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Qian T, Wang H, Wang P, Geng L, Mei L, Osakada T, Wang L, Tang Y, Kania A, Grinevich V, Stoop R, Lin D, Luo M, Li Y. A genetically encoded sensor measures temporal oxytocin release from different neuronal compartments. Nat Biotechnol 2023; 41:944-957. [PMID: 36593404 PMCID: PMC11182738 DOI: 10.1038/s41587-022-01561-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 10/12/2022] [Indexed: 01/03/2023]
Abstract
Oxytocin (OT), a peptide hormone and neuromodulator, is involved in diverse physiological and pathophysiological processes in the central nervous system and the periphery. However, the regulation and functional sequences of spatial OT release in the brain remain poorly understood. We describe a genetically encoded G-protein-coupled receptor activation-based (GRAB) OT sensor called GRABOT1.0. In contrast to previous methods, GRABOT1.0 enables imaging of OT release ex vivo and in vivo with suitable sensitivity, specificity and spatiotemporal resolution. Using this sensor, we visualize stimulation-induced OT release from specific neuronal compartments in mouse brain slices and discover that N-type calcium channels predominantly mediate axonal OT release, whereas L-type calcium channels mediate somatodendritic OT release. We identify differences in the fusion machinery of OT release for axon terminals versus somata and dendrites. Finally, we measure OT dynamics in various brain regions in mice during male courtship behavior. Thus, GRABOT1.0 provides insights into the role of compartmental OT release in physiological and behavioral functions.
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Affiliation(s)
- Tongrui Qian
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Huan Wang
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Peng Wang
- Medical Center for Human Reproduction, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Lan Geng
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Long Mei
- Neuroscience Institute, Department of Psychiatry, New York University Grossman School of Medicine, New York, NY, USA
| | - Takuya Osakada
- Neuroscience Institute, Department of Psychiatry, New York University Grossman School of Medicine, New York, NY, USA
| | - Lei Wang
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
- Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, Peking University, Beijing, China
| | - Yan Tang
- Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital Center (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| | - Alan Kania
- Department of Neuropeptide Research in Psychiatry, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Valery Grinevich
- Department of Neuropeptide Research in Psychiatry, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Ron Stoop
- Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital Center (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| | - Dayu Lin
- Neuroscience Institute, Department of Psychiatry, New York University Grossman School of Medicine, New York, NY, USA
| | - Minmin Luo
- National Institute of Biological Sciences (NIBS), Beijing, China
- Chinese Institute for Brain Research, Beijing, China
- Tsinghua Institute of Multidisciplinary Biomedical Research (TIMBR), Tsinghua University, Beijing, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China.
- Chinese Institute for Brain Research, Beijing, China.
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
- National Biomedical Imaging Center, Peking University, Beijing, China.
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Martinez Damonte V, Pomrenze MB, Manning CE, Casper C, Wolfden AL, Malenka RC, Kauer JA. Somatodendritic Release of Cholecystokinin Potentiates GABAergic Synapses Onto Ventral Tegmental Area Dopamine Cells. Biol Psychiatry 2023; 93:197-208. [PMID: 35961792 PMCID: PMC9976994 DOI: 10.1016/j.biopsych.2022.06.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 06/01/2022] [Accepted: 06/10/2022] [Indexed: 11/02/2022]
Abstract
BACKGROUND Neuropeptides are contained in nearly every neuron in the central nervous system and can be released not only from nerve terminals but also from somatodendritic sites. Cholecystokinin (CCK), among the most abundant neuropeptides in the brain, is expressed in the majority of midbrain dopamine neurons. Despite this high expression, CCK function within the ventral tegmental area (VTA) is not well understood. METHODS We confirmed CCK expression in VTA dopamine neurons through immunohistochemistry and in situ hybridization and detected optogenetically induced CCK release using an enzyme-linked immunosorbent assay. To investigate whether CCK modulates VTA circuit activity, we used whole-cell patch clamp recordings in mouse brain slices. We infused CCK locally in vivo and tested food intake and locomotion in fasted mice. We also used in vivo fiber photometry to measure Ca2+ transients in dopamine neurons during feeding. RESULTS Here we report that VTA dopamine neurons release CCK from somatodendritic regions, where it triggers long-term potentiation of GABAergic (gamma-aminobutyric acidergic) synapses. The somatodendritic release occurs during trains of optogenetic stimuli or prolonged but modest depolarization and is dependent on synaptotagmin-7 and T-type Ca2+ channels. Depolarization-induced long-term potentiation is blocked by a CCK2 receptor antagonist and mimicked by exogenous CCK. Local infusion of CCK in vivo inhibits food consumption and decreases distance traveled in an open field test. Furthermore, intra-VTA-infused CCK reduced dopamine cell Ca2+ signals during food consumption after an overnight fast and was correlated with reduced food intake. CONCLUSIONS Our experiments introduce somatodendritic neuropeptide release as a previously unknown feedback regulator of VTA dopamine cell excitability and dopamine-related behaviors.
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Oestrogen-dependent hypothalamic oxytocin expression with changes in feeding and body weight in female rats. Commun Biol 2022; 5:912. [PMID: 36064966 PMCID: PMC9445083 DOI: 10.1038/s42003-022-03889-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 08/25/2022] [Indexed: 11/08/2022] Open
Abstract
Oxytocin (OXT) is produced in the hypothalamic nuclei and secreted into systemic circulation from the posterior pituitary gland. In the central nervous system, OXT regulates behaviours including maternal and feeding behaviours. Our aim is to evaluate whether oestrogen regulates hypothalamic OXT dynamics. Herein, we provide the first evidence that OXT dynamics in the hypothalamus vary with sex and that oestrogen may modulate dynamic changes in OXT levels, using OXT-mRFP1 transgenic rats. The fluorescence intensity of OXT-mRFP1 and expression of the OXT and mRFP1 genes in the hypothalamic nuclei is highest during the oestrus stage in female rats and decreased significantly in ovariectomised rats. Oestrogen replacement caused significant increases in fluorescence intensity and gene expression in a dose-related manner. This is also demonstrated in the rats' feeding behaviour and hypothalamic Fos neurons using cholecystokinin-8 and immunohistochemistry. Hypothalamic OXT expression is oestrogen-dependent and can be enhanced centrally by the administration of oestrogen.
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Transport Mechanisms at the Blood–Brain Barrier and in Cellular Compartments of the Neurovascular Unit: Focus on CNS Delivery of Small Molecule Drugs. Pharmaceutics 2022; 14:pharmaceutics14071501. [PMID: 35890396 PMCID: PMC9324459 DOI: 10.3390/pharmaceutics14071501] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 07/13/2022] [Accepted: 07/15/2022] [Indexed: 02/06/2023] Open
Abstract
Ischemic stroke is a primary origin of morbidity and mortality in the United States and around the world. Indeed, several research projects have attempted to discover new drugs or repurpose existing therapeutics to advance stroke pharmacotherapy. Many of these preclinical stroke studies have reported positive results for neuroprotective agents; however, only one compound (3K3A-activated protein C (3K3A-APC)) has advanced to Phase III clinical trial evaluation. One reason for these many failures is the lack of consideration of transport mechanisms at the blood–brain barrier (BBB) and neurovascular unit (NVU). These endogenous transport processes function as a “gateway” that is a primary determinant of efficacious brain concentrations for centrally acting drugs. Despite the knowledge that some neuroprotective agents (i.e., statins and memantine) are substrates for these endogenous BBB transporters, preclinical stroke studies have largely ignored the role of transporters in CNS drug disposition. Here, we review the current knowledge on specific BBB transporters that either limit drug uptake into the brain (i.e., ATP-binding cassette (ABC) transporters) or can be targeted for optimized drug delivery (i.e., solute carrier (SLC) transporters). Additionally, we highlight the current knowledge on transporter expression in astrocytes, microglia, pericytes, and neurons with an emphasis on transport mechanisms in these cell types that can influence drug distribution within the brain.
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Pittman QJ. Vasopressin and central control of the cardiovascular system: A 40-year retrospective. J Neuroendocrinol 2021; 33:e13011. [PMID: 34235812 DOI: 10.1111/jne.13011] [Citation(s) in RCA: 5] [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: 05/26/2021] [Accepted: 06/25/2021] [Indexed: 01/24/2023]
Abstract
In the 40 years since vasopressin (AVP) was reported to have a central action with respect to raising blood pressure, the finding has been repeatedly replicated using a variety of complimentary approaches. The role of AVP as a central neurotransmitter involved in control of the cardiovascular system is now textbook material. However, it is evident that brain AVP plays, at best, a minor role in regulation of normal blood pressure. However, it appears to be an important player in a several cardiovascular-associated pathologies, ranging from hypertension to neural changes associated with heart failure. There are many interventions that have been shown to affect neural function, many of which are associated with alterations in behaviour. Possible alterations in neuronal AVP actions relevant to cardiovascular control in the setting of chronic inflammatory disease, early-life stress and inflammation are suggested areas for future research.
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Affiliation(s)
- Quentin J Pittman
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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Mueller M, Egger V. Dendritic integration in olfactory bulb granule cells upon simultaneous multispine activation: Low thresholds for nonlocal spiking activity. PLoS Biol 2020; 18:e3000873. [PMID: 32966273 PMCID: PMC7535128 DOI: 10.1371/journal.pbio.3000873] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 10/05/2020] [Accepted: 08/24/2020] [Indexed: 11/18/2022] Open
Abstract
The inhibitory axonless olfactory bulb granule cells form reciprocal dendrodendritic synapses with mitral and tufted cells via large spines, mediating recurrent and lateral inhibition. As a case in point for dendritic transmitter release, rat granule cell dendrites are highly excitable, featuring local Na+ spine spikes and global Ca2+- and Na+-spikes. To investigate the transition from local to global signaling, we performed holographic, simultaneous 2-photon uncaging of glutamate at up to 12 granule cell spines, along with whole-cell recording and dendritic 2-photon Ca2+ imaging in acute juvenile rat brain slices. Coactivation of less than 10 reciprocal spines was sufficient to generate diverse regenerative signals that included regional dendritic Ca2+-spikes and dendritic Na+-spikes (D-spikes). Global Na+-spikes could be triggered in one third of granule cells. Individual spines and dendritic segments sensed the respective signal transitions as increments in Ca2+ entry. Dendritic integration as monitored by the somatic membrane potential was mostly linear until a threshold number of spines was activated, at which often D-spikes along with supralinear summation set in. As to the mechanisms supporting active integration, NMDA receptors (NMDARs) strongly contributed to all aspects of supralinearity, followed by dendritic voltage-gated Na+- and Ca2+-channels, whereas local Na+ spine spikes, as well as morphological variables, barely mattered. Because of the low numbers of coactive spines required to trigger dendritic Ca2+ signals and thus possibly lateral release of GABA onto mitral and tufted cells, we predict that thresholds for granule cell-mediated bulbar lateral inhibition are low. Moreover, D-spikes could provide a plausible substrate for granule cell-mediated gamma oscillations.
