1
|
Sanetra AM, Jeczmien-Lazur JS, Pradel K, Klich JD, Palus-Chramiec K, Janik ME, Bajkacz S, Izowit G, Nathan C, Piggins HD, Delogu A, Belle MD, Lewandowski MH, Chrobok L. A novel developmental critical period of orexinergic signaling in the primary visual thalamus. iScience 2024; 27:110352. [PMID: 39055917 PMCID: PMC11269934 DOI: 10.1016/j.isci.2024.110352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 04/15/2024] [Accepted: 06/20/2024] [Indexed: 07/28/2024] Open
Abstract
The orexinergic system of the lateral hypothalamus plays crucial roles in arousal, feeding behavior, and reward modulation. Most research has focused on adult rodents, overlooking orexins' potential role in the nervous system development. This study, using electrophysiological and molecular tools, highlights importance of orexinergic signaling in the postnatal development of the rodent dorsolateral geniculate nucleus (DLG), a primary visual thalamic center. Orexin activation of DLG thalamocortical neurons occurs in a brief seven-day window around eye-opening, concurrent to transient OX2 receptor expression. Blocking OX2 receptors during this period reduces sensitivity of DLG neurons to green and blue light and lowers spontaneous firing rates in adulthood. This research reveals critical and temporally confined role of orexin signaling in postnatal brain development, emphasizing its contribution to experience-dependent refinement in the DLG and its long-term impact on visual function.
Collapse
Affiliation(s)
- Anna M. Sanetra
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Krakow, Poland
| | - Jagoda S. Jeczmien-Lazur
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Krakow, Poland
| | - Kamil Pradel
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Krakow, Poland
- Institute for Systems Physiology, University of Cologne, Cologne, Germany
| | - Jasmin D. Klich
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Krakow, Poland
- Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Katarzyna Palus-Chramiec
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Krakow, Poland
| | - Marcelina E. Janik
- Department of Glycoconjugate Biochemistry, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Krakow, Poland
| | - Sylwia Bajkacz
- Department of Inorganic Chemistry, Analytical Chemistry and Electrochemistry, Faculty of Chemistry, Silesian University of Technology, Gliwice, Poland
- The Biotechnology Centre, Silesian University of Technology, Gliwice, Poland
| | - Gabriela Izowit
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Krakow, Poland
| | - Christian Nathan
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
- University of Exeter Medical School, Hatherly Labs, Streatham Campus, Prince of Wales Road, Exeter, Devon, UK
| | - Hugh D. Piggins
- School of Physiology, Pharmacology, and Neuroscience, Faculty of Health and Life Sciences, University of Bristol, Bristol, UK
| | - Alessio Delogu
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
| | - Mino D.C. Belle
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
- University of Exeter Medical School, Hatherly Labs, Streatham Campus, Prince of Wales Road, Exeter, Devon, UK
| | - Marian H. Lewandowski
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Krakow, Poland
| | - Lukasz Chrobok
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Krakow, Poland
- School of Physiology, Pharmacology, and Neuroscience, Faculty of Health and Life Sciences, University of Bristol, Bristol, UK
| |
Collapse
|
2
|
Bigiani A, Tirindelli R, Bigiani L, Mapelli J. Changes of the biophysical properties of voltage-gated Na + currents during maturation of the sodium-taste cells in rat fungiform papillae. J Physiol 2022; 600:5119-5144. [PMID: 36250254 DOI: 10.1113/jp283636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 10/13/2022] [Indexed: 01/05/2023] Open
Abstract
Taste cells are a heterogeneous population of sensory receptors that undergo continuous turnover. Different chemo-sensitive cell lines rely on action potentials to release the neurotransmitter onto nerve endings. The electrical excitability is due to the presence of a tetrodotoxin-sensitive, voltage-gated sodium current (INa ) similar to that found in neurons. Since the biophysical properties of neuronal INa change during development, we wondered whether the same also occurred in taste cells. Here, we used the patch-clamp recording technique to study INa in salt-sensing cells (sodium cells) of rat fungiform papillae. We identified these cells by exploiting the known blocking effect of amiloride on ENaC, the sodium (salt) receptor. Based on the