OBJECTIVE: To investigate the changes of skin temperature, blood infusion and inflammatory cytokines of cutaneous tissue in the sensitized area of colitis model rats, as well as the relationship between sensory and sympathetic nerves and the formation of sensitized area, and to initially reveal the partial physical-chemical characteristics of the sensitized area in the colitis model rats. METHODS: Thirty-five male SD rats were randomly divided into a control group (n=10), a model group (n=18) and a guanethidine group (n=7). 5% dextran sulfate sodium (DSS) was adopted for 6-day free drinking to establish colitis model in the model group and the guanethidine group. On day 6 and 7, in the guanethidine group, guanethidine solution (30 mg/kg) was injected intraperitoneally for sympathetic block. On day 7, after injection of evans blue (EB) solution, the EB extravasation areas on the body surface were observed to investigate the distribution and physical-chemical characteristics of the sensitized area. The control area was set up, 0.5 cm away from the sensitized area, and with the same nerve segment innervation. Disease activity index (DAI) score of rats was compared between the normal group and the model group, and the morphological changes in the colon tissue were investigated with HE method. Using infrared thermal imaging technology and laser speckle flow imaging technology, skin temperature and blood infusion were determined in the sensitized area and the control area of the rats in the model group. Immunofluorescence technique was adopted to observe the expression levels of the positive nerve fibers of substance P (SP), calcitonin gene-related peptide (CGRP) and tyrosine hydroxylase (TH), and the correlation with blood vessels; as well as the expression levels of SP positive nerve fibers/tryptase⁺ mast cells, and tryptase⁺ mast cells/5-hydroxytryptamine (5-HT) in skin tissue in the sensitized area and the control area of the rats in the model group. MSD multi-level factorial method and ELISA were applied to determine the contents of pro-inflammatory and anti-inflammatory cytokines (e.g. TNF-α, IL-1β, IL-6, IL-4 and IL-10) and anti-inflammatory substance corticosterone (CORT). RESULTS: Sensitization occurred at the T₁₂-S₁ segments of the colitis model rats, especially at L₂-L₅ segments. Compared with the normal group, DAI score was increased in the rats of the model group (P<0.05), and the colonic mucosal damage was obvious, with the epithelial cells disordered, even disappeared, crypt destructed, submucosal edema and a large number of inflammatory cells infiltrated. In comparison with the control area, the skin temperature and blood infusion were increased in the sensitized area of the model group (P<0.05, P<0.01); as well as the expression levels of the positive nerve fibers of SP, CGRP and TH of skin tissue (P<0.05), which was specially distributed in peripheral vessels, the expression levels of SP positive nerve fibers/tryptase⁺ mast cells, and tryptase⁺ mast cells/5-HT of the skin tissue were all expanded (P<0.05) in the sensitized area of the model group. Compared with the model group, the number of sensitized areas was reduced in the guanethidine group (P<0.05). In comparison with the control area of the model group, in the sensitized area, the contents of pro-inflammatory cytokines, e.g. TNF-α, IL-1β and IL-6, and the anti-inflammatory substance CORT of skin tissue were all increased (P<0.05); and the contents of IL-6 and TNF-α were negatively correlated with CORT (P<0.05). CONCLUSION The sensitized areas on the body surface of colitis rats are mainly distributed in the L₂-L₅ segments. Sensory and sympathetic nerves are involved in the acupoint sensitization, and the sensitized areas may have the dynamic changes in pro-inflammatory and anti-inflammatory substances.
Animals ; Anti-Inflammatory Agents ; Calcitonin Gene-Related Peptide/metabolism* ; Colitis/metabolism* ; Cytokines/metabolism* ; Guanethidine ; Interleukin-6 ; Male ; Rats ; Rats, Sprague-Dawley ; Serotonin ; Skin Temperature ; Substance P/genetics* ; Tryptases ; Tumor Necrosis Factor-alpha

