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Panteleev SS, Sivachenko IB, Lyubashina OA. The Buspirone-dependent Abdominal Pain Transmission Within the Nucleus Tractus Solitarius in the Rat. Neuroscience 2020; 452:326-334. [PMID: 33248152 DOI: 10.1016/j.neuroscience.2020.11.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/22/2020] [Accepted: 11/18/2020] [Indexed: 01/07/2023]
Abstract
Buspirone, a partial agonist of the 5-HT1aR, due to potential antinociceptive properties can be useful for abdominal pain treatment in IBS patients. Pain-related effects of buspirone can be mediated by the 5-HT1aRs, located within the nucleus tractus solitarius. The 5-HT1aR involvement in pain transmission within the NTS is unclear. The objective of our study was to evaluate the involvement of the 5-HT1aR in abdominal pain transmission within the NTS. Using a model of abdominal pain on urethane-anesthetized rats, two types of NTS pain-related neurons responding to the noxious colorectal distension (CRD) with excitatory and inhibitory sustained patterns of evoked activity were revealed. Buspirone (1.0-4.0 mg kg-1, iv) has complex time- and dose-depended action on the CRD-induced NTS neuron responses. Buspirone inhibits the responses of the excitatory neurons and inverts the responses of the inhibitory pain-related neurons but at a dose of 4.0 buspirone, the effect on NTS pain-related neurons attenuates. The inhibitory effect of buspirone on the CRD-evoked responses of the excitatory NTS neurons is completely blocked by an intra-cerebroventricular administration of buspirone agonist WAY100,635. The inhibitory responses do not change by this agonist. The inhibitory action of buspirone is mediated by supraspinal 5-HT1a receptors however, its excitatory effect on inhibitory neurons does not dependents on these receptors. We proposed that the NTS pain-related neurons could be involved in anti- or pronociceptive effects of buspirone on abdominal pain.
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Affiliation(s)
- Sergey S Panteleev
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, Saint-Petersburg 199034, Russia.
| | - Ivan B Sivachenko
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, Saint-Petersburg 199034, Russia.
| | - Olga A Lyubashina
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, Saint-Petersburg 199034, Russia; Department of Neuropharmacology, Valdman Institute of Pharmacology, First Saint-Petersburg Pavlov State Medical University, 6/8 Lev Tolstoy Street, Saint-Petersburg 197022, Russia.
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Panteleev SS, Sivachenko IB, Lyubashina OA. The central effects of buspirone on abdominal pain in rats. Neurogastroenterol Motil 2018; 30:e13431. [PMID: 30101506 DOI: 10.1111/nmo.13431] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 06/08/2018] [Accepted: 06/24/2018] [Indexed: 12/28/2022]
Abstract
BACKGROUND Buspirone, a partial agonist of the 5-HT1a receptor (5-HT1a R), owing to potential antinociceptive properties may be useful in treatment of abdominal pain in IBS patients. The pain-related effects of buspirone are mediated via the 5-HT1a Rs, specifically located within the ventrolateral medulla (VLM). The most animal studies of the 5-HT1a R involvement in pain control have been carried out with somatic behavioral tests. The 5-HT1a R contribution in visceral pain transmission within the VLM is unclear. The objective of our study was to evaluate the 5-HT1a R contribution in abdominal pain transmission within the VLM. METHODS Using animal model of abdominal pain (urethane-anaesthetized rats), based on the noxious colorectal distension (CRD) as pain stimulus we studied effects of buspirone (1.0-4.0 mg kg-1 , iv) on the CRD-induced VLM neuron and blood pressure responses as markers of abdominal pain before and after the 5-HT1a R blockade by antagonist, WAY 100,635. RESULTS The CRD induced a significant increase in VLM neuron activity up to 201.5 ± 18.0% and depressor reactions up to 68 ± 1.8% of baseline. Buspirone (1.0-4.0 mg kg-1 , iv) resulted in an inhibition of the CRD-induced neuron responses which were changed inversely with dose increase and decreased depressor reactions directly with dose increase. These effects were antagonized by intracerebroventricular WAY 100,635. CONCLUSION Buspirone exerts complex biphasic action on the pain-related VLM neuron activity inversely depending on dose. The final effect of buspirone depends on the functional balance between of activation the pre- and postsynaptic 5-HT1a Rs in mediating pain control networks.
