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Szabo B. Presynaptic Adrenoceptors. Handb Exp Pharmacol 2024. [PMID: 38755350 DOI: 10.1007/164_2024_714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Presynaptic α2-adrenoceptors are localized on axon terminals of many noradrenergic and non-noradrenergic neurons in the peripheral and central nervous systems. Their activation by exogenous agonists leads to inhibition of the exocytotic release of noradrenaline and other transmitters from the neurons. Most often, the α2A-receptor subtype is involved in this inhibition. The chain of molecular events between receptor occupation and inhibition of the exocytotic release of transmitters has been determined. Physiologically released endogenous noradrenaline elicits retrograde autoinhibition of its own release. Some clonidine-like α2-receptor agonists have been used to treat hypertension. Dexmedetomidine is used for prolonged sedation in the intensive care; It also has a strong analgesic effect. The α2-receptor antagonist mirtazapine increases the noradrenaline concentration in the synaptic cleft by interrupting physiological autoinhibion of release. It belongs to the most effective antidepressive drugs. β2-Adrenoceptors are also localized on axon terminals in the peripheral and central nervous systems. Their activation leads to enhanced transmitter release, however, they are not activated by endogenous adrenaline.
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Affiliation(s)
- Bela Szabo
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany.
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Wang JY, Weng WC, Wang TQ, Liu Y, Qiu DL, Wu MC, Chu CP. Noradrenaline depresses facial stimulation-evoked cerebellar MLI-PC synaptic transmission via α2-AR/PKA signaling cascade in vivo in mice. Sci Rep 2023; 13:15908. [PMID: 37741947 PMCID: PMC10517918 DOI: 10.1038/s41598-023-42975-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 09/17/2023] [Indexed: 09/25/2023] Open
Abstract
The noradrenergic fibers of the locus coeruleus, together with mossy fibers and climbing fibers, comprise the three types of cerebellar afferents that modulate the cerebellar neuronal circuit. We previously demonstrated that noradrenaline (NA) modulated synaptic transmission in the mouse cerebellar cortex via adrenergic receptors (ARs). In the present study, we investigated the effect of NA on facial stimulation-evoked cerebellar molecular layer interneuron (MLI)-Purkinje cell (PC) synaptic transmission in urethane-anesthetized mice using an in vivo cell-attached recording technique and a pharmacological method. MLI-PC synaptic transmission was induced by air-puff stimulation (duration: 60 ms) of the ipsilateral whisker pad, which exhibited positive components (P1 and P2) accompanied by a pause in simple spike activity. Cerebellar molecular layer application of NA (15 µM) decreased the amplitude and area under the curve of P1, and the pause in simple spike activity, but increased the P2/P1 ratio. The NA-induced decrease in P1 amplitude was concentration-dependent, and the half-inhibitory concentration was 10.94 µM. The NA-induced depression of facial stimulation-evoked MLI-PC GABAergic synaptic transmission was completely abolished by blockade of α-ARs or α2-ARs, but not by antagonism of α1-ARs or β-ARs. Bath application of an α2-AR agonist inhibited MLI-PC synaptic transmission and attenuated the effect of NA on the synaptic response. NA-induced depression of MLI-PC synaptic transmission was completely blocked by a mixture of α2A- and 2B-AR antagonists, and was abolished by inhibition of protein kinase A. In addition, electrical stimulation of the molecular layer evoked MLI-PC GABAergic synaptic transmission in the presence of an AMPA receptor antagonist, which was inhibited by NA through α2-ARs. Our results indicate that NA inhibits MLI-PC GABAergic synaptic transmission by reducing GABA release via an α2-AR/PKA signaling pathway.
