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Simkins TJ, Fried D, Parikh K, Galligan JJ, Goudreau JL, Lookingland KJ, Kaplan BLF. Reduced Noradrenergic Signaling in the Spleen Capsule in the Absence of CB 1 and CB 2 Cannabinoid Receptors. J Neuroimmune Pharmacol 2016; 11:669-679. [PMID: 27287619 DOI: 10.1007/s11481-016-9689-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 06/02/2016] [Indexed: 11/27/2022]
Abstract
The spleen is a visceral organ that contracts during hypoxia to expel erythrocytes and immune cells into the circulation. Spleen contraction is under the control of noradrenergic sympathetic innervation. The activity of noradrenergic neurons terminating in the spleen capsule is regulated by α2-adrenergic receptors (AR). Interactions between endogenous cannabinoid signaling and noradrenergic signaling in other organ systems suggest endocannabinoids might also regulate spleen contraction. Spleens from mice congenitally lacking both CB1 and CB2 cannabinoid receptors (Cnr1 -/- /Cnr2 -/- mice) were used to explore the role of endocannabinoids in spleen contraction. Spleen contraction in response to exogenous norepinephrine (NE) was found to be significantly lower in Cnr1 -/- /Cnr2 -/- mouse spleens, likely due to decreased expression of capsular α1AR. The majority of splenic Cnr1 mRNA expression is by cells of the spleen capsule, suggestive of post-synaptic CB1 receptor signaling. Thus, these studies demonstrate a role for CB1 and/or CB2 in noradrenergic splenic contraction.
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Affiliation(s)
- Tyrell J Simkins
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
- Center for Integrative Toxicology, Michigan State University, East Lansing, MI, USA
| | - David Fried
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - Kevin Parikh
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - James J Galligan
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - John L Goudreau
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
- Center for Integrative Toxicology, Michigan State University, East Lansing, MI, USA
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - Keith J Lookingland
- Neuroscience Program, Michigan State University, East Lansing, MI, USA
- Center for Integrative Toxicology, Michigan State University, East Lansing, MI, USA
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - Barbara L F Kaplan
- Neuroscience Program, Michigan State University, East Lansing, MI, USA.
- Center for Integrative Toxicology, Michigan State University, East Lansing, MI, USA.
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA.
- Department of Basic Sciences, Mississippi State University, PO Box 6100, Mississippi State, MS, 39762, USA.
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Francis H, LeSage G, DeMorrow S, Alvaro D, Ueno Y, Venter J, Glaser S, Mancino MG, Marucci L, Benedetti A, Alpini G. The alpha2-adrenergic receptor agonist UK 14,304 inhibits secretin-stimulated ductal secretion by downregulation of the cAMP system in bile duct-ligated rats. Am J Physiol Cell Physiol 2007; 293:C1252-62. [PMID: 17634418 DOI: 10.1152/ajpcell.00031.2007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Secretin stimulates ductal secretion by activation of cAMP --> PKA --> CFTR --> Cl(-)/HCO(3)(-) exchanger in cholangiocytes. We evaluated the expression of alpha(2A)-, alpha(2B)-, and alpha(2C)-adrenergic receptors in cholangiocytes and the effects of the selective alpha(2)-adrenergic agonist UK 14,304, on basal and secretin-stimulated ductal secretion. In normal rats, we evaluated the effect of UK 14,304 on bile and bicarbonate secretion. In bile duct-ligated (BDL) rats, we evaluated the effect of UK 14,304 on basal and secretin-stimulated 1) bile and bicarbonate secretion; 2) duct secretion in intrahepatic bile duct units (IBDU) in the absence or presence of 5-(N-ethyl-N-isopropyl)amiloride (EIPA), an inhibitor of the Na(+)/H(+) exchanger isoform NHE3; and 3) cAMP levels, PKA activity, Cl(-) efflux, and Cl(-)/HCO(3)(-) exchanger activity in purified cholangiocytes. alpha(2)-Adrenergic receptors were expressed by all cholangiocytes in normal and BDL liver sections. UK 14,304 did not change bile and bicarbonate secretion of normal rats. In BDL rats, UK 14,304 inhibited secretin-stimulated 1) bile and bicarbonate secretion, 2) expansion of IBDU luminal spaces, and 3) cAMP levels, PKA activity, Cl(-) efflux, and Cl(-)/HCO(3)(-) exchanger activity in cholangiocytes. There was decreased lumen size after removal of secretin in IBDU pretreated with UK 14,304. In IBDU pretreated with EIPA, there was no significant decrease in luminal space after removal of secretin in either the absence or presence of UK 14,304. The inhibitory effect of UK 14,304 on ductal secretion is not mediated by the apical cholangiocyte NHE3. alpha(2)-Adrenergic receptors play a role in counterregulating enhanced ductal secretion associated with cholangiocyte proliferation in chronic cholestatic liver diseases.