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Affiliation(s)
- S S Panteleev
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia.,Department of Neuropharmacology, Valdman Institute of Pharmacology, First Saint-Petersburg Pavlov State Medical University, Saint Petersburg, Russia
| | - I B Sivachenko
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia
| | - O A Lyubashina
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia.,Department of Neuropharmacology, Valdman Institute of Pharmacology, First Saint-Petersburg Pavlov State Medical University, Saint Petersburg, Russia
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Yong CY, Chen S, Chen H, Chu X, Zhang C, Tan C, Ye L, Li JS. Central neuromechanisms underlying control of intragastric pressure through acupuncture at Zusanli (ST36) in rats: the upper cervical cord is the key link between the ascending and descending pathways. Neural Regen Res 2016; 11:971-6. [PMID: 27482227 PMCID: PMC4962596 DOI: 10.4103/1673-5374.184497] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Sensory inputs stimulated by Zusanli (ST36) acupuncture in the abdomen are known to converge in the upper cervical cord. However, it is unclear whether these inputs are subsequently conveyed to the hypothalamic paraventricular nucleus and what kind of afferent fibers are involved. We focused on the upper cervical cord, where afferent inputs converge, and detected c-fos expression in oxytocinergic neurons. We found that Zusanli acupuncture therapy effectively elevated intragastric pressure, but inhibited expression of c-fos in oxytocinergic neurons of the paraventricular nucleus in upper cervical cord injured rats. These Zusanli acupuncture effects remained even after complete dorsal cord transection. However, after complete transection of the spinal cord or dorsolateral funiculus, the effects were significantly attenuated and even disappeared. These findings suggest that the paraventricular nucleus is responsible for pooling and integrating signals from the Zusanli acupuncture and sensory information from the intragastric pressure variation, thereby contributing to the regulation of intragastric pressure. The upper cervical cord serves as the key link between ascending and descending pathways, which conveys afferent inputs to the paraventricular nucleus through the dorsolateral funiculus.
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Affiliation(s)
- Chun-Yan Yong
- Department of Integrative Medicine, Xiangya Hospital of Central South University, Changsha, Hunan Province, China
| | - Shu Chen
- School of Acupuncture and Massage, Hunan University of Chinese Medicine, Changsha, Hunan Province, China
| | - Heng Chen
- School of Acupuncture and Massage, Hunan University of Chinese Medicine, Changsha, Hunan Province, China
| | - Xiao Chu
- School of Acupuncture and Massage, Hunan University of Chinese Medicine, Changsha, Hunan Province, China
| | - Chao Zhang
- School of Acupuncture and Massage, Hunan University of Chinese Medicine, Changsha, Hunan Province, China
| | - Cheng Tan
- School of Acupuncture and Massage, Hunan University of Chinese Medicine, Changsha, Hunan Province, China
| | - Lan Ye
- School of Acupuncture and Massage, Hunan University of Chinese Medicine, Changsha, Hunan Province, China
| | - Jiang-Shan Li
- School of Acupuncture and Massage, Hunan University of Chinese Medicine, Changsha, Hunan Province, China
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The inhibitory effect of granisetron on ventrolateral medulla neuron responses to colorectal distension in rats. Eur J Pharmacol 2015; 749:49-55. [DOI: 10.1016/j.ejphar.2015.01.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 12/23/2014] [Accepted: 01/06/2015] [Indexed: 01/17/2023]
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Tjen-A-Looi SC, Guo ZL, Li M, Longhurst JC. Medullary GABAergic mechanisms contribute to electroacupuncture modulation of cardiovascular depressor responses during gastric distention in rats. Am J Physiol Regul Integr Comp Physiol 2013; 304:R321-32. [PMID: 23302958 DOI: 10.1152/ajpregu.00451.2012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Electroacupuncture (EA) at P5-P6 acupoints overlying the median nerves typically reduces sympathoexcitatory blood pressure (BP) reflex responses in eucapnic rats. Gastric distention in hypercapnic acidotic rats, by activating both vagal and sympathetic afferents, decreases heart rate (HR) and BP through actions in the rostral ventrolateral medulla (rVLM) and nucleus ambiguus (NAmb), leading to sympathetic withdrawal and parasympathetic activation, respectively. A GABAA mechanism in the rVLM mediates the decreased sympathetic outflow. The present study investigated the hypothesis that EA modulates gastric distention-induced hemodynamic depressor and bradycardia responses through nuclei that process parasympathetic and sympathetic outflow. Anesthetized hypercapnic acidotic rats manifested repeatable decreases in BP and HR with gastric distention every 10 min. Bilateral EA at P5-P6 for 30 min reversed the hypotensive response from -26 ± 3 to -6 ± 1 mmHg and the bradycardia from -35 ± 11 to -10 ± 3 beats/min for a period that lasted more than 70 min. Immunohistochemistry and in situ hybridization to detect c-Fos protein and GAD 67 mRNA expression showed that GABAergic caudal ventral lateral medulla (cVLM) neurons were activated by EA. Glutamatergic antagonism of cVLM neurons with kynurenic acid reversed the actions of EA. Gabazine used to block GABAA receptors microinjected into the rVLM or cVLM reversed EA's action on both the reflex depressor and bradycardia responses. EA modulation of the decreased HR was inhibited by microinjection of gabazine into the NAmb. Thus, EA through GABAA receptor mechanisms in the rVLM, cVLM, and NAmb modulates gastric distention-induced reflex sympathoinhibition and vagal excitation.
