• The Korean Journal of Zoology
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• v.36 no.1
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• pp.116-122
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• 1993

An immunocytochemical investigation has been carried out to localize serotoninimmunoreactive (5-HTi) neurons in suboesophageal ganglion of fifth instar lawn of cabbage worm Pieris rupae. The 285-HTi cell bodies were identified in the rind of suboesophaseal ganglion. The four 5-HTi cell bodies of them are 18rge in size (about 35 Um), while the remaining cell bodies are medium-sized (about 15 Uml. The 5-HTi nerve processes are abundantly located in central large neuropil, circumoesophageal connectives which join the suboesophaseal ganglion to the tritocerebrum of the brain, and connectives between the suboesophageal and the first thoracic ganglia. These results indicate that the 5-HTi nerve fibers, which constitute the central large neuropil, have structural connections with the above two connectives. Especially in central large neuropil, many 5-HTi nenre fibers form a large circular bundle, in which a 5-HTi nerve fiber bundle is crossing.

• Journal of Acupuncture Research
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• v.17 no.2
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• pp.119-138
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• 2000

This study was designed to evaluate the effect of the bee venom(BV) aqua-acupuncture on the neuronal activities of serotonergic(5-HT) system in the brainstem. After the BV aqua-acupuncture was applied on Chok-Samni(ST36) and the gluteal part(Blank locus) in rats, the number of Fos immunoreactive neurons was counted by using computerized image analyzing system. Also, the number of colocalization between 5-HT containing neurons Fos immunoreactive neurons were analyzed by using the double immunohistochemical technique. The results of the experiments were summarized as follows : 1. In almost every neucli, the Chok-Samni group and Blank locus group showed more increase in the number of Fos immunoreactive neurons than the control group. Especially, in Arc, DR, LC, RMg, Gi, PAG Rost and PAG LV, the Chok-Samni group showed more significant increase than the control group. Also, in PAG LV Mid and Arc, Chok-Samni group showed more significant increase than the Blank locus group. 2. In DR and PAG LV Mid, Chok-Samni group and the Blank locus group showed more significant increase in the number of colocalization between 5-HT containing neurons and Fos immunoreactive neurons than the control group after the BV aqua- acupuncture. Also, the Chok-Samni group showed more significant increase than the Blank locus group. Consequently, the BV aqua-acupuncture increased more potent the number of Fos immunoreactive neurons and the activity of serotonergic neurons. Furthermore, the BV aqua-acupuncture was more effective on Chok-Samni than Blank locus group. These results indicate that the BV aqua-acupuncture is very effective therapy to control pain. The therapeutic effect of BV aqua-acupunture may associated with the endogenous modulatory system such as serotonin Those data from the study can be applied to establish the effective treatment of the BV for pain control in the clinical field.

• The Korean Journal of Zoology
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• v.35 no.4
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• pp.428-438
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• 1992

The serotonin-immunoreactive (5-HTil neurons have been investigated in the brains of lanra, pupa and adult from Pieris ropae. There are ca. 54 5-HTi neurons in 5-instar larva, ca. 20 in 2-dav-old pupa and ca. 118 in 1-day-old adult, respectively. Most of these 5-HTi neurons are interneurons, but efferent and afferent 5-HTi neurons were also observed. Most of the 5-HTi neurons project into the central neuropils of postembrvonic brains. The larval brain contains abundant 5-HTi processes in the central neuropils, including those in three cerebral commissures. But in the pupal brain the 5-HTi processes are restricted in small numbers to the given regions of central neuropil. The adult brain contains a large number of 5-HTi processes in mushroom body, central body complex, lateral protocerebrum, protocerebral bridge, antennal lobe, and tritocerebral and suboesophageal neuropils. However, the 5-HTi processes are not found in the optic lobe of the brains. One prominent feature of the 5-HTi fibers in the postembrvonic brains is the fact that they are greatly arborized.

• The Korean Journal of Pharmacology
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• v.31 no.2
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• pp.141-144
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• 1995

Serotonergic neurons in brainstem play important roles in the endogenous descending pain inhibitory system. To illucidate the involvement of glutamate receptors in the regulation of brainstem serotonergic neurons, we studied the effects of glutamate receptor agonists on 5-hydroxytryptamine(5-HT) release from cultured neurons of rat fetal (gestational age 14th day) brainstem. Cultured cells maintained for 10 days in vitro were stimulated for 30 minutes with agonists of glutamate receptor subtypes at 10-1,000 micromolar concentration. Glutamate (10-1,000 M) increased 5-HT release in a concentration-dependent manner. N-methyl-D-aspartic acid $(NMDA)(10-1,000\;{\mu}M)$ increased 5-HT release in a concentration-dependent manner. Non-NMDA receptor agonists, kainate and $AMPA(3-1,000\;{\mu}M)$ also concentration-dependently increased 5-HT release. These results suggest that both NMDA and non-NMDA receptors regulate 5-HT release from brainstem serotonergic neurons.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.5
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• pp.449-457
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• 2021