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Affiliation(s)
- Jun-Ya Wang
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, China
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin, 132013, Jilin, China
| | - Wen-Cai Weng
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, China
- Department Radiology, Dalian Xinhua Hospital, Dalian University, Dalian, China
| | - Ting-Qi Wang
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, China
| | - Yue Liu
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, China
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin, 132013, Jilin, China
| | - De-Lai Qiu
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin, 132013, Jilin, China
| | - Mao-Cheng Wu
- Department of Osteology, Affiliated Hospital of Yanbian University, Yanji, 133002, Jilin, China.
| | - Chun-Ping Chu
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin, 132013, Jilin, China.
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Activation of 5-HT1A Receptors Promotes Retinal Ganglion Cell Function by Inhibiting the cAMP-PKA Pathway to Modulate Presynaptic GABA Release in Chronic Glaucoma. J Neurosci 2018; 39:1484-1504. [PMID: 30541912 DOI: 10.1523/jneurosci.1685-18.2018] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 12/12/2022] Open
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) receptor agonists are neuroprotective in CNS injury models. However, the neuroprotective functional implications and synaptic mechanism of 8-hydroxy-2- (di-n-propylamino) tetralin (8-OH-DPAT), a serotonin receptor (5-HT1A) agonist, in an adult male Wistar rat model of chronic glaucoma model remain unknown. We found that ocular hypertension decreased 5-HT1A receptor expression in rat retinas because the number of retinal ganglion cells (RGCs) was significantly reduced in rats with induced ocular hypertension relative to that in control retinas and 8-OH-DPAT enhanced the RGC viability. The protective effects of 8-OH-DPAT were blocked by intravitreal administration of the selective 5-HT1A antagonist WAY-100635 or the selective GABAA receptor antagonist SR95531. Using patch-clamp techniques, spontaneous and miniature GABAergic IPSCs (sIPSCs and mIPSCs, respectively) of RGCs in rat retinal slices were recorded. 8-OH-DPAT significantly increased the frequency and amplitude of GABAergic sIPSCs and mIPSCs in ON- and OFF-type RGCs. Among the signaling cascades mediated by the 5-HT1A receptor, the role of cAMP-protein kinase A (PKA) signaling was investigated. The 8-OH-DPAT-induced changes at the synaptic level were enhanced by PKA inhibition by H-89 and blocked by PKA activation with bucladesine. Furthermore, the density of phosphorylated PKA (p-PKA)/PKA was significantly increased in glaucomatous retinas and 8-OH-DPAT significantly decreased p-PKA/PKA expression, which led to the inhibition of PKA phosphorylation upon relieving neurotransmitter GABA release. These results showed that the activation of 5-HT1A receptors in retinas facilitated presynaptic GABA release functions by suppressing cAMP-PKA signaling and decreasing PKA phosphorylation, which could lead to the de-excitation of RGC circuits and suppress excitotoxic processes in glaucoma.SIGNIFICANCE STATEMENT We found that serotonin (5-HT) receptors in the retina (5-HT1A receptors) were downregulated after intraocular pressure elevation. Patch-clamp recordings demonstrated differences in the frequencies of miniature GABAergic IPSCs (mIPSCs) in ON- and OFF-type retinal ganglion cells (RGCs) and RGCs in normal and glaucomatous retinal slices. Therefore, phosphorylated protein kinase A (PKA) inhibition upon release of the neurotransmitter GABA was eliminated by 8-hydroxy-2- (di-n-propylamino) tetralin (8-OH-DPAT), which led to increased levels of GABAergic mIPSCs in ON- and OFF-type RGCs, thus enhancing RGC viability and function. These protective effects were blocked by the GABAA receptor antagonist SR95531 or the 5-HT1A antagonist WAY-100635. This study identified a novel mechanism by which activation of 5-HT1A receptors protects damaged RGCs via the cAMP-PKA signaling pathway that modulates GABAergic presynaptic activity.
