Transient and long‐lasting actions of 5‐HT on rat dentate gyrus neurones in vitro.

Piguet, Pascale; Galvan, M.

doi:10.1113/jphysiol.1994.sp020469

Cited by 100 publications

(61 citation statements)

References 39 publications

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“…The extrasynaptically located inhibitory serotonin 1A receptor on pyramidal cell dendrites (19) can be activated by serotonin released not only through spillover from synaptic terminals but also from nonsynaptic varicosities, resulting in further reduction of the temporal and spatial precision of the serotonergic control. Activation of the excitatory G protein-coupled serotonin 2A receptors expressed by GABA-expressing (GABAergic) interneurons (20) was also shown to have a long-lasting effect on pyramidal neurons (21,22).…”

Section: Discussionmentioning

confidence: 99%

Serotonergic neuron diversity: Identification of raphe neurons with discharges time-locked to the hippocampal theta rhythm

Kocsis

Varga

Dahan

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

141

117

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The serotonergic system plays a key role in the regulation of brain states, and many of the known features of serotonergic neurons appear to match this function. Midbrain raphe nuclei provide a diffuse projection to all regions of the forebrain, and raphe neurons exhibit a slow metronome-like activity that sets the ambient levels of serotonin across the sleep-wake cycle. Serotonergic cells have also been implicated, however, in a variety of more specific functions that can hardly be related to their low-rate monotonous patterns of discharges. The amazing variety of serotonergic receptors and their type-specific distribution on cortical neurons also raise the possibility of a more intimate coordination between the activity of serotonergic neurons and their target cortical circuits. Here we report an unexpected diversity in the behavior of immunohistochemically identified serotonergic neurons. Two outstanding subpopulations were identified by using the in vivo juxtacellular recording and labeling technique. The first subpopulation of serotonergic cells exhibited the classic clock-like activity with no apparent short timescale interaction with the hippocampal electroencephalogram. The other subpopulation discharged action potentials that were phase-locked to the hippocampal theta rhythm, the oscillatory pattern associated with acquisition of information and memory formation. These results indicate that the ascending serotonergic system comprises cells involved in complex information processing beyond the regulation of state transitions. The heterogeneity of serotonergic neuron behavior can also help to explain the complexity of symptoms associated with serotonergic dysfunction.hippocampus ͉ juxtacellular labeling ͉ midbrain raphe ͉ neuronal oscillations T he serotonergic system is a primary target of psychotherapy that stresses the importance of serotonin in normal and abnormal brain functioning. Serotonergic neurons of the midbrain raphe have been implicated in the control of affective and cognitive functions and in modulating the neural activities of networks across the sleep-wake cycle. Behaviorally related oscillations in the theta frequency range (4-8 Hz), which are most prominent in the hippocampus (1), are known to synchronize neuronal activity in a number of forebrain structures involved in these functions (2-4). Hippocampal theta oscillations occur selectively during exploratory behaviors and paradoxical sleep, whereas large-amplitude irregular activity is associated with quiet waking, consummatory behaviors, and slow-wave sleep (5, 6). As in sleep, hippocampal activity spontaneously alternates between theta and nontheta states under urethane anesthesia.The majority of putative serotonergic neurons have been reported to be most active during waking, to decrease their firing rate during slow-wave sleep, and to cease firing during paradoxical sleep (7). ʈ The silencing of serotonergic cells during paradoxical sleep is currently considered an important regulatory signal that contributes to the maintenance of ...

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Section: Discussionmentioning

confidence: 99%

Serotonergic neuron diversity: Identification of raphe neurons with discharges time-locked to the hippocampal theta rhythm

Kocsis

Varga

Dahan

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

141

117

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“…It has been well demonstrated that the glutamatergic transmission inhibits cell proliferation in the DG via NMDA receptors (Cameron et al, 1995;Gould et al, 1997;Nacher et al, 2001), which are expressed by granule cells, as 5-HT1A receptors. Hyperpolarization of these cells following activation of postsynaptic 5-HT1A receptors (Piguet and Galvan, 1994) would counterbalance this negative control. Finally, long-term analyses of neurogenesis following acute or chronic activation of 5-HT1A receptors indicate that the increases in cell proliferation are not transient and are followed by a significant augmentation in the number of newly formed neurons in DG.…”