amplitude of INa , which is known to increase during development, we subdivided sodium cells into two groups: cells with small sodium current (SSC cells; INa < 1 nA) and cells with large sodium current (LSC cells; INa > 1 nA). We found that: the voltage dependence of activation and inactivation significantly differed between these subsets; a slowly inactivating sodium current was more prominent in LSC cells; membrane capacitance in SSC cells was larger than in LSC cells. mRNA expression analysis of the α-subunits of voltage-gated sodium channels in fungiform taste buds supported the functional data. Lucifer Yellow labelling of recorded cells revealed that our electrophysiological criterion for distinguishing two broad groups of taste cells was in good agreement with morphological observations for cell maturity. Thus, all these findings are consistent with developmental changes in the voltage-dependent properties of sodium-taste cells. KEY POINTS: Taste cells are sensory receptors that undergo continuous turnover while they detect food chemicals and communicate with afferent nerve fibres. The voltage-gated sodium current (INa ) is a key ion current for generating action potentials in fully differentiated and chemo-sensitive taste cells, which use electrical signalling to release neurotransmitters. Here we show that, during the maturation of rat taste cells involved in salt detection (sodium cells), the biophysical properties of INa , such as voltage dependence of activation and inactivation, change significantly. Our results help reveal how taste cells gain electrical excitability during turnover, a property critical to their operation as chemical detectors that relay sensory information to nerve fibres.
Collapse
Affiliation(s)
- Albertino Bigiani
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze, Università di Modena e Reggio Emilia, Modena, Italy
| | - Roberto Tirindelli
- Dipartimento di Medicina e Chirurgia, SMart Laboratory, Università di Parma, Parma, Italy
| | | | - Jonathan Mapelli
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze, Università di Modena e Reggio Emilia, Modena, Italy
| |
Collapse
|
3
|
Saad AK, Akour A, Mahboob A, AbuRuz S, Sadek B. Role of Brain Modulators in Neurodevelopment: Focus on Autism Spectrum Disorder and Associated Comorbidities. Pharmaceuticals (Basel) 2022; 15:612. [PMID: 35631438 PMCID: PMC9144645 DOI: 10.3390/ph15050612] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 05/08/2022] [Accepted: 05/12/2022] [Indexed: 02/04/2023] Open
Abstract
Autism spectrum disorder (ASD) and associated neurodevelopmental disorders share similar pathogenesis and clinical features. Pathophysiological changes in these diseases are rooted in early neuronal stem cells in the uterus. Several genetic and environmental factors potentially perturb neurogenesis and synaptogenesis processes causing incomplete or altered maturation of the brain that precedes the symptomology later in life. In this review, the impact of several endogenous neuromodulators and pharmacological agents on the foetus during pregnancy, manifested on numerous aspects of neurodevelopment is discussed. Within this context, some possible insults that may alter these modulators and therefore alter their role in neurodevelopment are high-lighted. Sometimes, a particular insult could influence several neuromodulator systems as is supported by recent research in the field of ASD and associated disorders. Dopaminergic hy-pothesis prevailed on the table for discussion of the pathogenesis of schizophrenia (SCH), atten-tion-deficit hyperactivity disorder (ADHD) and ASD for a long time. However, recent cumulative evidence suggests otherwise. Indeed, the neuromodulators that are dysregulated in ASD and comorbid disorders are as diverse as the causes and symptoms of this disease. Additionally, these neuromodulators have roles in brain development, further complicating their involvement in comorbidity. This review will survey the current understanding of the neuromodulating systems to serve the pharmacological field during pregnancy and to minimize drug-related insults in pa-tients with ASD and associated comorbidity disorders, e.g., SCH or ADHD.
Collapse
Affiliation(s)
- Ali K. Saad
- Department of Pharmacology & Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, United Arab Emirates; (A.K.S.); (A.A.); (S.A.)
- Zayed Center for Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, United Arab Emirates
| | - Amal Akour
- Department of Pharmacology & Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, United Arab Emirates; (A.K.S.); (A.A.); (S.A.)
