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Ye Q, Zhang X. Serotonin activates paraventricular thalamic neurons through direct depolarization and indirect disinhibition from zona incerta. J Physiol 2021; 599:4883-4900. [PMID: 34510418 DOI: 10.1113/jp282088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 09/10/2021] [Indexed: 12/11/2022] Open
Abstract
Paraventricular thalamus (PVT) is a midline thalamic area that receives dense GABA projections from zona incerta (ZI) for the regulation of feeding behaviours. Activation of central serotonin (5-HT) signalling is known to inhibit food intake. Although previous studies have reported both 5-HT fibres and receptors in the PVT, it remains unknown how 5-HT regulates PVT neurons and whether PVT 5-HT signalling is involved in the control of food intake. Using slice patch-clamp recordings in combination with optogenetics, we found that 5-HT not only directly excited PVT neurons by activating 5-HT7 receptors to modulate hyperpolarization-activated cyclic nucleotide-gated (HCN) channels but also disinhibited these neurons by acting on presynaptic 5-HT1A receptors to reduce GABA inhibition. Specifically, 5-HT depressed photostimulation-evoked inhibitory postsynaptic currents (eIPSCs) in PVT neurons innervated by channelrhodopsin-2-positive GABA axons from ZI. Using paired-pulse photostimulation, we found 5-HT increased paired-pulse ratios of eIPSCs, suggesting 5-HT decreases ZI-PVT GABA release. Furthermore, we found that exposure to a high-fat-high-sucrose diet for 2 weeks impaired both 5-HT inhibition of ZI-PVT GABA transmission and 5-HT excitation of PVT neurons. Using retrograde tracer in combination with immunocytochemistry and slice electrophysiology, we found that PVT-projecting dorsal raphe neurons expressed 5-HT and were inhibited by food deprivation. Together, our study reveals the mechanism by which 5-HT activates PVT neurons through both direct excitation and indirect disinhibition from the ZI. The downregulation in 5-HT excitation and disinhibition of PVT neurons may contribute to the development of overeating and obesity after chronic high-fat diet. KEY POINTS: Serotonin (5-HT) depolarizes and excites paraventricular thalamus (PVT) neurons. 5-HT7 receptors are responsible for 5-HT excitation of PVT neurons and the coupling of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels to 5-HT receptors in part mediates the excitatory effect of 5-HT. 5-HT depresses the frequency of spontaneous inhibitory but not excitatory postsynaptic currents in PVT neurons. 5-HT1A receptors contribute to the depressive effect of 5-HT on inhibitory transmissions. 5-HT inhibits GABA release from zona incerta (ZI) GABA terminals in PVT. Chronic high-fat diet not only impairs 5-HT inhibition of the ZI-PVT GABA transmission but also downregulates 5-HT excitation of PVT neurons. PVT-projecting dorsal raphe neurons express 5-HT and are inhibited by food deprivation.
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Affiliation(s)
- Qiying Ye
- Department of Psychology, Florida State University, Tallahassee, FL, USA
| | - Xiaobing Zhang
- Department of Psychology, Florida State University, Tallahassee, FL, USA
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Abstract
Orexin/hypocretin peptide (orexin-A and orexin-B) signaling is believed to take place via the two G-protein-coupled receptors (GPCRs), named OX1 and OX2 orexin receptors, as described in the previous chapters. Signaling of orexin peptides has been investigated in diverse endogenously orexin receptor-expressing cells - mainly neurons but also other types of cells - and in recombinant cells expressing the receptors in a heterologous manner. Findings in the different systems are partially convergent but also indicate cellular background-specific signaling. The general picture suggests an inherently high degree of diversity in orexin receptor signaling.In the current chapter, I present orexin signaling on the cellular and molecular levels. Discussion of the connection to (potential) physiological orexin responses is only brief since these are in focus of other chapters in this book. The same goes for the post-synaptic signaling mechanisms, which are dealt with in Burdakov: Postsynaptic actions of orexin. The current chapter is organized according to the tissue type, starting from the central nervous system. Finally, receptor signaling pathways are discussed across tissues, cell types, and even species.
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Affiliation(s)
- Jyrki P Kukkonen
- Biochemistry and Cell Biology, Department of Veterinary Biosciences, University of Helsinki, POB 66, FIN-00014, Helsinki, Finland.