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Choy JMC, Agahari FA, Li L, Stricker C. Noradrenaline Increases mEPSC Frequency in Pyramidal Cells in Layer II of Rat Barrel Cortex via Calcium Release From Presynaptic Stores. Front Cell Neurosci 2018; 12:213. [PMID: 30100867 PMCID: PMC6072855 DOI: 10.3389/fncel.2018.00213] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 06/28/2018] [Indexed: 11/20/2022] Open
Abstract
Somatosensory cortex is innervated by afferents originating from the locus coeruleus which typically release noradrenaline. We tested if activation of presynaptic α1-adrenoceptors (AR) coupled to a Gq-mediated signaling cascade resulted in calcium (Ca2+) release from stores and thereby increased spontaneous transmitter release in rat barrel cortex. Adding 1–100 μM noradrenaline (NA) or 5 μM cirazoline (CO), a α1-AR specific agonist, to the standard artificial cerebrospinal fluid increased the frequency of miniature excitatory postsynaptic currents (mEPSC) by 64 ± 7% in 51% of pyramidal cells in layer II (responders) with no effect on the amplitude. In 42 responders, the mEPSC frequency during control was significantly smaller (39 ± 2 vs. 53 ± 4 Hz) and upon NA exposure, the input resistance (Rin) decreased (9 ± 7%) compared to non-responders. Experiments using CO and the antagonist prazosin revealed that NA acted via binding to α1-ARs, which was further corroborated by simultaneously blocking β- and α2-ARs with propranolol and yohimbine, which did not prevent the increase in mEPSC frequency. To verify elements in the signaling cascade, both the phospholipase C inhibitor edelfosine and the membrane permeable IP3 receptor blocker 2-APB averted the increase in mEPSC frequency. Likewise, emptying Ca2+ stores with cyclopiazonic acid or the chelation of intracellular Ca2+ with BAPTA-AM prevented the frequency increase, suggesting that the frequency increase was caused by presynaptic store release. When group I metabotropic glutamate receptors were activated with DHPG, co-application of NA occluded a further frequency increase suggesting that the two receptor activations may not signal independently of each other. The increased mEPSC frequency in a subset of pyramidal cells results in enhanced synaptic noise, which, together with the reduction in Rin, will affect computation in the network.
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Affiliation(s)
- Julian M C Choy
- Neuronal Network Laboratory, Eccles Institute of Neuroscience, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Fransiscus A Agahari
- Neuronal Network Laboratory, Eccles Institute of Neuroscience, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia.,Division of Cerebral Circuitry, National Institute for Physiological Sciences, Okazaki, Japan
| | - Li Li
- Neuronal Network Laboratory, Eccles Institute of Neuroscience, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia.,Zhejiang Provincial Key Laboratory of Anesthesiology, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Christian Stricker
- Neuronal Network Laboratory, Eccles Institute of Neuroscience, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia.,ANU Medical School, Australian National University, Canberra, ACT, Australia
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Raczak-Gutknecht J, Frąckowiak T, Nasal A, Kornicka A, Sączewski F, Kaliszan R. Are Alpha-2D Adrenoceptor Subtypes Involved in Rat Mydriasis Evoked by New Imidazoline Derivatives: Marsanidine and 7-Methylmarsanidine? Dose Response 2017; 15:1559325817701213. [PMID: 28491012 PMCID: PMC5405787 DOI: 10.1177/1559325817701213] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The imidazoline compounds may produce mydriasis after systemic administration to some species (rats, cats, and mice). In mydriatic activity of imidazolines, α2D-adrenoceptors subtype(s) seems to be involved. In this study, the pupil dilatory effect evoked by 2 newly synthesized imidazoline derivatives—α2-adrenoceptor agonists: marsanidine and 7-methylmarsanidine—was compared. The compounds were tested alone as well as in the presence of α2-adrenoceptor antagonists (nonselective, yohimbine, and selective toward the following α2-adrenoceptor subtypes—α2A-2-[(4,5-dihydro-1H-imidazol-2-yl)methyl]-2,3-dihydro-1-methyl-1H-isoindole maleate (BRL44408), α2B-2-[2-(4-(2-methoxyphenyl)piperazin-1-yl)ethyl]-4,4-dimethyl-1,3-(2H,4H)-isoquinolindione dihydrochloride (ARC239), α2C-JP1302, α2D-2-(2,3-dihydro-2-methoxy-1,4-benzodioxin-2-yl)-4,5-dihydro-1H-imidazole hydrochloride [RX821002]). The agonists were studied in male Wistar rats and were administered intravenously in cumulative doses. The antagonistic compounds were given in a single dose before the experiment with marsanidine or 7-methylmarsanidine. Pupil diameter was measured with stereoscopic microscope equipped in green light filter. Marsanidine and 7-methylmarsanidine exerted marked mydriatic effects. BRL44408, JP1302, and ARC239 did not cause significant parallel shift to the right of the dose–effect curves obtained for both imidazolines. In case of yohimbine and RX821002, the marked parallel shifts of dose–response curves were observed, with the antagonistic effects of RX821002 more pronounced. In vivo pharmacodynamics experiment suggests that α2D-adrenoceptor subtype is mainly engaged in mydriatic effects evoked in rats by imidazoline derivatives, in particular by clonidine.