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Affiliation(s)
- Max Mueller
- Neurophysiology, Institute of Zoology, Universität Regensburg, Regensburg, Germany
| | - Veronica Egger
- Neurophysiology, Institute of Zoology, Universität Regensburg, Regensburg, Germany
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Deol P, Kozlova E, Valdez M, Ho C, Yang EW, Richardson H, Gonzalez G, Truong E, Reid J, Valdez J, Deans JR, Martinez-Lomeli J, Evans JR, Jiang T, Sladek FM, Curras-Collazo MC. Dysregulation of Hypothalamic Gene Expression and the Oxytocinergic System by Soybean Oil Diets in Male Mice. Endocrinology 2020; 161:5698148. [PMID: 31912136 PMCID: PMC7041656 DOI: 10.1210/endocr/bqz044] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 01/04/2020] [Indexed: 01/04/2023]
Abstract
Soybean oil consumption has increased greatly in the past half-century and is linked to obesity and diabetes. To test the hypothesis that soybean oil diet alters hypothalamic gene expression in conjunction with metabolic phenotype, we performed RNA sequencing analysis using male mice fed isocaloric, high-fat diets based on conventional soybean oil (high in linoleic acid, LA), a genetically modified, low-LA soybean oil (Plenish), and coconut oil (high in saturated fat, containing no LA). The 2 soybean oil diets had similar but nonidentical effects on the hypothalamic transcriptome, whereas the coconut oil diet had a negligible effect compared to a low-fat control diet. Dysregulated genes were associated with inflammation, neuroendocrine, neurochemical, and insulin signaling. Oxt was the only gene with metabolic, inflammation, and neurological relevance upregulated by both soybean oil diets compared to both control diets. Oxytocin immunoreactivity in the supraoptic and paraventricular nuclei of the hypothalamus was reduced, whereas plasma oxytocin and hypothalamic Oxt were increased. These central and peripheral effects of soybean oil diets were correlated with glucose intolerance but not body weight. Alterations in hypothalamic Oxt and plasma oxytocin were not observed in the coconut oil diet enriched in stigmasterol, a phytosterol found in soybean oil. We postulate that neither stigmasterol nor LA is responsible for effects of soybean oil diets on oxytocin and that Oxt messenger RNA levels could be associated with the diabetic state. Given the ubiquitous presence of soybean oil in the American diet, its observed effects on hypothalamic gene expression could have important public health ramifications.
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Affiliation(s)
- Poonamjot Deol
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
| | - Elena Kozlova
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
- Neuroscience Graduate Program, University of California, Riverside, California
| | - Matthew Valdez
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
- Neuroscience Graduate Program, University of California, Riverside, California
| | - Catherine Ho
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
| | - Ei-Wen Yang
- Department of Computer Science and Engineering, University of California Riverside, California
| | - Holly Richardson
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
| | - Gwendolyn Gonzalez
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
| | - Edward Truong
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
| | - Jack Reid
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
| | - Joseph Valdez
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
| | - Jonathan R Deans
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
| | - Jose Martinez-Lomeli
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
| | - Jane R Evans
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
| | - Tao Jiang
- Department of Computer Science and Engineering, University of California Riverside, California
| | - Frances M Sladek
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
| | - Margarita C Curras-Collazo
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California
- Neuroscience Graduate Program, University of California, Riverside, California
- Correspondence: Margarita C. Curras-Collazo, PhD, FAPS, Department of Molecular, Cell and Systems Biology, University of California, 2110 Biological Sciences Building, Riverside, California 92521. E-mail:
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Fujitani T, Matsuura T, Kawasaki M, Suzuki H, Nishimura H, Baba K, Yamanaka Y, Ohnishi H, Ueta Y, Sakai A. Presynaptic glutamatergic transmission and feedback system of oxytocinergic neurons in the hypothalamus of a rat model of adjuvant arthritis. Mol Pain 2020; 16:1744806920943334. [PMID: 32686583 PMCID: PMC7372626 DOI: 10.1177/1744806920943334] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 05/31/2020] [Accepted: 06/10/2020] [Indexed: 02/06/2023] Open
Abstract
The neurohypophysial hormone oxytocin (OXT) is synthesized in the hypothalamic paraventricular and supraoptic nuclei. Recently, some studies have considered OXT to be important in sensory modulation and that the OXT protein is upregulated by acute and chronic nociception. However, the mechanism by which OXT is upregulated in neurons is unknown. In this study, we examined the resting membrane potentials and excitatory postsynaptic currents in OXT-ergic neurons in the paraventricular nucleus in adjuvant arthritis rat model, a model of chronic inflammation, using whole-cell patch-clamping. Transgenic rats expressing OXT and monomeric red fluorescent protein 1 (mRFP1) fusion protein to visualize the OXT-ergic neurons were used, and the OXT-mRFP1 transgenic rat model of adjuvant arthritis was developed by injection of heat-killed Mycobacterium butyricum. Furthermore, the feedback system of synthesized OXT was also examined using the OXT receptor antagonist L-368,899. We found that the resting membrane potentials and frequency of miniature excitatory postsynaptic currents and spontaneous excitatory postsynaptic currents in OXT-monomeric red fluorescent protein 1 neurons in the paraventricular nucleus were significantly increased in adjuvant arthritis rats. Furthermore, L-368,899 dose-dependently increased the frequency of miniature excitatory postsynaptic currents and spontaneous excitatory postsynaptic currents in OXT-ergic neurons. Following bath application of the GABAA receptor antagonist picrotoxin and the cannabinoid receptor 1 antagonist AM 251, L-368,899 still increased the frequency of miniature excitatory postsynaptic currents. However, following bath application of the nitric oxide synthase inhibitor Nω-Nitro-L-arginine methyl ester hydrochloride, L-368,899 did not alter the miniature excitatory postsynaptic current frequency. Thus, it is suggested that OXT-ergic neuron activity is upregulated via an increase in glutamate release, and that the upregulated OXT neurons have a feedback system with released endogenous OXT. It is possible that nitric oxide, but not GABA, may contribute to the feedback system of OXT neurons in chronic inflammation.
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Affiliation(s)
- Teruaki Fujitani
- Department of Orthopaedic Surgery, School of Medicine,
University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Takanori Matsuura
- Department of Orthopaedic Surgery, School of Medicine,
University of Occupational and Environmental Health, Kitakyushu, Japan
- Department of Physiology, School of Medicine, University of
Occupational and Environmental Health, Kitakyushu, Japan
| | - Makoto Kawasaki
- Department of Orthopaedic Surgery, School of Medicine,
University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Hitoshi Suzuki
- Department of Orthopaedic Surgery, School of Medicine,
University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Haruki Nishimura
- Department of Orthopaedic Surgery, School of Medicine,
University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Kazuhiko Baba
- Department of Orthopaedic Surgery, School of Medicine,
University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Yoshiaki Yamanaka
- Department of Orthopaedic Surgery, School of Medicine,
University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Hideo Ohnishi
- Department of Orthopaedic Surgery, School of Medicine,
University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Yoichi Ueta
- Department of Physiology, School of Medicine, University of
Occupational and Environmental Health, Kitakyushu, Japan
| | - Akinori Sakai
- Department of Orthopaedic Surgery, School of Medicine,
University of Occupational and Environmental Health, Kitakyushu, Japan
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Ardalan M, Svedin P, Baburamani AA, Supramaniam VG, Ek J, Hagberg H, Mallard C. Dysmaturation of Somatostatin Interneurons Following Umbilical Cord Occlusion in Preterm Fetal Sheep. Front Physiol 2019; 10:563. [PMID: 31178744 PMCID: PMC6538799 DOI: 10.3389/fphys.2019.00563] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 04/24/2019] [Indexed: 12/20/2022] Open
Abstract
INTRODUCTION Cerebral white matter injury is the most common neuropathology observed in preterm infants. However, there is increasing evidence that gray matter development also contributes to neurodevelopmental abnormalities. Fetal cerebral ischemia can lead to both neuronal and non-neuronal structural-functional abnormalities, but less is known about the specific effects on interneurons. OBJECTIVE In this study we used a well-established animal model of fetal asphyxia in preterm fetal sheep to study neuropathological outcome. We used comprehensive stereological methods to investigate the total number of oligodendrocytes, neurons and somatostatin (STT) positive interneurons as well as 3D morphological analysis of STT cells 14 days following umbilical cord occlusion (UCO) in fetal sheep. MATERIALS AND METHODS Induction of asphyxia was performed by 25 min of complete UCO in five preterm fetal sheep (98-100 days gestational age). Seven, non-occluded twins served as controls. Quantification of the number of neurons (NeuN), STT interneurons and oligodendrocytes (Olig2, CNPase) was performed on fetal brain regions by applying optical fractionator method. A 3D morphological analysis of STT interneurons was performed using IMARIS software. RESULTS The number of Olig2, NeuN, and STT positive cells were reduced in IGWM, caudate and putamen in UCO animals compared to controls. There were also fewer STT interneurons in the ventral part of the hippocampus, the subiculum and the entorhinal cortex in UCO group, while other parts of cortex were virtually unaffected (p > 0.05). Morphologically, STT positive interneurons showed a markedly immature structure, with shorter dendritic length and fewer dendritic branches in cortex, caudate, putamen, and subiculum in the UCO group compared with control group (p < 0.05). CONCLUSION The significant reduction in the total number of neurons and oligodendrocytes in several brain regions confirm previous studies showing susceptibility of both neuronal and non-neuronal cells following fetal asphyxia. However, in the cerebral cortex significant dysmaturation of STT positive neurons occurred in the absence of cell loss. This suggests an abnormal maturation pattern of GABAergic interneurons in the cerebral cortex, which might contribute to neurodevelopmental impairment in preterm infants and could implicate a novel target for neuroprotective therapies.