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Affiliation(s)
- Stephanie C Tjen-A-Looi
- Susan Samueli Center for Integrative Medicine, Department of Medicine, School of Medicine, University of California, Irvine, CA 92697, USA.
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Tjen-A-Looi SC, Hsiao AF, Longhurst JC. Central and peripheral mechanisms underlying gastric distention inhibitory reflex responses in hypercapnic-acidotic rats. Am J Physiol Heart Circ Physiol 2011; 300:H1003-12. [PMID: 21217073 PMCID: PMC3064299 DOI: 10.1152/ajpheart.01131.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 12/30/2010] [Indexed: 11/22/2022]
Abstract
We have observed that in chloralose-anesthetized animals, gastric distension (GD) typically increases blood pressure (BP) under normoxic normocapnic conditions. However, we recently noted repeatable decreases in BP and heart rate (HR) in hypercapnic-acidotic rats in response to GD. The neural pathways, central processing, and autonomic effector mechanisms involved in this cardiovascular reflex response are unknown. We hypothesized that GD-induced decrease in BP and HR reflex responses are mediated during both withdrawal of sympathetic tone and increased parasympathetic activity, involving the rostral (rVLM) and caudal ventrolateral medulla (cVLM) and the nucleus ambiguus (NA). Rats anesthetized with ketamine and xylazine or α-chloralose were ventilated and monitored for HR and BP changes. The extent of cardiovascular inhibition was related to the extent of hypercapnia and acidosis. Repeated GD with both anesthetics induced consistent falls in BP and HR. The hemodynamic inhibitory response was reduced after blockade of the celiac ganglia or the intraabdominal vagal nerves with lidocaine, suggesting that the decreased BP and HR responses were mediated by both sympathetic and parasympathetic afferents. Blockade of the NA decreased the bradycardia response. Microinjection of kainic acid into the cVLM reduced the inhibitory BP response, whereas depolarization blockade of the rVLM decreased both BP and HR inhibitory responses. Blockade of GABA(A) receptors in the rVLM also reduced the BP and HR reflex responses. Atropine methyl bromide completely blocked the reflex bradycardia, and atenolol blocked the negative chronotropic response. Finally, α(1)-adrenergic blockade with prazosin reversed the depressor. Thus, in the setting of hypercapnic-acidosis, a sympathoinhibitory cardiovascular response is mediated, in part, by splanchnic nerves and is processed through the rVLM and cVLM. Additionally, a vagal excitatory reflex, which involves the NA, facilitates the GD-induced decreases in BP and HR responses. Efferent chronotropic responses involve both increased parasympathetic and reduced sympathetic activity, whereas the decrease in BP is mediated by reduced α-adrenergic tone.
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Affiliation(s)
- Stephanie C Tjen-A-Looi
- Susan Samueli Center for Integrative Medicine, Department of Medicine, School of Medicine, University of California, Irvine, California 92697-4075, USA.