Section: Regulation Of Cell Proliferation and Neurogenesis In The Dgmentioning

confidence: 99%

Serotonin-Induced Increases in Adult Cell Proliferation and Neurogenesis are Mediated Through Different and Common 5-HT Receptor Subtypes in the Dentate Gyrus and the Subventricular Zone

Banasr

Héry

Printemps

et al. 2003

Neuropsychopharmacol

478

319

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Increase in serotonin (5-HT) transmission has profound antidepressant effects and has been associated with an increase in adult neurogenesis. The present study was aimed at screening the 5-HT receptor subtypes involved in the regulation of cell proliferation in the subgranular layer (SGL) of the dentate gyrus (DG) and the subventricular zone (SVZ) and to determine the long-term changes in adult neurogenesis. The 5-HT1A, 5-HT1B, and 5-HT2 receptor subtypes were chosen for their implication in depression and their location in/ or next to these regions. Using systemic administration of various agonists and antagonists, we show that the activation of 5-HT1A heteroreceptors produces similar increases in the number of bromodeoxyuridine-labeled cells in the SGL and the SVZ (about 50% over control), whereas 5-HT2A and 5-HT2C receptor subtypes are selectively involved in the regulation of cell proliferation in each of these regions. The activation of 5-HT2C receptors, largely expressed by the choroid plexus, produces a 56% increase in the SVZ, while blockade of 5-HT2A receptors produces a 63% decrease in the number of proliferating cells in the SGL. In addition to the influence of 5-HT1B autoreceptors on 5-HT terminals in the hippocampus and ventricles, 5-HT1B heteroreceptors also regulate cell proliferation in the SGL. These data indicate that multiple receptor subtypes mediate the potent, partly selective of each neurogenic zone, stimulatory action of 5-HT on adult brain cell proliferation. Furthermore, both acute and chronic administration of selective 5-HT1A and 5-HT2C receptor agonists produce consistent increases in the number of newly formed neurons in the DG and/or olfactory bulb, underscoring the beneficial effects of 5-HT on adult neurogenesis.

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“…Similarly to the hippocampus, modulation of GABA release from interneurons (mainly inhibition by 5-HT 1A receptors and stimulation by 5-HT 2 and/or 5-HT 3 receptors) has also been observed in other areas, among which dentate gyrus [132,152], enthorinal cortex [40,165], piriform cortex [115], frontal and anterior cingulate cortex [192].…”

Section: Modes Of Interactionmentioning

confidence: 99%

Serotonin as a Modulator of Glutamate- and GABA-Mediated Neurotransmission: Implications in Physiological Functions and in Pathology

Ciranna

2006

272

170

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Abstract:The neurotransmitter serotonin (5-HT), widely distributed in the central nervous system (CNS), is involved in a large variety of physiological functions. In several brain regions 5-HT is diffusely released by volume transmission and behaves as a neuromodulator rather than as a "classical" neurotransmitter. In some cases 5-HT is co-localized in the same nerve terminal with other neurotransmitters and reciprocal interactions take place. This review will focus on the modulatory action of 5-HT on the effects of glutamate and -amino-butyric acid (GABA), which are the principal neurotransmitters mediating respectively excitatory and inhibitory signals in the CNS. Examples of interaction at preand/or post-synaptic levels will be illustrated, as well as the receptors involved and their mechanisms of action. Finally, the physiological meaning of neuromodulatory effects of 5-HT will be briefly discussed with respect to pathologies deriving from malfunctioning of serotonin system.

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Transient and long‐lasting actions of 5‐HT on rat dentate gyrus neurones in vitro.

Cited by 100 publications

References 39 publications

Serotonergic neuron diversity: Identification of raphe neurons with discharges time-locked to the hippocampal theta rhythm

Serotonergic neuron diversity: Identification of raphe neurons with discharges time-locked to the hippocampal theta rhythm

Serotonin-Induced Increases in Adult Cell Proliferation and Neurogenesis are Mediated Through Different and Common 5-HT Receptor Subtypes in the Dentate Gyrus and the Subventricular Zone

Serotonin as a Modulator of Glutamate- and GABA-Mediated Neurotransmission: Implications in Physiological Functions and in Pathology

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