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Affiliation(s)
- Maryam Ardalan
- Centre for Perinatal Medicine and Health, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Pernilla Svedin
- Centre for Perinatal Medicine and Health, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ana A. Baburamani
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Veena G. Supramaniam
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
| | - Joakim Ek
- Centre for Perinatal Medicine and Health, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Henrik Hagberg
- Centre for the Developing Brain, Department of Perinatal Imaging and Health, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, United Kingdom
- Centre for Perinatal Medicine and Health, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Carina Mallard
- Centre for Perinatal Medicine and Health, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Maniezzi C, Talpo F, Spaiardi P, Toselli M, Biella G. Oxytocin Increases Phasic and Tonic GABAergic Transmission in CA1 Region of Mouse Hippocampus. Front Cell Neurosci 2019; 13:178. [PMID: 31133808 PMCID: PMC6516053 DOI: 10.3389/fncel.2019.00178] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 04/12/2019] [Indexed: 11/17/2022] Open
Abstract
Oxytocin is a neuropeptide that plays important peripheral and central neuromodulatory functions. Our data show that, following activation of oxytocin receptors (OtRs) with the selective agonist TGOT (Thr4,Gly7-oxytocin), a significant increase in frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSC) occurred in hippocampal CA1 pyramidal neurons (PYR) in mice. TGOT affected also sIPSC deactivation kinetics, suggesting the involvement of perisynaptic GABAA receptors (GABAARs) as well. By contrast, TGOT did not cause significant changes in frequency, amplitude or deactivation kinetics of miniature IPSC, suggesting that the effects elicited by the agonist are strictly dependent on the firing activity of presynaptic neurons. Moreover, TGOT was able to modulate tonic GABAergic current mediated by extrasynaptic GABAARs expressed by PYRs. Consistently, at spike threshold TGOT induced in most PYRs a significant membrane hyperpolarization and a decrease in firing rate. The source of increased inhibition onto PYRs was represented by stuttering fast-spiking GABAergic interneurons (INs) that directly respond to TGOT with a depolarization and an increase in their firing rate. One putative ionic mechanism underlying this effect could be represented by OtR activation-induced up-modulation of L-type Ca2+ channels. In conclusion, our results indicate that oxytocin can influence the activity of a subclass of hippocampal GABAergic INs and therefore regulate the operational modes of the downstream PYRs by increasing phasic and tonic GABAergic transmission in CA1 region of mouse hippocampus.
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Affiliation(s)
- Claudia Maniezzi
- Laboratory of Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Francesca Talpo
- Laboratory of Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Paolo Spaiardi
- Neurophysiology Unit, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Mauro Toselli
- Laboratory of Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Gerardo Biella
- Laboratory of Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
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Ashhad S, Narayanan R. Stores, Channels, Glue, and Trees: Active Glial and Active Dendritic Physiology. Mol Neurobiol 2019; 56:2278-2299. [PMID: 30014322 PMCID: PMC6394607 DOI: 10.1007/s12035-018-1223-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 07/03/2018] [Indexed: 02/07/2023]
Abstract
Glial cells and neuronal dendrites were historically assumed to be passive structures that play only supportive physiological roles, with no active contribution to information processing in the central nervous system. Research spanning the past few decades has clearly established this assumption to be far from physiological realities. Whereas the discovery of active channel conductances and their localized plasticity was the turning point for dendritic structures, the demonstration that glial cells release transmitter molecules and communicate across the neuroglia syncytium through calcium wave propagation constituted path-breaking discoveries for glial cell physiology. An additional commonality between these two structures is the ability of calcium stores within their endoplasmic reticulum (ER) to support active propagation of calcium waves, which play crucial roles in the spatiotemporal integration of information within and across cells. Although there have been several demonstrations of regulatory roles of glial cells and dendritic structures in achieving common physiological goals such as information propagation and adaptability through plasticity, studies assessing physiological interactions between these two active structures have been few and far. This lacuna is especially striking given the strong connectivity that is known to exist between these two structures through several complex and tightly intercoupled mechanisms that also recruit their respective ER structures. In this review, we present brief overviews of the parallel literatures on active dendrites and active glial physiology and make a strong case for future studies to directly assess the strong interactions between these two structures in regulating physiology and pathophysiology of the brain.
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Affiliation(s)
- Sufyan Ashhad
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India.
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Schulz K, Rotermund N, Grzelka K, Benz J, Lohr C, Hirnet D. Adenosine A 1 Receptor-Mediated Attenuation of Reciprocal Dendro-Dendritic Inhibition in the Mouse Olfactory Bulb. Front Cell Neurosci 2018; 11:435. [PMID: 29379418 PMCID: PMC5775233 DOI: 10.3389/fncel.2017.00435] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 12/26/2017] [Indexed: 12/14/2022] Open
Abstract
It is well described that A1 adenosine receptors inhibit synaptic transmission at excitatory synapses in the brain, but the effect of adenosine on reciprocal synapses has not been studied so far. In the olfactory bulb, the majority of synapses are reciprocal dendro-dendritic synapses mediating recurrent inhibition. We studied the effect of A1 receptor activation on recurrent dendro-dendritic inhibition in mitral cells using whole-cell patch-clamp recordings. Adenosine reduced dendro-dendritic inhibition in wild-type, but not in A1 receptor knock-out mice. Both NMDA receptor-mediated and AMPA receptor-mediated dendro-dendritic inhibition were attenuated by adenosine, indicating that reciprocal synapses between mitral cells and granule cells as well as parvalbumin interneurons were targeted by A1 receptors. Adenosine reduced glutamatergic self-excitation and inhibited N-type and P/Q-type calcium currents, but not L-type calcium currents in mitral cells. Attenuated glutamate release, due to A1 receptor-mediated calcium channel inhibition, resulted in impaired dendro-dendritic inhibition. In behavioral tests we tested the ability of wild-type and A1 receptor knock-out mice to find a hidden piece of food. Knock-out mice were significantly faster in locating the food. Our results indicate that A1 adenosine receptors attenuates dendro-dendritic reciprocal inhibition and suggest that they affect odor information processing.
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Affiliation(s)
- Kristina Schulz
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Natalie Rotermund
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Katarzyna Grzelka
- Department of Physiology and Pathophysiology, Medical University of Warsaw, Warsaw, Poland
| | - Jan Benz
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Daniela Hirnet
- Division of Neurophysiology, Institute of Zoology, University of Hamburg, Hamburg, Germany
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Abstract
Chronic stress is a major cause of anxiety disorders that can be reliably modeled preclinically, providing insight into alternative therapeutic targets for this mental health illness. Neuropeptides have been targeted in the past to no avail possibly due to our lack of understanding of their role in pathological models. In this study we use a rat model of chronic stress-induced anxiety-like behaviors and hypothesized that neuropeptidergic modulation of synaptic transmission would be altered in the bed nucleus of the stria terminalis (BNST), a brain region suspected to contribute to anxiety disorders. We use brain slice neurophysiology and behavioral pharmacology to compare the role of locally released endogenous neuropeptides on synaptic transmission in the oval (ov) BNST of non-stressed (NS) or chronic unpredictably stressed (CUS) rats. We found that in NS rats, post-synaptic depolarization induced the release of vesicular neurotensin (NT) and corticotropin-releasing factor (CRF) that co-acted to increase ovBNST inhibitory synaptic transmission in 59% of recorded neurons. CUS bolstered this potentiation (100% of recorded neurons) through an enhanced contribution of NT over CRF. In contrast, locally released opioid neuropeptides decreased ovBNST excitatory synaptic transmission in all recorded neurons, regardless of stress. Consistent with CUS-induced enhanced modulatory effects of NT, blockade of ovBNST NT receptors completely abolished stress-induced anxiety-like behaviors in the elevated plus maze paradigm. The role of NT has been largely unexplored in stress and our findings highlight its potential contribution to an important behavioral consequence of chronic stress, that is, exaggerated avoidance of open space in rats.
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Opiates Modulate Noxious Chemical Nociception through a Complex Monoaminergic/Peptidergic Cascade. J Neurosci 2017; 36:5498-508. [PMID: 27194330 DOI: 10.1523/jneurosci.4520-15.2016] [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: 12/18/2015] [Accepted: 04/13/2016] [Indexed: 01/11/2023] Open
Abstract
UNLABELLED The ability to detect noxious stimuli, process the nociceptive signal, and elicit an appropriate behavioral response is essential for survival. In Caenorhabditis elegans, opioid receptor agonists, such as morphine, mimic serotonin, and suppress the overall withdrawal from noxious stimuli through a pathway requiring the opioid-like receptor, NPR-17. This serotonin- or morphine-dependent modulation can be rescued in npr-17-null animals by the expression of npr-17 or a human κ opioid receptor in the two ASI sensory neurons, with ASI opioid signaling selectively inhibiting ASI neuropeptide release. Serotonergic modulation requires peptides encoded by both nlp-3 and nlp-24, and either nlp-3 or nlp-24 overexpression mimics morphine and suppresses withdrawal. Peptides encoded by nlp-3 act differentially, with only NLP-3.3 mimicking morphine, whereas other nlp-3 peptides antagonize NLP-3.3 modulation. Together, these results demonstrate that opiates modulate nociception in Caenorhabditis elegans through a complex monoaminergic/peptidergic cascade, and suggest that this model may be useful for dissecting opiate signaling in mammals. SIGNIFICANCE STATEMENT Opiates are used extensively to treat chronic pain. In Caenorhabditis elegans, opioid receptor agonists suppress the overall withdrawal from noxious chemical stimuli through a pathway requiring an opioid-like receptor and two distinct neuropeptide-encoding genes, with individual peptides from the same gene functioning antagonistically to modulate nociception. Endogenous opioid signaling functions as part of a complex, monoaminergic/peptidergic signaling cascade and appears to selectively inhibit neuropeptide release, mediated by a α-adrenergic-like receptor, from two sensory neurons. Importantly, receptor null animals can be rescued by the expression of the human κ opioid receptor, and injection of human opioid receptor ligands mimics exogenous opiates, highlighting the utility of this model for dissecting opiate signaling in mammals.