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Affiliation(s)
- Heather Francis
- Central Texas Veterans Health Care System, The Texas A & M University System Health Science Center College of Medicine, Medical Research Bldg, Temple, TX 76504, USA
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Serban DN, Serban IL, Nechifor M. Idazoxan effects upon contractile activity in the rat aorta are related to alpha adrenoceptors and L-type channels. Fundam Clin Pharmacol 2004; 18:635-41. [PMID: 15548234 DOI: 10.1111/j.1472-8206.2004.00278.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Idazoxan is an alpha(2) adrenoceptor antagonist and alpha(1)/alpha(2) partial agonist which also blocks imidazoline receptors. Although idazoxan is widely used in pharmacological studies, its intrinsic vasoactive properties could bring about some limitations. Others have shown that in rat aorta contracted by phenylephrine idazoxan induces relaxation and that in rat small arteries it preferentially antagonizes the alpha(1)-mediated response. We further investigated this matter, using the rat aorta and focusing on the endothelium-independent effects and on L-type channels. In our study, idazoxan inhibited the contraction induced by phenylephrine, an effect which was stronger in the presence of endothelium, but did not affect the contractions induced by various other agents (high potassium, angiotensin II, prostaglandin F(2alpha)). This preferential inhibition was attenuated by 10(-4) m, but not by 10(-5) m yohimbine, and also reduced by 10(-2) m tetraethylammonium and blunted by 10(-4) m methoxyverapamil. In concentrations above 10(-5) m idazoxan induced weak contractions of the de-endothelized rings, which were prazosin- and methoxyverapamil-sensitive. Others have suggested that cyclic guanosine monophospate mediates the idazoxan-induced endothelium-dependent relaxation, but this is difficult to reconcile with our findings. Potassium efflux could play some role in the direct relaxing effect of idazoxan. The observed idazoxan effects appear as based on action upon alpha(1) receptors, but a direct interaction with L-type calcium channels could also be taken into consideration.
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MESH Headings
- Adrenergic alpha-1 Receptor Antagonists
- Adrenergic alpha-Antagonists/pharmacology
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/physiology
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/physiology
- Dose-Response Relationship, Drug
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/physiology
- Idazoxan/pharmacology
- In Vitro Techniques
- Male
- Muscle Contraction/drug effects
- Muscle Relaxation/drug effects
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Phenylephrine/pharmacology
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/physiology
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Dragomir Nicolae Serban
- Department of Physiology, University of Medicine and Pharmacy Gr. T. Popa Iasi, Iasi, Romania.