- Zayed Center for Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, United Arab Emirates
- Department of Biopharmaceutics and Clinical Pharmacy, School of Pharmacy, The University of Jordan, Amman P.O. Box 11942, Jordan
| | - Abdulla Mahboob
- Department of Chemistry, College of Sciences, United Arab Emirates University, Al-Ain P.O. Box 15551, United Arab Emirates;
| | - Salahdein AbuRuz
- Department of Pharmacology & Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, United Arab Emirates; (A.K.S.); (A.A.); (S.A.)
- Zayed Center for Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, United Arab Emirates
- Department of Biopharmaceutics and Clinical Pharmacy, School of Pharmacy, The University of Jordan, Amman P.O. Box 11942, Jordan
| | - Bassem Sadek
- Department of Pharmacology & Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, United Arab Emirates; (A.K.S.); (A.A.); (S.A.)
- Zayed Center for Health Sciences, United Arab Emirates University, Al Ain P.O. Box 17666, United Arab Emirates
| |
Collapse
|
4
|
The evolutionarily conserved miRNA-137 targets the neuropeptide hypocretin/orexin and modulates the wake to sleep ratio. Proc Natl Acad Sci U S A 2022; 119:e2112225119. [PMID: 35452310 PMCID: PMC9169915 DOI: 10.1073/pnas.2112225119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The hypocretin (Hcrt, also known as orexin) neuropeptides regulate sleep and wake stability, and disturbances of Hcrt can lead to sleep disorders. MicroRNAs (miRNAs) are short noncoding RNAs that fine-tune protein expression levels, and miRNA-based therapeutics are emerging. We report a functional interaction between miRNA (miR-137) and Hcrt. We demonstrate that intracellular miR-137 levels in Hcrt neurons regulate Hcrt expression with downstream effects on wakefulness. Specifically, lowering of miR-137 levels increased wakefulness in mice. We further show that the miR-137:Hcrt interaction is conserved across mice and humans, that miR-137 also regulates sleep–wake balance in zebrafish, and that the MIR137 locus is genetically associated with sleep duration in humans. Together, our findings reveal an evolutionarily conserved sleep–wake regulatory role of miR-137. Hypocretin (Hcrt), also known as orexin, neuropeptide signaling stabilizes sleep and wakefulness in all vertebrates. A lack of Hcrt causes the sleep disorder narcolepsy, and increased Hcrt signaling has been speculated to cause insomnia, but while the signaling pathways of Hcrt are relatively well-described, the intracellular mechanisms that regulate its expression remain unclear. Here, we tested the role of microRNAs (miRNAs) in regulating Hcrt expression. We found that miR-137, miR-637, and miR-654-5p target the human HCRT gene. miR-137 is evolutionarily conserved and also targets mouse Hcrt as does miR-665. Inhibition of miR-137 specifically in Hcrt neurons resulted in Hcrt upregulation, longer episodes of wakefulness, and significantly longer wake bouts in the first 4 h of the active phase. IL-13 stimulation upregulated endogenous miR-137, while Hcrt mRNA decreased both in vitro and in vivo. Furthermore, knockdown of miR-137 in zebrafish substantially increased wakefulness. Finally, we show that in humans, the MIR137 locus is genetically associated with sleep duration. In conclusion, these results show that an evolutionarily conserved miR-137:Hcrt interaction is involved in sleep–wake regulation.