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Wang Y, Wu Q, Hu M, Liu B, Chai Z, Huang R, Wang Y, Xu H, Zhou L, Zheng L, Wang C, Zhou Z. Ligand- and voltage-gated Ca2+channels differentially regulate the mode of vesicular neuropeptide release in mammalian sensory neurons. Sci Signal 2017. [DOI: 10.1126/scisignal.aal1683] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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16
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Bywalez WG, Ona-Jodar T, Lukas M, Ninkovic J, Egger V. Dendritic Arborization Patterns of Small Juxtaglomerular Cell Subtypes within the Rodent Olfactory Bulb. Front Neuroanat 2017; 10:127. [PMID: 28163674 PMCID: PMC5247448 DOI: 10.3389/fnana.2016.00127] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 12/19/2016] [Indexed: 01/27/2023] Open
Abstract
Within the glomerular layer of the rodent olfactory bulb, numerous subtypes of local interneurons contribute to early processing of incoming sensory information. Here we have investigated dopaminergic and other small local juxtaglomerular cells in rats and mice and characterized their dendritic arborization pattern with respect to individual glomeruli by fluorescent labeling via patching and reconstruction of dendrites and glomerular contours from two-photon imaging data. Dopaminergic neurons were identified in a transgenic mouse line where the expression of dopamine transporter (DAT) was labeled with GFP. Among the DAT+ cells we found a small short-axon cell (SAC) subtype featuring hitherto undescribed dendritic specializations. These densely ramifying structures clasped mostly around somata of other juxtaglomerular neurons, which were also small, non-dopaminergic and to a large extent non-GABAergic. Clasping SACs were observed also in wild-type mice and juvenile rats. In DAT+ SAC dendrites, single backpropagating action potentials evoked robust calcium entry throughout both clasping and non-clasping compartments. Besides clasping SACs, most other small neurons either corresponded to the classical periglomerular cell type (PGCs), which was never DAT+, or were undersized cells with a small dendritic tree and low excitability. Aside from the presence of clasps in SAC dendrites, many descriptors of dendritic morphology such as the number of dendrites and the extent of branching were not significantly different between clasping SACs and PGCs. However, a detailed morphometric analysis in relation to glomerular contours revealed that the dendrites of clasping SACs arborized mostly in the juxtaglomerular space and never entered more than one glomerulus (if at all), whereas most PGC dendrites were restricted to their parent glomerulus, similar to the apical tufts of mitral cells. These complementary arborization patterns might underlie a highly complementary functional connectivity. The morphometric approach may serve to differentiate also other subtypes of juxtaglomerular neurons, help to identify putative synaptic partners and thus to establish a more refined picture of glomerular network interactions during odor sensing.
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Affiliation(s)
- Wolfgang G Bywalez
- Systems Neurobiology, Department II of Biology, Ludwig-Maximilians-Universität MünchenMunich, Germany; Neurophysiology, Institute of Zoology, Universität RegensburgRegensburg, Germany
| | - Tiffany Ona-Jodar
- Neurophysiology, Institute of Zoology, Universität Regensburg Regensburg, Germany
| | - Michael Lukas
- Neurophysiology, Institute of Zoology, Universität Regensburg Regensburg, Germany
| | - Jovica Ninkovic
- Institute for Stem Cell Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH)Munich, Germany; Institute of Physiological Genomics, Ludwig-Maximilians-Universität MünchenMunich, Germany; Cluster for Systems Neurology and BioMedical Center, Ludwig-Maximilians-Universität MünchenMunich, Germany
| | - Veronica Egger
- Systems Neurobiology, Department II of Biology, Ludwig-Maximilians-Universität MünchenMunich, Germany; Neurophysiology, Institute of Zoology, Universität RegensburgRegensburg, Germany; Regensburg Center of Neuroscience, Universität RegensburgRegensburg, Germany
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17
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Ludwig M, Apps D, Menzies J, Patel JC, Rice ME. Dendritic Release of Neurotransmitters. Compr Physiol 2016; 7:235-252. [PMID: 28135005 DOI: 10.1002/cphy.c160007] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Release of neuroactive substances by exocytosis from dendrites is surprisingly widespread and is not confined to a particular class of transmitters: it occurs in multiple brain regions, and includes a range of neuropeptides, classical neurotransmitters, and signaling molecules, such as nitric oxide, carbon monoxide, ATP, and arachidonic acid. This review is focused on hypothalamic neuroendocrine cells that release vasopressin and oxytocin and midbrain neurons that release dopamine. For these two model systems, the stimuli, mechanisms, and physiological functions of dendritic release have been explored in greater detail than is yet available for other neurons and neuroactive substances. © 2017 American Physiological Society. Compr Physiol 7:235-252, 2017.
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Affiliation(s)
- Mike Ludwig
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - David Apps
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - John Menzies
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Jyoti C Patel
- Department of Neurosurgery, New York University School of Medicine, New York, USA
| | - Margaret E Rice
- Department of Neurosurgery, New York University School of Medicine, New York, USA.,Department of Neuroscience and Physiology, New York University School of Medicine, New York, USA
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18
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Yavorska I, Wehr M. Somatostatin-Expressing Inhibitory Interneurons in Cortical Circuits. Front Neural Circuits 2016; 10:76. [PMID: 27746722 PMCID: PMC5040712 DOI: 10.3389/fncir.2016.00076] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 09/12/2016] [Indexed: 12/30/2022] Open
Abstract
Cortical inhibitory neurons exhibit remarkable diversity in their morphology, connectivity, and synaptic properties. Here, we review the function of somatostatin-expressing (SOM) inhibitory interneurons, focusing largely on sensory cortex. SOM neurons also comprise a number of subpopulations that can be distinguished by their morphology, input and output connectivity, laminar location, firing properties, and expression of molecular markers. Several of these classes of SOM neurons show unique dynamics and characteristics, such as facilitating synapses, specific axonal projections, intralaminar input, and top-down modulation, which suggest possible computational roles. SOM cells can be differentially modulated by behavioral state depending on their class, sensory system, and behavioral paradigm. The functional effects of such modulation have been studied with optogenetic manipulation of SOM cells, which produces effects on learning and memory, task performance, and the integration of cortical activity. Different classes of SOM cells participate in distinct disinhibitory circuits with different inhibitory partners and in different cortical layers. Through these disinhibitory circuits, SOM cells help encode the behavioral relevance of sensory stimuli by regulating the activity of cortical neurons based on subcortical and intracortical modulatory input. Associative learning leads to long-term changes in the strength of connectivity of SOM cells with other neurons, often influencing the strength of inhibitory input they receive. Thus despite their heterogeneity and variability across cortical areas, current evidence shows that SOM neurons perform unique neural computations, forming not only distinct molecular but also functional subclasses of cortical inhibitory interneurons.
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Affiliation(s)
| | - Michael Wehr
- Institute of Neuroscience and Department of Psychology, University of OregonEugene, OR, USA
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19
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Abstract
Aquaporins (AQPs) represent a diverse family of membrane proteins found in prokaryotes and eukaryotes. The primary aquaporins expressed in the mammalian brain are AQP1, which is densely packed in choroid plexus cells lining the ventricles, and AQP4, which is abundant in astrocytes and concentrated especially in the end-feet structures that surround capillaries throughout the brain and are present in glia limitans structures, notably in osmosensory areas such the supraoptic nucleus. Water movement in brain tissues is carefully regulated from the micro- to macroscopic levels, with aquaporins serving key roles as multifunctional elements of complex signaling assemblies. Intriguing possibilities suggest links for AQP1 in Alzheimer's disease, AQP4 as a target for therapy in brain edema, and a possible contribution of AQP9 in Parkinson's disease. For all the aquaporins, new contributions to physiological functions are likely to continue to be discovered with ongoing work in this rapidly expanding field of research. NEUROSCIENTIST 13(5):470—485, 2007.
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Affiliation(s)
- Andrea J Yool
- Department of Physiology, The BIO5 Institute, and the Arizona Research Laboratories Division of Neurobiology, University of Arizona, Tucson, AZ 84724, USA.
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20
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Harden SW, Frazier CJ. Oxytocin depolarizes fast-spiking hilar interneurons and induces GABA release onto mossy cells of the rat dentate gyrus. Hippocampus 2016; 26:1124-39. [PMID: 27068005 DOI: 10.1002/hipo.22595] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2016] [Indexed: 12/28/2022]
Abstract
Delivery of exogenous oxytocin (OXT) to central oxytocin receptors (OXT-Rs) is currently being investigated as a potential treatment for conditions such as post-traumatic stress disorder (PTSD), depression, social anxiety, and autism spectrum disorder (ASD). Despite significant research implicating central OXT signaling in modulation of mood, affect, social behavior, and stress response, relatively little is known about the cellular and synaptic mechanisms underlying these complex actions, particularly in brain regions which express the OXT-R but lie outside of the hypothalamus (where OXT-synthesizing neurons reside). We report that bath application of low concentrations of the selective OXT-R agonist Thr4,Gly7-OXT (TGOT) reliably and robustly drives GABA release in the dentate gyrus in an action potential dependent manner. Additional experiments led to identification of a small subset of small hilar interneurons that are directly depolarized by acute application of TGOT. From a physiological perspective, TGOT-responsive hilar interneurons have high input resistance, rapid repolarization velocity during an action potential, and a robust afterhyperpolarization. Further, they fire irregularly (or stutter) in response to moderate depolarization, and fire quickly with minimal spike frequency accommodation in response to large current injections. From an anatomical perspective, TGOT responsive hilar interneurons have dense axonal arborizations in the hilus that were found in close proximity with mossy cell somata and/or proximal dendrites, and also invade the granule cell layer. Further, they have primary dendrites that always extend into the granule cell layer, and sometimes have clear arborizations in the molecular layer. Overall, these data reveal a novel site of action for OXT in an important limbic circuit, and represent a significant step towards better understanding how endogenous OXT may modulate flow of information in hippocampal networks. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Scott W Harden
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, Florida.,Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, Florida
| | - Charles J Frazier
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, Florida.,Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida
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21
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El-Werfali W, Toomasian C, Maliszewska-Scislo M, Li C, Rossi NF. Haemodynamic and renal sympathetic responses to V1b vasopressin receptor activation within the paraventricular nucleus. Exp Physiol 2016; 100:553-65. [PMID: 25605313 DOI: 10.1113/expphysiol.2014.084426] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 01/16/2015] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does antagonism of V1b receptors prevent the haemodynamic and renal sympathetic nerve responses that occur with application of exogenous vasopressin into the paraventricular nucleus (PVN) of conscious, chronically instrumented rats? What is the main finding and its importance? Microinjection of vasopressin into the PVN increased mean arterial pressure, heart rate and renal sympathetic nerve activity, all of which were inhibited by pre-injection of the PVN with the V1b antagonist, nelivaptan. The administered vasopressin did not enter the peripheral circulation or increase plasma vasopressin. Ganglionic blockade prevented each of the responses, consistent with mediation by enhanced sympathetic output rather than an increase in circulating vasopressin. Vasopressin (VP) participates in regulation of haemodynamics and volume. Besides more classical actions as a circulating hormone, VP may act via release from axons and dendrites within the CNS. The paraventricular nucleus (PVN) possesses vasopressinergic neurons and a dense complement of VP receptors, including the V1b receptor, which has been implicated in several types of stress responses. We tested the hypothesis that antagonism of V1b receptors will prevent VP-induced increases in mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA). Studies were performed in conscious male Sprague-Dawley rats chronically instrumented with vascular catheters, renal nerve electrodes and a cannula stereotaxically directed into the PVN. Unilateral microinjection of VP into the PVN significantly increased MAP, HR and RSNA, peaking at 10 min. Pre-injection of the PVN with the selective V1b receptor antagonist, nelivaptan, did not alter baseline values but blocked the responses to VP. Ganglionic blockade with chlorisondamine decreased MAP and HR and abolished their increase in response to subsequent PVN application of VP. Injection of VP into the PVN did not alter plasma VP levels. Paraventricular nucleus injection with radiolabelled VP resulted in negligible radiolabelled VP in peripheral blood. These findings support the concept that, in basal conditions, PVN V1b receptor activation (rather than VP release into the periphery) may be implicated in the increases in MAP, HR and RSNA due to increased sympathetic outflow. While the role of V1a and oxytocin receptors cannot be excluded, these data suggest that further studies of the role of V1b receptor activation by endogenous VP during stress to effect neuroexcitation are warranted.
