Distribution and ultrastructure of dopaminergic neurons in the dorsal motor nucleus of the vagus projecting to the stomach of the rat

Hayakawa, Tetsu; Takanaga, Akinori; Tanaka, Kōichi; Maeda, Seishi; Seki, Makoto

doi:10.1016/j.brainres.2004.01.056

Cited by 24 publications

(20 citation statements)

References 34 publications

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“…There are some neurons containing dopamine in the DMV [25][26][27] . Tsukamoto et al (2005) 28) reported that about 10% of the DMV neurons contain dopamine and project to the subdiaphragmatic esophagus and the stomach, but only a few neurons containing dopamine project to the duodenum in the rat.…”

Section: Discussionmentioning

confidence: 99%

Collateral projections of the dorsal motor nucleus of the vagus nerve to the stomach and the intestines in the rat

Hayakawa

Kuwahara-Otani

Maeda

et al. 2013

Okajimas Folia Anat. Jpn.

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Summary:The vagal motor neurons project to the gastrointestinal tract by way of the gastric, celiac and hepatic branches of the vagus trunk. We have examined whether single neurons in the dorsal motor nucleus of the vagus nerve (DMV) have collateral projections to the stomach, the duodenum and the intestines using a double-labeling tracing method. Following application of Fluorogold to the cut end of the accessory celiac branch and injection of cholera toxin subunit b (CTb) into the body of stomach, many Fluorogold-and CTb-labeled neurons were found throughout the DMV. Most CTb-labeled neurons (about 90%) were also labeled with Fluorogold. When Fluorogold was applied to the cut end of the accessory celiac or the gastric branch and CTb was injected into the duodenum, many Fluorogold-labeled neurons and CTb-labeled neurons were found in the DMV. About 20% of CTb-labeled neurons were also labeled with Fluorogold. These results indicate that many neurons in the DMV send collateral projections to both the stomach and the intestines innervated by way of the celiac branch. However, many neurons in the DMV projecting to the duodenum do not project to the stomach or the intestines caudal to the duodenum.

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Section: Discussionmentioning

confidence: 99%

Collateral projections of the dorsal motor nucleus of the vagus nerve to the stomach and the intestines in the rat

Hayakawa

Kuwahara-Otani

Maeda

et al. 2013

Okajimas Folia Anat. Jpn.

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“…Although it is not our intention to settle the dispute about the neurochemical phenotype of these neurons, i.e., whether all the TH-IR-positive cells in the A2 area are also DβH-IR (i.e., noradrenergic and/ or adrenergic) or some of these cells are TH-IR only (i.e., dopaminergic but not noradrenergic and/or adrenergic) (18,20,21,40,42), we, however, conducted the present experiments with the intention of investigating whether a subpopulation of brain stem neurons is dopaminergic. The present manuscript confirms the previous reports that the vast majority of catecholaminergic DMV neurons are dopaminergic, since they contain TH-but not DβH-IR (3,21,32).…”

Section: Discussionmentioning

confidence: 99%

“…Studies on the relative distribution and colocalization of tyrosine hydroxylase (TH; whose presence implies that neurons synthesize DA but not necessarily NE) and dopamine-β-hydroxylase (DβH; whose presence implies the enzymatic transformation of DA to NE) report different degrees of colocalization in neurons of the A2 area, which encompasses both the NTS and the DMV (18,20,21,40,42). Although it is not clear whether specific GI-function related brain stem vagal circuits express D1-and D2-like dopamine receptors (15,29), a recent electrophysiological study focusing on cardiorespiratory circuits reports that DA activates D2-like receptors only and inhibits synaptic transmission between the tractus solitarius and NTS neurons (25).…”

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Dopamine effects on identified rat vagal motoneurons

