1
|
Siecinski SK, Giamberardino SN, Spanos M, Hauser AC, Gibson JR, Chandrasekhar T, Trelles MDP, Rockhill CM, Palumbo ML, Cundiff AW, Montgomery A, Siper P, Minjarez M, Nowinski LA, Marler S, Kwee LC, Shuffrey LC, Alderman C, Weissman J, Zappone B, Mullett JE, Crosson H, Hong N, Luo S, She L, Bhapkar M, Dean R, Scheer A, Johnson JL, King BH, McDougle CJ, Sanders KB, Kim SJ, Kolevzon A, Veenstra-VanderWeele J, Hauser ER, Sikich L, Gregory SG. Genetic and epigenetic signatures associated with plasma oxytocin levels in children and adolescents with autism spectrum disorder. Autism Res 2023; 16:502-523. [PMID: 36609850 PMCID: PMC10023458 DOI: 10.1002/aur.2884] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 12/19/2022] [Indexed: 01/09/2023]
Abstract
Oxytocin (OT), the brain's most abundant neuropeptide, plays an important role in social salience and motivation. Clinical trials of the efficacy of OT in autism spectrum disorder (ASD) have reported mixed results due in part to ASD's complex etiology. We investigated whether genetic and epigenetic variation contribute to variable endogenous OT levels that modulate sensitivity to OT therapy. To carry out this analysis, we integrated genome-wide profiles of DNA-methylation, transcriptional activity, and genetic variation with plasma OT levels in 290 participants with ASD enrolled in a randomized controlled trial of OT. Our analysis identified genetic variants with novel association with plasma OT, several of which reside in known ASD risk genes. We also show subtle but statistically significant association of plasma OT levels with peripheral transcriptional activity and DNA-methylation profiles across several annotated gene sets. These findings broaden our understanding of the effects of the peripheral oxytocin system and provide novel genetic candidates for future studies to decode the complex etiology of ASD and its interaction with OT signaling and OT-based interventions. LAY SUMMARY: Oxytocin (OT) is an abundant chemical produced by neurons that plays an important role in social interaction and motivation. We investigated whether genetic and epigenetic factors contribute to variable OT levels in the blood. To this, we integrated genetic, gene expression, and non-DNA regulated (epigenetic) signatures with blood OT levels in 290 participants with autism enrolled in an OT clinical trial. We identified genetic association with plasma OT, several of which reside in known autism risk genes. We also show statistically significant association of plasma OT levels with gene expression and epigenetic across several gene pathways. These findings broaden our understanding of the factors that influence OT levels in the blood for future studies to decode the complex presentation of autism and its interaction with OT and OT-based treatment.
Collapse
Affiliation(s)
- Stephen K Siecinski
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC, USA
| | | | - Marina Spanos
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Annalise C Hauser
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC, USA
| | - Jason R Gibson
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC, USA
| | - Tara Chandrasekhar
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - M D Pilar Trelles
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Carol M Rockhill
- Department of Psychiatry, Seattle Children’s Hospital and the University of Washington, Seattle, WA, USA
| | - Michelle L Palumbo
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | | | | | - Paige Siper
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Mendy Minjarez
- Department of Psychiatry, Seattle Children’s Hospital and the University of Washington, Seattle, WA, USA
| | - Lisa A Nowinski
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Sarah Marler
- Department of Psychiatry, Vanderbilt University, Nashville, TN, USA
| | - Lydia C Kwee
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC, USA
| | | | - Cheryl Alderman
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
- Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, USA
| | - Jordana Weissman
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Brooke Zappone
- Department of Psychiatry, Seattle Children’s Hospital and the University of Washington, Seattle, WA, USA
| | - Jennifer E Mullett
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Hope Crosson
- Department of Psychiatry, Columbia University, New York, NY, USA
| | - Natalie Hong
- Department of Psychiatry, Columbia University, New York, NY, USA
| | - Sheng Luo
- Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, USA
- Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC, USA
| | - Lilin She
- Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, USA
| | - Manjushri Bhapkar
- Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, USA
| | - Russell Dean
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Abby Scheer
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Jacqueline L Johnson
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Bryan H King
- Department of Psychiatry, Seattle Children’s Hospital and the University of Washington, Seattle, WA, USA
| | - Christopher J McDougle
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Kevin B Sanders
- Department of Psychiatry, Vanderbilt University, Nashville, TN, USA
| | - Soo-Jeong Kim
- Department of Psychiatry, Seattle Children’s Hospital and the University of Washington, Seattle, WA, USA
| | - Alexander Kolevzon
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | | | - Elizabeth R Hauser
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC, USA
- Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC, USA
| | - Linmarie Sikich
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
- Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, USA
| | - Simon G Gregory
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC, USA
- Department of Neurology, Duke University School of Medicine, Durham, NC, USA
| |
Collapse
|
2
|
Amato S, Averna M, Guidolin D, Pedrazzi M, Pelassa S, Capraro M, Passalacqua M, Bozzo M, Gatta E, Anderlini D, Maura G, Agnati LF, Cervetto C, Marcoli M. Heterodimer of A2A and Oxytocin Receptors Regulating Glutamate Release in Adult Striatal Astrocytes. Int J Mol Sci 2022; 23:ijms23042326. [PMID: 35216441 PMCID: PMC8879615 DOI: 10.3390/ijms23042326] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 02/16/2022] [Accepted: 02/18/2022] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Roles of astrocytes in the modulatory effects of oxytocin (OT) in central nervous system are increasingly considered. Nevertheless, OT effects on gliotransmitter release have been neglected. METHODS In purified astrocyte processes from adult rat striatum, we assessed OT receptor (OTR) and adenosine A2A receptor expression by confocal analysis. The effects of receptors activation on glutamate release from the processes were evaluated; A2A-OTR heteromerization was assessed by co-immunoprecipitation and PLA. Structure of the possible heterodimer of A2A and OT receptors was estimated by a bioinformatic approach. RESULTS Both A2A and OT receptors were expressed on the same astrocyte processes. Evidence for A2A-OTR receptor-receptor interaction was obtained by measuring the release of glutamate: OT inhibited the evoked glutamate release, while activation of A2A receptors, per se ineffective, abolished the OT effect. Biochemical and biophysical evidence for A2A-OTR heterodimers on striatal astrocytes was also obtained. The residues in the transmembrane domains 4 and 5 of both receptors are predicted to be mainly involved in the heteromerization. CONCLUSIONS When considering effects of OT in striatum, modulation of glutamate release from the astrocyte processes and of glutamatergic synapse functioning, and the interaction with A2A receptors on the astrocyte processes should be taken into consideration.