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Affiliation(s)
- Joanna Raczak-Gutknecht
- Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdańsk, Gdańsk, Poland
| | - Teresa Frąckowiak
- Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdańsk, Gdańsk, Poland
| | - Antoni Nasal
- Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdańsk, Gdańsk, Poland
- Antoni Nasal, Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416 Gdańsk, Poland.
| | - Anita Kornicka
- Department of Chemical Technology of Drugs, Medical University of Gdańsk, Gdańsk, Poland
| | - Franciszek Sączewski
- Department of Chemical Technology of Drugs, Medical University of Gdańsk, Gdańsk, Poland
| | - Roman Kaliszan
- Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdańsk, Gdańsk, Poland
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Amygdalar Gating of Early Sensory Processing through Interactions with Locus Coeruleus. J Neurosci 2017; 37:3085-3101. [PMID: 28188216 DOI: 10.1523/jneurosci.2797-16.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 12/18/2016] [Accepted: 01/09/2017] [Indexed: 11/21/2022] Open
Abstract
Fear- and stress-induced activity in the amygdala has been hypothesized to influence sensory brain regions through the influence of the amygdala on neuromodulatory centers. To directly examine this relationship, we used optical imaging to observe odor-evoked activity in populations of olfactory bulb inhibitory interneurons and of synaptic terminals of olfactory sensory neurons (the primary sensory neurons of the olfactory system, which provide the initial olfactory input to the brain) during pharmacological inactivation of amygdala and locus coeruleus (LC) in mice. Although the amygdala does not directly project to the olfactory bulb, joint pharmacological inactivation of the central, basolateral, and lateral nuclei of the amygdala nonetheless strongly suppressed odor-evoked activity in GABAergic inhibitory interneuron populations in the OB. This suppression was prevented by inactivation of LC or pretreatment of the olfactory bulb with a broad-spectrum noradrenergic receptor antagonist. Visualization of synaptic output from olfactory sensory neuron terminals into the olfactory bulb of the brain revealed that amygdalar inactivation preferentially strengthened the odor-evoked synaptic output of weakly activated populations of sensory afferents from the nose, thus demonstrating a change in sensory gating potentially mediated by local inhibition of olfactory sensory neuron terminals. We conclude that amygdalar activity influences olfactory processing as early as the primary sensory input to the brain by modulating norepinephrine release from the locus coeruleus into the olfactory bulb. These findings show that the amygdala and LC state actively determines which sensory signals are selected for processing in sensory brain regions. Similar local circuitry operates in the olfactory, visual, and auditory systems, suggesting a potentially shared mechanism across modalities.SIGNIFICANCE STATEMENT The affective state is increasingly understood to influence early neural processing of sensory stimuli, not just the behavioral response to those stimuli. The present study elucidates one circuit by which the amygdala, a critical structure for emotional learning, valence coding, and stress, can shape sensory input to the brain and early sensory processing through its connections to the locus coeruleus. One function of this interaction appears to be sensory gating, because inactivating the central, basolateral, and lateral nuclei of the amygdala selectively strengthened the weakest olfactory inputs to the brain. This linkage of amygdalar and LC output to primary sensory signaling may have implications for affective disorders that include sensory dysfunctions like hypervigilance, attentional bias, and impaired sensory gating.