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Cheng Y, Cohen B, Oréa V, Barrès C, Julien C. Baroreflex control of renal sympathetic nerve activity and spontaneous rhythms at Mayer wave's frequency in rats. Auton Neurosci 2004; 111:80-8. [PMID: 15182737 DOI: 10.1016/j.autneu.2004.02.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2003] [Revised: 02/10/2004] [Accepted: 02/16/2004] [Indexed: 11/16/2022]
Abstract
The effects of sedation with pentobarbital sodium (15 mg/kg followed by 15.9+/-1.2 mg/kg/h, i.v.) on arterial pressure (AP) Mayer waves and accompanying oscillations of renal sympathetic nerve activity (RSNA) were examined in rats (n=8). As compared with values observed in the conscious state, pentobarbital significantly (P<0.05) decreased AP (from 119+/-2 to 93+/-3 mm Hg), heart rate (HR; from 427+/-11 to 355+/-11 beats/min) and RSNA (from 1.20+/-0.27 to 0.62+/-0.13 microV). The baroreflex control of RSNA was analyzed by fitting a sigmoid logistic function to changes in RSNA and AP observed during nitroprusside and phenylephrine administrations. During pentobarbital infusion, the RSNA-AP relationship was reset towards lower AP values, but neither its maximum gain nor its gain at resting AP were significantly altered (from 6.3+/-1.0 to 5.8+/-1.4 and from 3.2+/-0.5 to 3.8+/-1.3 normalized units (n.u.)/mm Hg, respectively). Spectral power in the frequency band containing Mayer waves (0.29-0.73 Hz) was significantly decreased by pentobarbital for both AP (from 4.65+/-0.90 to 0.95+/-0.25 mm Hg2) and RSNA (from 1437+/-245 to 488+/-79 n.u.2). This effect was mainly secondary to the attenuation of strongly coherent oscillations of both variables at approximately 0.4 Hz. Although previous experimental evidence points to a major involvement of the sympathetic limb of the arterial baroreceptor reflex in the genesis of Mayer waves, the present study indicates that the amplitude of these oscillations cannot be used as a quantitative index of sympathetic baroreflex sensitivity.
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Affiliation(s)
- Yong Cheng
- Département de Physiologie et Pharmacologie Clinique, Centre National de la Recherche Scientifique Formation de Recherche en Evolution 2678, Faculté de Pharmacie, Université Claude Bernard Lyon 1, Lyon, Cedex 08, France
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Patel S, Huang DL, Sagher O. Sympathetic mechanisms in cerebral blood flow alterations induced by spinal cord stimulation. J Neurosurg 2003; 99:754-61. [PMID: 14567612 DOI: 10.3171/jns.2003.99.4.0754] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Cervical spinal cord stimulation (SCS) has been found to augment cerebral blood flow (CBF) in a number of animal models, although the mechanisms underlying the cerebrovascular effects of SCS are poorly described. In this study, the authors examined the role of sympathetic tone in CBF alterations induced by SCS in rats. METHODS Spinal cord stimulation was performed at three intervals while CBF was monitored with laser Doppler flowmetry (LDF). Either hexamethonium (5, 10, or 20 mg/kg), prazosin (0.25, 0.5, or 1 mg/kg), idazoxan (0.5, 1, or 2 mg/kg), propranolol (1, 2, or 4 mg/kg), or vehicle was administered intravenously before the second stimulation. Changes in LDF values due to SCS were recorded as the percentage of change from baseline values and were analyzed. In vehicle-treated animals, SCS increased LDF values by 60.5 +/- 1.8% over baseline, whereas both high-dose hexamethonium and prazosin completely abolished the SCS-induced increases in LDF values. On the other hand, LDF values increased by 50.9 +/- 4% and 61.4 +/- 4% after SCS in the presence of idazoxan or propranolol, respectively. Administration of sympathetic nervous system blockers resulted in a variable degree of systemic hypotension as well. Nevertheless, induced hypotension without sympathetic blockade had only a minimal effect on SCS-induced augmentation of LDF values (48 +/- 1.4% over baseline). CONCLUSIONS Sympathetic tone plays a major role in SCS-induced increases in CBF. This effect seems to be mediated primarily by alpha1-adrenergic receptors. Systemic hypotension alone cannot explain the effects of sympathetic blockade on the SCS response. Clinical use of SCS in the treatment of cerebral ischemia should take alpha1-adrenergic receptor sympathetic tone into account.