Collapse
|
5
|
Characterization of Hypothalamic MCH Neuron Development in a 3D Differentiation System of Mouse Embryonic Stem Cells. eNeuro 2022; 9:ENEURO.0442-21.2022. [PMID: 35437265 PMCID: PMC9047030 DOI: 10.1523/eneuro.0442-21.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 04/05/2022] [Accepted: 04/11/2022] [Indexed: 01/20/2023] Open
Abstract
Hypothalamic melanin-concentrating hormone (MCH) neurons are important regulators of multiple physiological processes, such as sleep, feeding, and memory. Despite the increasing interest in their neuronal functions, the molecular mechanism underlying MCH neuron development remains poorly understood. We report that a three-dimensional culture of mouse embryonic stem cells (mESCs) can generate hypothalamic-like tissues containing MCH-positive neurons, which reproduce morphologic maturation, neuronal connectivity, and neuropeptide/neurotransmitter phenotype of native MCH neurons. Using this in vitro system, we demonstrate that Hedgehog (Hh) signaling serves to produce major neurochemical subtypes of MCH neurons characterized by the presence or absence of cocaine- and amphetamine-regulated transcript (CART). Without exogenous Hh signals, mESCs initially differentiated into dorsal hypothalamic/prethalamic progenitors and finally into MCH+CART+ neurons through a specific intermediate progenitor state. Conversely, activation of the Hh pathway specified ventral hypothalamic progenitors that generate both MCH+CART− and MCH+CART+ neurons. These results suggest that in vivo MCH neurons may originate from multiple cell lineages that arise through early dorsoventral patterning of the hypothalamus. Additionally, we found that Hh signaling supports the differentiation of mESCs into orexin/hypocretin neurons, a well-defined cell group intermingled with MCH neurons in the lateral hypothalamic area (LHA). The present study highlights and improves the utility of mESC culture in the analysis of the developmental programs of specific hypothalamic cell types.
Collapse
|
6
|
Barbier M, Croizier S, Alvarez-Bolado G, Risold PY. The distribution of Dlx1-2 and glutamic acid decarboxylase in the embryonic and adult hypothalamus reveals three differentiated LHA subdivisions in rodents. J Chem Neuroanat 2022; 121:102089. [DOI: 10.1016/j.jchemneu.2022.102089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 01/15/2022] [Accepted: 03/08/2022] [Indexed: 11/28/2022]
|
7
|
Spinieli RL, Ben Musa R, Kielhofner J, Cornelius-Green J, Cummings KJ. Orexin contributes to eupnea within a critical period of postnatal development. Am J Physiol Regul Integr Comp Physiol 2021; 321:R558-R571. [PMID: 34405704 PMCID: PMC8560369 DOI: 10.1152/ajpregu.00156.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 08/10/2021] [Accepted: 08/10/2021] [Indexed: 02/03/2023]
Abstract
Orexin neurons are active in wakefulness and mostly silent in sleep. In adult rats and humans, orexin facilitates the hypercapnic ventilatory response but has little effect on resting ventilation. The influence of orexin on breathing in the early postnatal period, and across states of vigilance, have not been investigated. This is relevant as the orexin system may be impaired in Sudden Infant Death Syndrome (SIDS) cases. We addressed three hypotheses: 1) orexin provides a drive to breathe in infancy; 2) the effect of orexin depends on stage of postnatal development; and 3) orexin has a greater influence on breathing in wakefulness compared with sleep. Whole body plethysmography was used to monitor breathing of infant rats at three ages: postnatal days (P) 7-8, 12-14, and 17-19. Respiratory variables were analyzed in wakefulness (W), quiet sleep (QS), and active sleep (AS), following suvorexant (5 mg/kg ip), a dual orexin receptor antagonist, or vehicle (DMSO). Effects of suvorexant on ventilatory responses to graded hypercapnia ([Formula: see text] = 0.02, 0.04, 0.06), hypoxia ([Formula: see text] = 0.10), and hyperoxia ([Formula: see text] = 1.0) at P12-14 were also tested. At P12-14, but not at other ages, suvorexant significantly reduced respiratory frequency in all states, reduced the ventilatory equivalent in QW and QS, and increased [Formula: see text] to ∼5 mmHg. Suvorexant had no effect on ventilatory responses to graded hypercapnia or hypoxia. Hyperoxia eliminated the effects of suvorexant on respiratory frequency at P12-14. Our data suggest that orexin preserves eupneic frequency and ventilation in rats, specifically at ∼2 wk of age, perhaps by facilitating tonic peripheral chemoreflex activity.
