β2-Adrenoceptor Regulation of CGRP Release from Capsaicin-sensitive Neurons

2003 ◽  
Vol 82 (4) ◽  
pp. 308-311 ◽  
Author(s):  
W.R. Bowles ◽  
C.M. Flores ◽  
D.L. Jackson ◽  
K.M. Hargreaves
Keyword(s):  
Dental Pulp ◽  
Nociceptive Neurons ◽  
Adrenoceptor Antagonist ◽  
Adrenoceptor Agonist ◽  
In Vitro Superfusion ◽  
Adrenoceptor Agonists ◽  
Adrenoceptor Regulation ◽  
Pre Treatment ◽  
Neurotransmitter Substances

Previous studies have suggested that neurotransmitter substances from the sympatho-adrenomedullary system regulate pulpal blood flow (PBF), in part, by the inhibition of vasoactive neuropeptide release from pulpal sensory neurons. However, no study has evaluated the role of β-adrenoceptors. We evaluated the hypothesis that activation of β-adrenoceptors inhibits immunoreactive calcitonin gene-related peptide (iCGRP) release from capsaicin-sensitive nociceptive neurons via in vitro superfusion of bovine dental pulp. Either norepinephrine or epinephrine inhibited capsaicin-evoked iCGRP. The norepinephrine effect was blocked by the selective β2-adrenoceptor antagonist, ICI 118,551, but not by pre-treatment with the selective β1-adrenoceptor antagonist, atenolol. In addition, application of albuterol, a selective β2-adrenoceptor agonist, significantly blocked capsaicin-evoked release of iCGRP. Collectively, these studies demonstrate that activation of β2-adrenoceptors in dental pulp significantly reduces exocytosis of neuropeptides from capsaicin-sensitive nociceptors. This effect may have physiologic significance in regulating PBF. Moreover, since capsaicin selectively activates nociceptors, β2-adrenoceptor agonists may have clinical utility as peripherally acting therapeutics for dental pain and inflammation.

Sympathomimetic Drugs Stimulate the Output of Secretory Glycoproteins from Human Bronchi In Vitro

1982 ◽  
Vol 63 (1) ◽  
pp. 23-28 ◽  
Author(s):  
R. J. Phipps ◽  
I. P. Williams ◽  
P. S. Richardson ◽  
J. Pell ◽  
R. J. Pack ◽  
...  
Keyword(s):  
Secretory Cells ◽  
Ussing Chambers ◽  
Adrenoceptor Antagonist ◽  
Adrenoceptor Agonist ◽  
Sympathomimetic Drugs ◽  
Adrenoceptor Agonists ◽  
Secretory Glycoproteins ◽  
Glycoprotein Secretion ◽  
Human Bronchi

1. We describe a method for supporting pieces of human bronchi in Ussing chambers, for radiolabelling the contents of the secretory cells with 35S, and for collecting radiolabeled macromolecules secreted on to the luminal aspect of the tissue. This method has previously been used to study airway secretions in animals [R. J. Phipps, J. A. Nadel & B. Davis, American Review of Respiratory Disease, (1980) 121, 359–365]. Evidence is given that the radiolabelled molecules are secretory glycoproteins, probably mucus glycoproteins. 2. Phenylephrine, an α-adrenoceptor agonist, increased the rate at which the bronchi secreted radiolabeled glycoproteins. Thymoxamine, an α-adrenoceptor antagonist, blocked this effect but propranolol, a β-adrenoceptor antagonist, did not. 3. Dobutamine, a β1-adrenoceptor agonist, increased the rate of secretion of radiolabeled glycoproteins. Propranolol blocked this but thymoxamine did not. 4. Salbutamol, a β2-adrenoceptor agonist, also increased the rate of secretion of radiolabeled glycoproteins. Propranolol blocked this effect. 5. We conclude that both α and β-adrenoceptor agonists increase the rate of glycoprotein secretion in human bronchi in vitro and that this almost certainly means that they increase the rate of mucus secretion.

scholarly journals Alleviation of Oxidative Stress in Dental Pulp Cells Following 4-Hexylresorcinol Administration in a Rat Model

2021 ◽  
Vol 11 (8) ◽  
pp. 3637
Author(s):  
Jun-Ho Chang ◽  
Dae-Won Kim ◽  
Seong-Gon Kim ◽  
Tae-Woo Kim
Keyword(s):  
Oxidative Stress ◽  
Dental Pulp ◽  
Therapeutic Effects ◽  
Protective Effects ◽  
Mandibular Incisor ◽  
Tnf Α ◽  
Total Antioxidant ◽  
Pulp Cells ◽  
Pre Treatment

