C receptors are involved in the control of neuronal network excitability and in seizure pathophysiology. Here, we have addressed the relatively unexplored relationship between temporal lobe epilepsy ( TLE), the most frequent type of intractable epilepsy, and 5- HT2 CRs. Methods In this study, we investigated this issue using a model of partial complex (limbic) seizures in urethane-anesthetized rat, based on the phenomenon of maximal dentate activation ( MDA) using 5- HT2C compounds, electrophysiology, immunohistochemistry, and western blotting techniques. Results The 5-HT2C agonists mCPP (1 mg/kg, i.p) and lorcaserin (3 mg/kg, i.p), but not RO60-0175 (1-3 mg/kg i.p.), were antiepileptogenic reducing the MDA response duration. The selective 5-HT2C antagonist SB242084 (2 mg/kg, i.p) unveiled antiepileptogenic effects of RO60-0175 (3 mg/kg, i.p) but did not alter those induced by mCPP and lorcaserin. Compared with control rats, electrically stimulated rats showed an increase in glutamic acid decarboxylase levels and a heterogeneous decrease in 5-HT2CR immunoreactivity in different hippocampal areas. Conclusions In our animal model of TLE, mCPP and lorcaserin were anticonvulsant; likely acting on receptor subtypes other than 5-HT2C. Epileptogenesis induced early adaptive changes and reorganization in the 5-HT2CR and GABA systems. [ABSTRACT FROM AUTHOR]

The interaction between serotonin (5-HT) and dopamine (DA)-containing neurons in the brain is a research topic that has raised the interest of many scientists working in the field of neuroscience since the first demonstration of the presence of monoamine-containing neurons in the mid 1960. The bulk of neuroanatomical data available clearly indicate that DA-containing neurons in the brain receive a prominent innervation from serotonin (5-hydroxytryptamine, 5-HT) originating in the raphe nuclei of the brainstem. Compelling electrophysiological and neurochemical data show that 5-HT can exert complex effects on the activity of midbrain DA neurons mediated by its various receptor subtypes. The main control seems to be inhibitory, this effect being more marked in the mesocorticolimbic DA system as compared to the DA nigrostriatal system. In spite of a direct effect of 5-HT by its receptors located on DA cells, 5-HT can modulate their activity indirectly, modifying γ-aminobutyric (GABA)-ergic and glutamatergic input to the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc). Although 5-HT/DA interaction in the brain has been extensively studied, much work remains to be done to clarify this issue. The recent development of subtype-selective ligands for 5-HT receptors will not only allow a detailed understanding of this interaction but also will lead to the development of new treatment strategies, appropriate for those neuropsychiatric disorders in which an alteration of the 5-HT/DA balance is supposed. [ABSTRACT FROM AUTHOR]

Nicotine, the main psychoactive ingredient in tobacco, stimulates dopamine (DA) function, increasing DA neuronal activity and DA release. DA is involved in both motor control and in the rewarding and reinforcing effects of nicotine; however, the complete understanding of its molecular mechanisms is yet to be attained. Substantial evidence indicates that the reinforcing properties of drugs of abuse, including nicotine, can be affected by the nitric oxide (NO) system, which may act by modulating central dopaminergic function. In this study, using single cell recordings in vivo coupled with microiontophoresis and microdialysis in freely moving animals, the role of NO signaling on the hyperactivation elicited by nicotine of the nigrostriatal system was investigated in rats. Nicotine induced a dose-dependent increase of the firing activity of the substantia nigra pars compacta (SNc) DA neurons and DA and 3,4-dihydroxyphenylacetic acid (DOPAC) release in the striatum. Pharmacological manipulation of the NO system did not produce any change under basal condition in terms of neuronal discharge and DA release. In contrast, pretreatments with two NO synthase (NOS) inhibitors, N-ω-nitro-l-arginine methyl ester (l-NAME) and 7-nitroindazole (7-NI) were both capable of blocking the nicotine-induced increase of SNc DA neuron activity and DA striatal levels. The effects of nicotine inl-NAME and 7-NI-pretreated rats were partially restored when rats were pretreated with the NO donor molsidomine. These results further support the evidence of an important role played by NO on modulation of dopaminergic function and drug addiction, thus revealing new pharmacological possibilities in the treatment of nicotine dependence and other DA dysfunctions. [ABSTRACT FROM AUTHOR]

