Serotonergic Intraventricular Axons in the habenular region

Cupedo, Rnj; Weerd, Hd

doi:10.1007/bf00315907

Cited by 14 publications

(9 citation statements)

References 39 publications

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“…The available immunohistochemical data on the supraependymal fibers of the ventricular system of the rat are inconsistent; some investigators reported the absence of GAD immunoreactivity (Richards et al, 1981), but others found a positive reaction with the GABA antiserum after treatment with aminooxyacetic acid, an inhibitor of GABA catabolism (Harandi et al, 1986). It has been established that supraependymal fibers of the rat are principally derived from the RN (Aghajanian and Gallager, 1975;Cupédo and de Weerd, 1980;Lorez and Richards, 1982;Larsen et al, 1996). According to our electron microscopic immunocytochemical observations, the supraependymal fibers in the pineal recess of the tree shrew are also immunoreactive for TH (Kado et al, 1999).…”

Section: Discussionmentioning

confidence: 96%

Central GABAergic innervation of the mammalian pineal gland: A light and electron microscopic immunocytochemical investigation in rodent and nonrodent species

2000

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Light and electron microscopic immunocytochemical observations were made to demonstrate central pinealopetal fibers immunoreactive for gamma-aminobutyric acid (GABA) and synapses between their terminals and pinealocytes in the pineal gland of four rodent (Wistar-King rat; mouse; Syrian hamster, Mesocricetus auratus; Hartley strain guinea pig) and one nonrodent (tree shrew, Tupaia glis) species. GABA-immunoreactive myelinated and unmyelinated fibers and endings were found in the parenchyma of the pineal gland of all the animals examined. In the rodent species, GABAergic fibers were mainly found in the intermediate and proximal portions of the pineal gland and were nearly or entirely absent in the distal portion of the gland. Abundant GABAergic fibers were evenly distributed throughout the gland of the tree shrew. In all the animals, the habenular and posterior commissures contained abundant GABA-positive fibers, and some of them were followed to the pineal gland. GABA-positive endings made synaptic contact with pinealocytes, occasionally in mice and guinea pigs, and frequently in tree shrews; no synapses were observed in Syrian hamsters and rats. In the pineal gland of all the animals, GABA-immunoreactive cell bodies were not detected, and sympathetic fibers were not immunoreactive for GABA. These data indicate that GABAergic fibers are main pinealopetal projections from the brain. In view of the difference in the distribution of these fibers, central GABAergic innervation may play a more significant role in nonrodents than in rodents. The frequent occurrence of GABAergic synapses on pinealocytes in the tree shrew suggests that GABA released at these synapses directly controls activity of pinealocytes of this animal.

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Section: Discussionmentioning

confidence: 96%

Central GABAergic innervation of the mammalian pineal gland: A light and electron microscopic immunocytochemical investigation in rodent and nonrodent species

2000

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“…The CSF has previously been proposed to convey neuromodulatory messages to neurons in different brain areas (Nicholson, ; Veening & Barendregt, ). Although a number of interesting anatomical findings have added plausibility to this concept (Cupedo & de Weerd, ; Jackson, ; Buma et al . ; Calle et al .…”

Section: Discussionmentioning

confidence: 99%

“…An intriguing finding suggesting that neuromodulators distributed in CSF could act to regulate neuronal activity is the presence of CSF‐contacting neurons in vertebrate brains (Cupedo & de Weerd, ; Buma et al . ; Calle et al .…”

Section: Introductionmentioning

confidence: 99%

Human cerebrospinal fluid increases the excitability of pyramidal neurons in the in vitro brain slice

