1
|
Hernandez J, Perez L, Soto R, Le N, Gastelum C, Wagner EJ. Nociceptin/orphanin FQ neurons in the Arcuate Nucleus and Ventral Tegmental Area Act via Nociceptin Opioid Peptide Receptor Signaling to Inhibit Proopiomelanocortin and A 10 Dopamine Neurons and Thereby Modulate Ingestion of Palatable Food. Physiol Behav 2021; 228:113183. [PMID: 32979341 PMCID: PMC7736116 DOI: 10.1016/j.physbeh.2020.113183] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/13/2022]
Abstract
The neuropeptide nociceptin/orphanin FQ (N/OFQ) inhibits neuronal activity via its cognate nociceptin opioid peptide (NOP) receptor throughout the peripheral and central nervous systems, including those areas involved in the homeostatic and hedonic regulation of energy homeostasis. We thus tested the hypothesis that N/OFQ neurons in the hypothalamic arcuate nucleus (ARC) and ventral tegmental area (VTA) act via NOP receptor signaling to inhibit nearby anorexigenic proopiomelanocortin (POMC) and A10 dopamine neuronal excitability, respectively, and thereby modulate ingestion of palatable food. Electrophysiologic recordings were performed in slices prepared from transgenic male and ovariectomized (OVX) female N/OFQ-cre/enhanced green fluorescent protein-POMC, N/OFQ-cre and tyrosine hydroxylase-cre animals to see if optogenetically-stimulated peptide release from N/OFQ neurons could directly inhibit these neuronal populations. Binge-feeding behavioral experiments were also conducted where animals were exposed to a high-fat-diet (HFD) for one hour each day for five days and monitored for energy intake. Photostimulation of ARC and VTA N/OFQ neurons produces an outward current in POMC and A10 dopamine neurons receiving input from these cells. This is associated with a hyperpolarization and decreased firing. These features are also sex hormone- and diet-dependent; with estradiol-treated slices from OVX females being less sensitive, and obese males being more sensitive, to N/OFQ. Limited access to HFD causes a dramatic escalation in consumption, such that animals eat 25-45% of their daily intake during that one-hour exposure. Moreover, the NOP receptor-mediated regulation of these energy balance circuits are engaged, as N/OFQ injected directly into the VTA or ARC respectively diminishes or potentiates this binge-like increase in a manner heightened by diet-induced obesity or dampened by estradiol in females. Collectively, these findings provide key support for the idea that N/OFQ regulates appetitive behavior in sex-, site- and diet-specific ways, along with important insights into aberrant patterns of feeding behavior pertinent to the pathogenesis of food addiction.
Collapse
Affiliation(s)
- Jennifer Hernandez
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, USA
| | - Lynnea Perez
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA
| | - Rosy Soto
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, USA
| | - Nikki Le
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA
| | - Cassandra Gastelum
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA
| | - Edward J Wagner
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA; College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, USA.
| |
Collapse
|
2
|
Michael NJ, Zigman JM, Williams KW, Elmquist JK. Electrophysiological Properties of Genetically Identified Histaminergic Neurons. Neuroscience 2020; 444:183-195. [PMID: 32599122 DOI: 10.1016/j.neuroscience.2020.06.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 11/27/2022]
Abstract
Histaminergic neurons of the tuberomammillary nucleus (TMN) are important regulators of behavioral and homeostatic processes. Previous work suggested that histaminergic neurons exhibit a characteristic electrophysiological signature, allowing for their identification in brain slice preparations. However, these previous investigations focused on neurons in the ventral subregion of the TMN of rats. Consequently, it remains unclear whether such electrophysiological properties extend to mice, including other subregions of the TMN, and the potential for differences between males and females. To further characterize the electrophysiological properties of histaminergic neurons, we performed whole-cell patch-clamp recordings on transgenic mice expressing Cre recombinase in histidine decarboxylase (HDC)-expressing cells; the sole enzyme for histamine synthesis (Hdc-cre::tdTomato). Despite similarities with the electrophysiological properties reported in rats, we observed considerable variability in mouse HDC neuron passive membrane properties, action potential firing, and intrinsic subthreshold active membrane properties. Overall, the electrophysiological properties of HDC neurons appeared similar across subregions of the TMN, consistent with a lack of topographical organization in this nucleus. Moreover, we found no obvious sex differences in the electrical excitability of HDC neurons. However, our data reveal a diversity in the electrophysiological properties of genetically identified histaminergic neurons from mice not previously appreciated from rat studies. Thus, these data highlight the utility of mouse genetics to target the widespread histaminergic neuronal population within the TMN and support the idea that histaminergic neurons are a heterogeneous neuronal population.