PURPOSE: The urinary bladder (UB) is innervated by both sensory and autonomic nerves. Recent studies have shown that sensory neuropeptides induced contractions in the detrusor muscle. Therefore, in a mouse model, we investigated the presence of interactions between the submucosal sensory nerves and the autonomic nerves that regulate the motor function of the detrusor muscle. METHODS: UB samples from male C57BL/6 mice were isolated, cut into strips, and mounted in an organ bath. Dose-response curves to norepinephrine and phenylephrine were studied in UB strips with and without mucosa, and the effects of preincubation with a receptor antagonist and various drugs on relaxation were also studied using tissue bath myography. RESULTS: Phenylephrine-induced relaxation of the UB strips showed concentration-related effects. This relaxation appeared in both mucosa-intact and mucosa-denuded UB strips, and was significantly inhibited by lidocaine, silodosin, and guanethidine (an adrenergic neuronal blocker). Meanwhile, phenylephrine-induced relaxation was inhibited by pretreatment with propranolol and calcitonin gene-related peptide (CGRP)–depletory capsaicin in UB strips with and without mucosa. CONCLUSIONS: The present study suggests that phenylephrine activates the α-1A adrenergic receptor (AR) of the sensory nerve, and then activates capsaicin-sensitive sensory nerves to release an unknown substance that facilitates the release of norepinephrine from adrenergic nerves. Subsequently, norepinephrine stimulates β-ARs in the detrusor muscle in mice, leading to neurogenic relaxation of the UB. Further animal and human studies are required to prove this concept and to validate its clinical usefulness.
Adrenergic Neurons ; Animals ; Autonomic Pathways ; Baths ; Calcitonin Gene-Related Peptide ; Capsaicin ; Guanethidine ; Humans ; Lidocaine ; Male ; Mice ; Mucous Membrane ; Myography ; Neuropeptides ; Norepinephrine ; Phenylephrine ; Propranolol ; Receptors, Adrenergic ; Receptors, Adrenergic, alpha-1 ; Relaxation ; Urinary Bladder*

BACKGROUND/AIMS: The internal anal sphincter (IAS) plays an important role in maintaining continence and a number of neurotransmitters are known to regulate IAS tone. The aim of this study was to determine the relative importance of the neurotransmitters involved in the relaxant and contractile responses of the porcine IAS. METHODS: Responses of isolated strips of IAS to electrical field stimulation (EFS) were obtained in the absence and presence of inhibitors of neurotransmitter systems. RESULTS: Contractile responses of the sphincter to EFS were unaffected by the muscarinic receptor antagonist, atropine (1 muM), but were almost completely abolished by the adrenergic neuron blocker guanethidine (10 muM). Contractile responses were also reduced (by 45% at 5 Hz, P < 0.01) following desensitisation of purinergic receptors with alpha,beta-methylene-ATP (10 muM). In the presence of guanethidine, atropine, and alpha,beta-methylene-ATP, the remaining relaxatory responses to EFS were examined. These responses were not altered by the cyclooxygenase inhibitor, indomethacin (5 muM), the vasoactive intestinal polypeptide receptor antagonist, [D-p-Cl-Phe6,Leu17]-vasoactive intestinal peptide (PheLeu-VIP; 100 nM), or the purinoceptor antagonists, 8-phenyltheophyline (P1 receptors) or suramin (P2 receptors). However, relaxation responses were reduced by Nomega-nitro-L-arginine (L-NNA; 100 muM), an inhibitor of nitric oxide synthesis (40-50% reduction), zinc protoprophyrin IX (10 muM), an inhibitor of carbon monoxide synthesis (20-40% reduction), and also propargylglycine (30 muM) and aminooxyacetic acid (30 muM), inhibitors of hydrogen sulphide synthesis (15-20% reduction). CONCLUSIONS: Stimulation of IAS efferent nerves releases excitatory and inhibitory neurotransmitters: noradrenaline is the predominant contractile transmitter with a smaller component from ATP, whilst 3 gases mediate relaxation responses to EFS, with the combined contributions being nitric oxide > carbon monoxide > hydrogen sulfide.
Adenosine Triphosphate ; Adrenergic Neurons ; Aminooxyacetic Acid ; Anal Canal* ; Atropine ; Autonomic Pathways ; Carbon Monoxide* ; Carbon* ; Gases ; Guanethidine ; Hydrogen Sulfide* ; Hydrogen* ; Indomethacin ; Neurotransmitter Agents* ; Nitric Oxide* ; Norepinephrine ; Prostaglandin-Endoperoxide Synthases ; Purinergic Antagonists ; Receptors, Muscarinic ; Receptors, Purinergic ; Relaxation* ; Suramin ; Vasoactive Intestinal Peptide ; Zinc