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Mouton LJ, Eggens-Meijer E, Klop EM. The ventrolateral upper cervical cell group in cat projects to all rostrocaudal levels of the periaqueductal gray matter. Brain Res 2009; 1300:79-96. [DOI: 10.1016/j.brainres.2009.08.088] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 07/01/2009] [Accepted: 08/28/2009] [Indexed: 12/30/2022]
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Qin C, Chen JDZ, Zhang J, Foreman RD. Duodenal afferent input converges onto T9-T10 spinal neurons responding to gastric distension in rats. Brain Res 2007; 1186:180-7. [PMID: 17997398 DOI: 10.1016/j.brainres.2007.10.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 09/26/2007] [Accepted: 10/06/2007] [Indexed: 01/08/2023]
Abstract
Clinically, the overlap of gastroduodenal symptoms, such as visceral pain or hypersensitivity, is often observed in functional gastrointestinal disorders. The underlying mechanism may be related to intraspinal neuronal processing of noxious convergent inputs from the stomach and the intestine. The purpose of this study was to examine whether single low thoracic (T9-T10) spinal neurons responded to both gastric and duodenal mechanical stimulation. Extracellular potentials of single T9-T10 spinal neurons were recorded in pentobarbital anesthetized, paralyzed, and ventilated male rats. Graded gastric distensions (GD, 20, 40, 60 mm Hg, 20 s) were induced by air inflation of a latex balloon surgically placed in the stomach. Graded duodenal distensions (DD, 0.2, 0.4, 0.6 ml, 20 s) were produced by water inflation of a latex balloon placed into the duodenum. Of 70 deeper (depth from dorsal surface of spinal cord: 0.3-1.2 mm) spinal neurons responsive to noxious GD (> or =40 mm Hg), 44(63%) also responded to noxious DD (> or =0.4 ml). Similarly, 13/17 (76%) superficial neurons (depth <0.3 mm) responded to both GD and DD. Of 57 gastroduodenal convergent neurons, 41 (72%) had excitatory and 6 had inhibitory responses to both GD and DD; the remaining neurons exhibited multiple patterns of excitation and inhibition. 43/57 (75%) gastroduodenal convergent neurons had low-threshold (< or =20 mm Hg) responses to GD, whereas 42/57 (74%) of these neurons had high-threshold (> or =0.4 ml) responses to DD. In addition, 34/40 (85%) gastroduodenal convergent neurons had somatic receptive fields on the back, flank, and medial/lateral abdominal areas. These results suggested that superficial and deeper T9-T10 spinal neurons received innocuous and/or noxious convergent inputs from mechanical stimulation of the stomach and duodenum. Gastroduodenal convergent spinal neurons might contribute to intraspinal sensory transmission for cross-organ afferent-afferent communication between the stomach and duodenum and play a role in visceral nociception and reflexes.
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Affiliation(s)
- Chao Qin
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, USA.
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Qin C, Chen JDZ, Zhang J, Foreman RD. Modulatory effects and afferent pathways of gastric electrical stimulation on rat thoracic spinal neurons receiving input from the stomach. Neurosci Res 2006; 57:29-39. [PMID: 17046091 PMCID: PMC1855190 DOI: 10.1016/j.neures.2006.09.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 08/29/2006] [Accepted: 09/07/2006] [Indexed: 01/17/2023]
Abstract
Gastric electrical stimulation (GES) has been suggested as a potential therapy for patients with obesity or gastric motility disorders. The aim of this study was to investigate the spinal mechanism of GES effects on gastric functions. Extracellular potentials of single spinal (T9-T10) neurons were recorded in pentobarbital anesthetized, paralyzed, ventilated male rats (n=19). Gastric distension (GD) was produced by air inflation of a balloon. One pair of platinum electrodes (1.0-1.5cm apart) was sutured onto the serosal surface of the lesser curvature of the stomach. GES with four sets of parameters was applied for 1min: GES-A (6mA, 0.3ms, 40Hz, 2s on, 3s off), GES-B (6mA, 0.3ms, 14Hz, 0.1s on, 5s off), GES-C (6mA, 3ms, 40Hz, 2s on, 3s off), GES-D (6mA, 200ms, 12pulses/min). 62/158 (39%) spinal neurons responded to GD (20, 40, 60mmHg, 20s. Most GD-responsive neurons (n=43) had excitatory responses; the remainder had inhibitory (n=12) or biphasic responses (n=7). GES-A, -B, -C and -D affected activity of 12/33 (36%), 4/31 (13%), 22/29 (76%) and 13/30 (43%) GD-responsive neurons, respectively. Bilateral cervical vagotomy did not significantly alter mean excitatory neuronal responses to GD (n=5) or GES (n=6). Resiniferatoxin (2.0microg/kg, i.v.), an ultrapotent agonist of vanilloid receptor-1, abolished excitatory responses to GD and GES in 4/4 neurons recorded in vagotomized rats. The results suggested that GES mainly had an excitatory effect on T9-T10 spinal neurons with gastric inputs; neuronal responses to GES were strengthened with stimulation at an increased pulse width and/or number of pulses. The modulatory effect of GES involved thoracic spinal (sympathetic) afferent fibers containing vanilloid receptor-1.