Collapse
Affiliation(s)
- Richard L Spinieli
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
| | - Ruwaida Ben Musa
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
| | - Jane Kielhofner
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
| | | | - Kevin J Cummings
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| |
Collapse
|
8
|
Fonseca EM, Janes TA, Fournier S, Gargaglioni LH, Kinkead R. Orexin-A inhibits fictive air breathing responses to respiratory stimuli in the bullfrog tadpole (Lithobates catesbeianus). J Exp Biol 2021; 224:239725. [PMID: 33914034 DOI: 10.1242/jeb.240804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 02/25/2021] [Indexed: 11/20/2022]
Abstract
In pre-metamorphic tadpoles, the neural network generating lung ventilation is present but actively inhibited; the mechanisms leading to the onset of air breathing are not well understood. Orexin (ORX) is a hypothalamic neuropeptide that regulates several homeostatic functions, including breathing. While ORX has limited effects on breathing at rest, it potentiates reflexive responses to respiratory stimuli mainly via ORX receptor 1 (OX1R). Here, we tested the hypothesis that OX1Rs facilitate the expression of the motor command associated with air breathing in pre-metamorphic bullfrog tadpoles (Lithobates catesbeianus). To do so, we used an isolated diencephalic brainstem preparation to determine the contributions of OX1Rs to respiratory motor output during baseline breathing, hypercapnia and hypoxia. A selective OX1R antagonist (SB-334867; 5-25 µmol l-1) or agonist (ORX-A; 200 nmol l-1 to 1 µmol l-1) was added to the superfusion media. Experiments were performed under basal conditions (media equilibrated with 98.2% O2 and 1.8% CO2), hypercapnia (5% CO2) or hypoxia (5-7% O2). Under resting conditions gill, but not lung, motor output was enhanced by the OX1R antagonist and ORX-A. Hypercapnia alone did not stimulate respiratory motor output, but its combination with SB-334867 increased lung burst frequency and amplitude, lung burst episodes, and the number of bursts per episode. Hypoxia alone increased lung burst frequency and its combination with SB-334867 enhanced this effect. Inactivation of OX1Rs during hypoxia also increased gill burst amplitude, but not frequency. In contrast with our initial hypothesis, we conclude that ORX neurons provide inhibitory modulation of the CO2 and O2 chemoreflexes in pre-metamorphic tadpoles.
Collapse
Affiliation(s)
- Elisa M Fonseca
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Unesp. Jaboticabal, SP 14884-900, Brazil.,Department of Pediatrics, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada, G1V 4G5
| | - Tara A Janes
- Department of Pediatrics, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada, G1V 4G5
| | - Stéphanie Fournier
- Department of Pediatrics, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada, G1V 4G5
| | - Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Unesp. Jaboticabal, SP 14884-900, Brazil
| | - Richard Kinkead
- Department of Pediatrics, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada, G1V 4G5
| |
Collapse
|
9
|
Linehan V, Fang LZ, Parsons MP, Hirasawa M. High-fat diet induces time-dependent synaptic plasticity of the lateral hypothalamus. Mol Metab 2020; 36:100977. [PMID: 32277924 PMCID: PMC7170999 DOI: 10.1016/j.molmet.2020.100977] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 02/28/2020] [Accepted: 03/10/2020] [Indexed: 11/15/2022] Open
Abstract
Objective Orexin (ORX) and melanin-concentrating hormone (MCH) neurons in the lateral hypothalamus are critical regulators of energy homeostasis and are thought to differentially contribute to diet-induced obesity. However, it is unclear whether the synaptic properties of these cells are altered by obesogenic diets over time. Methods Rats and mice were fed a control chow or palatable high-fat diet (HFD) for various durations and then synaptic properties of ORX and MCH neurons were examined using exvivo whole-cell patch clamp recording. Confocal imaging was performed to assess the number of excitatory synaptic contacts to these neurons. Results ORX neurons exhibited a transient increase in spontaneous excitatory transmission as early as 1 day up to 1 week of HFD, which returned to control levels with prolonged feeding. Conversely, HFD induced a delayed increase in excitatory synaptic transmission to MCH neurons, which progressively increased as HFD became chronic. This increase occurred before the onset of significant weight gain. These synaptic changes appeared to be due to altered postsynaptic sensitivity or the number of active synaptic contacts depending on cell type and feeding duration. However, HFD induced no change in inhibitory transmission in either cell type at any time point. Conclusions These results suggest that the effects of HFD on feeding-related neurons are cell type-specific and dynamic. This highlights the importance of considering the feeding duration for research and weight loss interventions. ORX neurons may contribute to early hyperphagia, whereas MCH neurons may play a role in the onset and long-term maintenance of diet-induced obesity. High-fat diet increases excitatory transmission to orexin and MCH neurons. Increased excitatory drive to orexin neurons occurs within the first week but is transient. Excitatory synapses to MCH neurons increase with prolonged high-fat diet. Excitatory changes in MCH neurons are delayed but precede significant weight gain. These synaptic changes may contribute to the development and the maintenance of obesity.