Zheng¹,

Travagli²

2007

American Journal of Physiology-Gastrointestinal and Liver Physi

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Catecholaminergic neurons of the A2 area play a prominent role in brain stem vagal circuits. It is not clear, however, whether these neurons are noradrenergic or adrenergic, i.e., display tyrosine hydroxylase (TH) and dopamine-β-hydroxylase (DβH) immunoreactivity (-IR) or dopaminergic (i.e., TH-but not DβH-IR). Our aims were to investigate whether a subpopulation of neurons in the A2 area was dopaminergic and, if so, to investigate the effects of dopamine (DA) on the membrane of gastric-projecting vagal motoneurons. We observed that although the majority of A2 neurons were both TH-and DβH-IR, a small percentage of nucleus tractus solitarius neurons were TH-IR only, suggesting that DA itself may play role in these circuits. Whole cell recordings from thin brain stem slices showed that 71% of identified gastric-projecting motoneurons responded to DA (1-300 µM) with either an excitation (28%) or an inhibition (43%) of the membrane; the remaining 29% of the neurons were unresponsive. The DA-induced depolarization was mimicked by SK 38393 and prevented by pretreatment with SCH 23390. Conversely, the DA-induced inhibition was mimicked by bromoergocryptine and prevented by pretreatment with L741626. When tested on the same neuron, the effects of DA and NE were not always similar. In fact, in neurons in which DA induced a membrane depolarization, 77% were inhibited by NE, whereas 75% of neurons unresponsive to DA were inhibited by NE. Our data suggest that DA modulates the membrane properties of gastric-projecting motoneurons via D1-and D2-like receptors, and DA may play different roles than norepinephrine in brain stem vagal circuits. Keywords brain stem; electrophysiology; gastricThe dorsal vagal complex (DVC), i.e., the nucleus tractus solitarius (NTS), the dorsal motor nucleus of the vagus (DMV), and the area postrema (AP), plays an important role in the control of homeostatic and autonomic functions, including the modulation of functions in the gastrointestinal (GI) tract. Sensory information from the GI tract is received and integrated by NTS neurons where it is modulated and transferred to, among other areas, the preganglionic neurons of the DMV; DMV neurons then provide a regulated efferent motor vagal outflow to the GI tract (reviewed recently in Refs. 38,39).A vast array of neurotransmitters are present in the DVC; by modulating the neuronal membrane and/or the synaptic connections between the tractus solitarius, the NTS, and the DMV, each neurotransmitter may contribute to the fine tuning of selected circuits devoted to specific functions (reviewed recently in Ref. 33). Among these neurotransmitters catecholamines, originating either from neurons in the A6, A5, A2, and A1/C1 areas and/or

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“…The caudal region of the VLM and NTS (A1 and A2, respectively) generally contain NE neurons, whereas E neurons predominate in rostral portions of these nuclei (C1 and C2). Although many cells of the DMV are cholinergic preganglionic autonomic motoneurons (Schafer et al, 1998), others express the synthetic enzymes tyrosine hydroxylase (TH) and dopamine-␤-hydroxylase (D␤H) and are presumed to be a mixture of DA and NE neurons (Guo et al, 2001;Gwyn et al, 1985;Hayakawa et al, 2004;Manier et al, 1987). Neurons in this region have even been identified that express both choline acetyltransferase and TH (Armstrong et al, 1988;Manier et al, 1987).…”

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confidence: 99%

Nicotinic acetylcholine receptor subunit mRNA expression in adult and developing rat medullary catecholamine neurons

O’Leary

Loughlin

Leslie

2008

J of Comparative Neurology

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Nicotinic acetylcholine receptors (nAChRs) mediate numerous visceral functions via medullary catecholamine (CA) neurons found in the nucleus tractus solitarius (NTS), dorsal motor nucleus of the vagus (DMV), and ventrolateral medulla (VLM). However, the nAChR subtypes involved are not known. We have therefore characterized expression of nine nAChR subunit mRNAs in adult and developing rat medullary CA nuclei using combined isotopic/nonisotopic in situ hybridization. Tyrosine hydroxylase (TH) mRNA, the CA-synthesizing enzyme, was used as a marker for CA neurons, because these nuclei consist of heterogeneous populations of cells. Subunit mRNA expression varied within and between nuclei, along the rostrocaudal axis, between cell types, and across development. All CA neurons expressed beta2 mRNA, whereas alpha2 mRNA was completely absent. alpha6 And beta3 mRNA expression were restricted mainly to the VLM. alpha4, alpha5, And alpha7 mRNA expression was significantly greater in the rostral than in the caudal VLM. alpha3 And beta4 mRNAs were highly expressed in the dorsal region of the NTS, whereas dense alpha7 mRNA expression was restricted to the DMV and ventral NTS. The remaining subunit mRNAs were detected to some degree in both DMV and NTS. Except for alpha4 mRNA, which peaked prenatally, expression levels of subunit transcripts in the NTS and DMV were lower during development compared with adults. In the VLM, alpha3, alpha4, and alpha5 mRNAs expression peaked perinatally, whereas alpha6 and beta3 levels increased with age. These variations in nAChR subunit mRNA expression suggest that different receptor subtypes may produce function-specific regulation of medullary CA systems.

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Distribution and ultrastructure of dopaminergic neurons in the dorsal motor nucleus of the vagus projecting to the stomach of the rat

Cited by 24 publications

References 34 publications

Collateral projections of the dorsal motor nucleus of the vagus nerve to the stomach and the intestines in the rat

Collateral projections of the dorsal motor nucleus of the vagus nerve to the stomach and the intestines in the rat

Dopamine effects on identified rat vagal motoneurons

Nicotinic acetylcholine receptor subunit mRNA expression in adult and developing rat medullary catecholamine neurons

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