Damaged dental pulp undergoes oxidative stress and 4-hexylresorcinol (4HR) is a well-known antioxidant. In this study, we aimed to evaluate the therapeutic effects of a 4HR ointment on damaged dental pulp. Pulp cells from rat mandibular incisor were cultured and treated with 4HR or resveratrol (1–100 μM). These treatments (10–100 μM) exerted a protective effect during subsequent hydrogen peroxide treatments. The total antioxidant capacity and glutathione peroxidase activity were significantly increased following 4HR or resveratrol treatment (p < 0.05), while the expression levels of TNF-α and IL1β were decreased following the exposure to 4HR pre-treatment in an in vitro model. Additionally, the application of 4HR ointment in an exposed dental pulp model significantly reduced the expression of TNF-α and IL1β (p < 0.05). Conclusively, 4HR exerted protective effects against oxidative stress in dental pulp tissues through downregulating TNF-α and IL1β.

Effects of α-adrenoceptor agonists and antagonists on thyroid hormone secretion

1985 ◽  
Vol 108 (2) ◽  
pp. 184-191 ◽  
Author(s):  
Bo Ahrén
Keyword(s):  
Thyroid Hormone ◽  
Dose Level ◽  
Hormone Secretion ◽  
High Dose ◽  
Inhibitory Effects ◽  
High Dose Level ◽  
Adrenoceptor Antagonist ◽  
Adrenoceptor Agonist ◽  
Adrenoceptor Agonists

Abstract. The effects of various α-adrenoceptor agonists and antagonists on blood radioiodine levels were studied in mice pre-treated with 125I and thyroxine. The non-selective α-adrenoceptor agonist noradrenaline and the selective α1-adrenoceptor agonist phenylephrine both enhanced blood radioiodine levels. Noradrenaline was more potent than phenylephrine. Contrary, the selective α2-adrenoceptor agonist clonidine depressed basal levels of blood radioiodine. The non-selective α-adrenoceptor antagonist phentolamine and the selective α1-adrenoceptor antagonist prazosin both inhibited the noradrenaline-induced elevation of radioiodine levels, whereas the α2-adrenoceptor antagonist yohimbine had no such effect, except at a high dose level. All three α-adrenoceptor agonists, noradrenaline, phenylephrine and clonidine, inhibited the radioiodine response to TSH. In addition, TSH-induced increase in radioiodine levels was inhibited by prazosin, whereas yohimbine had no effect. Phentolamine inhibited the radioiodine response to TSH when given 2 h prior to TSH, whereas when given 15 min prior to TSH the response to TSH was potentiated by Phentolamine. It is concluded, that under in vivo conditions in the mouse, α1-adrenoceptor activation stimulates basal thyroid hormone secretion and inhibits TSH-induced thyroid hormone secretion. Further, α2-adrenoceptor activation inhibits basal thyroid hormone secretion. In addition, TSH-induced thyroid hormone secretion is inhibited by α1-adrenoceptor antagonism. Thus, α-adrenoceptors induce both stimulatory and inhibitory effects of thyroid function.

The Effect of Imidazoline Receptors and α2-adrenoceptors on the Anesthetic Requirement (MAC) for Halothane in Rats 

1997 ◽  
Vol 87 (4) ◽  
pp. 963-967 ◽  
Author(s):  
Kiyokazu Kagawa ◽  
Tadanori Mammoto ◽  
Yukio Hayashi ◽  
Takahiko Kamibayashi ◽  
Takashi Mashimo ◽  
...  
Keyword(s):  
Minimum Alveolar Concentration ◽  
Inhibitory Effect ◽  
Imidazoline Receptors ◽  
Adrenoceptor Antagonist ◽  
Adrenoceptor Agonist ◽  
Adrenoceptor Agonists ◽  
The Central Nervous System ◽  
Anesthetic Requirement ◽  
Alpha2 Adrenoceptor ◽  
Pharmacologic Actions