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Respiratory Rhythm Generation: The Whole Is Greater Than the Sum of the Parts. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1015:147-161. [DOI: 10.1007/978-3-319-62817-2_9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Kolaj M, Zhang L, Renaud LP. L-type calcium channels and MAP kinase contribute to thyrotropin-releasing hormone-induced depolarization in thalamic paraventricular nucleus neurons. Am J Physiol Regul Integr Comp Physiol 2016; 310:R1120-7. [PMID: 27009047 PMCID: PMC4935505 DOI: 10.1152/ajpregu.00082.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 03/18/2016] [Indexed: 12/11/2022]
Abstract
In rat paraventricular thalamic nucleus (PVT) neurons, activation of thyrotropin-releasing hormone (TRH) receptors enhances neuronal excitability via concurrent decrease in a G protein-coupled inwardly rectifying K (GIRK)-like conductance and opening of a cannabinoid receptor-sensitive transient receptor potential canonical (TRPC)-like conductance. Here, we investigated the calcium (Ca(2+)) contribution to the components of this TRH-induced response. TRH-induced membrane depolarization was reduced in the presence of intracellular BAPTA, also in media containing nominally zero [Ca(2+)]o, suggesting a critical role for both intracellular Ca(2+) release and Ca(2+) influx. TRH-induced inward current was unchanged by T-type Ca(2+) channel blockade, but was decreased by blockade of high-voltage-activated Ca(2+) channels (HVACCs). Both the pharmacologically isolated GIRK-like and the TRPC-like components of the TRH-induced response were decreased by nifedipine and increased by BayK8644, implying Ca(2+) influx via L-type Ca(2+) channels. Only the TRPC-like conductance was reduced by either thapsigargin or dantrolene, suggesting a role for ryanodine receptors and Ca(2+)-induced Ca(2+) release in this component of the TRH-induced response. In pituitary and other cell lines, TRH stimulates MAPK. In PVT neurons, only the GIRK-like component of the TRH-induced current was selectively decreased in the presence of PD98059, a MAPK inhibitor. Collectively, the data imply that TRH-induced depolarization and inward current in PVT neurons involve both a dependency on extracellular Ca(2+) influx via opening of L-type Ca(2+) channels, a sensitivity of a TRPC-like component to intracellular Ca(2+) release via ryanodine channels, and a modulation by MAPK of a GIRK-like conductance component.
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Affiliation(s)
- Miloslav Kolaj
- Ottawa Hospital Research Institute, Neuroscience Program and University of Ottawa, Department of Medicine, Ottawa, Ontario, Canada
| | - Li Zhang
- Ottawa Hospital Research Institute, Neuroscience Program and University of Ottawa, Department of Medicine, Ottawa, Ontario, Canada
| | - Leo P Renaud
- Ottawa Hospital Research Institute, Neuroscience Program and University of Ottawa, Department of Medicine, Ottawa, Ontario, Canada
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Zhang L, Kolaj M, Renaud LP. Endocannabinoid 2-AG and intracellular cannabinoid receptors modulate a low-threshold calcium spike-induced slow depolarizing afterpotential in rat thalamic paraventricular nucleus neurons. Neuroscience 2016; 322:308-19. [PMID: 26924019 DOI: 10.1016/j.neuroscience.2016.02.047] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/18/2016] [Accepted: 02/19/2016] [Indexed: 12/01/2022]
Abstract
In rat paraventricular thalamic nucleus (PVT) neurons, activation of low-threshold calcium (Ca(2+)) channels triggers a low-threshold spike (LTS) which may be followed by slow afterpotentials that can dramatically influence action potential patterning. Using gluconate-based internal recording solutions, we investigated the properties of a LTS-induced slow afterdepolarization (sADP) observed in a subpopulation of PVT neurons recorded in brain slice preparations. This LTS-induced sADP required T-type Ca(2+) channel opening, exhibited variable magnitudes between neurons and a voltage dependency with a maximum near -50 mV. The area under the sADP remained stable during control monitoring, but displayed gradual suppression in media where strontium replaced Ca(2+). The sADP was suppressed following bath application of 2-APB or ML204, suggesting engagement of transient receptor potential canonical (TRPC)-like channels. Further investigation revealed a reversible suppression during bath applications of membrane permeable cannabinoid receptor (CBR) blockers rimonabant, AM630 or SR144528 suggesting the presence of both CB1Rs and CB2Rs. Similar results were achieved by intracellular, but not bath application of the membrane impermeant CB1R blocker hemopressin, suggesting an intracellular localization of CB1Rs. Data from pharmacologic manipulation of endocannabinoid biosynthetic pathways suggested 2-arachidonlyglycerol (2-AG) as the endogenous cannabinoid ligand, derived via hydrolysis of diacylglycerol (DAG), with the latter formed from the pathway involving phosphatidylcholine-specific phospholipase D and phosphatic acid phosphohydrolase. The sADP suppression observed during recordings with pipettes containing LY294002, a PI3-kinase inhibitor, suggested a role for PI3kinase in the translocation of these TRPC-like channels to the plasma membrane. Drug-induced attenuation of the availability of 2-AG influences the number of action potentials that surmount the LTS evoked in PVT neurons, implying an ongoing intracellular CBR modulation of neuronal excitability during LTS-induced bursting behavior.