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Affiliation(s)
- Wafa El-Werfali
- Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI, USA; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
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Ludwig M, Stern J. Multiple signalling modalities mediated by dendritic exocytosis of oxytocin and vasopressin. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2014.0182. [PMID: 26009761 DOI: 10.1098/rstb.2014.0182] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The mammalian hypothalamic magnocellular neurons of the supraoptic and paraventricular nuclei are among the best understood of all peptidergic neurons. Through their anatomical features, vasopressin- and oxytocin-containing neurons have revealed many important aspects of dendritic functions. Here, we review our understanding of the mechanisms of somato-dendritic peptide release, and the effects of autocrine, paracrine and hormone-like signalling on neuronal networks and behaviour.
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Affiliation(s)
- Mike Ludwig
- Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - Javier Stern
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, GA, USA
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Postsynaptic Depolarization Enhances GABA Drive to Dorsomedial Hypothalamic Neurons through Somatodendritic Cholecystokinin Release. J Neurosci 2015; 35:13160-70. [PMID: 26400945 DOI: 10.1523/jneurosci.3123-14.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Somatodendritically released peptides alter synaptic function through a variety of mechanisms, including autocrine actions that liberate retrograde transmitters. Cholecystokinin (CCK) is a neuropeptide expressed in neurons in the dorsomedial hypothalamic nucleus (DMH), a region implicated in satiety and stress. There are clear demonstrations that exogenous CCK modulates food intake and neuropeptide expression in the DMH, but there is no information on how endogenous CCK alters synaptic properties. Here, we provide the first report of somatodendritic release of CCK in the brain in male Sprague Dawley rats. CCK is released from DMH neurons in response to repeated postsynaptic depolarizations, and acts in an autocrine fashion on CCK2 receptors to enhance postsynaptic NMDA receptor function and liberate the retrograde transmitter, nitric oxide (NO). NO subsequently acts presynaptically to enhance GABA release through a soluble guanylate cyclase-mediated pathway. These data provide the first demonstration of synaptic actions of somatodendritically released CCK in the hypothalamus and reveal a new form of retrograde plasticity, depolarization-induced potentiation of inhibition. Significance statement: Somatodendritic signaling using endocannabinoids or nitric oxide to alter the efficacy of afferent transmission is well established. Despite early convincing evidence for somatodendritic release of neurohypophysial peptides in the hypothalamus, there is only limited evidence for this mode of release for other peptides. Here, we provide the first evidence for somatodendritic release of the satiety peptide cholecystokinin (CCK) in the brain. We also reveal a new form of synaptic plasticity in which postsynaptic depolarization results in enhancement of inhibition through the somatodendritic release of CCK.
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Sladek CD, Michelini LC, Stachenfeld NS, Stern JE, Urban JH. Endocrine‐Autonomic Linkages. Compr Physiol 2015; 5:1281-323. [DOI: 10.1002/cphy.c140028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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25
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Wamsteeker Cusulin JI, Bains JS. Embedded synaptic feedback in the neuroendocrine stress axis. J Neuroendocrinol 2015; 27:481-6. [PMID: 25612538 DOI: 10.1111/jne.12260] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 01/07/2015] [Accepted: 01/15/2015] [Indexed: 11/28/2022]
Abstract
Neural regulation of blood glucocorticoid levels is critical for defence of homeostasis during physiological or psychoemotional challenges. In mammals, this function is carried out by the neuroendocrine stress axis, coordinated by parvocellular neuroendocrine cells (PNCs) of the paraventricular hypothalamic nucleus. Feedback regulation of PNCs by glucocorticoids provides complex experience-dependent shaping of neuroendocrine responses. We review recent evidence for metaplastic actions of glucocorticoids as 'circuit breakers' at synapses directly regulating PNC excitability and explore how such mechanisms may serve as substrates for stress adaptation.
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Affiliation(s)
- J I Wamsteeker Cusulin
- Hotchkiss Brain Institute and the Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - J S Bains
- Hotchkiss Brain Institute and the Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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26
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Stern JE. Neuroendocrine-autonomic integration in the paraventricular nucleus: novel roles for dendritically released neuropeptides. J Neuroendocrinol 2015; 27:487-97. [PMID: 25546497 PMCID: PMC4447596 DOI: 10.1111/jne.12252] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 12/09/2014] [Accepted: 12/18/2014] [Indexed: 12/21/2022]
Abstract
Communication between pairs of neurones in the central nervous system typically involves classical 'hard-wired' synaptic transmission, characterised by high temporal and spatial precision. Over the last two decades, however, knowledge regarding the repertoire of communication modalities used in the brain has notably expanded to include less conventional forms, characterised by a diffuse and less temporally precise transfer of information. These forms are best suited to mediate communication among entire neuronal populations, now recognised to be a fundamental process in the brain for the generation of complex behaviours. In response to an osmotic stressor, the hypothalamic paraventricular nucleus (PVN) generates a multimodal homeostatic response that involves orchestrated neuroendocrine (i.e. systemic release of vasopressin) and autonomic (i.e. sympathetic outflow to the kidneys) components. The precise mechanisms that underlie interpopulation cross-talk between these two distinct neuronal populations, however, remain largely unknown. The present review summarises and discusses a series of recent studies that have identified the dendritic release of neuropeptides as a novel interpopulation signalling modality in the PVN. A current working model is described in which it is proposed that the activity-dependent dendritic release of vasopressin from neurosecretory neurones in the PVN acts in a diffusible manner to increase the activity of distant presympathetic neurones, resulting in an integrated sympathoexcitatory population response, particularly within the context of a hyperosmotic challenge. The cellular mechanism underlying this novel form of intercellular communication, as well as its physiological and pathophysiological implications, is discussed.
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Affiliation(s)
- J E Stern
- Department of Physiology, Georgia Regents University, Augusta, GA, USA
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27
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Murphy NP. Dynamic measurement of extracellular opioid activity: status quo, challenges, and significance in rewarded behaviors. ACS Chem Neurosci 2015; 6:94-107. [PMID: 25585132 DOI: 10.1021/cn500295q] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Opioid peptides are the endogenous ligands of opioid receptors, which are also the molecular target of naturally occurring and synthetic opiates, such as morphine and heroin. Since their discovery in the 1970s, opioid peptides, which are found widely throughout the central nervous system and the periphery, have been intensely studied because of their involvement in pain and pleasure. Over the years, our understanding of opioid peptides has widened to cover a multitude of functions, including learning and memory, affective state, gastrointestinal transit, feeding, immune function, and metabolism. Unsurprisingly, aberrant opioid activity is implicated in numerous pathologies, including drug addiction, overeating, pain, depression, and obesity. To date, virtually all preclinical and clinical studies aimed at understanding the function of endogenous opioids have relied upon manipulating endogenous opioid fluxes using opioid receptor ligands or genetic manipulations of opioid receptors and endogenous opioids. Difficulties in directly monitoring endogenous opioid fluxes, particularly in the central nervous system, have presented a major obstacle to fully understanding endogenous opioid function. This review summarizes these challenges and offers suggestions for future goals while focusing on the neurobiology of reward, specifically drawing attention to studies that have succeeded in dynamically measuring opioid peptides.
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Affiliation(s)
- Niall P. Murphy
- Department of Psychiatry
and Biobehavioral Sciences, Univesity of California, Los Angeles, 2579 MacDonald
Research Laboratories, 675 Charles E. Young Drive
South Los Angeles, California 90095, United States
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Ryglewski S, Kadas D, Hutchinson K, Schuetzler N, Vonhoff F, Duch C. Dendrites are dispensable for basic motoneuron function but essential for fine tuning of behavior. Proc Natl Acad Sci U S A 2014; 111:18049-54. [PMID: 25453076 PMCID: PMC4273390 DOI: 10.1073/pnas.1416247111] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dendrites are highly complex 3D structures that define neuronal morphology and connectivity and are the predominant sites for synaptic input. Defects in dendritic structure are highly consistent correlates of brain diseases. However, the precise consequences of dendritic structure defects for neuronal function and behavioral performance remain unknown. Here we probe dendritic function by using genetic tools to selectively abolish dendrites in identified Drosophila wing motoneurons without affecting other neuronal properties. We find that these motoneuron dendrites are unexpectedly dispensable for synaptic targeting, qualitatively normal neuronal activity patterns during behavior, and basic behavioral performance. However, significant performance deficits in sophisticated motor behaviors, such as flight altitude control and switching between discrete courtship song elements, scale with the degree of dendritic defect. To our knowledge, our observations provide the first direct evidence that complex dendrite architecture is critically required for fine-tuning and adaptability within robust, evolutionarily constrained behavioral programs that are vital for mating success and survival. We speculate that the observed scaling of performance deficits with the degree of structural defect is consistent with gradual increases in intellectual disability during continuously advancing structural deficiencies in progressive neurological disorders.
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Affiliation(s)
- Stefanie Ryglewski
- Institute of Neurobiology, Johannes Gutenberg University of Mainz, 55099 Mainz, Germany
| | - Dimitrios Kadas
- Institute of Neurobiology, Johannes Gutenberg University of Mainz, 55099 Mainz, Germany
| | - Katie Hutchinson
- Institute of Neurobiology, Johannes Gutenberg University of Mainz, 55099 Mainz, Germany
| | - Natalie Schuetzler
- Institute of Neurobiology, Johannes Gutenberg University of Mainz, 55099 Mainz, Germany
| | - Fernando Vonhoff
- Institute of Neurobiology, Johannes Gutenberg University of Mainz, 55099 Mainz, Germany
| | - Carsten Duch
- Institute of Neurobiology, Johannes Gutenberg University of Mainz, 55099 Mainz, Germany
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Vega-Zuniga T, Mpodozis J, Karten HJ, Marín G, Hain S, Luksch H. Morphology, projection pattern, and neurochemical identity of Cajal's "centrifugal neurons": the cells of origin of the tectoventrogeniculate pathway in pigeon (Columba livia) and chicken (Gallus gallus). J Comp Neurol 2014; 522:2377-96. [PMID: 24435811 DOI: 10.1002/cne.23539] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 01/13/2014] [Accepted: 01/13/2014] [Indexed: 01/13/2023]
Abstract
The nucleus geniculatus lateralis pars ventralis (GLv) is a prominent retinal target in all amniotes. In birds, it is in receipt of a dense and topographically organized retinal projection. The GLv is also the target of substantial and topographically organized projections from the optic tectum and the visual wulst (hyperpallium). Tectal and retinal afferents terminate homotopically within the external GLv-neuropil. Efferents from the GLv follow a descending course through the tegmentum and can be traced into the medial pontine nucleus. At present, the cells of origin of the Tecto-GLv projection are only partially described. Here we characterized the laminar location, morphology, projection pattern, and neurochemical identity of these cells by means of neural tracer injections and intracellular fillings in slice preparations and extracellular tracer injections in vivo. The Tecto-GLv projection arises from a distinct subset of layer 10 bipolar neurons, whose apical dendrites show a complex transverse arborization at the level of layer 7. Axons of these bipolar cells arise from the apical dendrites and follow a course through the optic tract to finally form very fine and restricted terminal endings inside the GLv-neuropil. Double-label experiments showed that these bipolar cells were choline acetyltransferase (ChAT)-immunoreactive. Our results strongly suggest that Tecto-GLv neurons form a pathway by which integrated tectal activity rapidly feeds back to the GLv and exerts a focal cholinergic modulation of incoming retinal inputs.