Background Recent evidences have documented that several pharmacologic actions of alpha2-adrenoceptor agonists are mediated via activation of not only alpha2-adrenoceptors, but also by imidazoline receptors, which are nonadrenergic receptors in the central nervous system. However, the effect of imidazoline receptors on the anesthesia is not well known, and it is important to clarify the effects of both receptors on anesthesia. Methods Seventy-two rats were anesthetized with halothane, and the anesthetic requirement for halothane was evaluated as minimum alveolar concentration (MAC). The MAC for halothane was determined in the presence of dexmedetomidine (0, 10, 20, and 30 microg/kg, intraperitoneally [IP]), a selective alpha2-adrenoceptor agonist with weak affinity for imidazoline receptors. Then, the authors evaluated the inhibitory effect of rauwolscine (20 mg/kg, IP), an alpha2-adrenoceptor antagonist with little affinity for imidazoline receptors, on the MAC-reducing action of dexmedetomidine (30 microg/kg). Further, the effect of rilmenidine (20, 50, 100, 1000 microg/kg, IP), a selective imidazoline receptor agonist, on the MAC for halothane was also investigated. Results Dexmedetomidine decreased the MAC for halothane dose-dependently, and this MAC-reducing action of dexmedetomidine was completely blocked by rauwolscine. Rilmenidine alone did not change the MAC for halothane. Conclusions The present data indicate that the anesthetic sparing action of dexmedetomidine is most likely mediated through alpha2- adrenoceptors, and the stimulation of imidazoline receptors exerts little effect on the anesthetic requirement for halothane.

scholarly journals Catecholamines modulate podocyte function.

1998 ◽  
Vol 9 (3) ◽  
pp. 335-345 ◽  
Author(s):  
T B Huber ◽  
J Gloy ◽  
A Henger ◽  
P Schollmeyer ◽  
R Greger ◽  
...  
Keyword(s):  
Channel Blocker ◽  
Patch Clamp Technique ◽  
Extracellular Solution ◽  
Adrenoceptor Antagonist ◽  
Adrenoceptor Agonist ◽  
Adrenoceptor Agonists ◽  
Beta 2 ◽  
Cl Conductance ◽  
Stimulation Of ◽  
Ion Conductances

The aim of this study was to investigate the influence of adrenoceptor agonists on the intracellular calcium activity ([Ca2+]i), membrane voltage (Vm), and ion conductances (Gm) in differentiated mouse podocytes. [Ca2+]i was measured by the Fura-2 fluorescence method in single podocytes. Noradrenaline and the alpha 1-adrenoceptor agonist phenylephrine induced a reversible and concentration-dependent biphasic increase of [Ca2+]i in podocytes (EC50 approximately 0.1 microM for peak and plateau), whereas the alpha 2-adrenoceptor agonist UK 14.304 did not influence [Ca2+]i. The [Ca2+]i response induced by noradrenaline was completely inhibited by the alpha 1-adrenoceptor antagonist prazosin (10 nM). In a solution with a high extracellular K+ (72.5 mM), [Ca2+]i was unchanged and the [Ca2+]i increase induced by noradrenaline was not inhibited by the L-type Ca2+ channel blocker nicardipine (1 microM). Vm and Gm were examined with the patch-clamp technique in the slow whole-cell configuration. Isoproterenol, phenylephrine, and noradrenaline depolarized podocytes and increased Gm. The order of potency for the adrenoceptor agonists was isoproterenol (EC50 approximately 1 nM) > noradrenaline (EC50 approximately 0.3 microM) > phenylephrine (EC50 approximately 0.5 microM). The beta 2-adrenoceptor antagonist ICI 118.551 (5 to 100 nM) inhibited the effect of isoproterenol on Vm. Stimulation of adenylate cyclase by forskolin mimicked the effect of isoproterenol on Vm and Gm (EC50 approximately 40 nM). Isoproterenol induced a time- and concentration-dependent increase of cAMP in podocytes. The effect of isoproterenol was unchanged in the absence of Na+ or in an extracellular solution with a reduced Ca2+ concentration, whereas it was significantly increased in an extracellular solution with a reduced Cl- concentration (from 145 to 32 mM). The data indicate that adrenoceptor agonists regulate podocyte function: They increase [Ca2+]i via an alpha 1-adrenoceptor and induce a depolarization via a beta 2-adrenoceptor. The depolarization is probably due to an opening of a cAMP-dependent Cl- conductance.