Collapse
Affiliation(s)
- Sarah Amato
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genova, Italy; (S.A.); (S.P.); (G.M.)
| | - Monica Averna
- Department of Experimental Medicine, Section of Biochemistry, University of Genova, Viale Benedetto XV 1, 16132 Genova, Italy; (M.A.); (M.P.); (M.C.); (M.P.)
| | - Diego Guidolin
- Department of Neuroscience, University of Padova, Via Gabelli 63, 35122 Padova, Italy;
| | - Marco Pedrazzi
- Department of Experimental Medicine, Section of Biochemistry, University of Genova, Viale Benedetto XV 1, 16132 Genova, Italy; (M.A.); (M.P.); (M.C.); (M.P.)
| | - Simone Pelassa
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genova, Italy; (S.A.); (S.P.); (G.M.)
| | - Michela Capraro
- Department of Experimental Medicine, Section of Biochemistry, University of Genova, Viale Benedetto XV 1, 16132 Genova, Italy; (M.A.); (M.P.); (M.C.); (M.P.)
| | - Mario Passalacqua
- Department of Experimental Medicine, Section of Biochemistry, University of Genova, Viale Benedetto XV 1, 16132 Genova, Italy; (M.A.); (M.P.); (M.C.); (M.P.)
- Italian Institute of Biostructures and Biosystems, Viale delle Medaglie d’Oro 305, 00136 Roma, Italy
| | - Matteo Bozzo
- Department of Earth, Environment and Life Sciences, University of Genova, Viale Benedetto XV 5, 16132 Genova, Italy;
| | - Elena Gatta
- DIFILAB, Department of Physics, University of Genoa, Via Dodecaneso 33, 16146 Genova, Italy;
| | - Deanna Anderlini
- Centre for Sensorimotor Performance, The University of Queensland, Brisbane, Blair Drive, St. Lucia, QLD 4067, Australia;
| | - Guido Maura
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genova, Italy; (S.A.); (S.P.); (G.M.)
| | - Luigi F. Agnati
- Department of Biomedical, Metabolic Sciences and Neuroscience, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy;
| | - Chiara Cervetto
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genova, Italy; (S.A.); (S.P.); (G.M.)
- Correspondence: (C.C.); (M.M.)
| | - Manuela Marcoli
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genova, Italy; (S.A.); (S.P.); (G.M.)
- Center of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV 9, 16132 Genova, Italy
- Correspondence: (C.C.); (M.M.)
| |
Collapse
|
3
|
Wei HH, Yuan XS, Chen ZK, Chen PP, Xiang Z, Qu WM, Li RX, Zhou GM, Huang ZL. Presynaptic inputs to vasopressin neurons in the hypothalamic supraoptic nucleus and paraventricular nucleus in mice. Exp Neurol 2021; 343:113784. [PMID: 34139240 DOI: 10.1016/j.expneurol.2021.113784] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 05/29/2021] [Accepted: 06/13/2021] [Indexed: 11/29/2022]
Abstract
Arginine vasopressin (AVP) neurons in the hypothalamic supraoptic nucleus (SON) and paraventricular nucleus (PVN) are involved in important physiological behaviors, such as controling osmotic stability and thermoregulation. However, the presynaptic input patterns governing AVP neurons have remained poorly understood due to their heterogeneity, as well as intermingling of AVP neurons with other neurons both in the SON and PVN. In the present study, we employed a retrograde modified rabies-virus system to reveal the brain areas that provide specific inputs to AVP neurons in the SON and PVN. We found that AVP neurons of the SON and PVN received similar input patterns from multiple areas of the brain, particularly massive afferent inputs from the diencephalon and other brain regions of the limbic system; however, PVNAVP neurons received relatively broader and denser inputs compared to SONAVP neurons. Additionally, SONAVP neurons received more projections from the median preoptic nucleus and organum vasculosum of the lamina terminalis (a circumventricular organ), compared to PVNAVP neurons, while PVNAVP neurons received more afferent inputs from the bed nucleus of stria terminalis and dorsomedial nucleus of the hypothalamus, both of which are thermoregulatory nuclei, compared to those of SONAVP neurons. In addition, both SONAVP and PVNAVP neurons received direct afferent projections from the bilateral suprachiasmatic nucleus, which is the master regulator of circadian rhythms and is concomitantly responsible for fluctuations in AVP levels. Taken together, our present results provide a comprehensive understanding of the specific afferent framework of AVP neurons both in the SON and PVN, and lay the foundation for further dissecting the diverse roles of SONAVP and PVNAVP neurons.
Collapse
Affiliation(s)
- Hao-Hua Wei
- Department of Anatomy and Histoembryology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China; Department of Pharmacology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Xiang-Shan Yuan
- Department of Anatomy and Histoembryology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China; Department of Pharmacology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Ze-Ka Chen
- Department of Pharmacology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Pei-Pei Chen
- Department of Pharmacology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Zhe Xiang
- Department of Anatomy and Histoembryology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Wei-Min Qu
- Department of Pharmacology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Rui-Xi Li
- Department of Anatomy and Histoembryology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Guo-Min Zhou
- Department of Anatomy and Histoembryology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Zhi-Li Huang
- Department of Pharmacology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| |
Collapse
|
4
|
Iovino M, Messana T, Tortora A, Giusti C, Lisco G, Giagulli VA, Guastamacchia E, De Pergola G, Triggiani V. Oxytocin Signaling Pathway: From Cell Biology to Clinical Implications. Endocr Metab Immune Disord Drug Targets 2021; 21:91-110. [PMID: 32433011 DOI: 10.2174/1871530320666200520093730] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 04/04/2020] [Accepted: 04/16/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND In addition to the well-known role played in lactation and parturition, Oxytocin (OT) and OT receptor (OTR) are involved in many other aspects such as the control of maternal and social behavior, the regulation of the growth of the neocortex, the maintenance of blood supply to the cortex, the stimulation of limbic olfactory area to mother-infant recognition bond, and the modulation of the autonomic nervous system via the vagal pathway. Moreover, OT and OTR show antiinflammatory, anti-oxidant, anti-pain, anti-diabetic, anti-dyslipidemic and anti-atherogenic effects. OBJECTIVE The aim of this narrative review is to summarize the main data coming from the literature dealing with the role of OT and OTR in physiology and pathologic conditions focusing on the most relevant aspects. METHODS Appropriate keywords and MeSH terms were identified and searched in Pubmed. Finally, references of original articles and reviews were examined. RESULTS We report the most significant and updated data on the role played by OT and OTR in physiology and different clinical contexts. CONCLUSION Emerging evidence indicates the involvement of OT system in several pathophysiological mechanisms influencing brain anatomy, cognition, language, sense of safety and trust and maternal behavior, with the possible use of exogenous administered OT in the treatment of specific neuropsychiatric conditions. Furthermore, it modulates pancreatic β-cell responsiveness and lipid metabolism leading to possible therapeutic use in diabetic and dyslipidemic patients and for limiting and even reversing atherosclerotic lesions.