To see the inhibitory mechanism of gentamicin in response to electrical field stimulation (EFS) using the rat bladder smooth muscle, atropine or guanethidine was treated but had no effect. Methylsergide, a non-selective 5-HT1, 5-HT2 receptor antagonist was also treated but had on effect. Kinase inhibitors, such as chelerythrine (PKC inhibitor), ML-9 (MLCK inhibitor), or Y27632 (rho kinase inhibitor) were pretreated before gentamicin treatment, but did not have effect. For U73122, a phospholipase C (PLC) inhibitor however, the inhibitory effect to gentamicin was significantly attenuated in all frequencies given by the EFS. Therefore gentamicin induced inhibitory effect on EFS response in rat bladder smooth muscle was not mediated by the activation of adrenergic, cholinergic, or serotonergic receptor. The inhibition of gentamicin might be mediated through the PLC dependent pathway, but not through the PKC, MLCK or rho kinase dependent pathway.
Animals ; Atropine ; Gentamicins* ; Guanethidine ; Muscle, Smooth* ; Phosphotransferases ; Rats* ; rho-Associated Kinases ; Type C Phospholipases ; Urinary Bladder*

A number of studies have demonstrated that 5-hydroxytryptamine (5-HT) can induce muscle contraction or relaxation response and enhance secretion in the gastrointestinal tract via a multiplicity of 5-HT receptor subtypes. In the present study, we investigated the pharmacological characterization of the 5-HT-induced contractile response in longitudinal smooth muscle isolated from the feline ileum. Addition of 5-HT into muscle chambers enhanced the basal tone and spontaneous activity in a concentration-dependent manner. The neurotoxin tetrodotoxin did not alter the 5-HT-induced contraction of the longitudinal muscles. Neither atropine nor guanethidine affected the contraction. The 5-HT agonists, 5-methylserotonin hydrochloride and mosapride, also evoked concentration-dependent contractions. The 5-HT-induced contraction was enhanced by the 5HT2 receptor antagonist ketanserin and the 5-HT3 receptor antagonist ondansetron but was inhibited by the 5-HT1 receptor antagonist methysergide and 5-HT4 receptor antagonist GR113808. These results indicate that 5-HT1 and 5-HT4 receptors may mediate the contraction of the 5-HT-induced response and 5-HT2 and 5-HT3 receptors may mediate 5-HT-induced relaxation in feline ileal longitudinal smooth muscles.
Atropine ; Benzamides ; Contracts ; Gastrointestinal Tract ; Guanethidine ; Ileum ; Indoles ; Ketanserin ; Methysergide ; Morpholines ; Muscle Contraction ; Muscle, Smooth ; Muscles ; Ondansetron ; Receptors, Serotonin ; Receptors, Serotonin, 5-HT1 ; Receptors, Serotonin, 5-HT3 ; Receptors, Serotonin, 5-HT4 ; Relaxation ; Serotonin ; Serotonin Receptor Agonists ; Sulfonamides ; Tetrodotoxin

In order to characterize the role of sympathetic activity in obesity, we repeatedly assessed sympathetic activity via power spectral analyses of heart rate variability in the same subjects at 7, 11, 25, and 60 weeks, using monosodium glutamate (MSG)-induced obese and control rats. The effects of lower sympathetic activity on obesity were also evaluated. Fat mass in MSG rats was already higher at 7 weeks, but the sympathetic activity did not differ between 7 and 25 weeks. Between 25 and 60 weeks, the increase in fat mass, food efficiency, and body weight gain was higher in MSG rats. The increase in sympathetic activity between 25 and 60 weeks and sympathetic activity at 60 weeks were lower in MSG rats. Fat mass at 60 weeks was inversely correlated with changes in sympathetic activity between 25 and 60 weeks. Reduced plasma epinephrine levels by bilateral adrenal demedullation induced increase of fat mass. In summary, an attenuated increase of sympathetic activity with age may partly be responsible for aggravated obesity in MSG rats. Additionally, reduced sympathetic activity per se induced obesity in rats. These results suggest that lower sympathetic activity contributes to obesity in rats.
Animals ; Body Weight ; Epinephrine ; Guanethidine ; Heart Rate ; Obesity* ; Plasma ; Rats* ; Sodium Glutamate*