Collapse
Affiliation(s)
- Natalie J Michael
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390-9077, United States; Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, QC G1V 4G5, Canada
| | - Jeffrey M Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390-9077, United States
| | - Kevin W Williams
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390-9077, United States.
| | - Joel K Elmquist
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390-9077, United States; Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX 75390-9077, United States.
| |
Collapse
|
3
|
Flores-Balter G, Cordova-Jadue H, Chiti-Morales A, Lespay C, Espina-Marchant P, Falcon R, Grinspun N, Sanchez J, Bustamante D, Morales P, Herrera-Marschitz M, Valdés JL. Effect of perinatal asphyxia on tuberomammillary nucleus neuronal density and object recognition memory: A possible role for histamine? Behav Brain Res 2016; 313:226-232. [PMID: 27444242 DOI: 10.1016/j.bbr.2016.07.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 07/01/2016] [Accepted: 07/15/2016] [Indexed: 11/15/2022]
Abstract
Perinatal asphyxia (PA) is associated with long-term neuronal damage and cognitive deficits in adulthood, such as learning and memory disabilities. After PA, specific brain regions are compromised, including neocortex, hippocampus, basal ganglia, and ascending neuromodulatory pathways, such as dopamine system, explaining some of the cognitive disabilities. We hypothesize that other neuromodulatory systems, such as histamine system from the tuberomammillary nucleus (TMN), which widely project to telencephalon, shown to be relevant for learning and memory, may be compromised by PA. We investigated here the effect of PA on (i) Density and neuronal activity of TMN neurons by double immunoreactivity for adenosine deaminase (ADA) and c-Fos, as marker for histaminergic neurons and neuronal activity respectively. (ii) Expression of the histamine-synthesizing enzyme, histidine decarboxylase (HDC) by western blot and (iii) thioperamide an H3 histamine receptor antagonist, on an object recognition memory task. Asphyxia-exposed rats showed a decrease of ADA density and c-Fos activity in TMN, and decrease of HDC expression in hypothalamus. Asphyxia-exposed rats also showed a low performance in object recognition memory compared to caesarean-delivered controls, which was reverted in a dose-dependent manner by the H3 antagonist thioperamide (5-10mg/kg, i.p.). The present results show that the histaminergic neuronal system of the TMN is involved in the long-term effects induced by PA, affecting learning and memory.
Collapse
Affiliation(s)
- Gabriela Flores-Balter
- Program of Physiology & Biophysics, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile
| | - Héctor Cordova-Jadue
- Program of Physiology & Biophysics, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile
| | - Alessandra Chiti-Morales
- Program of Physiology & Biophysics, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile
| | - Carolyne Lespay
- Program of Molecular & Clinical Pharmacology, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile
| | - Pablo Espina-Marchant
- Program of Physiology & Biophysics, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile; Program of Molecular & Clinical Pharmacology, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile
| | - Romina Falcon
- Program of Physiology & Biophysics, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile; Biomedical Neuroscience Institute, BNI, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile
| | - Noemi Grinspun
- Program of Physiology & Biophysics, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile; Biomedical Neuroscience Institute, BNI, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile
| | - Jessica Sanchez
- Program of Physiology & Biophysics, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile; Biomedical Neuroscience Institute, BNI, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile
| | - Diego Bustamante
- Program of Molecular & Clinical Pharmacology, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile
| | - Paola Morales
- Program of Molecular & Clinical Pharmacology, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile
| | - Mario Herrera-Marschitz
- Program of Molecular & Clinical Pharmacology, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile; Biomedical Neuroscience Institute, BNI, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile.
| | - José L Valdés
- Program of Physiology & Biophysics, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile; Biomedical Neuroscience Institute, BNI, ICBM, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile.