Collapse
Affiliation(s)
- Michele Iovino
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Tullio Messana
- Infantile Neuropsychiatry, IRCCS - Institute of Neurological Sciences, Bologna, Italy
| | - Anna Tortora
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Consuelo Giusti
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Giuseppe Lisco
- Hospital Unit of Endocrinology, Perrino Hospital, Brindisi, Italy
| | - Vito Angelo Giagulli
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Edoardo Guastamacchia
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Giovanni De Pergola
- Clinical Nutrition Unit, Medical Oncology, Department of Internal Medicine and Clinical Oncology, University of Bari, School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Vincenzo Triggiani
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| |
Collapse
|
5
|
Khodagholi F, Maleki A, Motamedi F, Mousavi MA, Rafiei S, Moslemi M. Oxytocin Prevents the Development of 3-NP-Induced Anxiety and Depression in Male and Female Rats: Possible Interaction of OXTR and mGluR2. Cell Mol Neurobiol 2020; 42:1105-1123. [PMID: 33201416 DOI: 10.1007/s10571-020-01003-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 11/07/2020] [Indexed: 01/01/2023]
Abstract
Huntington disease (HD) is a progressive neurological disorder with dominant motor symptoms. It also has psychiatric manifestations, like anxiety and depression, that can emerge themselves before motor symptoms and impose a major burden on patients. Oxytocin (OXT) is a newly emerged treatment for disorders like autism and schizophrenia and recently is using to alleviate depression and anxiety. In the current study, we investigated the behavioral and molecular effects of OXT on the development of anxiety and depression in 3-nitropropionic acid (3-NP)-induced model of HD. Anxiety- and depression-like behaviors as well as the levels of oxytocin receptor (OXTR), metabotropic glutamate receptor (mGluR) 2, mGluR5, and glutathione (GSH) were measured in striatum, hippocampus, prefrontal cortex, and amygdala. Also, we questioned if sex had any modulatory effect. We found that 3-NP increased anxiety and depression compared to controls. It also reduced the levels of OXTR and mGluR2, increased mGluR5, and reduced GSH in studied brain regions. Pretreatment with OXT before the injection of 3-NP ameliorated anxiety and depression. Additionally, it protected the brain from developing low levels of OXTR, mGluR2, and GSH and high levels of mGluR5 in studied regions. The protective effects of OXT were similar between male and female animals. These data suggest that OXTR, mGluR2, mGluR5, and GSH may contribute to psychiatric manifestations of HD. In addition, pretreatment with OXT could prevent the mood changes in male and female rats.
Collapse
Affiliation(s)
- Fariba Khodagholi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ali Maleki
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fereshteh Motamedi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Maryam Alsadat Mousavi
- Neurobiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Shahrbanoo Rafiei
- Neurobiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mehdi Moslemi
- Neurobiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| |
Collapse
|
6
|
Balapattabi K, Little JT, Bachelor M, Cunningham JT. Brain-Derived Neurotrophic Factor and Supraoptic Vasopressin Neurons in Hyponatremia. Neuroendocrinology 2019; 110:630-641. [PMID: 31557760 PMCID: PMC7385921 DOI: 10.1159/000503723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 09/24/2019] [Accepted: 09/24/2019] [Indexed: 12/16/2022]
Abstract
Hyponatremia due to elevated arginine vasopressin (AVP) secretion increases mortality in liver failure patients. The mechanisms causing dysregulation of AVP secretion are unknown. Our hypothesis is that inappropriate AVP release associated with liver failure is due to increased brain-derived neurotrophic factor (BDNF) in the supraoptic nucleus (SON). BDNF diminishes GABAA inhibition in SON AVP neurons by increasing intracellular chloride through tyrosine receptor kinase B (TrkB) activation and downregulation of K+/Cl- cotransporter 2 (KCC2). This loss of inhibition could increase AVP secretion. This hypothesis was tested using shRNA against BDNF (shBDNF) in the SON in bile duct ligated (BDL) male rats. All BDL rats had significantly increased liver weight (p < 0.05; 6-9) compared to shams. BDL rats with control -shRNA injections (BDL scrambled [SCR]) developed hyponatremia with increased plasma AVP and copeptin (CPP; all p < 0.05; 6-9) compared to sham groups. This is the first study to show that phosphorylation of TrkB is significantly increased along with significant decrease in phosphorylation of KCC2 in BDL SCR rats compared to the sham rats (p < 0.05;6-8). Knockdown of BDNF in the SON of BDL rats (BDL shBDNF) significantly increased plasma osmolality and hematocrit compared to BDL SCR rats (p < 0.05; 6-9). The BDL shBDNF rats had significant (p < 0.05; 6-9) decreases in plasma AVP and CPP concentration compared to BDL SCR rats. The BDNF knockdown also significantly blocked the increase in TrkB phosphorylation and decrease in KCC2 phosphorylation (p < 0.05; 6-8). The results indicate that BDNF produced in the SON contributes to increased AVP secretion and hyponatremia during liver failure.
Collapse
Affiliation(s)
- Kirthikaa Balapattabi
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, USA
| | - Joel T Little
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, USA
| | - Martha Bachelor
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, USA
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas, USA,
| |
Collapse
|
7
|
Ivetic M, Bhattacharyya A, Zemkova H. P2X2 Receptor Expression and Function Is Upregulated in the Rat Supraoptic Nucleus Stimulated Through Refeeding After Fasting. Front Cell Neurosci 2019; 13:284. [PMID: 31297050 PMCID: PMC6607214 DOI: 10.3389/fncel.2019.00284] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 06/12/2019] [Indexed: 01/12/2023] Open
Abstract
Magnocellular neurons in the supraoptic nucleus (SON), which synthesize and release arginine vasopressin (AVP) and oxytocin (OT), express several subtypes of ATP-stimulated purinergic P2X receptors (P2XR) that modulate neuronal activity as well as neurotransmitter and hormone release. However, the physiological impact of this modulation is not well understood. Here, we tested a hypothesis that P2XRs play a role in the sustained release of hormones from SON neurons stimulated through fasting/refeeding. We studied the effect of 2 h of refeeding after 48 h of fasting on P2XR and P2YR mRNA expression and ATP-induced presynaptic and postsynaptic responses in the SON of 30-day-old rats. Quantitative real-time PCR revealed that the expression of P2X2R and AVP mRNA was upregulated, whereas P2X4R, P2X7R, P2Y2R, and OT mRNA levels were not significantly changed and P2Y1R mRNA expression was decreased. Whole-cell patch clamp recordings performed on isolated rat brain slices showed that the amplitude of the ATP-stimulated somatic current and the ATP-induced increases in the frequency of spontaneous GABAergic inhibitory postsynaptic currents were significantly higher in SON neurons from fasted/refed rats than in SON neurons from normally fed rats. No evidence was found for changes in the presynaptic effect of ATP in SON neurons not expressing somatic P2XRs. These results suggest that the increased activity of SON neurons synthesizing AVP is associated with enhanced expression of P2X2Rs on neuronal cell bodies and their GABAergic presynaptic nerve terminals.