The sleep-wake cycle is regulated by the alternating activity of sleep- and wake-promoting neurons. The dorsal raphe nucleus (DRN) secretes 5-hydroxytryptamine (5-HT, serotonin), promoting wakefulness. Melatonin secreted from the pineal gland also promotes wakefulness in rats. Our laboratory recently demonstrated that daily changes in nitric oxide (NO) production regulates a signaling pathway involving with-no-lysine kinase (WNK), Ste20-related proline alanine rich kinase (SPAK)/oxidative stress response kinase 1 (OSR1), and cation-chloride co-transporters (CCC) in rat DRN serotonergic neurons. This study was designed to investigate the effect of melatonin on NO-regulated WNK-SPAK/OSR1-CCC signaling in wake-inducing DRN neurons to elucidate the mechanism underlying melatonin's wake-promoting actions in rats. Ex vivo treatment of DRN slices with melatonin suppressed neuronal nitric oxide synthase (nNOS) expression and increased WNK4 expression without altering WNK1, 2, or 3. Melatonin increased phosphorylation of OSR1 and the expression of sodium-potassium-chloride co-transporter 1 (NKCC1), while potassium-chloride co-transporter 2 (KCC2) remained unchanged. Melatonin increased the expression of tryptophan hydroxylase 2 (TPH2, serotonin-synthesizing enzyme). The present study suggests that melatonin may promote its wakefulness by modulating NO-regulated WNK-SPAK/OSR1-KNCC1 signaling in rat DRN serotonergic neurons.

• Sleep Medicine and Psychophysiology
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• v.2 no.2
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• pp.133-137
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• 1995

The author reviews current knowledge about what REM sleep is and where and how it is generated. REM sleep is the state in which our most vivid dreams occur. REM sleep is identified by the simultaneous presence of a desynchronized cortical EEG, an absence of activity in the antigravity muscles(atonia), and periodic bursts of rapid eye movements. Another characteristic phenomena of REM sleep are the highly synchronized hippocampal EEG of theta frequency and the ponto-geniculo-occipital(PGO) spike. All these phenomena can be explained in terms of changes in neuronal activity. Transection studies have determined that the pons is sufficient for generating REM sleep. Lesion studies have identified a small region in the lateral pontine tegmentum corresponding to lateral portions of the nucleus reticularis pontis oralis(RPO) and the region immediately ventral to the locus coeruleus, which is required for REM sleep. Unit recording studies have found a population of cells within this region that is selectively active in REM sleep. Cholinergic neurons of the giant cell field of pontine tegmentum(ETG), which is 'REM a sleep-on cells', has shown to be critically involved in the generation of REM sleep. Noradrenergic neurons of the locus coeruleus and serotonergic neurons of the dorsal raphe, which are called 'REM sleep-off cells', appear to act in a reciprocal manner to the cholinergic neurons. It is proposed that the periodic cessations of discharge of 'REM sleep-off cells' during REM sleep might be significant for the prevention of the desensitization of receptors of these neurons.

• The Korean Journal of Pharmacology
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• v.26 no.1
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• pp.1-6
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• 1990

We established an in vitro system of central serotonergic neurons by culturing dissociated rat embryonic (El4) brainstem cells to 14 days in vitro and monitored the serotonergic neuronal growth by measuring 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) contents in the cells with hish performance liquid chromatography with electrochemical detection (HPLC-EC). We studied also tile effects of various drugs on the contents of 5-HT and 5-HIAA, confirming in vivo reports. The 5-HT content (13 ng/mg protein) and 5-HT turnover rate (17 pmol/mg protein/h) at 14 days in vitro were in good agreement with those reported in the adult rat brain. The 5-HT content was more easily depleted with p-chlorophenylalanine, a tryptophan hydroxylase inhibitor than with NSD 1015 (3-hydroxybenzylhydrazine), an aromatic L-amino acid decarboxylase (AADC) inhibitor. Incubation of the cultures with tryptophan or 5-hydroxytryptophan increased the rate of serotonin formation implying that neither tryptophan hydroxylase nor AADC is saturated with its amino acid substrate in this in vitro system . The 5-HT content was depleted by reserpine. The 5-HT and 5-HIAA contents were increased and decreased, respectively, by monoamine oxidase inhibitors. All the above results indicate that the biochemical properties of the central serotonergic neurons in this culture system reflect reliably those of central serotonergic neurons in vivo. We suggest that measuring 5-HT and 5-HIAA contents in the primary cultured dissociated brainstem-cells with HPLC-EC is useful in the study of pharmacology as well as toxicolgy of the central serotonergic neurons.