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Affiliation(s)
- Chao Qin
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, USA.
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Sun Y, Qin C, Foreman RD, Chen JDZ. Intestinal electric stimulation modulates neuronal activity in the nucleus of the solitary tract in rats. Neurosci Lett 2005; 385:64-9. [PMID: 15951110 DOI: 10.1016/j.neulet.2005.05.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2005] [Revised: 04/20/2005] [Accepted: 05/06/2005] [Indexed: 02/04/2023]
Abstract
Intestinal electric stimulation (IES) has been shown to produce an inhibitory effect on gastric motility and secretion. The possible central mechanism of this entero-gastric inhibitory effect induced by IES is unknown. The objective of this study was to evaluate the effects of various IES on the activity of neurons in nucleus tractus solitarii (NTS). We examined the extracellular neuronal activity in NTS of the medulla in pentobarbital anesthetized, paralyzed, ventilated male adult rats. The aortic depressor, superior laryngeal, and carotid sinus nerves were crushed or sectioned bilaterally to avoid neuronal responses in NTS to cardiovascular baroreceptors. After NTS neurons with gastric input were identified, responses of single neurons in NTS to IES were determined. IES with different parameters was performed via a pair of platinum electrodes sutured onto the serosal surface of the duodenum 2 cm below the pylorus. IES with different parameters activated 39--72% of the solitary tract nucleus neurons responsive to gastric distension. Moreover, we demonstrated that IES activated the neuronal activity in NTS, which was stimulation energy dependent. The modulatory effect of IES on the central neurons receiving vagal inputs may contribute to the neural mechanisms of IES therapy for the treatment of patients with obesity and gastrointestinal motility disorders.
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Affiliation(s)
- Ying Sun
- Transneuronix Inc. & VA Medical Center, 921 NE 13th Street, VREF-151, Oklahoma City, OK 73104, USA
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Holzer P, Painsipp E, Schuligoi R. Differential effects of intragastric acid and capsaicin on gastric emptying and afferent input to the rat spinal cord and brainstem. BMC Neurosci 2005; 6:60. [PMID: 16162281 PMCID: PMC1239919 DOI: 10.1186/1471-2202-6-60] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Accepted: 09/14/2005] [Indexed: 11/25/2022] Open
Abstract
Background Hydrochloric acid (HCl) is a potential threat to the integrity of the gastric mucosa and is known to contribute to upper abdominal pain. We have previously found that gastric mucosal challenge with excess HCl is signalled to the rat brainstem, but not spinal cord, as visualized by expression of c-fos messenger ribonucleic acid (mRNA), a surrogate marker of neuronal excitation. This study examined whether gastric mucosal exposure to capsaicin, a stimulant of nociceptive afferents that does not damage the gastric mucosa, is signalled to both brainstem and spinal cord and whether differences in the afferent signalling of gastric HCl and capsaicin challenge are related to different effects on gastric emptying. Results Rats were treated intragastrically with vehicle, HCl or capsaicin, activation of neurons in the brainstem and spinal cord was visualized by in situ hybridization autoradiography for c-fos mRNA, and gastric emptying deduced from the retention of intragastrically administered fluid. Relative to vehicle, HCl (0.5 M) and capsaicin (3.2 mM) increased c-fos transcription in the nucleus tractus solitarii by factors of 7.0 and 2.1, respectively. Capsaicin also caused a 5.2-fold rise of c-fos mRNA expression in lamina I of the caudal thoracic spinal cord, although the number of c-fos mRNA-positive cells in this lamina was very small. Thus, on average only 0.13 and 0.68 c-fos mRNA-positive cells were counted in 0.01 mm sections of the unilateral lamina I following intragastric administration of vehicle and capsaicin, respectively. In contrast, intragastric HCl failed to induce c-fos mRNA in the spinal cord. Measurement of gastric fluid retention revealed that HCl suppressed gastric emptying while capsaicin did not. Conclusion The findings of this study show that gastric mucosal exposure to HCl and capsaicin is differentially transmitted to the brainstem and spinal cord. Since only HCl blocks gastric emptying, it is hypothesized that the two stimuli are transduced by different afferent pathways. We infer that HCl is exclusively signalled by gastric vagal afferents whereas capsaicin is processed both by gastric vagal and intestinal spinal afferents.