Collapse
Affiliation(s)
- Milorad Ivetic
- Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Anirban Bhattacharyya
- Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Hana Zemkova
- Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czechia
| |
Collapse
|
8
|
Intracerebroventricular injection of phoenixin alters feeding behavior and activates nesfatin-1 immunoreactive neurons in rats. Brain Res 2019; 1715:188-195. [DOI: 10.1016/j.brainres.2019.03.034] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 03/21/2019] [Accepted: 03/28/2019] [Indexed: 01/20/2023]
|
9
|
Yuan XS, Wei HH, Xu W, Wang L, Qu WM, Li RX, Huang ZL. Whole-Brain Monosynaptic Afferent Projections to the Cholecystokinin Neurons of the Suprachiasmatic Nucleus. Front Neurosci 2018; 12:807. [PMID: 30455627 PMCID: PMC6230653 DOI: 10.3389/fnins.2018.00807] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 10/16/2018] [Indexed: 11/24/2022] Open
Abstract
The suprachiasmatic nucleus (SCN) is the principal pacemaker driving the circadian rhythms of physiological behaviors. The SCN consists of distinct neurons expressing neuropeptides, including arginine vasopressin (AVP), vasoactive intestinal polypeptide (VIP), gastrin-releasing peptide (GRP), cholecystokinin (CCK), and so on. AVP, VIP, and GRP neurons receive light stimulation from the retina to synchronize endogenous circadian clocks with the solar day, whereas CCK neurons are not directly innervated by retinal ganglion cells and may be involved in the non-photic regulation of the circadian clock. To better understand the function of CCK neurons in non-photic circadian rhythm, it is vital to clarify the direct afferent inputs to CCK neurons in the SCN. Here, we utilized a recently developed rabies virus- and Cre/loxP-based, cell type-specific, retrograde tracing system to map and quantitatively analyze the whole-brain monosynaptic inputs to SCN CCK neurons. We found that SCN CCK neurons received direct inputs from 29 brain nuclei. Among these nuclei, paraventricular nucleus of the hypothalamus (PVH), paraventricular nucleus of the thalamus (PVT), supraoptic nucleus (SON), ventromedial nucleus of the hypothalamus, and seven other nuclei sent numerous inputs to CCK neurons. Moderate inputs originated from the zona incerta, periventricular hypothalamic nucleus, and five other nuclei. A few inputs to CCK neurons originated from the orbital frontal cortex, prelimbic cortex, cingulate cortex, claustrum, and seven other nuclei. In addition, SCN CCK neurons were preferentially innervated by AVP neurons of the ipsilateral PVH and SON rather than their contralateral counterpart, whereas the contralateral PVT sent more projections to CCK neurons than to its ipsilateral counterpart. Taken together, these results expand our knowledge of the specific innervation to mouse SCN CCK neurons and provide an important indication for further investigations on the function of CCK neurons.
Collapse
Affiliation(s)
- Xiang-Shan Yuan
- Department of Pharmacology, Department of Anatomy, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Hao-Hua Wei
- Department of Pharmacology, Department of Anatomy, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Wei Xu
- Department of Pharmacology, Department of Anatomy, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Lu Wang
- Department of Pharmacology, Department of Anatomy, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Wei-Min Qu
- Department of Pharmacology, Department of Anatomy, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Rui-Xi Li
- Department of Pharmacology, Department of Anatomy, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| | - Zhi-Li Huang
- Department of Pharmacology, Department of Anatomy, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
| |
Collapse
|
10
|
Molecular Mechanisms of Oxytocin Signaling at the Synaptic Connection. Neural Plast 2018; 2018:4864107. [PMID: 30057594 PMCID: PMC6051047 DOI: 10.1155/2018/4864107] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 05/27/2018] [Indexed: 12/12/2022] Open
Abstract
Aberrant regulation of oxytocin signaling is associated with the etiology of neurodevelopmental disorders. Synaptic dysfunctions in neurodevelopmental disorders are becoming increasingly known, and their pathogenic mechanisms could be a target of potential therapeutic intervention. Therefore, it is important to pay attention to the role of oxytocin and its receptor in synapse structure, function, and neuron connectivity. An early alteration in oxytocin signaling may disturb neuronal maturation and may have short-term and long-term pathological consequences. At the molecular level, neurodevelopmental disorders include alterations in cytoskeletal rearrangement and neuritogenesis resulting in a diversity of synaptopathies. The presence of oxytocin receptors in the presynaptic and postsynaptic membranes and the direct effects of oxytocin on neuronal excitability by regulating the activity of ion channels in the cell membrane implicate that alterations in oxytocin signaling could be involved in synaptopathies. The ability of oxytocin to modulate neurogenesis, synaptic plasticity, and certain parameters of cytoskeletal arrangement is discussed in the present review.
Collapse
|
11
|
Abstract
The posterior pituitary gland secretes oxytocin and vasopressin (the antidiuretic hormone) into the blood system. Oxytocin is required for normal delivery of the young and for delivery of milk to the young during lactation. Vasopressin increases water reabsorption in the kidney to maintain body fluid balance and causes vasoconstriction to increase blood pressure. Oxytocin and vasopressin secretion occurs from the axon terminals of magnocellular neurons whose cell bodies are principally found in the hypothalamic supraoptic nucleus and paraventricular nucleus. The physiological functions of oxytocin and vasopressin depend on their secretion, which is principally determined by the pattern of action potentials initiated at the cell bodies. Appropriate secretion of oxytocin and vasopressin to meet the challenges of changing physiological conditions relies mainly on integration of afferent information on reproductive, osmotic, and cardiovascular status with local regulation of magnocellular neurons by glia as well as intrinsic regulation by the magnocellular neurons themselves. This review focuses on the control of magnocellular neuron activity with a particular emphasis on their regulation by reproductive function, body fluid balance, and cardiovascular status. © 2016 American Physiological Society. Compr Physiol 6:1701-1741, 2016.