Cardiac neurotransmission imaging allows in vivo assessment of presynaptic reuptake, neurotransmitter storage and postsynaptic receptors. Among the various neurotransmitter, I-123 MIBG is most available and relatively well- established. Metaiodobenzylguanidine (MIBG) is an analogue of the false neurotransmitter guanethidine. It is taken up to adrenergic neurons by uptake-1 mechanism as same as norepinephrine. As tagged with I-123, it can be used to image sympathetic function in various organs including heart with planar or SPECT techniques. I-123 MIBG imaging has a unique advantage to evaluate myocardial neuronal activity in which the heart has no significant structural abnormality or even no functional derangement measured with other conventional examination. In patients with cardiomyopathy and heart failure, this imaging has most sensitive technique to predict prognosis and treatment response of betablocker or ACE inhibitor. In diabetic patients, it allow very early detection of autonomic neuropathy. In patients with dangerous arrhythmia such as ventricular tachycardia or fibrillation, MIBG imaging may be only an abnormal result among various exams. In patients with ischemic heart disease, sympathetic derangement may be used as the method of risk stratification. In heart transplanted patients, sympathetic reinnervation is well evaluated. Adriamycin-induced cardiotoxicity is detected earlier than ventricular dysfunction with sympathetic dysfunction. Neurodegenerative disorder such as Parkinson's disease or dementia with Lewy bodies has also cardiac sympathetic dysfunction. Noninvasive assessment of cardiac sympathetic nerve activity with I-123 MIBG imaging may be improve understanding of the pathophysiology of cardiac disease and make a contribution to predict survival and therapy efficacy.
3-Iodobenzylguanidine* ; Adrenergic Neurons ; Arrhythmias, Cardiac ; Cardiomyopathies ; Dementia ; Guanethidine ; Heart ; Heart Diseases ; Heart Failure ; Humans ; Lewy Bodies ; Myocardial Ischemia ; Neurodegenerative Diseases ; Neurons ; Neurotransmitter Agents ; Norepinephrine ; Parkinson Disease ; Prognosis ; Synaptic Transmission ; Tachycardia, Ventricular ; Tomography, Emission-Computed, Single-Photon ; Ventricular Dysfunction

Many reports suggest that neurotensin (NT) in the gastrointestinal tract may play a possible role as a neurotransmitter, a circulating hormone, or a modulator of motor activity. NT exerts various actions in the intestine; it produces contractile and relaxant responses in intestinal smooth muscle. This study was designed to investigate the effect of NT on motility of antral circular muscle strips in guinea-pig stomach. To assess the role of Ca2+ influx in underlying mechanism, slow waves were simultaneously recorded with spontaneous contractions using conventional intracellular mircoelectrode technique. At the concentration of 10-7 M, where NT showed maximum response, NT enhanced the magnitude (863 +/- 198%, mean +/- SEM, n = 13) and the frequency (154 +/- 10.3%, n = 11) of spontaneous contractions. NT evoked a slight hyperpolarization of membrane potential, tall and steep slow waves with abortive spikes (278 +/- 50%, n = 4). These effects were not affected by atropine (2 micrometer), guanethidine (2 micrometer) and tetrodotoxin (0.2 micrometer). NT-induced contractile responses were abolished in Ca2+-free solution and reduced greatly to near abolition by 10 micrometer of verapamil or 0.2 mM of CdCl2. Verapamil attenuated the effects of NT on frequency and amplitude of the slow waves. Taken together, these results indicate that NT enhances contractility in guinea-pig gastric antral circular muscle and Ca2+ influx through the voltage-operated Ca2+ channel appears to play an important role in the NT-induced contractile mechanism.
Atropine ; Cadmium Chloride ; Gastrointestinal Tract ; Guanethidine ; Intestines ; Membrane Potentials ; Motor Activity ; Muscle, Smooth ; Neurotensin* ; Neurotransmitter Agents ; Stomach ; Tetrodotoxin ; Verapamil