• The Korean Journal of Pharmacology
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• v.25 no.1
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• pp.1-11
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• 1989

In this study, it was aimed to investigate the role of serotonergic neurotransmission in nucleus tractus solitarius (NTS) for the central regulation of blood pressure and heart rate and its involvement in baroreceptor reflex activation in rats. A microinjection of 5-hydroxytryptamine (5-HT) into the NTS produced decreases in blood pressure and heart rate. Maximal decreases were $34.4{\pm}1.6$ mmHg and $41.7{\pm}10.2$ beats per min by 300 pmol of 5-HT. Microinjections of ${\alpha}-methylnor-adrenaline$ $({\alpha}-MNE)$ and clonidine manifested similar decreases in blood pressure and heart rate. The hypotensive and bradycardial effects of 5-HT were blocked by previous applications of 5-HT antagonists, ritanserin, methysergide and ketanserin into the NTS, respectively. By pretreatment with reserpine and 6-hydroxydopamine (6-OHDA, i.c.v.), both hypotensive and bradycardial effects of 5-HT were significantly attenuated. Pretreatment with 5, 7-dihydroxytryptamine (5,7-DHT, i.c.v.) enhanced the hypotensive and bradycardial effects of 5-HT. Similarly, following pretreatment with 6-OHDA, the effects of clonidine were increased. Pretreatment either with 5,7-DHT or 6-OHDA significantly attenuated the sensitivity of baroreflex produced either by phenylephrine or by sodium nitroprusside. When either 5,7-DHT or 6-OHDA was injected into the NTS $(5,7-DHT;\;8{\mu}g\;6-OHDA;\;10{\mu}g)$, both of the baroreflex sensitivities were impaired. In the immunohistochemical study, the injection of 6-OHDA into the the NTS led to reduction of axon terminal varicosity, however, the injection did not reduce the numbers of catecholaminergic cell bodies. Likewise, when 5,7-DHT was injected into the NTS, the varicosity of serotonergic axon terminals was markedly reduced. Based on these results, it is suggested that (1) stimulation of serotonergic receptors in the NTS leads to decreases in blood pressure and heart rate as observed with the stimulation of catecholaminergic system, (2) both serotonergic and catecholaminergic receptors may be located postsynaptically, and (3) the serotonergic neurons as well as catecholaminergic neurons may have a close relevance for the activation of baroreflex.

• The Korean Journal of Zoology
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• v.38 no.3
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• pp.348-355
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• 1995

This Investigation was carried out to map the morphological development of serotonin-immunoreactive neurons in the larval brain of the cabbage butterfly, Artogeia rapae, during five larval stages. Both the first instar larva and the second instar larva contained twenty serotonin-immunoreactive (5-HTi) neurons in each brain. The fibres of 5-HTI commissure was interconnected to two cerebral hemispheres in both brains. However, the 5-HTi commissural fibres was Increased in number in the second-instar larva brain. In the brain of the second Insar larva these 5-HTi fibres formed rich arborization in contralateral neuropils, especially In the posterior parts of it. The third-Instar larva braIn, which Included twenty two 5-HTi neurons, had three groups of 5-HTi commissural fibres. In the fourth Instar larva, the number of 5-HTi fibres as well as 5-HTi cell bodies increased in the brain. The fifth-instar larva brain, which contained fifty four 5-HTi cell bodies, showed the largest number of 5-HTi cell bodies In developing larval brains. The 5-HTi fibres formed richest commissural fibres and some of them run parallel to anteroposterior axis.

• The Korean Journal of Pharmacology
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• v.31 no.1 s.57
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• pp.11-15
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• 1995

Serotonergic neurons in medulla oblongata play an important role in the endogenous descending pain inhibitory system. To illucidate the factors involved in the regulation of medullary serotonergic neurons, we studied the effects of cholecystokinin (CCK) and agents acting on various second messenger systems on 5-hydroxytryptamine (5-HT) release from cultured neurons of rat fetal (gestational age 14th day) medulla oblongata. Cultured cells maintained for 10 days in vitro were stimulated for 48 hours with CCK or other neuropeptides at 10 micromolar concentration. CCK ($10{\mu}M$) and substance P ($10{\mu}M$) significantly increased. 5-HT release. However, somatostatin, proctolin, thyrotropin releasing hormone, and interleukin-6 did not have any effects on 5-HT release. Nimodipine ($1{\mu}M$), a calcium channel blocker, almost completely, and calmidazolium ($1{\mu}M$), a calmodulin antagonist, significantly inhibited the CCK-induced 5-HT release. The total 5-HT content (intracellular 5-HT plus released 5-HT) was significantly increased by CCK. However, the intracellular 5-HT content was not significantly changed by CCK. Forskolin ($5{\mu}M$), an adenylate cyclase activiator, but not $2{\mu}M$ phorbol myristate acetate (PMA), a protein kinase C activator, significantly enhanced 5-HT release. The total 5-HT content (intracellular 5-HT plus released 5-HT) was significantly increased by forskolin. However, the intracellular 5-HT content was not significantly changed by forskolin. PMA had no effect on intracellular 5-HT levels. These results suggest that CCK regulates serotonergic neurons in the medulla oblongata by enhancing 5-HT secretion through calcium influx and caimodulin, and that cyclic AMP system but not protein kinase C system is involved in 5-HT release.