Collapse
Affiliation(s)
- Victoria Linehan
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, 300 Prince Philip Drive, St. John's, Newfoundland, A1B 3V6, Canada
| | - Lisa Z Fang
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, 300 Prince Philip Drive, St. John's, Newfoundland, A1B 3V6, Canada
| | - Matthew P Parsons
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, 300 Prince Philip Drive, St. John's, Newfoundland, A1B 3V6, Canada
| | - Michiru Hirasawa
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, 300 Prince Philip Drive, St. John's, Newfoundland, A1B 3V6, Canada.
| |
Collapse
|
10
|
Chang GQ, Collier AD, Karatayev O, Gulati G, Boorgu DSSK, Leibowitz SF. Moderate Prenatal Ethanol Exposure Stimulates CXCL12/CXCR4 Chemokine System in Radial Glia Progenitor Cells in Hypothalamic Neuroepithelium and Peptide Neurons in Lateral Hypothalamus of the Embryo and Postnatal Offspring. Alcohol Clin Exp Res 2020; 44:866-879. [PMID: 32020622 DOI: 10.1111/acer.14296] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 01/21/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND Prenatal exposure to ethanol (EtOH) has lasting effects on neuropeptide and neuroimmune systems in the brain alongside detrimental alcohol-related behaviors. At low-to-moderate doses, prenatal EtOH stimulates neurogenesis in lateral hypothalamus (LH) and increases neurons that express the orexigenic peptides hypocretin/orexin (Hcrt/OX) and melanin-concentrating hormone (MCH), and the proinflammatory chemokine CCL2, which through its receptor CCR2 stimulates cell differentiation and movement. Our recent studies demonstrated that CCL2 and CCR2 colocalize with MCH neurons and are involved in EtOH's stimulatory effect on their development but show no relation to Hcrt/OX. Here, we investigated another chemokine, CXCL12, and its receptor, CXCR4, which promote neurogenesis and neuroprogenitor cell proliferation, to determine if they also exhibit peptide specificity in their response to EtOH exposure. METHODS Pregnant rats were intraorally administered a moderate dose of EtOH (2 g/kg/d) from embryonic day 10 (E10) to E15. Their embryos and postnatal offspring were examined using real-time quantitative PCR and immunofluorescence histochemistry, to determine if EtOH affects CXCL12 and CXCR4 and the colocalization of CXCR4 with Hcrt/OX and MCH neurons in the LH and with radial glia neuroprogenitor cells in the hypothalamic neuroepithelium (NEP). RESULTS Prenatal EtOH strongly stimulated CXCL12 and CXCR4 in LH neurons of embryos and postnatal offspring. This stimulation was significantly stronger in Hcrt/OX than MCH neurons in LH and also occurred in radial glia neuroprogenitor cells dense in the NEP. These effects were sexually dimorphic, consistently stronger in females than males. CONCLUSIONS While showing prenatal EtOH exposure to have a sexually dimorphic, stimulatory effect on CXCL12 and CXCR4 in LH similar to CCL2 and its receptor, these results reveal their distinct relationship to the peptide neurons, with the former closely related to Hcrt/OX and the latter to MCH, and they link EtOH's actions in LH to a stimulatory effect on neuroprogenitor cells in the NEP.