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Taoka N, Kamiizawa R, Wada S, Minami M, Kaneda K. Chronic cocaine exposure induces noradrenergic modulation of inhibitory synaptic transmission to cholinergic neurons of the laterodorsal tegmental nucleus. Eur J Neurosci 2016; 44:3035-3045. [DOI: 10.1111/ejn.13405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 08/23/2016] [Accepted: 09/16/2016] [Indexed: 01/30/2023]
Affiliation(s)
- Naofumi Taoka
- Department of Pharmacology; Graduate School of Pharmaceutical Sciences; Hokkaido University; Sapporo Japan
| | - Ryota Kamiizawa
- Department of Pharmacology; Graduate School of Pharmaceutical Sciences; Hokkaido University; Sapporo Japan
| | - Shintaro Wada
- Laboratory of Molecular Pharmacology; Institute of Medical, Pharmaceutical and Health Sciences; Kanazawa University; Kakuma-machi Kanazawa 920-1192 Japan
| | - Masabumi Minami
- Department of Pharmacology; Graduate School of Pharmaceutical Sciences; Hokkaido University; Sapporo Japan
| | - Katsuyuki Kaneda
- Department of Pharmacology; Graduate School of Pharmaceutical Sciences; Hokkaido University; Sapporo Japan
- Laboratory of Molecular Pharmacology; Institute of Medical, Pharmaceutical and Health Sciences; Kanazawa University; Kakuma-machi Kanazawa 920-1192 Japan
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Hara M, Zhou ZY, Hemmings HC. α2-Adrenergic Receptor and Isoflurane Modulation of Presynaptic Ca2+ Influx and Exocytosis in Hippocampal Neurons. Anesthesiology 2016; 125:535-46. [PMID: 27337223 PMCID: PMC4988866 DOI: 10.1097/aln.0000000000001213] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Evidence indicates that the anesthetic-sparing effects of α2-adrenergic receptor (AR) agonists involve α2A-AR heteroreceptors on nonadrenergic neurons. Since volatile anesthetics inhibit neurotransmitter release by reducing synaptic vesicle (SV) exocytosis, the authors hypothesized that α2-AR agonists inhibit nonadrenergic SV exocytosis and thereby potentiate presynaptic inhibition of exocytosis by isoflurane. METHODS Quantitative imaging of fluorescent biosensors of action potential-evoked SV exocytosis (synaptophysin-pHluorin) and Ca influx (GCaMP6) were used to characterize presynaptic actions of the clinically used α2-AR agonists dexmedetomidine and clonidine, and their interaction with isoflurane, in cultured rat hippocampal neurons. RESULTS Dexmedetomidine (0.1 μM, n = 10) or clonidine (0.5 μM, n = 8) inhibited action potential-evoked exocytosis (54 ± 5% and 59 ± 8% of control, respectively; P < 0.001). Effects on exocytosis were blocked by the subtype-nonselective α2-AR antagonist atipamezole or the α2A-AR-selective antagonist BRL 44408 but not by the α2C-AR-selective antagonist JP 1302. Dexmedetomidine inhibited exocytosis and presynaptic Ca influx without affecting Ca coupling to exocytosis, consistent with an effect upstream of Ca-exocytosis coupling. Exocytosis coupled to both N-type and P/Q-type Ca channels was inhibited by dexmedetomidine or clonidine. Dexmedetomidine potentiated inhibition of exocytosis by 0.7 mM isoflurane (to 42 ± 5%, compared to 63 ± 8% for isoflurane alone; P < 0.05). CONCLUSIONS Hippocampal SV exocytosis is inhibited by α2A-AR activation in proportion to reduced Ca entry. These effects are additive with those of isoflurane, consistent with a role for α2A-AR presynaptic heteroreceptor inhibition of nonadrenergic synaptic transmission in the anesthetic-sparing effects of α2A-AR agonists.