Slow and incomplete sympathetic reinnervation of rat tail artery restores the amplitude of nerve-evoked contractions provided a perivascular plexus is present

2011 ◽  
Vol 300 (2) ◽  
pp. H541-H554 ◽  
Author(s):  
Diana Tripovic ◽  
Svetlana Pianova ◽  
Elspeth M. McLachlan ◽  
James A. Brock
Keyword(s):  
Rat Tail Artery ◽  
Adult Rats ◽  
Tail Artery ◽  
Adrenoceptor Antagonist ◽  
Adrenoceptor Agonist ◽  
Perivascular Plexus ◽  
Evoked Contractions ◽  
Comparable Amplitude ◽  
Rat Tail

We have investigated the recovery of sympathetic control following reinnervation of denervated rat tail arteries by relating the reappearance of noradrenergic terminals to the amplitude of nerve-evoked contractions of isometrically mounted artery segments in vitro. We have also assessed reactivity to vasoconstrictor agonists. Freezing the collector nerves near the base of the tail in adult rats denervated the artery from ∼40 mm along the tail. Restoration of the perivascular plexus declined along the length of the tail, remaining incomplete for >6 mo. After 4 mo, nerve-evoked contractions were prolonged but of comparable amplitude to control at ∼60 mm along the tail; they were smaller at ∼110 mm. At ∼60 mm, facilitation of contractions to short trains of stimuli by the norepinephrine transporter blocker, desmethylimipramine, and by the α2-adrenoceptor antagonist, idazoxan, was reduced in reinnervated arteries. Blockade of nerve-evoked contractions by the α1-adrenoceptor antagonist, prazosin, was less and by idazoxan greater than control after 8 wk but similar to control after 16 wk. Sensitivity of reinnervated arteries to the α1-adrenoceptor agonist, phenylephrine, was raised in the absence but not in the presence of desmethylimipramine. Sensitivity to the α2-adrenoceptor agonist, clonidine, was maintained in 16-wk reinnervated arteries when it had declined in controls. Thus regenerating sympathetic axons have a limited capacity to reinnervate the rat tail artery, but nerve-evoked contractions match control once a relatively sparse perivascular plexus is reestablished. Functional recovery involves prolongation of contractions and deficits in both clearance of released norepinephrine and autoinhibition of norepinephrine release.

Acute and chronic regulation of α2-adrenoceptor number and function in man

1985 ◽  
Vol 68 (s10) ◽  
pp. 129s-132s ◽  
Author(s):  
C. R. Jones ◽  
C. A. Hamilton ◽  
K. F. Whyte ◽  
H. L. Elliott ◽  
J. L. Reid
Keyword(s):  
Radioligand Binding ◽  
Plasma Catecholamines ◽  
Platelet Response ◽  
Dynamic Regulation ◽  
Α2 Adrenoceptor ◽  
Adrenoceptor Agonist ◽  
Adrenoceptor Agonists ◽  
Receptor Inactivation ◽  
And Function

1. Agonist regulation of platelet α2-adrenoceptors was examined in human volunteers after acute elevations of adrenoceptor agonist and during chronic elevation of plasma catecholamines in two patients with phaeochromocytoma. 2. Platelet α2-adrenoceptor number was measured by radioligand binding ([3H]yohimbine) and α2-adrenoceptor function measured by turbidimetric platelet aggregation. 3. Short term infusion of adrenoceptor agonists with α2 activity caused reductions in the platelet response to adrenaline in vitro; conversely an increase in activity was observed postoperatively in two patients after removal of phaeochromocytoma. 4. The changes in platelet response were not accompanied by changes in α2-adrenoceptor number. 5. It is proposed that a process of receptor inactivation occurs during desensitization and this is responsible for the dynamic regulation of platelet responses.

α-Adrenoceptor regulation in vivo and in vitro in the rabbit

1985 ◽  
Vol 68 (s10) ◽  
pp. 125s-128s ◽  
Author(s):  
C. A. Hamilton ◽  
C. R. Jones ◽  
J. L. Reid
Keyword(s):  
Radioligand Binding ◽  
Receptor Activation ◽  
Oestrogen Treatment ◽  
Α2 Adrenoceptor ◽  
Adrenoceptor Agonists ◽  
Organ Response ◽  
Adrenoceptor Regulation ◽  
Adrenaline Infusion