Collapse
Affiliation(s)
- Colin H Brown
- Brain Health Research Centre, Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin, New Zealand
| |
Collapse
|
12
|
Dose F, Zanon P, Coslovich T, Taccola G. Nanomolar oxytocin synergizes with weak electrical afferent stimulation to activate the locomotor CpG of the rat spinal cord in vitro. PLoS One 2014; 9:e92967. [PMID: 24658101 PMCID: PMC3962494 DOI: 10.1371/journal.pone.0092967] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 02/27/2014] [Indexed: 01/08/2023] Open
Abstract
Synergizing the effect of afferent fibre stimulation with pharmacological interventions is a desirable goal to trigger spinal locomotor activity, especially after injury. Thus, to better understand the mechanisms to optimize this process, we studied the role of the neuropeptide oxytocin (previously shown to stimulate locomotor networks) on network and motoneuron properties using the isolated neonatal rat spinal cord. On motoneurons oxytocin (1 nM–1 μM) generated sporadic bursts with superimposed firing and dose-dependent depolarization. No desensitization was observed despite repeated applications. Tetrodotoxin completely blocked the effects of oxytocin, demonstrating the network origin of the responses. Recording motoneuron pool activity from lumbar ventral roots showed oxytocin mediated depolarization with synchronous bursts, and depression of reflex responses in a stimulus and peptide-concentration dependent fashion. Disinhibited bursting caused by strychnine and bicuculline was accelerated by oxytocin whose action was blocked by the oxytocin antagonist atosiban. Fictive locomotion appeared when subthreshold concentrations of NMDA plus 5HT were coapplied with oxytocin, an effect prevented after 24 h incubation with the inhibitor of 5HT synthesis, PCPA. When fictive locomotion was fully manifested, oxytocin did not change periodicity, although cycle amplitude became smaller. A novel protocol of electrical stimulation based on noisy waveforms and applied to one dorsal root evoked stereotypic fictive locomotion. Whenever the stimulus intensity was subthreshold, low doses of oxytocin triggered fictive locomotion although oxytocin per se did not affect primary afferent depolarization evoked by dorsal root pulses. Among the several functional targets for the action of oxytocin at lumbar spinal cord level, the present results highlight how small concentrations of this peptide could bring spinal networks to threshold for fictive locomotion in combination with other protocols, and delineate the use of oxytocin to strengthen the efficiency of electrical stimulation to activate locomotor circuits.
Collapse
Affiliation(s)
- Francesco Dose
- Neuroscience Department, International School for Advanced Studies (S.I.S.S.A.), Trieste, Italy
- Spinal Person Injury Neurorehabilitation Applied Laboratory (S.P.I.N.A.L.), Istituto di Medicina Fisica e Riabilitazione (IMFR), Udine, Italy
| | - Patrizia Zanon
- Neuroscience Department, International School for Advanced Studies (S.I.S.S.A.), Trieste, Italy
- Spinal Person Injury Neurorehabilitation Applied Laboratory (S.P.I.N.A.L.), Istituto di Medicina Fisica e Riabilitazione (IMFR), Udine, Italy
| | - Tamara Coslovich
- Neuroscience Department, International School for Advanced Studies (S.I.S.S.A.), Trieste, Italy
- Spinal Person Injury Neurorehabilitation Applied Laboratory (S.P.I.N.A.L.), Istituto di Medicina Fisica e Riabilitazione (IMFR), Udine, Italy
| | - Giuliano Taccola
- Neuroscience Department, International School for Advanced Studies (S.I.S.S.A.), Trieste, Italy
- Spinal Person Injury Neurorehabilitation Applied Laboratory (S.P.I.N.A.L.), Istituto di Medicina Fisica e Riabilitazione (IMFR), Udine, Italy
- * E-mail:
| |
Collapse
|
13
|
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.
Collapse
Affiliation(s)
- C H Brown
- Department of Physiology and Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand.
| | | | | | | |
Collapse
|
14
|
Abstract
Neuropeptides are found in many mammalian CNS neurons where they play key roles in modulating neuronal activity. In contrast to amino acid transmitter release at the synapse, neuropeptide release is not restricted to the synaptic specialization, and after release, a neuropeptide may diffuse some distance to exert its action through a G protein-coupled receptor. Some neuropeptides such as hypocretin/orexin are synthesized only in single regions of the brain, and the neurons releasing these peptides probably have similar functional roles. Other peptides such as neuropeptide Y (NPY) are synthesized throughout the brain, and neurons that synthesize the peptide in one region have no anatomical or functional connection with NPY neurons in other brain regions. Here, I review converging data revealing a complex interaction between slow-acting neuromodulator peptides and fast-acting amino acid transmitters in the control of energy homeostasis, drug addiction, mood and motivation, sleep-wake states, and neuroendocrine regulation.
Collapse
|
15
|
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.
Collapse
Affiliation(s)
- Vicky Tobin
- Centre for Integrative Physiology, University of Edinburgh Edinburgh, UK
| | | | | |
Collapse
|
16
|
Abstract
The antidiuretic hormone vasopressin (VP) promotes water reabsorption from the kidney and levels of circulating VP are normally related linearly to plasma osmolality, aiming to maintain the latter close to a predetermined set point. Interestingly, VP levels rise also in the absence of an increase in osmolality during late sleep in various mammals, including rats and humans. This circadian rhythm is functionally important because the absence of a late night VP surge results in polyuria and disrupts sleep in humans. Previous work has indicated that the VP surge may be caused by facilitation of the central processes mediating the osmotic control of VP release, and the mechanism by which this occurs was recently studied in angled slices of rat hypothalamus that preserve intact network interactions between the suprachiasmatic nucleus (SCN; the biological clock), the organum vasculosum lamina terminalis (OVLT; the central osmosensory nucleus) and the supraoptic nucleus (SON; which contains VP-releasing neurohypophysial neurones). These studies confirmed that the electrical activity of SCN clock neurones is higher during the middle sleep period (MSP) than during the late sleep period (LSP). Moreover, they revealed that the excitation of SON neurones caused by hyperosmotic stimulation of the OVLT was greater during the LSP than during the MSP. Activation of clock neurones by repetitive electrical stimulation, or by injection of glutamate into the SCN, caused a presynaptic inhibition of glutamatergic synapses made between the axon terminals of OVLT neurones and SON neurones. Consistent with this effect, activation of clock neurones with glutamate also reduced the excitation of SON neurones caused by hyperosmotic stimulation of the OVLT. These results suggest that clock neurones in the SCN can mediate an increase in VP release through a disinhibition of excitatory synapses between the OVLT and the SON during the LSP.