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Affiliation(s)
- Peter Holzer
- Department of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, A-8010 Graz, Austria
| | - Evelin Painsipp
- Department of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, A-8010 Graz, Austria
| | - Rufina Schuligoi
- Department of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, A-8010 Graz, Austria
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Qin C, Sun Y, Chen JDZ, Foreman RD. Gastric electrical stimulation modulates neuronal activity in nucleus tractus solitarii in rats. Auton Neurosci 2005; 119:1-8. [PMID: 15893702 DOI: 10.1016/j.autneu.2005.01.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2004] [Revised: 01/18/2005] [Accepted: 01/31/2005] [Indexed: 11/18/2022]
Abstract
Implantable gastric electric stimulation (GES) has been under investigation for the treatment of gastric motor disorders and obesity. However, possible central mechanisms involving the effects of GES on gastric function are unclear. The purpose of this study was to examine the effects of GES with different parameters on neuronal activity in the nucleus tractus solitarii (NTS) of the medulla. Extracellular potentials of single neurons in NTS were recorded in pentobarbital anesthetized, paralyzed, ventilated male rats. GES with four sets of parameters was applied for one minute: GES-A (6 mA, 0.3 ms, 40 Hz, 2 s-on and 3 s-off), GES-B (20 mA, 0.3 ms, 40 Hz, 2 s-on and 3 s-off), GES-C (6 mA, 6 ms, 40 Hz, 2 s-on and 3 s-off), and GES-D (6 mA, 200 ms, 12 imps/min). 35/118 (30%) neurons in NTS were responsive to gastric distension (GD, 20 mmHg, 20 s). Forty-one percent, 67%, 76% and 42% of all the responsive NTS neurons were affected by GES-A, -B, -C and -D, respectively. More NTS neurons with gastric inputs were affected with GES-C (19/25) than with GES-A (11/27, P<0.05) and GES-D (10/24, P<0.05). Maximal excitatory responses (17.9+/-2.6 imp/s) of NTS neurons to GES-C were significantly greater than GES-D (9.7+/-4.8 imp/s, P<0.05), whereas average duration of excitatory response (74.8+/-4.3 s) of NTS neurons to GES-B was significant longer than GES-A (60.3+/-3.3 s). Gastric electrical stimulation primarily has an excitatory effect on NTS neurons receiving input from the stomach; the central neuronal response to GES is enhanced with stimulation using an increased pulse width and/or amplitude. This modulatory effect of GES on the central neurons receiving vagal inputs may contribute to the neural mechanisms of GES therapy for the treatment of patients with obesity and gastric motility disorders.
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Affiliation(s)
- Chao Qin
- Department of Physiology, University of Oklahoma Health Sciences Center, P.O. Box 26901, Oklahoma City, OK 73190, United States.
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Yun AJ, Lee PY, Bazar KA. Clinical benefits of hydration and volume expansion in a wide range of illnesses may be attributable to reduction of sympatho-vagal ratio. Med Hypotheses 2005; 64:646-50. [PMID: 15617881 DOI: 10.1016/j.mehy.2004.07.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2004] [Accepted: 07/26/2004] [Indexed: 12/31/2022]
Abstract
Hydration and volume expansion regimens are widely thought to offer symptomatic benefit in many human ailments. Many varied theories for the phenomenon exists such as decreased blood viscocity in cardiac disease, dilution of toxins in cancer, and cleansing effect on airways in asthma. While it is plausible that disparate mechanisms are involved in different conditions, we propose an alternative, unifying hypothesis that many of the clinical benefits of hydration and volume expansion are partly related to reduced sympatho-vagal ratio. Hypovolemia triggers baroreceptor-mediated sympathetic response and neurohormonal activation to promote fluid retention. Emerging evidence suggests that many diseases including cardiovascular, neurologic, gastrointestinal, metabolic, inflammatory, thrombotic, viral, and oncologic conditions are manifestations of abnormal sympathetic bias and associated T helper 2 bias. Hypovolemia-induced sympathetic activation, especially if baroreceptor dysfunction is involved, can worsen these conditions. Hydration and volume expansion may lower sympatho-vagal ratio, thereby tempering a wide variety of clinical conditions linked directly or indirectly to adrenergia including, but not limited to, acute coronary syndromes, asthma, cancer, and stroke. Interestingly, isotonic or hypertonic hydration, rather than a low-salt diet, may be a counterintuitive potential strategy to treat some cases of hypertension associated with dehydration and autonomic dysfunction. In contrast to the putative causal relationship between them, perhaps hypertension and end-organ damage represent independent consequences of dysfunctional sympathetic and neurohormonal activation. Venipuncture enables faster volume expansion but may also be a source of sympathetic hyperactivity. Oral hydration may additionally promote vagal tone by triggering gastric distension, a benefit not offered by intravenous fluids. The empiric benefits of hydration and volume expansion portend novel methods to treat a wide range of clinical conditions through pharmacologic or electrical modulation of cardiovascular or gastrointestinal baroreceptors.