1. The relationship between α-adrenoceptor number and response has been studied in rabbits under a range of physiological and pathological conditions. 2. The effects of irreversible α-adrenoceptor blockade, maturation, ageing, oestrogen treatment, adrenaline infusion, perinephritis hypertension and sinoaortic denervation on α-adrenoceptor number and response were examined. 3. α-Adrenoceptor number was measured by radioligand binding. [3H]Prazosin and [3H]clonidine were used as ligands to measure α1- and α2-adrenoceptor number in spleen and [3H]yohimbine to measure α2-adrenoceptor number on platelets. Responses in vivo were studied by examining the pressor responses to a range of α-adrenoceptor agonists. The functional response of platelets was examined in vitro by using the aggregatory response to adrenaline. 4. Reductions in α2-adrenoceptor ligand binding were consistently accompanied by equivalent reductions in α2-adrenoceptor-mediated responses. In contrast large reductions in [3H]prazosin binding were observed with little or no change in α1-adrenoceptor-mediated responses. 5. These results would be consistent with a large receptor reserve for α1-adrenoceptors but few if any spare α2-adrenoceptors in the vasculature or on platelets. 6. Increased responses to both α1- and α2-adrenoceptor agonists were observed in animals with sinoaortic denervation and to α1-adrenoceptor agonists in rabbits with perinephritis hypertension. These increases in response were not accompanied by increases in radioligand binding and may be related to alterations in the coupling of receptor activation to end-organ response.

scholarly journals The Inhibitory Effect ofHaloxylon salicornicumon Contraction of the Mouse Uterus

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Nabila H. Saleem ◽  
Valerie A. Ferro ◽  
Ann M. Simpson ◽  
John Igoli ◽  
Alexander I. Gray ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Inhibitory Effects ◽  
Mouse Uterus ◽  
Adrenoceptor Antagonist ◽  
Adrenoceptor Agonist ◽  
Detailed Evaluation ◽  
Pharmacologic Effect ◽  
Spontaneous Contractions ◽  
Crude Aqueous Extract

Haloxylon salicornicum(H. salicornicum) is a plant that is frequently taken as a tea by Bedouin women in Egypt who are experiencing difficulties during pregnancy, as well as to provide relief from dysmenorrhoea. Despite its medical use, there has been no detailed evaluation of the effect of this plant on uterine tissue. Therefore, the initial aim of this study was to determine whetherH. salicornicumaffected the contraction of the mouse uterusin vitro. The crude aqueous extract ofH. salicornicumwas found to inhibit the spontaneous contractions of the uterus, with the effect being rapid in onset and completely reversible upon washout. Subsequent purification of the plant extract resulted in the identification of synephrine and N-methyltyramine, both of which were found to have inhibitory effects on the spontaneous contractions of the uterus. The EC50for the purified constituent identified as synephrine was 0.82 ± 0.24 μg/mL. The inhibitory activity of crudeH. salicornicum, as well as the isolated constituents, could be prevented by pretreatment of the uterus with theβ-adrenoceptor antagonist propranolol. In conclusion, the use ofH. salicornicumduring preterm labour appears to be justified, and its pharmacologic effect is consistent with it acting as aβ-adrenoceptor agonist.

Central catecholaminergic neurons are involved in expression of the 10-Hz rhythm in SND

1996 ◽  
Vol 270 (2) ◽  
pp. R333-R341 ◽  
Author(s):  
H. S. Orer ◽  
S. Zhong ◽  
S. M. Barman ◽  
G. L. Gebber
Keyword(s):  
Intravenous Administration ◽  
Sympathetic Nerve ◽  
Ventrolateral Medulla ◽  
Imidazoline Receptors ◽  
Catecholaminergic Neurons ◽  
Adrenoceptor Antagonist ◽  
Adrenoceptor Agonist ◽  
Adrenoceptor Agonists ◽  
Nerve Discharge ◽  
Lower Frequencies

We studied the effects of adrenoceptor agonists and antagonists on sympathetic nerve discharge (SND) of urethan-anesthetized, baroreceptor-denervated cats. In cats in which a 10-Hz rhythm coexisted with irregular 2- to 6-Hz oscillations in SND, intravenous clonidine, an alpha 2-adrenoceptor agonist, blocked the 10-Hz rhythm without affecting power at lower frequencies. In contrast, power at frequencies < or = 6 Hz was depressed by clonidine in cats in which the 10-Hz rhythm was absent. These effects were reversed by intravenous administration of alpha 2-adrenoceptor antagonists, idazoxan and rauwolscine. Rauwolscine is devoid of affinity for imidazoline receptors. Furthermore, in cats untreated with clonidine, idazoxan and rauwolscine enhanced or induced the 10-Hz rhythm without affecting power at lower frequencies. Prazosin, an alpha 1-adrenoceptor antagonist, selectively blocked the 10-Hz rhythm in SND. Finally, the 10-Hz rhythm in SND was blocked by microinjection of clonidine into the rostral or caudal ventrolateral medulla. The results support the view that central catecholaminergic neurons play a role in expression of the 10-Hz rhythm in SND.

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