Previous neurochemical and behavioral studies suggest that muscarinic receptor antagonism has an excitatory effect on the nigrostriatal dopamine (DA) system. Using in vivo extracellular single unit recording, this study examined whether blockade of the muscarinic receptor by scopolamine alters the firing properties of DA neurons in the substantia nigra (SN). Scopolamine was administered either systemically or locally to DA neurons using microiontophoresis. Surprisingly, scopolamine did not cause any significant change in either the firing rate or pattern of the spontaneously active DA neurons. However, systemic injection of scopolamine significantly increased the number of active DA neurons in the SN. Local infusion of scopolamine into the pedunculopontine tegmental nucleus (PPT) mimicked the effect induced by systemically administered scopolamine, significantly increasing the number of active DA neurons without altering the firing rate and pattern. These results suggest that the reported increase in striatal DA release induced by scopolamine is in part mediated by activation of silent nigral DA neurons. The experiments with PPT local infusion further suggest that part of the effect of scopolamine may be due to its blockade of the inhibitory muscarinic autoreceptors on PPT cholinergic cells. The latter effect may lead to activation of quiescent DA neurons by increasing acetylcholine (ACh) release in the SN or in other brain areas providing inputs to DA neurons. Further understanding of the mechanism of action of scopolamine may help us further understand the role of ACh in both the pathophysiology and treatment of DA-related disorders including schizophrenia and Parkinson's disease. Synapse 63:673-680, 2009. © 2009 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The present study was undertaken to explore the involvement of nitric oxide (NO) in the 6-hydroxydopamine (6-OHDA) experimental model of Parkinson's disease (PD) in rats. The effect of pharmacological manipulation of the NO system was evaluated on striatal dopamine (DA) level decrease produced by the toxin. 7-nitroindazole (7-NI, 50 mg/kg i.p.; n= 5) pretreatment significantly restored the striatal DA contents. Conversely, 40 mg/kg i.p. of molsidomine (MOL, n= 5), an NO donor, significantly worsened the neurodegeneration ( n= 5) and completely counteracted the neuroprotective effect of 7-NI ( n= 5). Thus, a crucial role for NO in 6-OHDA induced neurodegeneration is suggested together with a protective benefit for inhibitors of NOS in the treatment of PD. [ABSTRACT FROM AUTHOR]

6-Hydroxydopamine (6-OHDA) is a neurotoxic compound commonly used to induce dopamine (DA) depletion in the nigrostriatal system, mimicking Parkinson's disease (PD) in animals. The aim of the present study was to evaluate the 7-day effect of unilateral nigral lesion on rat brain monoamine neurochemistry. Five brain regions were examined: the brain stem, cerebellum, hippocampus, striatum, and cortex. 6-OHDA-unilateral lesion dramatically modified DA, serotonin (5-HT) and their metabolites contents in both sides of the different brain nuclei. Furthermore, unilateral 6-OHDA lesion reduced DA and 5-HT contents and produced a robust inversion of their turnover in the nonlesioned side compared to sham-operated rats. These data suggest that 6-OHDA unilateral nigral lesion produces bilateral monoamine level modifications, and this piece of evidence should be taken into account when one interprets data from animal models of unilateral PD. [ABSTRACT FROM AUTHOR]

In this article, the author discusses pharmacological therapy in the treatment of parkinson's disease (PD) with focus on the neuroprotection. Authors opine, research into neuroprotective molecules with proven efficiency in countering the disease still represents a challenge for neuroscientists. They add, though animal models are useful tools for studying the physiopathology of PD, however, temporal course and anatomopathological differences to humans, pose significant obstacles to research.

The author reflects on the physiological role of catecholaminergic neurotransmitter dopamine (DA). The author presents a review of the research on functions of DA and its role in various pathophysiological conditions, behavioral changes and cellular action potential patterns. The author also presents an introduction to the reports published in the present issue of the journal on dopaminergic neurotransmission.

Cortistatin (CST)-14, a neuropeptide that is structurally and functionally related to somatostatin-14 (SRIF) binds all five somatostatin receptor subtypes (sst1-sst5). Using in vivo microdialysis and telemetry-based electroencephalographic recordings, we provide the first experimental evidence for anticonvulsive effects of CST-14 in a pilocarpine-induced seizure model in rats and mice and for the involvement of sst2 and sst3 receptors in these anticonvulsant actions of CST-14. Both receptor subtypes are required for the anticonvulsant effects of CST-14 given that co-perfusion of a selective sst2 antagonist (cyanamid15486) or a selective sst3 antagonist (SST3-ODN-8) reversed anticonvulsant effect of CST-14, and this, independently of each other. Next, as the ghrelin receptor has been proposed as a target for the biological effects of CST-14, we used ghrelin receptor knockout mice and their wild type littermates to study the involvement of this receptor in the anticonvulsive actions of CST-14. Our results show a significant decrease in seizure duration in both genotypes when CST-14 treated mice were compared with corresponding control animals receiving only pilocarpine. In addition, this CST-14-induced decrease was comparable in both genotypes. We here thus provide the first evidence that ghrelin receptors are not involved in mediating anticonvulsant actions of CST-14 in vivo., (© 2014 John Wiley & Sons Ltd.)