Björefeldt

Andréasson

Daborg

et al. 2014

The Journal of Physiology

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Key pointsr The cerebrospinal fluid contains numerous neuromodulators at ambient levels but whether, and how, they affect the activity of central neurons is unknown.r This study provides experimental evidence that human cerebrospinal fluid (hCSF) increases the excitability of hippocampal and neocortical pyramidal neurons.r Hippocampal CA1 pyramidal neurons in hCSF displayed lowered firing thresholds, depolarized resting membrane potentials and reduced input resistance, mimicking properties of pyramidal neurons recorded in vivo.r The excitability-increasing effect of hCSF on CA1 pyramidal neurons was entirely occluded by intracellular application of GTPγS, suggesting that neuromodulatory effects were mediated by G-protein coupled receptors.r These results indicate that the CSF promotes spontaneous excitatory neuronal activity, and may help to explain observed differences in the activity of pyramidal neurons recorded in vivo and in vitro.Abstract The composition of brain extracellular fluid is shaped by a continuous exchange of substances between the cerebrospinal fluid (CSF) and interstitial fluid. The CSF is known to contain a wide range of endogenous neuromodulatory substances, but their collective influence on neuronal activity has been poorly investigated. We show here that replacing artificial CSF (aCSF), routinely used for perfusion of brain slices in vitro, with human CSF (hCSF) powerfully boosts spontaneous firing of CA1, CA3 and layer 5 pyramidal neurons in the rat brain slice. CA1 pyramidal neurons in hCSF display lowered firing thresholds, more depolarized resting membrane potentials and reduced input resistance, mimicking properties of pyramidal neurons recorded in vivo. The increased excitability of CA1 pyramidal neurons was completely occluded by intracellular application of GTPγS, suggesting that endogenous neuromodulators in hCSF act on G-protein coupled receptors to enhance excitability. We found no increase in spontaneous inhibitory synaptic transmission by hCSF, indicating a differential effect on glutamatergic and GABAergic neurons. Our findings highlight a previously unknown function of the CSF in promoting spontaneous excitatory activity, and may help to explain differences observed in the activity of pyramidal neurons recorded in vivo and in vitro.

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“…Their abundant presence near the median eminence suggests that these supraependymal elements are involved in a variety of functions [112-117] (Fig 3A, B). Among these, serotonergic fibers have been described as originating from the raphe nuclei with nerve terminals located in the CSF.…”

Section: Introductionmentioning

confidence: 99%

The regulation of brain states by neuroactive substances distributed via the cerebrospinal fluid; a review

Veening

Barendregt

2010

Fluids Barriers CNS

143

112

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The cerebrospinal fluid (CSF) system provides nutrients to and removes waste products from the brain. Recent findings suggest, however, that in addition, the CSF contains message molecules in the form of actively released neuroactive substances. The concentrations of these vary between locations, suggesting they are important for the changes in brain activity that underlie different brain states, and induce different sensory input and behavioral output relationships.The cranial CSF displays a rapid caudally-directed ventricular flow followed by a slower rostrally-directed subarachnoid flow (mainly towards the cribriform plate and from there into the nasal lymphatics). Thus, many brain areas are exposed to and can be influenced by substances contained in the CSF. In this review we discuss the production and flow of the CSF, including the mechanisms involved in the regulation of its composition. In addition, the available evidence for the release of neuropeptides and other neuroactive substances into the CSF is reviewed, with particular attention to the selective effects of these on distant downstream receptive brain areas. As a conclusion we suggest that (1) the flowing CSF is involved in more than just nutrient and waste control, but is also used as a broadcasting system consisting of coordinated messages to a variety of nearby and distant brain areas; (2) this special form of volume transmission underlies changes in behavioral states.

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Serotonergic Intraventricular Axons in the habenular region

Cited by 14 publications

References 39 publications

Central GABAergic innervation of the mammalian pineal gland: A light and electron microscopic immunocytochemical investigation in rodent and nonrodent species

Central GABAergic innervation of the mammalian pineal gland: A light and electron microscopic immunocytochemical investigation in rodent and nonrodent species

Human cerebrospinal fluid increases the excitability of pyramidal neurons in the in vitro brain slice

The regulation of brain states by neuroactive substances distributed via the cerebrospinal fluid; a review

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