Collapse
Affiliation(s)
- E Trudel
- Centre for Research in Neuroscience, McGill University and Montreal General Hospital, Montreal, Canada
| | | |
Collapse
|
17
|
Currás-Collazo MC. Nitric oxide signaling as a common target of organohalogens and other neuroendocrine disruptors. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2011; 14:495-536. [PMID: 21790323 DOI: 10.1080/10937404.2011.578564] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Organohalogen compounds such as polychlorinated biphenyls (PCB) and polybrominated diphenyl ethers (PBDE) are global environmental pollutants and highly persistent, bioaccumulative chemicals that produce adverse effects in humans and wildlife. Because of the widespread use of these organohalogens in household items and consumer products, indoor contamination is a significant source of human exposure, especially for children. One significant concern with regard to health effects associated with exposure to organohalogens is endocrine disruption. Toxicological studies on organohalogen pollutants primarily focused on sex steroid and thyroid hormone actions, and findings have largely shaped the way one envisions their disruptive effects occurring. Organohalogens exert additional effects on other systems including other complex endocrine systems that may be disregulated at various levels of organization. Over the last 20 years evidence has mounted in favor of a critical role of nitric oxide (NO) in numerous functions ranging from neuroendocrine functions to learning and memory. With its participation in multiple systems and action at several levels of integration, NO signaling has a pervasive influence on nervous and endocrine functions. Like blockers of NO synthesis, PCBs and PBDEs produce multifaceted effects on physiological systems. Based on this unique set of converging information it is proposed that organohalogen actions occur, in part, by hijacking processes associated with this ubiquitous bioactive molecule. The current review examines the emerging evidence for NO involvement in selected organohalogen actions and includes recent progress from our laboratory that adds to our current understanding of the actions of organohalogens within hypothalamic neuroendocrine circuits. The thyroid, vasopressin, and reproductive systems as well as processes associated with long-term potentiation were selected as sample targets of organohalogens that rely on regulation by NO. Information is provided about other toxicants with demonstrated interference of NO signaling. Our focus on the convergence between NO system and organohalogen toxicity offers a novel approach to understanding endocrine and neuroendocrine disruption that is particularly problematic for developing organisms. This new working model is proposed as a way to encourage future study in elucidating common mechanisms of action that are selected with a better operational understanding of the systems affected.
Collapse
Affiliation(s)
- Margarita C Currás-Collazo
- Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, California 92521, USA.
| |
Collapse
|
18
|
Shahrokh DK, Zhang TY, Diorio J, Gratton A, Meaney MJ. Oxytocin-dopamine interactions mediate variations in maternal behavior in the rat. Endocrinology 2010; 151:2276-86. [PMID: 20228171 PMCID: PMC2869254 DOI: 10.1210/en.2009-1271] [Citation(s) in RCA: 251] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Variations in maternal behavior among lactating rats associate with differences in estrogen-oxytocin interactions in the medial preoptic area (mPOA) and in dopamine levels in the nucleus accumbens (nAcc). Thus, stable, individual differences in pup licking/grooming (LG) are abolished by oxytocin receptor blockade or treatments that eliminate differences in the nAcc dopamine signal. We provide novel evidence for a direct effect of oxytocin at the level of the ventral tegmental area (VTA) in the regulation of nAcc dopamine levels. Mothers that exhibit consistently increased pup LG (i.e. high LG mothers) by comparison with low LG mothers show increased oxytocin expression in the mPOA and the paraventricular nucleus of the hypothalamus and increased projections of oxytocin-positive cells from both mPOA and paraventricular nucleus of the hypothalamus to the VTA. Direct infusion of oxytocin into the VTA increased the dopamine signal in the nAcc. Finally, high compared with low LG mothers show greater increases in dopamine signal in the nAcc during bouts of pup LG, and this difference is abolished with infusions of an oxytocin receptor antagonist directly into the VTA. These studies reveal a direct effect of oxytocin on dopamine release within the mesocorticolimbic dopamine system and are consistent with previous reports of oxytocin-dopamine interactions in the establishment and maintenance of social bonds.
Collapse
Affiliation(s)
- Dara K Shahrokh
- Sackler Program for Epigenetics and Psychobiology at McGill University, Douglas Mental Health University Institute, McGill University, Montréal, Canada
| | | | | | | | | |
Collapse
|
19
|
Abstract
It has been previously suggested that oxytocin (Oxt) may act as a natural antipsychotic. To test this hypothesis, we investigated whether disruption of the oxytocin gene (Oxt-/-) made mice more susceptible to the psychosis-related effects of amphetamine (Amp), apomorphine (Apo) and phencyclidine (PCP). We examined drug-induced changes in the prepulse inhibition (PPI) of the startle reflex, a measure of sensorimotor gating deficits characteristic of several psychiatric and neurological disorders, including schizophrenia. We found that treatment with Amp, Apo and PCP all had effects on PPI. However, in Oxt-/- mice, but not Oxt+/+ mice, PCP treatment resulted in large PPI deficits. As PCP is a noncompetitive N-methyl-D-aspartic acid receptor antagonist, these findings suggest that the absence of Oxt alters the glutamatergic component of the PPI.
Collapse
|
20
|
Cameron NM, Shahrokh D, Del Corpo A, Dhir SK, Szyf M, Champagne FA, Meaney MJ. Epigenetic programming of phenotypic variations in reproductive strategies in the rat through maternal care. J Neuroendocrinol 2008; 20:795-801. [PMID: 18513204 DOI: 10.1111/j.1365-2826.2008.01725.x] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Studies across multiple organisms reveal considerable phenotypic variation in reproductive tactics. In some species, this variation is associated with maternal effects in which variation in maternal investment results in stable individual differences in reproductive function. Recent studies with the rat suggest that maternal effects can alter the function of neuroendocrine systems associated with female sexual behaviour as well as maternal behaviour. These maternal effects appear to be mediated by epigenetic modifications at the promoter for oestrogen receptor alpha (ERalpha) and subsequent effects on gene expression. The tissue-specific nature of such effects may underlie the co-ordinated variation in multiple forms of reproductive function, resulting in distinct reproductive strategies.