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Affiliation(s)
- Tomas Vega-Zuniga
- Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany
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Vargas-Martínez F, Uvnäs-Moberg K, Petersson M, Olausson HA, Jiménez-Estrada I. Neuropeptides as neuroprotective agents: Oxytocin a forefront developmental player in the mammalian brain. Prog Neurobiol 2014; 123:37-78. [DOI: 10.1016/j.pneurobio.2014.10.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 10/06/2014] [Indexed: 02/07/2023]
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31
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Toshinai K, Saito T, Yamaguchi H, Sasaki K, Tsuchimochi W, Minamino N, Ueta Y, Nakazato M. Neuroendocrine regulatory peptide-1 and -2 (NERPs) inhibit the excitability of magnocellular neurosecretory cells in the hypothalamus. Brain Res 2014; 1563:52-60. [DOI: 10.1016/j.brainres.2014.03.038] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 03/21/2014] [Accepted: 03/25/2014] [Indexed: 10/25/2022]
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Carta M, Lanore F, Rebola N, Szabo Z, Da Silva SV, Lourenço J, Verraes A, Nadler A, Schultz C, Blanchet C, Mulle C. Membrane lipids tune synaptic transmission by direct modulation of presynaptic potassium channels. Neuron 2014; 81:787-99. [PMID: 24486086 DOI: 10.1016/j.neuron.2013.12.028] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2013] [Indexed: 12/20/2022]
Abstract
Voltage-gated potassium (Kv) channels are involved in action potential (AP) repolarization in excitable cells. Exogenous application of membrane-derived lipids, such as arachidonic acid (AA), regulates the gating of Kv channels. Whether membrane-derived lipids released under physiological conditions have an impact on neuronal coding through this mechanism is unknown. We show that AA released in an activity-dependent manner from postsynaptic hippocampal CA3 pyramidal cells acts as retrograde messenger, inducing a robust facilitation of mossy fiber (Mf) synaptic transmission over several minutes. AA acts by broadening presynaptic APs through the direct modulation of Kv channels. This form of short-term plasticity can be triggered when postsynaptic cell fires with physiologically relevant patterns and sets the threshold for the induction of the presynaptic form of long-term potentiation (LTP) at hippocampal Mf synapses. Hence, direct modulation of presynaptic Kv channels by activity-dependent release of lipids serves as a physiological mechanism for tuning synaptic transmission.
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Affiliation(s)
- Mario Carta
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Frederic Lanore
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Nelson Rebola
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Zsolt Szabo
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Silvia Viana Da Silva
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Joana Lourenço
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Agathe Verraes
- Institut Jacques Monod, UMR 7592, CNRS and INSERM ERL U950, University Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - André Nadler
- EMBL Heidelberg, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Carsten Schultz
- EMBL Heidelberg, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Christophe Blanchet
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - Christophe Mulle
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France.
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Karsai G, Pollák E, Wacker M, Vömel M, Selcho M, Berta G, Nachman RJ, Isaac RE, Molnár L, Wegener C. Diverse in- and output polarities and high complexity of local synaptic and non-synaptic signaling within a chemically defined class of peptidergic Drosophila neurons. Front Neural Circuits 2013; 7:127. [PMID: 23914156 PMCID: PMC3729985 DOI: 10.3389/fncir.2013.00127] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 07/12/2013] [Indexed: 12/31/2022] Open
Abstract
Peptidergic neurons are not easily integrated into current connectomics concepts, since their peptide messages can be distributed via non-synaptic paracrine signaling or volume transmission. Moreover, the polarity of peptidergic interneurons in terms of in- and out-put sites can be hard to predict and is very little explored. We describe in detail the morphology and the subcellular distribution of fluorescent vesicle/dendrite markers in CCAP neurons (NCCAP), a well defined set of peptidergic neurons in the Drosophila larva. NCCAP can be divided into five morphologically distinct subsets. In contrast to other subsets, serial homologous interneurons in the ventral ganglion show a mixed localization of in- and output markers along ventral neurites that defy a classification as dendritic or axonal compartments. Ultrastructurally, these neurites contain both pre- and postsynaptic sites preferably at varicosities. A significant portion of the synaptic events are due to reciprocal synapses. Peptides are mostly non-synaptically or parasynaptically released, and dense-core vesicles and synaptic vesicle pools are typically well separated. The responsiveness of the NCCAP to ecdysis-triggering hormone may be at least partly dependent on a tonic synaptic inhibition, and is independent of ecdysteroids. Our results reveal a remarkable variety and complexity of local synaptic circuitry within a chemically defined set of peptidergic neurons. Synaptic transmitter signaling as well as peptidergic paracrine signaling and volume transmission from varicosities can be main signaling modes of peptidergic interneurons depending on the subcellular region. The possibility of region-specific variable signaling modes should be taken into account in connectomic studies that aim to dissect the circuitry underlying insect behavior and physiology, in which peptidergic neurons act as important regulators.
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Affiliation(s)
- Gergely Karsai
- Department of Comparative Anatomy and Developmental Biology, Institute of Biology, Faculty of Science, University of Pécs Pécs, Hungary ; Neurobiology and Genetics, Biocenter, Theodor-Boveri-Institute, University of Würzburg Würzburg, Germany
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34
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Brown CH, Bains JS, Ludwig M, Stern JE. Physiological regulation of magnocellular neurosecretory cell activity: integration of intrinsic, local and afferent mechanisms. J Neuroendocrinol 2013; 25:678-710. [PMID: 23701531 PMCID: PMC3852704 DOI: 10.1111/jne.12051] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 05/08/2013] [Accepted: 05/20/2013] [Indexed: 01/12/2023]
Abstract
The hypothalamic supraoptic and paraventricular nuclei contain magnocellular neurosecretory cells (MNCs) that project to the posterior pituitary gland where they secrete either oxytocin or vasopressin (the antidiuretic hormone) into the circulation. Oxytocin is important for delivery at birth and is essential for milk ejection during suckling. Vasopressin primarily promotes water reabsorption in the kidney to maintain body fluid balance, but also increases vasoconstriction. The profile of oxytocin and vasopressin secretion is principally determined by the pattern of action potentials initiated at the cell bodies. Although it has long been known that the activity of MNCs depends upon afferent inputs that relay information on reproductive, osmotic and cardiovascular status, it has recently become clear that activity depends critically on local regulation by glial cells, as well as intrinsic regulation by the MNCs themselves. Here, we provide an overview of recent advances in our understanding of how intrinsic and local extrinsic mechanisms integrate with afferent inputs to generate appropriate physiological regulation of oxytocin and vasopressin MNC activity.
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Affiliation(s)
- C H Brown
- Department of Physiology and Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand.
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35
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Crespo C, Liberia T, Blasco-Ibáñez JM, Nácher J, Varea E. The Circuits of the Olfactory Bulb. The Exception as a Rule. Anat Rec (Hoboken) 2013; 296:1401-12. [DOI: 10.1002/ar.22732] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 02/28/2013] [Accepted: 03/07/2013] [Indexed: 12/22/2022]
Affiliation(s)
- Carlos Crespo
- Department of Cell Biology, Faculty of Biology; University of Valencia; C/ Dr. Moliner, 50, 46100 Burjassot Valencia Spain
| | - Teresa Liberia
- Department of Cell Biology, Faculty of Biology; University of Valencia; C/ Dr. Moliner, 50, 46100 Burjassot Valencia Spain
| | - José Miguel Blasco-Ibáñez
- Department of Cell Biology, Faculty of Biology; University of Valencia; C/ Dr. Moliner, 50, 46100 Burjassot Valencia Spain
| | - Juan Nácher
- Department of Cell Biology, Faculty of Biology; University of Valencia; C/ Dr. Moliner, 50, 46100 Burjassot Valencia Spain
| | - Emilio Varea
- Department of Cell Biology, Faculty of Biology; University of Valencia; C/ Dr. Moliner, 50, 46100 Burjassot Valencia Spain
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36
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Iremonger KJ, Wamsteeker Cusulin JI, Bains JS. Changing the tune: plasticity and adaptation of retrograde signals. Trends Neurosci 2013; 36:471-9. [PMID: 23706151 DOI: 10.1016/j.tins.2013.04.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/18/2013] [Accepted: 04/18/2013] [Indexed: 11/25/2022]
Abstract
Retrograde signaling is a fundamental means by which neurons communicate. The acceptance of this statement has required a revision of how we view transmission and storage of information at the synapse. Although there is a substantial body of literature on the diverse molecules that serve as retrograde signals, less is known about how retrograde signal capacity can be modified. Is retrograde signaling plastic? How does this plasticity manifest? Are there behavioral correlates that may bias a neuron towards 'changing its tune', retrogradely speaking, of course? Here, we review recent findings that retrograde signaling is a highly labile process that adds additional layers of complexity that must be untangled to understand information processing in the nervous system.