Collapse
Affiliation(s)
- Guo-Qing Chang
- From the, Laboratory of Behavioral Neurobiology, (GQC, ADC, OK, GG, SFL), The Rockefeller University, New York, New York
| | - Adam D Collier
- From the, Laboratory of Behavioral Neurobiology, (GQC, ADC, OK, GG, SFL), The Rockefeller University, New York, New York
| | - Olga Karatayev
- From the, Laboratory of Behavioral Neurobiology, (GQC, ADC, OK, GG, SFL), The Rockefeller University, New York, New York
| | - Gazal Gulati
- From the, Laboratory of Behavioral Neurobiology, (GQC, ADC, OK, GG, SFL), The Rockefeller University, New York, New York
| | | | - Sarah F Leibowitz
- From the, Laboratory of Behavioral Neurobiology, (GQC, ADC, OK, GG, SFL), The Rockefeller University, New York, New York
| |
Collapse
|
11
|
Tanaka S, Honda Y, Takaku S, Koike T, Oe S, Hirahara Y, Yoshida T, Takizawa N, Takamori Y, Kurokawa K, Kodama T, Yamada H. Involvement of PLAGL1/ZAC1 in hypocretin/orexin transcription. Int J Mol Med 2019; 43:2164-2176. [PMID: 30896835 PMCID: PMC6445593 DOI: 10.3892/ijmm.2019.4143] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 03/19/2019] [Indexed: 12/16/2022] Open
Abstract
The hypocretin/orexin neuropeptide system coordinates the regulation of various physiological processes. Our previous study reported that a reduction in the expression of pleomorphic adenoma gene-like 1 (Plagl1), which encodes a C2H2 zinc-finger transcription factor, occurs in hypocretin neuron-ablated transgenic mice, suggesting that PLAGL1 is co-expressed in hypocretin neurons and regulates hypocretin transcription. The present study examined whether canonical prepro-hypocretin transcription is functionally modulated by PLAGL1. Double immunostaining indicated that the majority of hypocretin neurons were positive for PLAGL1 immunore-activity in the nucleus. Notably, PLAGL1 immunoreactivity in hypocretin neurons was altered in response to several conditions affecting hypocretin function. An uneven localization of PLAGL1 was detected in the nuclei of hypocretin neurons following sleep deprivation. Chromatin immunoprecipitation revealed that endogenous PLAGL1 may bind to a putative PLAGL1-binding site in the proximal region of the hypocretin gene, in the murine hypothalamus. In addition, electroporation of the PLAGL1 expression vector into the fetal hypothalamus promoted hypothalamic hypocretin transcription. These results suggested that PLAGL1 may regulate hypothalamic hypocretin transcription.
Collapse
Affiliation(s)
- Susumu Tanaka
- Department of Anatomy and Cell Science, Kansai Medical University, Hirakata, Osaka 573‑1010, Japan
| | - Yoshiko Honda
- SLEEP Disorders Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156‑8506, Japan
| | - Shizuka Takaku
- SLEEP Disorders Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156‑8506, Japan
| | - Taro Koike
- Department of Anatomy and Cell Science, Kansai Medical University, Hirakata, Osaka 573‑1010, Japan
| | - Souichi Oe
- Department of Anatomy and Cell Science, Kansai Medical University, Hirakata, Osaka 573‑1010, Japan
| | - Yukie Hirahara
- Department of Anatomy and Cell Science, Kansai Medical University, Hirakata, Osaka 573‑1010, Japan
| | - Takashi Yoshida
- Department of Urology and Andrology, Kansai Medical University, Hirakata, Osaka 573‑1191, Japan
| | - Nae Takizawa
- Department of Anatomy and Cell Science, Kansai Medical University, Hirakata, Osaka 573‑1010, Japan
| | - Yasuharu Takamori
- Department of Anatomy and Cell Science, Kansai Medical University, Hirakata, Osaka 573‑1010, Japan
| | - Kiyoshi Kurokawa
- Department of Anatomy and Cell Science, Kansai Medical University, Hirakata, Osaka 573‑1010, Japan
| | - Tohru Kodama
- SLEEP Disorders Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156‑8506, Japan
| | - Hisao Yamada
- Department of Anatomy and Cell Science, Kansai Medical University, Hirakata, Osaka 573‑1010, Japan
| |
Collapse
|
12
|
Linehan V, Hirasawa M. Electrophysiological Properties of Melanin-Concentrating Hormone and Orexin Neurons in Adolescent Rats. Front Cell Neurosci 2018; 12:70. [PMID: 29662440 PMCID: PMC5890094 DOI: 10.3389/fncel.2018.00070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/27/2018] [Indexed: 01/05/2023] Open
Abstract