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Affiliation(s)
- A Joon Yun
- Department of Radiology, Stanford University, 470 University Avenue, Palo Alto, CA 94301, USA.
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Rong PJ, Zhu B, Huang QF, Gao XY, Ben H, Li YH. Acupuncture inhibition on neuronal activity of spinal dorsal horn induced by noxious colorectal distention in rat. World J Gastroenterol 2005; 11:1011-7. [PMID: 15742405 PMCID: PMC4250762 DOI: 10.3748/wjg.v11.i7.1011] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To observe how acupuncture stimulation influences the visceral nociception in rat and to clarify the interactions between acupuncture or somatic input and visceral nociceptive inputs in the spinal dorsal horn. These will provide scientific base for illustrating the mechanism of acupuncture on visceral pain.
METHODS: Experiments were performed on Sprague-Dawley rats and the visceral nociceptive stimulus was generated by colorectal distention (CRD). Unit discharges from individual single neuron were recorded extracellularly with glass-microelectrode in L1-3 spinal dorsal horn. Acupuncture stimulation was applied at contralateral heterotopic acupoint and ipsilateral homotopic acupoint, both of which were innervated by the same segments that innervate also the colorectal-gut.
RESULTS: The visceral nociception could be inhibited at the spinal level by the heterotopic somatic mechanical stimulation and acupuncture. The maximal inhibition was induced by acupuncture or the somatic noxious stimulation at spinal dorsal horn level with inhibiting rate of 68.61% and 60.79%, respectively (P<0.01 and <0.001). In reversible spinalized rats (cervical-thoracic cold block) both spontaneous activity and responses to CRD increased significantly in 16/20 units examined, indicating the existence of tonic descending inhibition. The inhibition of acupuncture on the noxious CRD disappeared totally in the reversible spinalized rats (P<0.001).
CONCLUSION: The inputs of noxious CRD and acupuncture may interact at the spinal level. The nociceptive visceral inputs could be inhibited by acupuncture applied to hetero-topic acupoint. The effect indicates that the spinal dorsal horn plays a significant role in mediating the inhibition of acupuncture and somatic stimulation on the neuronal response to the noxious visceral stimulation and the inhibition is modulated by upper cervical cord and/or supra-spinal center.
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Affiliation(s)
- Pei-Jing Rong
- Institute of Acupuncture, China Academy of Chinese Medicine, 16 Nanxiaojie of Dongzhimen, Beijing 100700, China
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Lu F, Qin C, Foreman RD, Farber JP. Chemical activation of C1-C2 spinal neurons modulates intercostal and phrenic nerve activity in rats. Am J Physiol Regul Integr Comp Physiol 2004; 286:R1069-76. [PMID: 14764434 DOI: 10.1152/ajpregu.00427.2003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chemical activation of upper cervical spinal neurons modulates activity of thoracic respiratory interneurons in rats. The aim of the present study was to examine the effects of chemical activation of C1-C2 spinal neurons on thoracic spinal respiratory motor outflows. Electroneurograms of left phrenic ( n = 23) and intercostal nerves (ICNs, n = 93) between T3 and T8 spinal segments were recorded from 36 decerebrated, vagotomized, paralyzed, and ventilated male rats. To activate upper cervical spinal neurons, glutamate pledgets (1 M, 1 min) were placed on the dorsal surface of the C1-C2 spinal cord. Glutamate on C1-C2 increased ICN tonic activity in 56/59 (95%) ICNs. The average maximal tonic activity of ICN was increased by 174% ( n = 59). After spinal transection at rostral C1, glutamate on C1-C2 still increased ICN tonic activity in 33/35 ICNs. However, the effects of C1-C2 glutamate on ICN phasic activity were highly variable, with observations of augmentation or suppression of both inspiratory and expiratory discharge. C1-C2 glutamate augmented the average amplitude of phrenic burst by 20%, whereas the increases in amplitude of ICN inspiratory activity, when they occurred, averaged 120%. The burst rate of phrenic nerve discharge was decreased from 34.2 ± 1.6 to 26.3 ± 2.0 (mean ± SE) breaths/min during C1-C2 glutamate. These data suggested that upper cervical propriospinal neurons might play a role in descending modulation of thoracic respiratory and nonrespiratory motor activity.