| |
Collapse
|
4
|
Borgquist A, Kachani M, Tavitian N, Sinchak K, Wagner EJ. Estradiol negatively modulates the pleiotropic actions of orphanin FQ/nociceptin at proopiomelanocortin synapses. Neuroendocrinology 2013; 98:60-72. [PMID: 23735696 PMCID: PMC4170741 DOI: 10.1159/000351868] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 05/08/2013] [Indexed: 12/11/2022]
Abstract
Orphanin FQ/nociceptin (OFQ/N) inhibits the activity of proopiomelanocortin (POMC) neurons located in the hypothalamic arcuate nucleus (ARH) that regulate female sexual behavior and energy balance. We tested the hypothesis that estradiol modulates the ability of OFQ/N to pre- and postsynaptically decrease the excitability of these cells. To this end, whole-cell patch-clamp recordings were performed in hypothalamic slices prepared from ovariectomized rats, including some that were injected with the retrograde tracer Fluorogold in the medial preoptic nucleus (MPN) to label the POMC neurons regulating sexual receptivity. OFQ/N (1 µM) evoked a robust outward current in ARH neurons from vehicle-treated animals that was blocked by the opioid receptor-like (ORL)1 receptor antagonist UFP-101 (100 nM) and the G protein-gated, inwardly rectifying K⁺ (GIRK-1) channel blocker tertiapin (10 nM). OFQ/N also produced a decrease in the frequency of glutamatergic, miniature excitatory postsynaptic currents (mEPSCs), which was also antagonized by UFP-101. Estradiol benzoate (2 µg) increased basal mEPSC frequency and markedly diminished both the OFQ/N-induced activation of postsynaptic GIRK-1 channel currents and the presynaptic inhibition of glutamatergic neurotransmission. These effects were observed in identified POMC neurons, including eight that projected to the MPN. Taken together, these data reveal that estradiol attenuates the pleiotropic inhibitory actions of OFQ/N on POMC neurons: presynaptically through reducing the OFQ/N inhibition of glutamate release and postsynaptically by reducing ORL1 signaling through GIRK channels. As such, they impart critical insight into a mechanism for estradiol to increase the activity of POMC neurons that inhibit sexual receptivity.
Collapse
Affiliation(s)
- Amanda Borgquist
- Department of Basic Medical Sciences, College of Osteopathic Medicine, Western University of Health Sciences, Pomona, CA 91766
| | - Malika Kachani
- College of Veterinary Medicine, Western University of Health Sciences, Pomona, CA 91766
| | - Nadia Tavitian
- Department of Basic Medical Sciences, College of Osteopathic Medicine, Western University of Health Sciences, Pomona, CA 91766
| | - Kevin Sinchak
- Department of Biological Sciences, California State University, Long Beach, Long Beach, CA 90840
| | - Edward J. Wagner
- Department of Basic Medical Sciences, College of Osteopathic Medicine, Western University of Health Sciences, Pomona, CA 91766
| |
Collapse
|
5
|
Potassium Current Is Not Affected by Long-Term Exposure to Ghrelin or GHRP-6 in Somatotropes GC Cells. JOURNAL OF BIOPHYSICS 2013; 2013:913792. [PMID: 23533398 PMCID: PMC3600309 DOI: 10.1155/2013/913792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 12/17/2012] [Indexed: 11/17/2022]
Abstract
Ghrelin is a growth hormone (GH) secretagogue (GHS) and GHRP-6 is a synthetic peptide analogue; both act through the GHS receptor. GH secretion depends directly on the intracellular concentration of Ca(2+); this is determined from the intracellular reserves and by the entrance of Ca(2+) through the voltage-dependent calcium channels, which are activated by the membrane depolarization. Membrane potential is mainly determined by K(+) channels. In the present work, we investigated the effect of ghrelin (10 nM) or GHRP-6 (100 nM) for 96 h on functional expression of voltage-dependent K(+) channels in rat somatotropes: GC cell line. Physiological patch-clamp whole-cell recording was used to register the K(+) currents. With Cd(2+) (1 mM) and tetrodotoxin (1 μ m) in the bath solution recording, three types of currents were characterized on the basis of their biophysical and pharmacological properties. GC cells showed a K(+) current with a transitory component (I A) sensitive to 4-aminopyridine, which represents ~40% of the total outgoing current; a sustained component named delayed rectifier (I K), sensitive to tetraethylammonium; and a third type of K(+) current was recorded at potentials more negative than -80 mV, permitting the entrance of K(+) named inward rectifier (KIR). Chronic treatment with ghrelin or GHRP-6 did not modify the functional expression of K(+) channels, without significant changes (P < 0.05) in the amplitudes of the three currents observed; in addition, there were no modifications in their biophysical properties and kinetic activation or inactivation.