Collapse
Affiliation(s)
- N M Cameron
- Sackler Program for Epigenetics and Psychobiology at McGill University and Douglas University Mental Health Institute, McGill University, Montréal, Canada
| | | | | | | | | | | | | |
Collapse
|
21
|
Role of neuronal nitric oxide synthase in the regulation of the neuroendocrine stress response in rodents: insights from mutant mice. Amino Acids 2008; 35:17-27. [DOI: 10.1007/s00726-007-0630-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Accepted: 10/31/2007] [Indexed: 02/04/2023]
|
22
|
|
23
|
Oliet SHR, Baimoukhametova DV, Piet R, Bains JS. Retrograde regulation of GABA transmission by the tonic release of oxytocin and endocannabinoids governs postsynaptic firing. J Neurosci 2007; 27:1325-33. [PMID: 17287507 PMCID: PMC6673587 DOI: 10.1523/jneurosci.2676-06.2007] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The probability of neurotransmitter release at the nerve terminal is an important determinant of synaptic efficacy. At some central synapses, the postsynaptic, or target, neuron determines neurotransmitter release probability (P(r)) at the presynaptic terminal. The mechanisms responsible for this target-cell dependent control of P(r) have not been elucidated. Using whole-cell patch-clamp recordings from magnocellular neurosecretory cells in the paraventricular and supraoptic nuclei of the hypothalamus, we demonstrate that inhibitory, GABA synapses specifically onto oxytocin (OT)-producing neurosecretory cells exhibit a low P(r) that is relatively uniform at multiple synapses onto the same cell. This low P(r) results from a two-step process that requires the tonic release of OT from the postsynaptic cell. The ambient extracellular levels of neuropeptide are sufficient to activate postsynaptic OT receptors and trigger the Ca2+-dependent production of endocannabinoids, which act in a retrograde manner at presynaptic cannabinoid CB1 receptors to decrease GABA release. The functional consequence of this tonic inhibition of GABA release is that all inhibitory inputs facilitate uniformly when activated at high rates of activity. This causes inhibition in the postsynaptic cell that is sufficiently powerful to disrupt firing. Blockade of CB1 receptors increases P(r) at these synapses, resulting in a rapid depression of IPSCs at high rates of activity, thereby eliminating the ability of afferent inputs to inhibit postsynaptic firing. By playing a deterministic role in GABA release at the afferent nerve terminal, the postsynaptic OT neuron effectively filters synaptic signals and thereby modulates its own activity patterns.
Collapse
Affiliation(s)
- Stéphane H. R. Oliet
- Institut National de la Santé et de la Recherche Médicale, Unité 862, Université Victor Segalen Bordeaux 2, Bordeaux 33077, France, and
| | - Dinara V. Baimoukhametova
- Department of Biophysics and Physiology, The Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | - Richard Piet
- Institut National de la Santé et de la Recherche Médicale, Unité 862, Université Victor Segalen Bordeaux 2, Bordeaux 33077, France, and
| | - Jaideep S. Bains
- Department of Biophysics and Physiology, The Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| |
Collapse
|
24
|
Neumann ID, Torner L, Toschi N, Veenema AH. Oxytocin actions within the supraoptic and paraventricular nuclei: differential effects on peripheral and intranuclear vasopressin release. Am J Physiol Regul Integr Comp Physiol 2006; 291:R29-36. [PMID: 16424083 DOI: 10.1152/ajpregu.00763.2005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In response to forced swimming (FS), AVP is released somato-dendritically within the supraoptic nucleus (SON) and paraventricular nucleus (PVN), but not from neurohypophyseal terminals into blood. Together with AVP, oxytocin (OXT) is released within the SON and PVN. Here, we studied the role of intra-SON and intra-PVN OXT in the regulation of local AVP release and into the blood in male rats. Within the SON, bilateral retrodialysis of an OXT receptor antagonist (OXT-A) increased local AVP release in response to FS [60 s, 21°C, vehicle twofold, not significant (ns); OXT-A: 15-fold increase, P < 0.05] without significantly affecting basal AVP release. In addition, local OXT-A elevated plasma AVP secretion under basal conditions (twofold increase, P < 0.05) without further elevation after FS. Within the PVN, exposure to FS elevated local AVP release, reaching significance only in the OXT-A group (vehicle: 1.4-fold, ns; OXT-A: 1.6-fold increase, P = 0.050). Bilateral OXT-A into the PVN did not affect peripheral AVP secretion either under basal or stress conditions. Basal ACTH concentrations tended to be elevated by local OXT-A within the PVN (1.7-fold increase, P = 0.076). In contrast, the swim-induced ACTH secretion was attenuated after retrodialysis of OXT-A within both the SON (at 5 min) and PVN (at 15 min) ( P < 0.05 both) compared with vehicle. The results demonstrate a receptor-mediated effect of OXT within the SON and PVN on local and neurohypophyseal AVP release, which depends upon the activity conditions. Further, while exerting an inhibitory effect on hypothalamo-pituitary-adrenal axis activity under basal conditions, hypothalamic OXT is essential for an adequate acute ACTH response.
Collapse
Affiliation(s)
- Inga D Neumann
- Institute of Zoology, Department of Behavioural Neuroendocrinology, University of Regensburg, Resenburg, Germany.
| | | | | | | |
Collapse
|
25
|
Callewaere C, Banisadr G, Desarménien MG, Mechighel P, Kitabgi P, Rostène WH, Mélik Parsadaniantz S. The chemokine SDF-1/CXCL12 modulates the firing pattern of vasopressin neurons and counteracts induced vasopressin release through CXCR4. Proc Natl Acad Sci U S A 2006; 103:8221-6. [PMID: 16702540 PMCID: PMC1570101 DOI: 10.1073/pnas.0602620103] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Indexed: 11/18/2022] Open
Abstract
Chemokines play a key role in inflammation. They are expressed not only in neuroinflammatory conditions, but also constitutively by different cell types, including neurons in the normal brain, suggesting that they may act as modulators of neuronal functions. Here, we investigated a possible neuroendocrine role of the chemokine stromal cell-derived factor 1 (SDF-1)/CXCL12. We demonstrated the colocalization of SDF-1 and its receptor CXCR4 with arginine vasopressin (AVP) in the magnocellular neurons of the supraoptic nucleus (SON) and the paraventricular hypothalamic nucleus and on AVP projections to the neurohypophysis. Electrophysiological recordings of SON neurons demonstrated that SDF-1 affects the electrical activity of AVP neurons through CXCR4, resulting in changes in AVP release. We observed that SDF-1 can blunt the autoregulation of AVP release in vitro and counteract angiotensin II-induced plasma AVP release in vivo. Furthermore, a short-term physiological increase in AVP release induced by enhanced plasma osmolarity, which was produced by the administration of 1 M NaCl i.p., was similarly blocked by central injection of SDF-1 through CXCR4. A change in water balance by long-term salt loading induced a decrease in both SDF-1 and CXCR4 parallel to that of AVP immunostaining in SON. From these data, we demonstrate that chemokine actions in the brain are not restricted to inflammatory processes. We propose to add to the known autoregulation of AVP on its own neurons, a second autocrine system induced by SDF-1 able to modulate central AVP neuronal activity and release.