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Affiliation(s)
- Fang Lu
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, 73190, USA
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Qin C, Chandler MJ, Jou CJ, Foreman RD. Responses and afferent pathways of C1-C2 spinal neurons to cervical and thoracic esophageal stimulation in rats. J Neurophysiol 2003; 91:2227-35. [PMID: 14695350 DOI: 10.1152/jn.00971.2003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Because vagal and sympathetic inputs activate upper cervical spinal neurons, we hypothesized that stimulation of the esophagus would activate C(1)-C(2) neurons. This study examined responses of C(1)-C(2) spinal neurons to cervical and thoracic esophageal distension (CED, TED) and afferent pathways for CED and TED inputs to C(1)-C(2) spinal neurons. Extracellular potentials of single C(1)-C(2) spinal neurons were recorded in pentobarbital-anesthetized male rats. Graded CED or TED was produced by water inflation (0.1-0.5 ml) of a latex balloon. CED changed activity of 48/219 (22%) neurons; 34 were excited (E), 12 were inhibited (I), and 2 were E-I. CED elicited responses for 18/18 neurons tested after ipsilateral cervical vagotomy, for 12/14 neurons tested after bilateral vagotomy and for 9/11 neurons tested after bilateral vagotomy and C(6)-C(7) spinal cord transection. TED changed activity of 31/190 (16%) neurons (28E, 3 I). Ipsilateral cervical vagotomy abolished TED-evoked responses of 5/12 neurons. Bilateral vagotomy eliminated responses of 2/4 neurons tested, and C(6)-C(7) spinal transection plus bilateral vagotomy eliminated responses of 2/2 neurons. Thus inputs from CED to C(1)-C(2) neurons most likely entered upper cervical dorsal roots, whereas inputs from TED were dependent on vagal pathways and/or sympathetic afferent pathways that entered the thoracic dorsal roots. These results supported a concept that C(1)-C(2) spinal neurons play a role in integrating visceral information from cervical and thoracic esophagus.
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Affiliation(s)
- Chao Qin
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA.
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Qin C, Chandler MJ, Foreman RD. Effects of urinary bladder distension on activity of T3-T4 spinal neurons receiving cardiac and somatic noxious inputs in rats. Brain Res 2003; 971:210-20. [PMID: 12706237 DOI: 10.1016/s0006-8993(03)02362-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aims of this study were to examine effects of urinary bladder distension (UBD) on T(3)-T(4) spinal neurons receiving cardiac and somatic noxious inputs and to determine the pathway involved in transmitting urinary bladder inputs to thoracic spinal segments. Extracellular potentials of single T(3)-T(4) neurons were recorded in pentobarbital anesthetized male rats. Either bradykinin solution (10(-5) M) or an allogenic mixture (adenosine 10(-3) M, bradykinin, histamine, serotonin, prostaglandin E2 10(-5) M each) was administered intrapericardially. UBD was produced by saline inflation (0.5-2.0 ml, 20 s). Of 487 neurons tested for responses to UBD, 70 were inhibited and 37 were excited. Seventy-six out of 336 neurons received convergent input from UBD and heart; 69/76 viscerovisceral convergent neurons had somatic fields. Spinal transection at rostral C(1) abolished UBD inhibition in 5/9 neurons; whereas transections at L(1)-L(2) abolished UBD inhibition in 3/3 cells tested. Results showed that T(3)-T(4) spinal neurons processing cardiac and somatic nociceptive information were primarily inhibited by input from the urinary bladder through either supraspinal structures or direct intraspinal pathways.
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Affiliation(s)
- Chao Qin
- Department of Physiology, University of Oklahoma Health Sciences Center, P.O. Box 26901, Oklahoma City, OK 73190, USA.
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