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Affiliation(s)
- Masato Hara
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10065, USA
- Department of Anesthesiology, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan
| | - Zhen-Yu Zhou
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Hugh C. Hemmings
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10065, USA
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA
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Atzori M, Cuevas-Olguin R, Esquivel-Rendon E, Garcia-Oscos F, Salgado-Delgado RC, Saderi N, Miranda-Morales M, Treviño M, Pineda JC, Salgado H. Locus Ceruleus Norepinephrine Release: A Central Regulator of CNS Spatio-Temporal Activation? Front Synaptic Neurosci 2016; 8:25. [PMID: 27616990 PMCID: PMC4999448 DOI: 10.3389/fnsyn.2016.00025] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 08/05/2016] [Indexed: 12/22/2022] Open
Abstract
Norepinephrine (NE) is synthesized in the Locus Coeruleus (LC) of the brainstem, from where it is released by axonal varicosities throughout the brain via volume transmission. A wealth of data from clinics and from animal models indicates that this catecholamine coordinates the activity of the central nervous system (CNS) and of the whole organism by modulating cell function in a vast number of brain areas in a coordinated manner. The ubiquity of NE receptors, the daunting number of cerebral areas regulated by the catecholamine, as well as the variety of cellular effects and of their timescales have contributed so far to defeat the attempts to integrate central adrenergic function into a unitary and coherent framework. Since three main families of NE receptors are represented-in order of decreasing affinity for the catecholamine-by: α2 adrenoceptors (α2Rs, high affinity), α1 adrenoceptors (α1Rs, intermediate affinity), and β adrenoceptors (βRs, low affinity), on a pharmacological basis, and on the ground of recent studies on cellular and systemic central noradrenergic effects, we propose that an increase in LC tonic activity promotes the emergence of four global states covering the whole spectrum of brain activation: (1) sleep: virtual absence of NE, (2) quiet wake: activation of α2Rs, (3) active wake/physiological stress: activation of α2- and α1-Rs, (4) distress: activation of α2-, α1-, and β-Rs. We postulate that excess intensity and/or duration of states (3) and (4) may lead to maladaptive plasticity, causing-in turn-a variety of neuropsychiatric illnesses including depression, schizophrenic psychoses, anxiety disorders, and attention deficit. The interplay between tonic and phasic LC activity identified in the LC in relationship with behavioral response is of critical importance in defining the short- and long-term biological mechanisms associated with the basic states postulated for the CNS. While the model has the potential to explain a large number of experimental and clinical findings, a major challenge will be to adapt this hypothesis to integrate the role of other neurotransmitters released during stress in a centralized fashion, like serotonin, acetylcholine, and histamine, as well as those released in a non-centralized fashion, like purines and cytokines.