Collapse
|
6
|
Ogaya M, Kim J, Sasaki K. Ghrelin postsynaptically depolarizes dorsal raphe neurons in rats in vitro. Peptides 2011; 32:1606-16. [PMID: 21763741 DOI: 10.1016/j.peptides.2011.07.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 07/01/2011] [Accepted: 07/01/2011] [Indexed: 01/03/2023]
Abstract
Ghrelin promotes growth hormone (GH) secretion and feeding. Recent studies further showed that ghrelin displayed a defending effect against the depressive-like symptoms and affected sleep in animals and humans. Serotonergic system is considered to be implicated in feeding, depression and other mood disorders, and sleep. The dorsal raphe nucleus (DRN) utilizes serotonin (5-HT) as its major neurotransmitter and expresses GH secretagogue receptors (GHS-Rs). Therefore, the present study was carried out to examine the electrophysiological effect of ghrelin on rat DRN neurons in vitro and determine the ionic mechanism involved. Whole-cell recording revealed that ghrelin depolarized DRN neurons dose-dependently in tetrodotoxin-containing artificial cerebrospinal fluid (TTX ACSF). Pretreatment with [D-Lys(3)]-GHRP-6, a selective antagonist for GHS-Rs, antagonized the ghrelin-induced depolarization. The depolarization was significantly reduced in a low-Na(+) TTX ACSF and in a high-K(+) TTX ACSF and was abolished in the combination of both ACSFs, suggesting that the ghrelin-induced depolarization is mediated by a dual ionic mechanism including an increase in nonselective cationic conductance and a decrease in K(+) conductance. The experiments on the reversal potential also supported an involvement of the dual ionic mechanism in the ghrelin-induced depolarization. On the basis of their electrophysiological and pharmacological properties, approximately 80% of DRN neurons were classified as putative 5-HT-containing neurons and ghrelin depolarized 75% of them. These results suggest that DRN neurons, especially 5-HT-containing neurons, might be involved in the neural mechanisms through which ghrelin participates in the development and/or regulation of feeding behavior, sleep-wake states and depressive-like symptoms.
Collapse
Affiliation(s)
- Masaki Ogaya
- Division of Bio-Information Engineering, Faculty of Engineering, University of Toyama, 3190 Gofuku, Toyama City, Toyama 930-8555, Japan
| | | | | |
Collapse
|
7
|
Feng DD, Yang SK, Loudes C, Simon A, Al-Sarraf T, Culler M, Alvear-Perez R, Llorens-Cortes C, Chen C, Epelbaum J, Gardette R. Ghrelin and obestatin modulate growth hormone-releasing hormone release and synaptic inputs onto growth hormone-releasing hormone neurons. Eur J Neurosci 2011; 34:732-44. [DOI: 10.1111/j.1460-9568.2011.07787.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
8
|
Hansson C, Haage D, Taube M, Egecioglu E, Salomé N, Dickson SL. Central administration of ghrelin alters emotional responses in rats: behavioural, electrophysiological and molecular evidence. Neuroscience 2011; 180:201-11. [PMID: 21303683 DOI: 10.1016/j.neuroscience.2011.02.002] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 01/06/2011] [Accepted: 02/01/2011] [Indexed: 12/20/2022]
Abstract
The orexigenic and pro-obesity hormone ghrelin targets key hypothalamic and mesolimbic circuits involved in energy balance, appetite and reward. Given that such circuits are closely integrated with those regulating mood and cognition, we sought to determine whether chronic (>2 weeks) CNS exposure to ghrelin alters anxiety- and depression-like behaviour in rats as well as some physiological correlates. Rats bearing chronically implanted i.c.v. catheters were treated with ghrelin (10 μg/d) or vehicle for 4 weeks. Tests used to assess anxiety- and depression-like behaviour were undertaken during weeks 3-4 of the infusion. These revealed an increase in anxiety- and depression-like behaviour in the ghrelin-treated rats relative to controls. At the end of the 4-week infusion, brains were removed and the amygdala dissected for subsequent qPCR analysis that revealed changes in expression of a number of genes representing key systems implicated in these behavioural changes. Finally, given the key role of the dorsal raphe serotonin system in emotional reactivity, we examined the electrophysiological response of dorsal raphe neurons after a ghrelin challenge, and found mainly inhibitory responses in this region. We demonstrate that the central ghrelin signalling system is involved in emotional reactivity in rats, eliciting pro-anxiety and pro-depression effects and have begun to explore novel target systems for ghrelin that may be of importance for these effects.
