1,721,213 research outputs found
The anticonvulsant action of fluoxetine in substantia nigra is dependent upon endogenous serotonin
No full textFluoxetine, a serotonin (5-HT) reuptake inhibitor, has been documented to exert a protective action against convulsive seizures in animal models, when administered either systemically, or focally into substantia nigra. It is likely that the mechanism of anticonvulsant action of fluoxetine is due to an enhancement of endogenous 5-HT transmission. To evaluate this possibility in the context of the anticonvulsant action of intranigral fluoxetine, we examined the influence of 5-HT-mediated transmission in substantia nigra on seizure susceptibility in a rat model of focally evoked complex partial seizures. In addition to fluoxetine (3.5 nmol), we found that the directly acting 5-HT receptor agonists, 1-[3-(trifluoromethyl)phenyl]piperazine (TFMPP) (10 nmol), 1-(3-cnlorophenyl)piperazine (m-CPP) (7.4 nmol), gepirone (70 nmol) and 2-dipropylamino-8-hydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide (8-OH-DPAT) (10 nmol), when microinjected bilaterally into substantia nigra, protected rats from limbic motor seizures evoked focally from area tempestas, an epileptogenic site in the deep rostral piriform cortex. This indicates that multiple 5-HT receptor subtypes in substantia nigra may contribute to seizure regulation. Consistent with this, the 5-HT antagonist, metergoline, partially reversed the anticonvulsant action of intranigral fluoxetine. Depletion of endogenous 5-HT, by pretreatment with parachlorophenylalanine (PCPA), completely prevented the anticonvulsant action of intranigral fluoxetine, without modifying the anticonvulsant effect of intranigral TFMPP. These findings support the proposal that the anticonvulsant action of fluoxetine in substantia nigra is due to an enhancement of the synaptic action of endogenous 5-HT in substantia nigra which in turn is mediated via multiple 5-HT receptors. Endogenous 5-HT transmission in substantia nigra is therefore capable of limiting the development and propagation of seizure activity generated in limbic circuits
Sleep-deprivation decreases mu and delta opioid receptor-binding in the rat limbic system
No full textSleep deprivation induced by the platform technique is considered to be a heavy stressful situation in rats. At the end of the sleep deprivation period (72 h) the rat displayed particular behavior characterized by wakefulness, a high degree of motor and exploratory activity, increased alertness and reactivity to environmental stimuli. Our previous results indicated that this behavior was antagonized by the administration of the opioid receptor antagonist naloxone and increased by opioid agonists. In this paper we show that concomitantly with this behavior, a decreased B(max) of mu and delta-opioid receptors is present in the limbic system of these animals. These data suggest an active role of limbic-mu and delta-receptors in the generation of arousal and insomnia related to sleep deprivation induced stress
Shifted Contact Structures on Differentiable Stacks
No full textWe define 0-shifted and +1-shifted contact structures on differentiable stacks, thus laying the foundations of shifted Contact Geometry. As a side result we show that the kernel of a multiplicative 1-form on a Lie groupoid (might not exist as a Lie groupoid but it) always exists as a differentiable stack, and it is naturally equipped with a stacky version of the curvature of a distribution. Contact structures on orbifolds provide examples of 0-shifted contact structures, while prequantum bundles over +1-shifted symplectic groupoids provide examples of +1-shifted contact structures. Our shifted contact structures are related to shifted symplectic structures via a Symplectic-to-Contact Dictionary
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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