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Affiliation(s)
- Marco Atzori
- Neurobiology of Stress Laboratory, Facultad de Ciencias, Universidad Autónoma de San Luis PotosíSan Luis Potosí, Mexico; School for Behavior and Brain Sciences, University of Texas at DallasRichardson, TX, USA
| | - Roberto Cuevas-Olguin
- Neurobiology of Stress Laboratory, Facultad de Ciencias, Universidad Autónoma de San Luis Potosí San Luis Potosí, Mexico
| | - Eric Esquivel-Rendon
- Neurobiology of Stress Laboratory, Facultad de Ciencias, Universidad Autónoma de San Luis Potosí San Luis Potosí, Mexico
| | | | - Roberto C Salgado-Delgado
- Neurobiology of Stress Laboratory, Facultad de Ciencias, Universidad Autónoma de San Luis Potosí San Luis Potosí, Mexico
| | - Nadia Saderi
- Neurobiology of Stress Laboratory, Facultad de Ciencias, Universidad Autónoma de San Luis Potosí San Luis Potosí, Mexico
| | - Marcela Miranda-Morales
- Neurobiology of Stress Laboratory, Facultad de Ciencias, Universidad Autónoma de San Luis Potosí San Luis Potosí, Mexico
| | - Mario Treviño
- Laboratory of Cortical Plasticity and Learning, Universidad de Guadalajara Guadalajara, Mexico
| | - Juan C Pineda
- Electrophysiology Laboratory, Centro de Investigaciones Regionales "Dr. Hideyo Noguchi", Universidad Autónoma de Yucatán Mérida, Mexico
| | - Humberto Salgado
- Electrophysiology Laboratory, Centro de Investigaciones Regionales "Dr. Hideyo Noguchi", Universidad Autónoma de Yucatán Mérida, Mexico
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Jang IS. Metabotropic glutamate receptors inhibit GABA release in rat histamine neurons. Neurosci Lett 2014; 579:106-9. [PMID: 25062585 DOI: 10.1016/j.neulet.2014.07.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 07/09/2014] [Accepted: 07/14/2014] [Indexed: 12/16/2022]
Abstract
The modulation of GABAergic transmission by metabotropic glutamate (mGlu) receptors was examined in histaminergic neurons using a conventional whole-cell patch clamp technique. DHPG, a selective group I mGlu receptor agonist, had no effect on GABAergic inhibitory postsynaptic currents (IPSCs). However, DCG-IV (1μМ) and L-AP4 (1μМ), selective group II or III mGlu receptor agonists, respectively, decreased the amplitude of GABAergic IPSCs and simultaneously increased the paired-pulse ratio. The inhibitory effect of DCG-IV was completely blocked by 200nM LY341495, a group II and III mGlu receptor antagonist, and the inhibitory effect of L-AP4 was completely blocked by 10μМ LY341495. These results suggest that multiple mGlu receptors are involved in regulating the excitability of histaminergic neurons.
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Affiliation(s)
- Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu, Republic of Korea.
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Satiety factor oleoylethanolamide recruits the brain histaminergic system to inhibit food intake. Proc Natl Acad Sci U S A 2014; 111:11527-32. [PMID: 25049422 DOI: 10.1073/pnas.1322016111] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Key factors driving eating behavior are hunger and satiety, which are controlled by a complex interplay of central neurotransmitter systems and peripheral stimuli. The lipid-derived messenger oleoylethanolamide (OEA) is released by enterocytes in response to fat intake and indirectly signals satiety to hypothalamic nuclei. Brain histamine is released during the appetitive phase to provide a high level of arousal in anticipation of feeding, and mediates satiety. However, despite the possible functional overlap of satiety signals, it is not known whether histamine participates in OEA-induced hypophagia. Using different experimental settings and diets, we report that the anorexiant effect of OEA is significantly attenuated in mice deficient in the histamine-synthesizing enzyme histidine decarboxylase (HDC-KO) or acutely depleted of histamine via interocerebroventricular infusion of the HDC blocker α-fluoromethylhistidine (α-FMH). α-FMH abolished OEA-induced early occurrence of satiety onset while increasing histamine release in the CNS with an H3 receptor antagonist-increased hypophagia. OEA augmented histamine release in the cortex of fasted mice within a time window compatible to its anorexic effects. OEA also increased c-Fos expression in the oxytocin neurons of the paraventricular nuclei of WT but not HDC-KO mice. The density of c-Fos immunoreactive neurons in other brain regions that receive histaminergic innervation and participate in the expression of feeding behavior was comparable in OEA-treated WT and HDC-KO mice. Our results demonstrate that OEA requires the integrity of the brain histamine system to fully exert its hypophagic effect and that the oxytocin neuron-rich nuclei are the likely hypothalamic area where brain histamine influences the central effects of OEA.
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