Collapse
Affiliation(s)
- C Hansson
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, SE-40530 Gothenburg, Sweden
| | | | | | | | | | | |
Collapse
|
9
|
Farhang B, Pietruszewski L, Lutfy K, Wagner EJ. The role of the NOP receptor in regulating food intake, meal pattern, and the excitability of proopiomelanocortin neurons. Neuropharmacology 2010; 59:190-200. [PMID: 20510254 PMCID: PMC2946834 DOI: 10.1016/j.neuropharm.2010.05.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 05/17/2010] [Accepted: 05/18/2010] [Indexed: 11/16/2022]
Abstract
We evaluated the role of the nociceptin/orphanin FQ (NOP) receptor in regulating food intake, meal pattern and the activity of hypothalamic arcuate (ARC) neurons. The microstructural analysis of food intake and meal pattern was performed under both food-deprived and ad libitum conditions. Whole-cell patch clamp recordings were obtained using the in vitro hypothalamic slice preparation and biocytin-filled electrodes. NOP receptor knockout mice exhibited significantly reduced body weight. Fasting-induced hyperphagia was diminished for the first 2h of a 6-h re-feeding period, and was associated with decreased meal duration and size, as well as a biphasic effect on meal frequency. The genotype effect observed under ad libitum conditions was comparatively unremarkable. Orphanin FQ/nociceptin (OFQ/N) was able to decrease evoked excitatory postsynaptic current amplitude, increase the S(2):S(1) ratio via the paired-pulse paradigm, and decrease miniature excitatory postsynaptic current frequency in ARC neurons from wild type animals but not NOP receptor knockouts. In addition OFQ/N activated a reversible outward current that was antagonized by the G-protein activated, inwardly-rectifying K(+) (GIRK) channel blocker tertiapin in wild type but not NOP knockout animals. Both the presynaptic and postsynaptic actions of OFQ/N were observed in ARC neurons subsequently determined to be immunopositive for characteristic phenotypic markers of anorexigenic proopiomelanocortin (POMC) neurons. Taken together, these results demonstrate the contribution of the NOP receptor in controlling food intake and meal pattern, as well as glutamate release and GIRK1 channel activity at POMC synapses.
Collapse
Affiliation(s)
- Borzoo Farhang
- College of Osteopathic Medicine, Western University of Health Sciences, Pomona, CA 91766, USA
| | | | | | | |
Collapse
|
10
|
Takano S, Kim J, Ikari Y, Ogaya M, Nakajima K, Oomura Y, Wayner MJ, Sasaki K. Electrophysiological effects of ghrelin on laterodorsal tegmental neurons in rats: an in vitro study. Peptides 2009; 30:1901-8. [PMID: 19646496 DOI: 10.1016/j.peptides.2009.07.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 07/20/2009] [Indexed: 10/20/2022]
Abstract
Ghrelin, a gut and brain peptide, is a potent stimulant for growth hormone (GH) secretion and feeding. Recent studies further show a critical role of ghrelin in the regulation of sleep-wakefulness. Laterodorsal tegmental nucleus (LDT), that regulates waking and rapid eye movement (REM) sleep, expresses GH secretagogue receptors (GHS-Rs). Thus, the present study was carried out to examine electrophysiological effects of ghrelin on LDT neurons using rat brainstem slices, and to determine the ionic mechanism involved. Whole cell recording revealed that ghrelin depolarizes LDT neurons dose-dependently in normal artificial cerebrospinal fluid (ACSF). The depolarization persisted in tetrodotoxin-containing ACSF (TTX ACSF), and is partially blocked by the application of [D-Lys3]-GHRP-6, a selective antagonist for GHS-Rs. Membrane resistance during the ghrelin-induced depolarization increased by about 18% than that before the depolarization. In addition, the ghrelin-induced depolarization was drastically reduced in high-K+ TTX ACSF with a K+ concentration of 13.25 mM. Reversal potentials obtained from I-V curves before and during the depolarization were about -83 mV, close to the equilibrium potential of the K+ channel. Most of the LDT neurons recorded were characterized by an A-current or both the A-current and a low threshold Ca2+ spike, and they were predominantly cholinergic. These results indicate that ghrelin depolarizes LDT neurons postsynaptically and dose-dependently via GHS-Rs, and that the ionic mechanisms underlying the ghrelin-induced depolarization include a decrease of K+ conductance. The results also suggest that LDT neurons are implicated in the cellular processes through which ghrelin participates in the regulation of sleep-wakefulness.