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Affiliation(s)
- L Zhang
- Neuroscience Program, Ottawa Hospital Research Institute and Department of Medicine, University of Ottawa, 725 Parkdale Avenue, Ottawa, Ontario K1Y 4E9, Canada
| | - M Kolaj
- Neuroscience Program, Ottawa Hospital Research Institute and Department of Medicine, University of Ottawa, 725 Parkdale Avenue, Ottawa, Ontario K1Y 4E9, Canada
| | - L P Renaud
- Neuroscience Program, Ottawa Hospital Research Institute and Department of Medicine, University of Ottawa, 725 Parkdale Avenue, Ottawa, Ontario K1Y 4E9, Canada.
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Intracellular postsynaptic cannabinoid receptors link thyrotropin-releasing hormone receptors to TRPC-like channels in thalamic paraventricular nucleus neurons. Neuroscience 2015; 311:81-91. [DOI: 10.1016/j.neuroscience.2015.10.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 10/07/2015] [Accepted: 10/08/2015] [Indexed: 12/16/2022]
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Kodirov SA, Wehrmeister M, Colom L. Nicotine-Mediated ADP to Spike Transition: Double Spiking in Septal Neurons. J Membr Biol 2015; 249:107-18. [PMID: 26463358 DOI: 10.1007/s00232-015-9853-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Accepted: 09/29/2015] [Indexed: 11/25/2022]
Abstract
The majority of neurons in lateral septum (LS) are electrically silent at resting membrane potential. Nicotine transiently excites a subset of neurons and occasionally leads to long lasting bursting activity upon longer applications. We have observed simultaneous changes in frequencies and amplitudes of spontaneous action potentials (AP) in the presence of nicotine. During the prolonged exposure, nicotine increased numbers of spikes within a burst. One of the hallmarks of nicotine effects was the occurrences of double spikes (known also as bursting). Alignment of 51 spontaneous spikes, triggered upon continuous application of nicotine, revealed that the slope of after-depolarizing potential gradually increased (1.4 vs. 3 mV/ms) and neuron fired the second AP, termed as double spiking. A transition from a single AP to double spikes increased the amplitude of after-hyperpolarizing potential. The amplitude of the second (premature) AP was smaller compared to the first one, and this correlation persisted in regard to their duration (half-width). A similar bursting activity in the presence of nicotine, to our knowledge, has not been reported previously in the septal structure in general and in LS in particular.
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Affiliation(s)
- Sodikdjon A Kodirov
- Department of Biological Sciences, Center for Biomedical Studies, University of Texas at Brownsville, Brownsville, TX, 78520, USA.
- Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, GA, 30310, USA.