We explore the question of whether adenosine 5'-triphosphate (ATP) acts as an excitatory neurotransmitter in guinea-pig gastric smooth muscle. In an organ bath system, isometric force of the circular smooth muscle of guinea-pig gastric antrum was measured in the presence of atropine and guanethidine. Under electrical field stimulation (EFS) at high frequencies (>20 Hz), NO-mediated relaxation during EFS was followed by a strong contraction after the cessation of EFS (a "rebound-contraction"). Exogenous ATP mimicked the rebound-contraction. A known P2Y-purinoceptor antagonist, reactive blue 2 (RB-2), blocked the rebound-contraction while selective desensitization of P2x-purinoceptor with alpha, beta-MeATP did not affect it. ATP and 2-MeSATP induced smooth muscle contraction, which was effectively blocked by RB-2 and suramin, a nonselective P2-purinoceptor antagonist. Particularly, in the presence of RB-2, exogenous ATP and 2-MeSATP inhibited spontaneous phasic contractions, suggestingthe existence of different populations of purinoceptors. Both the rebound-contraction and the agonist-induced contraction were not inhibited by indomethacin. The rank orders of agonists' potency were 2-MeSATP > ATP gtoreq UTP for contraction and alpha, beta-MeATP gtoreq beta, gamma-MeATP for inhibition of the phasic contraction, that accord with the commonly accepted rank order of the classical P2Y-purinoceptor subtypes. Electrical activities of smooth muscles were only slightly influenced by ATP and 2-MeSATP, whereas alpha, beta-MeATP attenuated slow waves with membrane hyperpolarization. From the above results, it is suggested that ATP acts as an excitatory neurotransmitter, which mediates the rebound-contraction via P2Y-purinoceptor in guinea-pig gastric antrum.
Adenosine Triphosphate* ; Adenosine* ; Atropine ; Baths ; Guanethidine ; Indomethacin ; Membranes ; Muscle, Smooth ; Neurotransmitter Agents* ; Pyloric Antrum* ; Receptors, Purinergic ; Relaxation ; Stomach ; Suramin ; Uridine Triphosphate

BACKGROUND: Neuropathic pain produced by nerve injury has the characteristics of enhanced pain responses - allodynia. To understand the pathophysiology of the neuropathic pain, We evaluated the effect of NMDA antagonists and chemical sympathectomy on the c-fos mRNA expression. METHODS: We have divided rats(Sprague-Dawley, N=24) that their left L5 and L6 nerve were tightly ligated into two groups. In NMDA antagonist group(N=17), We injected 10 g MK801 and 10 g 5-amino-phosphonovalerate in three ways, intrathecally before the ligation, after ligation and subcutaneous continuously. Then behavioral tests for mechanical allodynia and cold allodynia were performed. After the test of allodynia,the expression of c-fos were assessed by Northern blot hybridization. In chemical sympathectomy group(N=7), We injected 70 mg/kg guanethidine into the peritoneum in two ways, before the ligation and after ligation. Then same methods were performed in NMDA antagonist group as well. RESULTS: Intrathecal NMDA antagonists before the ligation supressed the elevation of c-fos mRNA expression. Intrathecal NMDA antagonists on the 7 days after the ligation reduced the c-fos mRNA expression and neuropathic pain. Continuous treatment of subcutaneous NMDA antagonists supressed the development of neuropathic pain and the elevation of c-fos mRNA expression. Chemical sympathectomy before the ligation did not supress the elevation of c-fos mRNA expression. Chemical sympathectomy on the 7 days after the ligation reduced neuropathic pain and the elevation of c-fos mRNA expression. CONCLUSIONS: NMDA receptor is related to the induction and maitenance of neuropatic pain, and sympathetic nervous system has a main role in the already induced neuropathic pain.
Animals ; Blotting, Northern ; Dizocilpine Maleate ; Guanethidine ; Hyperalgesia ; Ligation ; N-Methylaspartate* ; Neuralgia ; Peritoneum ; Rats* ; RNA, Messenger* ; Sympathectomy* ; Sympathectomy, Chemical ; Sympathetic Nervous System