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Affiliation(s)
- Sachin Patel
- University of Michigan Medical School and Department of Neurosurgery, University of Michigan Health System, Ann Arbor, Michigan 48109-0338, USA
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Petiot E, Barrès C, Chapuis B, Julien C. Frequency response of renal sympathetic nervous activity to aortic depressor nerve stimulation in the anaesthetized rat. J Physiol 2001; 537:949-59. [PMID: 11744767 PMCID: PMC2278997 DOI: 10.1111/j.1469-7793.2001.00949.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
1. The contribution of central baroreceptor reflex pathways to the dynamic regulation of sympathetic nervous activity (SNA) has not been properly examined thus far. The aim of this study was to characterize the transfer function of the central arc of the baroreceptor reflex (from baroreceptor afferent activity to SNA) over a wide range of frequencies. 2. In nine baroreceptor-intact and six sino-aortic baroreceptor-denervated rats anaesthetized with urethane, the renal SNA was recorded while applying sinusoidal stimulation to the aortic depressor nerve at 26 discrete frequencies ranging from 0.03 to 20 Hz. At each modulation frequency, cross-power spectrum analysis using a fast Fourier transform algorithm was performed between the stimulation and renal SNA, which provided the transfer function of the central arc. 3. In both baroreceptor intact and denervated rats, the transfer gain increased by a factor of about three between 0.03 and 1 Hz. At higher frequencies, the gain decreased but remained above the static gain of the system up to 12 Hz. There was a slight phase lead up to 0.4 Hz, then a continuously increasing phase lag. A three-element linear model satisfactorily described the experimental transfer function. The model combined a derivative gain (corner frequency approximately 0.15 Hz), an overdamped second-order low-pass filter (natural frequency approximately 1 Hz) and a fixed time delay (approximately 100 ms). 4. These results indicate that the central arc of the baroreceptor reflex shows derivative properties that are essential for compensating the filtering of fast oscillations of baroreceptor afferent activity and thus for the generation of fast oscillations of renal SNA (e.g. those related to the cardiac cycle).
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Affiliation(s)
- E Petiot
- Centre National de la Recherche Scientifique UMR 5014, Faculté de Pharmacie, Institut Fédératif de Recherche Cardio-vasculaire no. 39, Université Claude Bernard Lyon 1, 69373 Lyon Cedex 08, France
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Barrès C, de Souza Neto EP, Julien C. Effect of alpha-adrenoceptor blockade on the 0.4 Hz sympathetic rhythm in conscious rats. Clin Exp Pharmacol Physiol 2001; 28:983-5. [PMID: 11903298 DOI: 10.1046/j.1440-1681.2001.03561.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. The present study examined the origin of the 0.4 Hz rhythm in renal sympathetic nerve activity (RSNA) in rats. It was anticipated that, after elimination of 0.4 Hz oscillations of arterial pressure (AP) by alpha-adrenoceptor blockade, the persistence or disappearance of a 0.4 Hz rhythm in RSNA would point to an endogenous (central oscillator) or baroreflex origin, respectively. 2. Arterial pressure and RSNA were recorded in seven conscious rats, before and after acute alpha-adrenoceptor blockade with phentolamine (5 mg/kg, i.v.). In each condition, power and coherence spectra were calculated over 15 min periods of rest. 3. In control conditions, highly coherent AP and RSNA oscillations were observed near 0.4 Hz. After phentolamine administration, spectral power in the mid-frequency (0.27-0.74 Hz) band was significantly reduced for both AP and RSNA and maximum power was shifted towards 0.7 Hz. 4. The disappearance of the RSNA rhythm at 0.4 Hz after phentolamine administration favours the hypothesis of a baroreflex origin. The new oscillation near 0.7 Hz can derive either from the activity of a previously unrecognized central oscillator or from a faster feedback mechanism involving cotransmitters of noradrenaline acting with shorter time constants (e.g. ATP).
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Affiliation(s)
- C Barrès
- CNRS UMR 5014, Faculté de Pharmacie, Lyon, France.
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