Collapse
Affiliation(s)
- Shinobu Takano
- Division of Bio-Information Engineering, Faculty of Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Kim J, Nakajima K, Oomura Y, Wayner MJ, Sasaki K. Electrophysiological effects of ghrelin on pedunculopontine tegmental neurons in rats: An in vitro study. Peptides 2009; 30:745-57. [PMID: 19118591 DOI: 10.1016/j.peptides.2008.12.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 12/03/2008] [Accepted: 12/03/2008] [Indexed: 01/08/2023]
Abstract
Ghrelin is a potent stimulant for growth hormone (GH) secretion and feeding. Recent studies further show a critical role of ghrelin in the regulation of sleep-wakefulness. Pedunculopontine tegmental nucleus (PPT), which regulates waking and rapid eye movement (REM) sleep, expresses GH secretagogue receptors (GHS-Rs). Thus, the present study was carried out to examine electrophysiological effects of ghrelin on PPT neurons using rat brainstem slices, and to determine the ionic mechanism involved. Whole cell recording revealed that ghrelin depolarizes PPT neurons dose-dependently in normal artificial cerebrospinal fluid (ACSF). The depolarization persisted in tetrodotoxin-containing ACSF, although action potentials did not occur. Application of [d-Lys(3)]-GHRP-6, a selective antagonist for GHS-Rs, almost blocked the ghrelin-induced depolarization. Furthermore, the ghrelin-induced depolarization was reduced in high K(+) ACSF or low Na(+) ACSF, and abolished in high K(+)-low Na(+) ACSF or in a combination of low Na(+) ACSF and recordings with Cs(+)-containing pipettes. An inhibitor of Na(+)/Ca(2+) exchanger had no effect on the depolarization. Most of the PPT neurons recorded were characterized by an A-current or both the A-current and a low threshold Ca(2+) spike, and they were predominantly cholinergic as revealed by nicotinamide adenine dinucleotide phosphate-diaphorase staining. These results suggest that ghrelin depolarizes PPT neurons postsynaptically and dose-dependently via GHS-Rs, and that the ionic mechanisms underlying the ghrelin-induced depolarization include a decrease of K(+) conductance and an increase of non-selective cationic conductance. The results also support the notion that ghrelin plays a role in the regulation of sleep-wakefulness.
Collapse
|
12
|
Abstract
Histamine is a transmitter in the nervous system and a signaling molecule in the gut, the skin, and the immune system. Histaminergic neurons in mammalian brain are located exclusively in the tuberomamillary nucleus of the posterior hypothalamus and send their axons all over the central nervous system. Active solely during waking, they maintain wakefulness and attention. Three of the four known histamine receptors and binding to glutamate NMDA receptors serve multiple functions in the brain, particularly control of excitability and plasticity. H1 and H2 receptor-mediated actions are mostly excitatory; H3 receptors act as inhibitory auto- and heteroreceptors. Mutual interactions with other transmitter systems form a network that links basic homeostatic and higher brain functions, including sleep-wake regulation, circadian and feeding rhythms, immunity, learning, and memory in health and disease.
Collapse
Affiliation(s)
- Helmut L Haas
- Institute of Neurophysiology, Heinrich-Heine-University, Duesseldorf, Germany.
| | | | | |
Collapse
|
13
|
Pinar M, Gulsun M, Tasci I, Erdil A, Bolu E, Acikel C, Doruk A. Maprotiline induced weight gain in depressive disorder: changes in circulating ghrelin and adiponectin levels and insulin sensitivity. Prog Neuropsychopharmacol Biol Psychiatry 2008; 32:135-9. [PMID: 17825464 DOI: 10.1016/j.pnpbp.2007.07.028] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 07/30/2007] [Accepted: 07/31/2007] [Indexed: 10/23/2022]
Abstract
Agents such as clozapine, olanzapine and mirtazapine frequently trigger an increase in body weight. Though the mechanisms have not been thoroughly clarified, recent studies indicate a role for ghrelin in regulation of appetite and weight gain. We investigated the relation of maprotiline induced weight gain to serum ghrelin and adiponectin levels, as well as insulin resistance in lean subjects with depressive disorder. A total of 40 male lean subjects with depressive disorder were treated with maprotiline (150 mg/day) for 30-days. Clinical data, fasting plasma glucose, lipids, insulin levels, serum ghrelin and adiponectin concentrations were determined before and after treatment. Insulin resistance was estimated using the homeostasis model assessment (HOMA) formula. After 30 days of treatment with maprotiline, mean body mass index increased significantly. Blood ghrelin and insulin levels and HOMA indexes increased, and adiponectin concentration decreased (p<0.001, for all) after the treatment period. Changes in ghrelin levels correlated neither of the parameters tested; whereas decrease in plasma adiponectin was associated with an increase in BMI (r=-0.671, p<0.001). In conclusion, the results indicate that treatment of lean patients with depressive disorder with maprotiline results in an increase in serum ghrelin and reduction in adiponectin levels. Weight gain due to maprotiline treatment may be related to its negative effects on the metabolic variables.