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Affiliation(s)
- Karl J Iremonger
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, PO Box 913, Dunedin 9054, New Zealand
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37
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Croushore CA, Sweedler JV. Microfluidic systems for studying neurotransmitters and neurotransmission. LAB ON A CHIP 2013; 13:1666-76. [PMID: 23474943 PMCID: PMC3632338 DOI: 10.1039/c3lc41334a] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Neurotransmitters and neuromodulators are molecules within the nervous system that play key roles in cell-to-cell communication. Upon stimulation, neurons release these signaling molecules, which then act at local or distant locations to elicit a physiological response. Ranging from small molecules, such as diatomic gases and amino acids, to larger peptides, these chemical messengers are involved in many functional processes including growth, reproduction, memory and behavior. Understanding signaling molecules and the conditions that govern their release in healthy or damaged networks promises to deliver insights into neural network formation and function. Microfluidic devices can provide optimal cell culture conditions, reduced volume systems, and precise control over the chemical and physical nature of the extracellular environment, making them well-suited for studying neurotransmission and other forms of cell-to-cell signaling. Here we review selected microfluidic approaches that are suitable for monitoring cell-to-cell signaling molecules. We highlight devices that improve in vivo sample collection as well as compartmentalized devices designed to isolate individual neurons or co-cultures in vitro, including a focus on systems used for studying neural injury and regeneration, and devices that allow selective chemical stimulations and the characterization of released molecules.
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Affiliation(s)
- Callie A. Croushore
- Department of Chemistry and the Beckman Institute for Advanced Science
and Technology, University of Illinois at Urbana-Champaign, Urbana IL 61801,
USA
| | - Jonathan V. Sweedler
- Department of Chemistry and the Beckman Institute for Advanced Science
and Technology, University of Illinois at Urbana-Champaign, Urbana IL 61801,
USA
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38
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Wamsteeker Cusulin JI, Füzesi T, Inoue W, Bains JS. Glucocorticoid feedback uncovers retrograde opioid signaling at hypothalamic synapses. Nat Neurosci 2013; 16:596-604. [PMID: 23563581 PMCID: PMC4844536 DOI: 10.1038/nn.3374] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 03/05/2013] [Indexed: 01/11/2023]
Abstract
Stressful experience initiates a neuroendocrine response culminating in the release of glucocorticoid hormones into the blood. Glucocorticoids feed back to the brain causing adaptations that prevent excessive hormone responses to subsequent challenges. How these changes occur remains unknown. We report that glucocorticoid receptor activation in rodent hypothalamic neuroendocrine neurons following in vivo stress is a metaplastic signal that allows GABA synapses to undergo activity–dependent long–term depression (LTDGABA). LTDGABA is unmasked through glucocorticoid receptor inhibition of Regulator of G–protein Signaling 4 (RGS4), which amplifies signaling through postsynaptic metabotropic glutamate receptors (mGluRs). This drives somatodendritic opioid release, resulting in a persistent retrograde suppression of synaptic transmission through presynaptic μ–receptors. Together our data provide new evidence for retrograde opioid signaling at synapses in neuroendocrine circuits and represent a potential mechanism underlying GC contributions to stress adaptation.
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39
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Laux-Biehlmann A, Mouheiche J, Vérièpe J, Goumon Y. Endogenous morphine and its metabolites in mammals: History, synthesis, localization and perspectives. Neuroscience 2013; 233:95-117. [DOI: 10.1016/j.neuroscience.2012.12.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 12/07/2012] [Indexed: 10/27/2022]
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40
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Ronaldson PT, Davis TP. Targeted drug delivery to treat pain and cerebral hypoxia. Pharmacol Rev 2013; 65:291-314. [PMID: 23343976 DOI: 10.1124/pr.112.005991] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Limited drug penetration is an obstacle that is often encountered in treatment of central nervous system (CNS) diseases including pain and cerebral hypoxia. Over the past several years, biochemical characteristics of the brain (i.e., tight junction protein complexes at brain barrier sites, expression of influx and efflux transporters) have been shown to be directly involved in determining CNS permeation of therapeutic agents; however, the vast majority of these studies have focused on understanding those mechanisms that prevent drugs from entering the CNS. Recently, this paradigm has shifted toward identifying and characterizing brain targets that facilitate CNS drug delivery. Such targets include the organic anion-transporting polypeptides (OATPs in humans; Oatps in rodents), a family of sodium-independent transporters that are endogenously expressed in the brain and are involved in drug uptake. OATP/Oatp substrates include drugs that are efficacious in treatment of pain and/or cerebral hypoxia (i.e., opioid analgesic peptides, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors). This clearly suggests that OATP/Oatp isoforms are viable transporter targets that can be exploited for optimization of drug delivery to the brain and, therefore, improved treatment of CNS diseases. This review summarizes recent knowledge in this area and emphasizes the potential that therapeutic targeting of OATP/Oatp isoforms may have in facilitating CNS drug delivery and distribution. Additionally, information presented in this review will point to novel strategies that can be used for treatment of pain and cerebral hypoxia.
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Affiliation(s)
- Patrick T Ronaldson
- Department of Medical Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Avenue, P.O. Box 245050, Tucson, AZ 85724-5050, USA.
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41
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Action potential-independent and pharmacologically unique vesicular serotonin release from dendrites. J Neurosci 2013; 32:15737-46. [PMID: 23136413 DOI: 10.1523/jneurosci.0020-12.2012] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Serotonin released within the dorsal raphe nucleus (DR) induces feedback inhibition of serotonin neuron activity and consequently regulates mood-controlling serotonin release throughout the forebrain. Serotonin packaged in vesicles is released in response to action potentials by the serotonin neuron soma and terminals, but the potential for release by dendrites is unknown. Here, three-photon microscopy imaging of endogenous serotonin in living rat brain slice, immunofluorescence, and immunogold electron microscopy detection of VMAT2 (vesicular monoamine transporter 2) establish the presence of vesicular serotonin within DR dendrites. Furthermore, activation of glutamate receptors is shown to induce vesicular serotonin release from dendrites. However, unlike release from the soma and terminals, dendritic serotonin release is independent of action potentials, relies on L-type Ca(2+) channels, is induced preferentially by NMDA, and displays distinct sensitivity to the selective serotonin reuptake inhibitor (SSRI) antidepressant fluoxetine. The unique control of dendritic serotonin release has important implications for DR physiology and the antidepressant action of SSRIs, dihydropyridines, and NMDA receptor antagonists.
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42
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Zeng Q, Han J, Wang B, An S, Duan Y, Dong S, Ma J, Yang L, Cao X. Water Maze Spatial Learning Enhances Social Recognition Ability in Aged Rats. NEUROPHYSIOLOGY+ 2012. [DOI: 10.1007/s11062-012-9319-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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43
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Perrenoud Q, Rossier J, Férézou I, Geoffroy H, Gallopin T, Vitalis T, Rancillac A. Activation of cortical 5-HT(3) receptor-expressing interneurons induces NO mediated vasodilatations and NPY mediated vasoconstrictions. Front Neural Circuits 2012; 6:50. [PMID: 22907992 PMCID: PMC3415676 DOI: 10.3389/fncir.2012.00050] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 07/10/2012] [Indexed: 11/17/2022] Open
Abstract
GABAergic interneurons are local integrators of cortical activity that have been reported to be involved in the control of cerebral blood flow (CBF) through their ability to produce vasoactive molecules and their rich innervation of neighboring blood vessels. They form a highly diverse population among which the serotonin 5-hydroxytryptamine 3A receptor (5-HT3A)-expressing interneurons share a common developmental origin, in addition to the responsiveness to serotonergic ascending pathway. We have recently shown that these neurons regroup two distinct subpopulations within the somatosensory cortex: Neuropeptide Y (NPY)-expressing interneurons, displaying morphological properties similar to those of neurogliaform cells and Vasoactive Intestinal Peptide (VIP)-expressing bipolar/bitufted interneurons. The aim of the present study was to determine the role of these neuronal populations in the control of vascular tone by monitoring blood vessels diameter changes, using infrared videomicroscopy in mouse neocortical slices. Bath applications of 1-(3-Chlorophenyl)biguanide hydrochloride (mCPBG), a 5-HT3R agonist, induced both constrictions (30%) and dilations (70%) of penetrating arterioles within supragranular layers. All vasoconstrictions were abolished in the presence of the NPY receptor antagonist (BIBP 3226), suggesting that they were elicited by NPY release. Vasodilations persisted in the presence of the VIP receptor antagonist VPAC1 (PG-97-269), whereas they were blocked in the presence of the neuronal Nitric Oxide (NO) Synthase (nNOS) inhibitor, L-NNA. Altogether, these results strongly suggest that activation of neocortical 5-HT3A-expressing interneurons by serotoninergic input could induces NO mediated vasodilatations and NPY mediated vasoconstrictions.
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Affiliation(s)
- Quentin Perrenoud
- Laboratoire de Neurobiologie, CNRS UMR 7637, ESPCI ParisTech Paris, France
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44
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Tobin V, Leng G, Ludwig M. The involvement of actin, calcium channels and exocytosis proteins in somato-dendritic oxytocin and vasopressin release. Front Physiol 2012; 3:261. [PMID: 22934017 PMCID: PMC3429037 DOI: 10.3389/fphys.2012.00261] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 06/22/2012] [Indexed: 11/25/2022] Open
Abstract
Hypothalamic magnocellular neurons release vasopressin and oxytocin not only from their axon terminals into the blood, but also from their somata and dendrites into the extracellular space of the brain, and this can be regulated independently. Differential release of neurotransmitters from different compartments of a single neuron requires subtle regulatory mechanisms. Somato-dendritic, but not axon terminal release can be modulated by changes in intracellular calcium concentration [(Ca2+)] by release of calcium from intracellular stores, resulting in priming of dendritic pools for activity-dependent release. This review focuses on our current understanding of the mechanisms of priming and the roles of actin remodeling, voltage-operated calcium channels (VOCCs) and SNARE proteins in the regulation somato-dendritic and axon terminal peptide release.
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Affiliation(s)
- Vicky Tobin
- Centre for Integrative Physiology, University of Edinburgh Edinburgh, UK
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45
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Kojima S, Stewart RA, Demas GE, Alberts JR. Maternal contact differentially modulates central and peripheral oxytocin in rat pups during a brief regime of mother-pup interaction that induces a filial huddling preference. J Neuroendocrinol 2012; 24:831-40. [PMID: 22260655 PMCID: PMC4060530 DOI: 10.1111/j.1365-2826.2012.02280.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Central oxytocin mediates the acquisition of a filial preference for maternal odour in rat pups, manifested by their huddling preferences. The present study was designed to examine whether maternal care modulates oxytocin concentrations in rat pups and, if so, how different types of maternal contact are associated with the pups' oxytocin concentrations. Pairs of 14-day-old littermates were removed from their home cage for 1 h and then placed with a lactating foster mother for 2 h, or they remained isolated at room temperature. Enzyme immunoassays revealed that maternal care and maternal separation can differentially modulate pups' oxytocin concentrations. Both hypothalamic and serum oxytocin increased during the 1-h separation. Pups placed with a foster mother after the separation maintained the same concentrations in the hypothalamus and serum through the fostering period. By contrast, pups placed with no mother showed a further increase in hypothalamic oxytocin but serum oxytocin decreased. Behavioural analyses revealed that skin-to-skin contact with the mother, but not simple physical contact or maternal licking/grooming, was positively correlated with the pups' hypothalamic oxytocin concentrations. These neuroendocrine data match previous findings showing that skin-to-skin contact with mother facilitates the acquisition of the pups' huddling preference for a maternally-associated odour. Taken together, the present study suggests that maternal skin-to-skin contact stimulates pups' central oxytocin, at the same time as creating the conditions for inducing a preference for maternal odour and establishing a social affiliation in rat pups; the natural schedule of maternal separation and reunion may modulate pups' oxytocin concentrations, providing scaffolding for the acquisition of their filial huddling preference.
