• Toxicological Research
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• v.14 no.4
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• pp.495-500
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• 1998

The effect of acute toluene exposure on behaviour and monoamine concentrations in the various brain regions were investigated in the rat. Toluene was adminstered via inhalation to rats at concentrations of 0, 1000, 10000, 40000 ppm for 20 min. During exposure to toluene, spontaneous locomotor activity was counted. After exposure, animals were sacrificed instantly and brains were separated. Regional concentratons of brain monoamines (norepinephrine, NE; dopamine, DA; 5- hydroxytryptamine, 5-HT) and its metabolites (3,4-dihydroxyphenylacetic acid, DOPAC; homovanillic acid, HVA; 5-hydroxyindole-3-acetic acid, 5-HIAA) were determined. The changes in locomotor activity during toluene exposure depended on the toluene concentration. At 1000 ppm concentration, spontaneous locomotor activity increased initially and thereafter decreased. At higher concentrations (10000 ppm and 40000 ppm), spontaneous locomotor activity decreased and eventually ceased. A regional analysis of VA, NE, 5-HT, VOPAC, HVA, and 5-HIAA indicated a significant decrease in VA concentrations in cerebellum and striatum while NE and 5-HT concentrations were significantly increased in the cerebellum and cortex. 5-HIAA concentrations were significantly increased in all brain regions. DOPAC concentrations were significantly increased in cerebellum and cortex while decreased in striatum. These results especially indicated that metabolic conversion of DA to HVA in striatum was highly increased by toluene inhalation. However, It remains to elucidate between behavioural responses and monoamine changes.

• The Korean Journal of Physiology
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• v.4 no.2
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• pp.45-51
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• 1970

In an attempt to better understand the effect of whole body irradiation on the spontaneous motility and oxygen consumption rate of the isolated mouse duodenum, a whole body X-irradiation of 1,000r. was given to albino mouse, and 1) the total length of contraction of isolated duodenum was recorded on kymograph every five minutes for 60 minutes, 2) glucose and 5-hydroxytryptamine(5-HT) were added to the reaction medium of Kreb's-Ringer-bicarbonate buffer(KRB) and response of the isolated duodenum to the drugs was observed, and 3) the oxygen consumption rate $(QO_2)$ of the isolated duodenum as well as the effect of glucose and 5-HT on $QO_2$ were measured by Warburg's standard manometric method and the comparison was made with the control(i.e. normal) group. The results thus obtained are summarized as follows. 1. The spontaneous motility of the isolated duodenum in the irradiated groups showed a significantly elevated pattern for the first 15 minutes comparing with the control. The motility, however, decreased after 15 minutes and remained so in the irradiated groups to the level of the nonirradiated control, but 24 hours post-irradiation group showed a tendency of an increased motility while one hour post-irradiation group showed no difference comparing with the control. 2. Addition of glucose produced generally elevated motility of the isolated duodenum in both irradiated and non-irradiated groups comparing with the control throughout the experiment, but no difference was observed in contractile amplitude between the irradiated and non·irradiated groups. 3. When 5-HT was added to the irradiated group, the contractile amplitude of isolated duodenum was similar to that of the control, and 5-HT alone caused a slight increase of the motility comparing with the control. 4. The oxygen consumption rate $(QO_2)$ of the isolated duodenum was found to be ,slightly increased in one hour post·irradiated group, but similar in 24 hour post·irradiated group comparing with the control. Glucose produced a significant increase of $QO_2$ in all the groups, but 5-HT produced a tendency of decrease of $QO_2$ in all the groups.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.6
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• pp.293-297
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• 2002

The role of 5-hydroxytryptamine $(5-HT)_1A$ receptor activity in prenatal ischemia was studied, by injecting 8-hydroxy-dipropylaminotetraline (8-OH-DPAT; $50{\mu}g/kg,$ s.c.), a $5-HT_1A$ agonist on gestation day 17, and 30 min later inducing transient ischemia by ligating the uterine vessels for 30 min. On postnatal day 95, rats that had experienced prenatal ischemia showed impaired motor coordination and reduced concentration of 5-HT in the cerebellum compared with Sham-operated controls. In addition, they showed increased $5-HT_1A$ receptor densities in the cerebral cortex. Pretreatment with 8-OH-DPAT ameliorated the behavioral and neurochemical sequelae measured in the present study. The results suggest that $5-HT_1A$ receptors protect the brain from ischemic insult and/or facilitate recovery after prenatally experienced ischemia.