Collapse
Affiliation(s)
- Murat Pinar
- Tatvan Military Hospital, Internal Medicine Service, Tatvan-Bitlis, Turkey.
| | | | | | | | | | | | | |
Collapse
|
14
|
Yasufuku-Takano J, Nakajima S, Nakajima Y. Morphological and physiological properties of serotonergic neurons in dissociated cultures from the postnatal rat dorsal raphe nucleus. J Neurosci Methods 2007; 167:258-67. [PMID: 17920133 DOI: 10.1016/j.jneumeth.2007.08.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 08/23/2007] [Accepted: 08/23/2007] [Indexed: 11/30/2022]
Abstract
We have developed dissociated primary cultures of the dorsal raphe nucleus from postnatal 9-12-day-old rats. The nucleus was dissected out from brain slices, dissociated, and cultured over a glial feeder layer. Serotonin immunocytochemistry revealed that 62% of cultured neurons were serotonergic. There was no significant difference in diameters between serotonergic and non-serotonergic neurons. With the whole-cell patch-clamp method, cultured neurons were tested for responses to 8-hydroxydipropylaminotetraline (8-OH-DPAT, a selective agonist for 5-HT(1A)), and then treated with serotonin immunocytochemistry. Ninety-two percent of neurons responding to 8-OH-DPAT were serotonergic. These results were used to identify serotonergic neurons. In most cases, serotonergic neurons did not show spontaneous firings of action potentials. Constant current depolarizations elicited trains of action potentials that usually did not show marked adaptation. Application of 8-OH-DPAT inhibited action potential firing. The current-voltage relation of the 8-OH-DPAT-induced current indicated an inward rectification with its reversal potential near E(K). Serotonergic neurons were depolarized by phenylephrine, bombesin, and gastrin-releasing peptide. This culture system will serve as a useful tool for elucidating the cellular, physiological, and molecular properties of brain serotonergic neurons.
Collapse
Affiliation(s)
- Junko Yasufuku-Takano
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, College of Medicine (M/C 512), 808 South Wood Street, Chicago, IL 60612, USA
| | | | | |
Collapse
|
15
|
Kawano T, Zhao P, Floreani CV, Nakajima Y, Kozasa T, Nakajima S. Interaction of Galphaq and Kir3, G protein-coupled inwardly rectifying potassium channels. Mol Pharmacol 2007; 71:1179-84. [PMID: 17296805 DOI: 10.1124/mol.106.032508] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of substance P receptors, which are coupled to Galpha(q), inhibits the Kir3.1/3.2 channels, resulting in neuronal excitation. We have shown previously that this channel inactivation is not caused by reduction of the phosphatidylinositol 4,5-bisphosphate level in membrane. Moreover, Galpha(q) immunoprecipitates with Kir3.2 (J Physiol 564:489-500, 2005), suggesting that Galpha(q) interacts with Kir3.2. Positive immunoprecipitation, however, does not necessarily indicate direct interaction between the two proteins. Here, the glutathione transferase pull-down assay was used to investigate interaction between Galpha(q) and the K(+) channels. We found that Galpha(q) interacted with N termini of Kir3.1, Kir3.2, and Kir3.4. However, Galpha(q) did not interact with the C terminus of any Kir3 or with the C or N terminus of Kir2.1. TRPC6 is regulated by the signal initiated by Galpha(q). Immunoprecipitation, however, showed that Galpha(q) did not interact with TRPC6. Thus, the interaction between Galpha(q) and the Kir3 N terminus is quite specific. This interaction occurred in the presence of GDP or GDP-AlF(-)(4). The Galpha(q) binding could take place somewhere between residues 51 to 90 of Kir3.2; perhaps the segment between 81 to 90 residues is crucial. Gbetagamma, which is known to bind to N terminus of Kir3, did not compete with Galpha(q) for the binding, suggesting that these two binding regions are different. These findings agree with the hypothesis (J Physiol 564:489-500, 2005) that the signal to inactivate the Kir3 channel could be mainly transmitted directly from Galpha(q) to Kir3.