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Affiliation(s)
- S Kojima
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA.
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Tobin V, Schwab Y, Lelos N, Onaka T, Pittman QJ, Ludwig M. Expression of exocytosis proteins in rat supraoptic nucleus neurones. J Neuroendocrinol 2012; 24:629-41. [PMID: 21988098 PMCID: PMC3569506 DOI: 10.1111/j.1365-2826.2011.02237.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In magnocellular neurones of the supraoptic nucleus (SON), the neuropeptides vasopressin and oxytocin are synthesised and packaged into large dense-cored vesicles (LDCVs). These vesicles undergo regulated exocytosis from nerve terminals in the posterior pituitary gland and from somata/dendrites in the SON. Regulated exocytosis of LDCVs is considered to involve the soluble N-ethylmaleimide sensitive fusion protein attachment protein receptor (SNARE) complex [comprising vesicle associated membrane protein 2 (VAMP-2), syntaxin-1 and soluble N-ethylmaleimide attachment protein-25 (SNAP-25)] and regulatory proteins [such as synaptotagmin-1, munc-18 and Ca(2+) -dependent activator protein for secretion (CAPS-1)]. Using fluorescent immunocytochemistry and confocal microscopy, in both oxytocin and vasopressin neurones, we observed VAMP-2, SNAP-25 and syntaxin-1-immunoreactivity in axon terminals. The somata and dendrites contained syntaxin-1 and other regulatory exocytosis proteins, including munc-18 and CAPS-1. However, the distribution of VAMP-2 and synaptotagmin-1 in the SON was limited to putative pre-synaptic contacts because they co-localised with synaptophysin (synaptic vesicle marker) and had no co-localisation with either oxytocin or vasopressin. SNAP-25 immunoreactivity in the SON was limited to glial cell processes and was not detected in oxytocin or vasopressin somata/dendrites. The present results indicate differences in the expression and localisation of exocytosis proteins between the axon terminals and somata/dendritic compartment. The absence of VAMP-2 and SNAP-25 immunoreactivity from the somata/dendrites suggests that there might be different SNARE protein isoforms expressed in these compartments. Alternatively, exocytosis of LDCVs from somata/dendrites may use a different mechanism from that described by the SNARE complex theory.
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Affiliation(s)
- V. Tobin
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Y. Schwab
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Canada
| | - N. Lelos
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - T. Onaka
- Department of Physiology, Jichi Medical University, Tochigi, Japan
| | - Q. J. Pittman
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Canada
| | - M. Ludwig
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
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Kalló I, Vida B, Deli L, Molnár CS, Hrabovszky E, Caraty A, Ciofi P, Coen CW, Liposits Z. Co-localisation of kisspeptin with galanin or neurokinin B in afferents to mouse GnRH neurones. J Neuroendocrinol 2012; 24:464-76. [PMID: 22129075 DOI: 10.1111/j.1365-2826.2011.02262.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The gonadotrophin-releasing hormone (GnRH) secreting neurones, which form the final common pathway for the central regulation of reproduction, are directly targeted by kisspeptin (KP) via the G protein-coupled receptor, GPR54. In these multiple labelling studies, we used ovariectomised mice treated with 17β-oestradiol (OVX + E(2)) or vehicle (OVX + oil) to determine: (i) the ultrastructural characteristics of KP-immunoreactive (IR) afferents to GnRH neurones; (ii) their galanin or neurokinin B (NKB) content; and (iii) the co-expression of galanin or NKB with KP in the two major subpopulations of KP neurones located in the rostral periventricular area of the third ventricle (RP3V) and the arcuate nucleus (Arc). Electron microscopic investigation of the neuronal juxtapositions revealed axosomatic and axodendritic synapses; these showed symmetrical or asymmetrical characteristics, suggesting a phenotypic diversity of KP afferents. Heterogeneity of afferents was also demonstrated by differential co-expression of neuropeptides; in OVX + E(2) mice, KP afferents to GnRH neurones showed galanin-immunoreactivity with an incidence of 22.50 ± 2.41% and NKB-immunoreactivity with an incidence of 5.61 ± 2.57%. In OVX + oil animals, galanin-immunoreactivity in the KP afferents showed a major reduction, appearing in only 5.78 ± 1.57%. Analysis for co-localisation of galanin or NKB with KP was extended to the perikaryal level in animal models, which showed the highest KP incidence; these were OVX + E(2) females for the RP3V and OVX + oil females for the ARC. In the RP3V of colchicine-treated OVX + E(2) animals, 87.84 ± 2.65% of KP-IR neurones were galanin positive. In the Arc of the colchicine-treated OVX + oil animals, galanin immunoreactivity was detected in only 12.50 ± 1.92% of the KP expressing neurones. By contrast, the incidence of co-localisation with NKB in the Arc of those animals was 98.09 ± 1.30%. In situ hybridisation histochemistry of sections from OVX + E(2) animals identified galanin message in more than a third of the KP neurones in the RP3V (38.67 ± 11.57%) and in the Arc (42.50 ± 12.52%). These data suggest that GnRH neurones are innervated by chemically heterogeneous KP cell populations, with a small proportion deriving from the Arc group. The presence of galanin within KP axons innervating GnRH neurones and the oestrogen-dependent regulation of that presence add a new dimension to the roles played by galanin in the central regulation of reproduction.
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Affiliation(s)
- I Kalló
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
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Abstract
Dendritic exocytosis underpins a broad range of integrative and homeostatic synaptic functions. Emerging data highlight the essential role of SNAREs in trafficking and fusion of secretory organelles with release of peptides and neurotransmitters from dendrites. This Perspective analyzes recent evidence inferring axo-dendritic polarization of vesicular release machinery and pinpoints progress made with existing challenges in this rapidly progressing field of dendritic research. Interpreting the relation of new molecular data to physiological results on secretion from dendrites would greatly advance our understanding of this facet of neuronal mechanisms.
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Affiliation(s)
- Saak V. Ovsepian
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - J. Oliver Dolly
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland
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Fuenzalida LC, Keen KL, Terasawa E. Colocalization of FM1-43, Bassoon, and GnRH-1: GnRH-1 release from cell bodies and their neuroprocesses. Endocrinology 2011; 152:4310-21. [PMID: 21896672 PMCID: PMC3199012 DOI: 10.1210/en.2011-1416] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pulsatile release of GnRH-1 is critical for reproductive function. However, the cellular mechanism of GnRH-1 neurosecretion is still elusive. In this study, we examined the neurosecretory process of GnRH-1 neurons using time-lapse image acquisition followed by immunocytochemistry with confocal microscopy. To monitor exocytotic processes, cultured GnRH-1 neurons derived from monkey embryos were labeled with the lipophilic dye, FM1-43, or its fixable form FM1-43Fx, in the presence or absence of depolarization signals, and changes in vesicles labeled with FM1-43 were analyzed. The results show FM1-43 was taken up into the cell and labeled puncta in the soma and neuroprocesses in the absence of depolarization signals, indicating that GnRH-1 neurons were spontaneously active. Depolarization of GnRH-1 neurons with high K+ or veratridine challenge increased the intensity and size of puncta in both soma and neuroprocesses, and the veratridine-induced changes in puncta were blocked by tetrodotoxin, indicating that changes in the puncta intensity and size reflect neurosecretory activity. Subsequent double immunocytochemistry for GnRH-1 and the synaptic vesicle marker, vesicle-associated membrane protein, demonstrated that the FM1-43Fx-labeled puncta were synaptic vesicles with the GnRH-1 peptide. Additional double immunocytochemistry for GnRH-1 and the marker of the neurosecretory active zone, Bassoon, indicated that the FM1-43Fx-labeled puncta were located at the sites of neurosecretory active zones in GnRH-1 neurons. These results suggest that GnRH-1 neurons have the capacity to release the peptide from the soma and dendrites. Collectively, we hypothesize that soma-dendritic release of the peptide may be a mechanism of synchronized activity among GnRH-1 neurons.
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Affiliation(s)
- Lidia C Fuenzalida
- Department of Pediatrics and Wisconsin National Primate Research Center, 1223 Capitol Court, Madison, Wisconsin 53715-1299, USA
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Tobin VA, Douglas AJ, Leng G, Ludwig M. The involvement of voltage-operated calcium channels in somato-dendritic oxytocin release. PLoS One 2011; 6:e25366. [PMID: 22028774 PMCID: PMC3197583 DOI: 10.1371/journal.pone.0025366] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 09/02/2011] [Indexed: 11/18/2022] Open
Abstract
Magnocellular neurons of the supraoptic nucleus (SON) secrete oxytocin and vasopressin from axon terminals in the neurohypophysis, but they also release large amounts of peptide from their somata and dendrites, and this can be regulated both by activity-dependent Ca2+ influx and by mobilization of intracellular Ca2+. This somato-dendritic release can also be primed by agents that mobilise intracellular Ca2+, meaning that the extent to which it is activity-dependent, is physiologically labile. We investigated the role of different Ca2+ channels in somato-dendritic release; blocking N-type channels reduced depolarisation-induced oxytocin release from SONs in vitro from adult and post-natal day 8 (PND-8) rats, blocking L-type only had effect in PND-8 rats, while blocking other channel types had no significant effect. When oxytocin release was primed by prior exposure to thapsigargin, both N- and L-type channel blockers reduced release, while P/Q and R-type blockers were ineffective. Using confocal microscopy, we found immunoreactivity for Cav1.2 and 1.3 channel subunits (which both form L-type channels), 2.1 (P/Q type), 2.2 (N-type) and 2.3 (R-type) in the somata and dendrites of both oxytocin and vasopressin neurons, and the intensity of the immunofluorescence signal for different subunits differed between PND-8, adult and lactating rats. Using patch-clamp electrophysiology, the N-type Ca2+ current density increased after thapsigargin treatment, but did not alter the voltage sensitivity of the channel. These results suggest that the expression, location or availability of N-type Ca2+ channels is altered when required for high rates of somato-dendritic peptide release.
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Affiliation(s)
- Vicky A. Tobin
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Alison J. Douglas
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Gareth Leng
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Mike Ludwig
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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