Orexin and melanin-concentrating hormone (MCH) neurons have complementary roles in various physiological functions including energy balance and the sleep/wake cycle. in vitro electrophysiological studies investigating these cells typically use post-weaning rodents, corresponding to adolescence. However, it is unclear whether these neurons are functionally mature at this period and whether these studies can be generalized to adult cells. Therefore, we examined the electrophysiological properties of orexin and MCH neurons in brain slices from post-weaning rats and found that MCH neurons undergo an age-dependent reduction in excitability, but not orexin neurons. Specifically, MCH neurons displayed an age-dependent hyperpolarization of the resting membrane potential (RMP), depolarizing shift of the threshold, and decrease in excitatory transmission, which reach the adult level by 7 weeks of age. In contrast, basic properties of orexin neurons were stable from 4 weeks to 14 weeks of age. Furthermore, a robust short-term facilitation of excitatory synapses was found in MCH neurons, which showed age-dependent changes during the post-weaning period. On the other hand, a strong short-term depression was observed in orexin neurons, which was similar throughout the same period. These differences in synaptic responses and age dependence likely differentially affect the network activity within the lateral hypothalamus where these cells co-exist. In summary, our study suggests that orexin neurons are electrophysiologically mature before adolescence whereas MCH neurons continue to develop until late adolescence. These changes in MCH neurons may contribute to growth spurts or consolidation of adult sleep patterns associated with adolescence. Furthermore, these results highlight the importance of considering the age of animals in studies involving MCH neurons.
Collapse
Affiliation(s)
- Victoria Linehan
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
| | - Michiru Hirasawa
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
| |
Collapse
|
13
|
Linehan V, Fang LZ, Hirasawa M. Short-term high-fat diet primes excitatory synapses for long-term depression in orexin neurons. J Physiol 2017; 596:305-316. [PMID: 29143330 DOI: 10.1113/jp275177] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 11/09/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS High-fat diet consumption is a major cause of obesity. Orexin neurons are known to be activated by a high-fat diet and in turn promote further consumption of a high-fat diet. Our study shows that excitatory synapses to orexin neurons become amenable to long-term depression (LTD) after 1 week of high-fat diet feeding. However, this effect reverses after 4 weeks of a high-fat diet. This LTD may be a homeostatic response to a high-fat diet to curb the activity of orexin neurons and hence caloric consumption. Adaptation seen after prolonged high-fat diet intake may contribute to the development of obesity. ABSTRACT Overconsumption of high-fat diets is one of the strongest contributing factors to the rise of obesity rates. Orexin neurons are known to be activated by a palatable high-fat diet and mediate the activation of the mesolimbic reward pathway, resulting in further food intake. While short-term exposure to a high-fat diet is known to induce synaptic plasticity within the mesolimbic pathway, it is unknown if such changes occur in orexin neurons. To investigate this, 3-week-old male rats were fed a palatable high-fat western diet (WD) or control chow for 1 week and then in vitro patch clamp recording was performed. In the WD condition, an activity-dependent long-term depression (LTD) of excitatory synapses was observed in orexin neurons, but not in chow controls. This LTD was presynaptic and depended on postsynaptic metabotropic glutamate receptor 5 (mGluR5) and retrograde endocannabinoid signalling. WD also increased extracellular glutamate levels, suggesting that glutamate spillover and subsequent activation of perisynaptic mGluR5 may occur more readily in the WD condition. In support of this, pharmacological inhibition of glutamate uptake was sufficient to prime chow control synapses to undergo a presynaptic LTD. Interestingly, these WD effects are transient, as extracellular glutamate levels were similar to controls and LTD was no longer observed in orexin neurons after 4 weeks of WD. In summary, excitatory synapses to orexin neurons become amenable to LTD under a palatable high-fat diet, which may represent a homeostatic mechanism to prevent overactivation of these neurons and to curtail high-fat diet consumption.
Collapse
Affiliation(s)
- Victoria Linehan
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada, A1B 3V6
| | - Lisa Z Fang
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada, A1B 3V6
| | - Michiru Hirasawa
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada, A1B 3V6
| |
Collapse
|