| | - Michael Wehrmeister
- Johannes Gutenberg University, 55099, Mainz, Germany
- Heidelberg University, Heidelberg, Germany
| | - Luis Colom
- Department of Biological Sciences, Center for Biomedical Studies, University of Texas at Brownsville, Brownsville, TX, 78520, USA
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Limbic thalamus and state-dependent behavior: The paraventricular nucleus of the thalamic midline as a node in circadian timing and sleep/wake-regulatory networks. Neurosci Biobehav Rev 2015; 54:3-17. [DOI: 10.1016/j.neubiorev.2014.11.021] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 11/09/2014] [Accepted: 11/21/2014] [Indexed: 12/21/2022]
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Zhu Y, Lu Y, Qu C, Miller M, Tian J, Thakur DP, Zhu J, Deng Z, Hu X, Wu M, McManus OB, Li M, Hong X, Zhu MX, Luo HR. Identification and optimization of 2-aminobenzimidazole derivatives as novel inhibitors of TRPC4 and TRPC5 channels. Br J Pharmacol 2015; 172:3495-509. [PMID: 25816897 DOI: 10.1111/bph.13140] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 02/16/2015] [Accepted: 03/18/2015] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND AND PURPOSE Transient receptor potential canonical (TRPC) channels play important roles in a broad array of physiological functions and are involved in various diseases. However, due to a lack of potent subtype-specific inhibitors the exact roles of TRPC channels in physiological and pathophysiological conditions have not been elucidated. EXPERIMENTAL APPROACH Using fluorescence membrane potential and Ca(2+) assays and electrophysiological recordings, we characterized new 2-aminobenzimidazole-based small molecule inhibitors of TRPC4 and TRPC5 channels identified from cell-based fluorescence high-throughput screening. KEY RESULTS The original compound, M084, was a potent inhibitor of both TRPC4 and TRPC5, but was also a weak inhibitor of TRPC3. Structural modifications of the lead compound resulted in the identification of analogues with improved potency and selectivity for TRPC4 and TRPC5 channels. The aminobenzimidazole derivatives rapidly inhibited the TRPC4- and TRPC5-mediated currents when applied from the extracellular side and this inhibition was independent of the mode of activation of these channels. The compounds effectively blocked the plateau potential mediated by TRPC4-containing channels in mouse lateral septal neurons, but did not affect the activity of heterologously expressed TRPA1, TRPM8, TRPV1 or TRPV3 channels or that of the native voltage-gated Na(+) , K(+) and Ca(2) (+) channels in dissociated neurons. CONCLUSIONS AND IMPLICATIONS The TRPC4/C5-selective inhibitors developed here represent novel and useful pharmaceutical tools for investigation of physiological and pathophysiological functions of TRPC4/C5 channels.
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Affiliation(s)
- Yingmin Zhu
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Yungang Lu
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX, USA.,The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Chunrong Qu
- State Key Laboratory of Virology, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery (Wuhan University), Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, Hubei, China
| | - Melissa Miller
- Department of Neuroscience, High Throughput Biology Center and Johns Hopkins Ion Channel Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jinbin Tian
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Dhananjay P Thakur
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Jinmei Zhu
- State Key Laboratory of Virology, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery (Wuhan University), Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, Hubei, China
| | - Zixin Deng
- State Key Laboratory of Virology, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery (Wuhan University), Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, Hubei, China
| | - Xianming Hu
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Meng Wu
- Department of Neuroscience, High Throughput Biology Center and Johns Hopkins Ion Channel Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Owen B McManus
- Department of Neuroscience, High Throughput Biology Center and Johns Hopkins Ion Channel Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Min Li
- Department of Neuroscience, High Throughput Biology Center and Johns Hopkins Ion Channel Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Xuechuan Hong
- State Key Laboratory of Virology, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery (Wuhan University), Ministry of Education, Wuhan University School of Pharmaceutical Sciences, Wuhan, Hubei, China
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Huai-Rong Luo
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, The Chinese Academy of Sciences, Kunming, Yunnan, China
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Zhang H, Cilz NI, Yang C, Hu B, Dong H, Lei S. Depression of neuronal excitability and epileptic activities by group II metabotropic glutamate receptors in the medial entorhinal cortex. Hippocampus 2015; 25:1299-313. [DOI: 10.1002/hipo.22437] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/24/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Haopeng Zhang
- Department of Basic Sciences; School of Medicine and Health Sciences, University of North Dakota; Grand Forks North Dakota
- Department of Anesthesiology; Xijing Hospital, Fourth Military Medical University; Xi'an Shaanxi Province China
| | - Nicholas I. Cilz
- Department of Basic Sciences; School of Medicine and Health Sciences, University of North Dakota; Grand Forks North Dakota
| | - Chuanxiu Yang
- Department of Basic Sciences; School of Medicine and Health Sciences, University of North Dakota; Grand Forks North Dakota
| | - Binqi Hu
- Department of Basic Sciences; School of Medicine and Health Sciences, University of North Dakota; Grand Forks North Dakota
| | - Hailong Dong
- Department of Anesthesiology; Xijing Hospital, Fourth Military Medical University; Xi'an Shaanxi Province China
| | - Saobo Lei
- Department of Basic Sciences; School of Medicine and Health Sciences, University of North Dakota; Grand Forks North Dakota
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