• The Korean Journal of Pain
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• v.26 no.2
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• pp.125-129
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• 2013

Background: 5-hydroxytryptamine 3 (5-HT3) receptors have been known to be associated with the modulation of nociceptive transmission. However, it is uncertain whether 5-HT3 plays a role in the antinociceptive or pronociceptive pathway for incisional pain. In this study, we evaluated the effects of palonosetron, a 5-HT3 receptor antagonist, on incisional pain in rats when administered intrathecally or intraplantarly. Methods: An intrathecal catheter was implanted through the cisterna magna and placed in the intrathecal space of rats. An incision in the plantaris muscle of the right hind paw was done under anesthesia with sevoflurane. Withdrawal thresholds were evaluated with the von Frey filament after 2 hours. Palonosetron (0.5 and 0.1 ${\mu}g$ intrathecally; 0.5 ${\mu}g$ intraplantarly) was administered and the thresholds were observed for 4 hours. Results: Mechanical hypersensitivity developed after the incision. Intrathecal palonosetron (0.5 ${\mu}g$ and 0.1 ${\mu}g$) did not alter the paw withdrawal threshold. Intraplantar palonosetron (0.5 ${\mu}g$) also did not change the paw withdrawal threshold. Conclusions: Intrathecal and intraplantar palonosetron (0.5 ${\mu}g$) had no effect on modulating the mechanical hypersensitivity in the incisional pain model of rats.

• The Journal of Korean Medicine
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• v.24 no.4
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• pp.87-91
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• 2003

Objectives: To examine the relaxational response to the water extract of Rheum palmatum L. and Rheum undulatum L. on rat thoracic aorta and abdominal aorta. Methods: Segments of thoracic aorta and abdominal aorta obtained from rats immediately after delivery were mounted in organ baths superfused on a polygraph. Results : We found that the thoracic aorta segments responded to the water extract of genus Rheum with a dose-dependent vasorelaxation. At $10^{-4}$ M 5-HT, the maximal contraction force was 93.5% of the maximum KCI-response. The 5-HT induced contractions at $10^{-4}$ M were inhibited by 86.4% and 62.1 % after addition of the high concentrations of R. palmatum root (RPR) and leaf (RPL) and R. undulatum root (RUR) and leaf (RUL). At 10 mg/ml RPR and RUR, the relaxational response at thoracic aorta and abdominal aorta with and without endothelium were 86.4%, 83.2%, 85.8%, and 62.1% of the maximum 5-HT induced contraction. Conclusion: Our result showed that RPL and RUL induced dose-dependent vasorelaxation on rat thoracic aorta and abdominal aorta, and that RPL and RUL roots have more potent effects than the leaves.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.5
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• pp.547-553
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• 1997

It has been known that activation of tyrosine kinases is involved in signal transduction. Role of the tyrosine kinase in vascular smooth muscle contraction was examined in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Male Sprague-Dawley rats underwent uninephrectomy, one week after which they were subcutaneously implanted with DOCA (200 mg/kg) and supplied with 1% NaCl and 0.2% KCl drinking water for $4{\sim}6$ weeks. Control rats were treated the same except for that no DOCA was implanted. Helical strips of carotid arteries were mounted in organ baths for measurement of isometric force development. Genistein was used as a tyrosine kinase inhibitor. Concentration-response curves to 5-hydroxytryptamine (5-HT) shifted to the right by genistein in both DOCA-salt hypertensive and control rats. Although the sensitivity to genistein was similar between the two groups, the maximum force generation by 5-HT was less inhibited by genistein in arteries from DOCA-salt hypertensive rats than in those from controls. Genistein-induced relaxations were attenuated in arteries from DOCA-salt rats. Genistein affected the contraction to phorbol 12, 13-dibutyrate (PDBu) neither in DOCA-salt nor in control arteries. These observations suggest that tyrosine kinase is involved in 5-HT-induced vascular contraction, of which role is reduced in DOCA-salt hypertension.

• Animal cells and systems
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• v.8 no.3
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• pp.221-229
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• 2004

The projections from the dorsal raphe (DR) to the locus coeruleus (LC) or vice versa were analyzed in the rat using an anterograde tracer, Phaseolus vulgaris leucoagglutinin (PHA-L) combined with serotonin (5-hydroxytryptamine, 5-HT) or dopamine-beta-hydroxylase (DBH) immunostaining. Following the injection of PHA-L into the middle DR, DR-originating fibers with varicosities have contacted DBH-immunolabeled cells in the rostral, middle, and caudal LC. Axon terminals were also observed in the subcoeruleus nucleus. When the PHA-L injection was confined within the caudal DR, axonal fibers with varicosities were observed mainly at the rostral pole of the LC. Following the injection of PHA-L into the caudal, principal LC, labeled fibers with varicosities have contacted 5-HT-immunolabeled neurons at dorsomedial, ventromedial, lateral wing, and caudal sub-divisions of the DR. The present anterograde study suggests that the DR or the LC nuclei communicate with each other in order to perform a variety of functions including vigilance, analgesia, and stress responses.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2003.10a
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• pp.99-99
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• 2003