Collapse
Affiliation(s)
- Takeharu Kawano
- Departments of Anatomy & Cell Biology, College of Medicine, University of Illinois at Chicago, Illinois 60612, USA
| | | | | | | | | | | |
Collapse
|
16
|
Abstract
With the availability of an increased number of experimental tools, for example potent and brain-penetrating H1-, H2-, and H3-receptor ligands and mutant mice lacking the histamine synthesis enzyme or the histamine receptors, the functional roles of histaminergic neurons in the brain have been considerably clarified during the recent years, particularly their major role in the control of arousal, cognition, and energy balance. Various approaches tend to establish the implication of histaminergic neurons in schizophrenia. A strong hyperactivity of histamine neurons is induced in rodent brain by administration of methamphetamine or NMDA-receptor antagonists. Histamine neuron activity is modulated by typical and atypical neuroleptics. H3-receptor antagonists/inverse agonists display antipsychotic-like properties in animal models of the disease. Because of the limited predictability value of most animal models and the paucity of drugs affecting histaminergic transmission that were tried so far in human, the evidence remains therefore largely indirect, but supports a role of histamine neurons in schizophrenia.
Collapse
Affiliation(s)
- Jean-Michel Arrang
- INSERM, U573, Unité de Neurobiologie et Pharmacologie Moléculaire, Centre Paul Broca, 2 ter rue d'Alésia, 75014 Paris, France
| |
Collapse
|
17
|
Han XF, Zhu YL, Hernandez M, Keating DJ, Chen C. Ghrelin reduces voltage-gated potassium currents in GH3 cells via cyclic GMP pathways. Endocrine 2005; 28:217-24. [PMID: 16388096 DOI: 10.1385/endo:28:2:217] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Revised: 06/05/2005] [Accepted: 06/10/2005] [Indexed: 11/11/2022]
Abstract
Ghrelin is an endogenous growth hormone secretagogue (GHS) causing release of GH from pituitary somatotropes through the GHS receptor. Secretion of GH is linked directly to intracellular free Ca(2+) concentration ([Ca(2+)]i), which is determined by Ca(2+) influx and release from intracellular Ca(2+) storage sites. Ca(2+) influx is via voltage-gated Ca(2+) channels, which are activated by cell depolarization. Membrane potential is mainly determined by transmembrane K(+) channels. The present study investigates the in vitroeffect of ghrelin on membrane voltage-gated K(+) channels in the GH3 rat somatotrope cell line. Nystatin-perforated patch clamp recording was used to record K(+) currents under voltage-clamp conditions. In the presence of Co(2+) (1 mM, Ca(2+) channel blocker) and tetrodotoxin (1 microM, Na(+) channel blocker) in the bath solution, two types of voltage-gated K(+) currents were characterized on the basis of their biophysical kinetics and pharmacological properties. We observed that transient K(+) current (IA) represented a significant proportion of total K(+) currents in some cells, whereas delayed rectifier K(+) current (IK) existed in all cells. The application of ghrelin (10 nM) reversibly and significantly decreased the amplitude of both IA and IK currents to 48% and 64% of control, respectively. Application of apamin (1 microM, SK channel blocker) or charybdotoxin (1 microM, BK channel blocker) did not alter the K(+) current or the response to ghrelin. The ghrelin-induced reduction in K(+) currents was not affected by PKC and PKA inhibitors. KT5823, a specific PKG inhibitor, totally abolished the K+ current response to ghrelin. These results suggest that ghrelin-induced reduction of voltage-gated K(+) currents in GH3 cells is mediated through a PKG-dependent pathway. A decrease in voltage-gated K(+) currents may increase the frequency, duration, and amplitude of action potentials and contribute to GH secretion from somatotropes.
Collapse
Affiliation(s)
- Xue Feng Han
- Department of Physiology, Fourth Military Medical University, Shannxi, China
| | | | | | | | | |
Collapse
|