Brain-derived neurotrophic factor (BDNF) induced a significant neurite extension of antennal lobe (AL) neurons from the silk moth Bombyx mori in culture on lamini/ concanavalin A-coated dishes, in comparison with smaller effect of 20-hydroxyecdy-sone (20-HE). But the effect fur neurite extension by 5-hydroxytryptamine (5-HT) could not be found. A significant increase in the number of new primary branches from the principal neurites of AL neurons was also shown in culture with BDNF and 5-HT, but not with 20-HE. (omitted)

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.6
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• pp.605-611
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• 2016

Ketamine is an anesthetic with hypertensive effects, which make it useful for patients at risk of shock. However, previous ex vivo studies reported vasodilatory actions of ketamine in isolated arteries. In this study, we reexamined the effects of ketamine on arterial tones in the presence and absence of physiological concentrations of 5-hydroxytryptamine (5-HT) and norepinephrine (NE) by measuring the isometric tension of endothelium-denuded rat mesenteric arterial rings. Ketamine little affected the resting tone of control mesenteric arterial rings, but, in the presence of 5-HT (100~200 nM), ketamine ($10{\sim}100{\mu}M$) markedly contracted the arterial rings. Ketamine did not contract arterial rings in the presence of NE (10 nM), indicating that the vasoconstrictive action of ketamine is 5-HT-dependent. The concentration-response curves (CRCs) of 5-HT were clearly shifted to the left in the presence of ketamine ($30{\mu}M$), whereas the CRCs of NE were little affected by ketamine. The left shift of the 5-HT CRCs caused by ketamine was reversed with ketanserin, a competitive 5-$HT_{2A}$ receptor inhibitor, indicating that ketamine facilitated the activation of 5-$HT_{2A}$ receptors. Anpirtoline and BW723C86, selective agonists of 5-$HT_{1B}$ and 5-$HT_{2B}$ receptors, respectively, did not contract arterial rings in the absence or presence of ketamine. These results indicate that ketamine specifically enhances 5-$HT_{2A}$ receptor-mediated vasoconstriction and that it is vasoconstrictive in a clinical setting. The facilitative action of ketamine on 5-$HT_{2A}$ receptors should be considered in ketamine-induced hypertension as well as in the pathogenesis of diseases such as schizophrenia, wherein experimental animal models are frequently generated using ketamine.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.3
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• pp.315-323
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• 1997

Central tryptaminergic system has been shown to play an important role in the regulation of renal function: $5-HT_1(5-hydroxytryptamine_1)$ receptors might seem to mediate the diuresis and natriuresis, whereas the $5-HT_2\;and\;5-HT_3$ receptors mediate the antidiuretic and antinatriuretic effects. This study attempted to delineate the role of central $5-HT_{1A}$ subtype in the regulation of rabbit renal function by observing the renal effects of intracerebrovent-ricularly(icv)-administered PAPP(p-aminorhenylethyl-m-trifluoromethytphenyl piperazine, LY165163), a selective agonist of $5-HT_{1A}$ receptors. PAPP in doses ranging from 40 to $350{\mu}g/kg$ icv induced significantly diuresis, natriuresis, and kaliuresis, along with increased renal perfusion and glomerular filtration. Systemic blood pressure was also increased. Free water reabsorption$(T^cH_2O)$, a measure of ADH(antidiuretic hormone) secretion, was increased also. Intravenous $350{\mu}g/kg$ of PAPP elicited antidiuresis and antinatriuresis together with decreased blood pressure, thus indicating that the effects of icv PAPP were brought about through the central mechanisms, not by direct peripheral effects of the drug on kidney. Ketanserin, a selective $5-HT_2$ antagonist, $40{\mu}g/kg$ icv, did not affect the renal effects of the icv PAPP. Methysergide, a non-selective $5-HT_1$ antagonist, also did not block the renal functional responses by the icv PAPP. NAN-190, a $5-HT_{1A}$ antagonist, also did not antagonized the renal action of the icv PAPP. However the increased free water reabsorption was abolished by both methysergide or ketanserin pretreatment. The increments of blood pressure by icv PAPP was blocked only by NAN-190 pretreatment. These observations suggest that the central $5-HT_{1A}$ receptor might be involved in the central regulation of rabbit renal function by exerting the diuretic and natriuretic influences.