Collapse
Affiliation(s)
- Céline Callewaere
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
| | - Ghazal Banisadr
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
| | - Michel G. Desarménien
- Institut de Génomique Fonctionnelle, Université Montpellier, Faculté de Médecine, F-34094 Montepellier, France
- Institut National de la Santé et de la Recherche Médicale, Unité 661, F-34094 Montpellier, France; and
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5203, F-34094 Montpellier, France
| | - Patricia Mechighel
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
| | - Patrick Kitabgi
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
| | - William H. Rostène
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
| | - Stéphane Mélik Parsadaniantz
- *Institut National de la Santé et de la Recherche Médicale, Unité 732, F-75012 Paris, France
- Université Pierre et Marie Curie-Paris 6, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, F-75571 Paris Cedex 12, France
| |
Collapse
|
26
|
Ponzio TA, Ni Y, Montana V, Parpura V, Hatton GI. Vesicular glutamate transporter expression in supraoptic neurones suggests a glutamatergic phenotype. J Neuroendocrinol 2006; 18:253-65. [PMID: 16503920 PMCID: PMC1413582 DOI: 10.1111/j.1365-2826.2006.01410.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Magnocellular neuroendocrine cells of the supraoptic nucleus (SON) release the peptides oxytocin (OT) and vasopressin (VP) from their dendrites and terminals. In addition to peptide-containing large dense-core vesicles, axon terminals from these cells contain clear microvesicles that have been shown to contain glutamate. Using multilabelling confocal microscopy, we investigated the presence of vesicular glutamate transporters (VGLUTs) in astrocytes as well as VP and OT neurones of the SON. Simultaneous probing of the SON with antibodies against VGLUT isoforms 1-3, OT, VP and glial fibrillary acidic protein (GFAP) revealed the presence of VGLUT-2 in somata and dendrites of SON neurones. Immunoreactivity (-ir) for VGLUT-3 was also detected in both OT and VP neurones as well as in GFAP-ir astrocytes and other cells of the ventral glial lamina. Colocalisation of VGLUT-2 and VGLUT-3 in individual SON neurones was also examined and VGLUT-ir with both antibodies could be detected in both types of SON neurones. Although VGLUT-1-ir was strong lateral to the SON, only sparse labelling was apparent within the nucleus, and no colocalisation with either SON neurones or astrocytes was observed. The SON or the SON plus its surrounding perinuclear zone was probed using the reverse transcriptase-polymerase chain reaction and the presence of mRNA for all three VGLUT isoforms was detected. These results suggest that similar arrangements of transmitters exist in SON neuronal dendrites and their neurohypophysial terminals and that magnocellular neuroendocrine somata and dendrites may be capable of glutamatergic transmission.
Collapse
Affiliation(s)
- T A Ponzio
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA, USA.
| | | | | | | | | |
Collapse
|
27
|
Terenzi MG, Ingram CD. Oxytocin-induced excitation of neurones in the rat central and medial amygdaloid nuclei. Neuroscience 2005; 134:345-54. [PMID: 15961240 DOI: 10.1016/j.neuroscience.2005.04.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2004] [Revised: 03/29/2005] [Accepted: 04/01/2005] [Indexed: 11/15/2022]
Abstract
Central oxytocin plays an important role in regulating emotionality. The amygdala expresses gonadal steroid-sensitive oxytocin binding sites in both the central and medial sub-nuclei, although the densities markedly differ between these nuclei. These studies examined the in vitro electrophysiological effects of oxytocin in the two amygdaloid nuclei and compared responses in female rats in different reproductive states (virgin, pregnant and lactating). Oxytocin (10(-9)-10(-6)M) caused a concentration-dependent increase in the firing rate of 20-36% of the neurones in both nuclei. Although autoradiographic studies using the oxytocin receptor antagonist [(125)I]d(CH(2))(5)[Tyr(Me)(2),Thr(4),Orn(8),Tyr-NH(2)(9)]-vasotocin showed a higher density of binding in the central nucleus of the amygdala than medial nucleus of the amygdala, neurones in the central nucleus of the amygdala had a much lower sensitivity to oxytocin: equivalent responses obtained with 10(-6)M in the central nucleus of the amygdala and 10(-8)M in the medial nucleus of the amygdala, and neurones in the central nucleus of the amygdala were insensitive to concentrations below 10(-6)M. Furthermore, repeated applications of oxytocin induced homologous desensitization in the central nucleus of the amygdala, but not medial nucleus of the amygdala-a single application of oxytocin producing long duration suppression of responses. This indicates that oxytocin has contrasting modes of action in the amygdala. Studies made across the reproductive cycle showed that lactating animals exhibited a larger proportion of oxytocin-responsive neurones in the medial nucleus of the amygdala and a smaller proportion in the central nucleus of the amygdala, compared with virgin or pregnant animals, indicating a peripartum shift in relative activation within the amygdala. However, changes in responses were not accompanied by changes in the density of oxytocin binding sites. These data show that oxytocin has a markedly different efficacy on neuronal activation in the central and medial sub-nuclei of the amygdala. The relative shift in excitatory responses between these two nuclei may underlie some of the neuroendocrine, behavioral and anxiolytic effects which have been ascribed to oxytocin in the periparturient rat.
Collapse
Affiliation(s)
- M G Terenzi
- Department of Physiological Sciences, Federal University of Santa Catarina, Florianopolis SC 88040-900, Brazil
| | | |
Collapse
|
28
|
Abstract
A baby sucks at a mother's breast for comfort and, of course, for milk. Milk is made in specialized cells of the mammary gland, and for a baby to feed, the milk must be released into a collecting chamber from where it can be extracted by sucking. Milk "let-down" is a reflex response to the suckling and kneading of the nipple--and sometimes in response to the sight, smell, and sound of the baby--and is ultimately affected by the secretion of oxytocin. Oxytocin has many physiological roles, but its only irreplaceable role is to mediate milk let-down: oxytocin-deficient mice cannot feed their young; the pups suckle but no milk is let down, and they will die unless cross-fostered. Most other physiological roles of oxytocin, including its role in parturition, are redundant in the sense that the roles can be assumed by other mechanisms in the absence of oxytocin throughout development and adult life. Nevertheless, physiological function in these roles can be altered or impaired by acute interventions that alter oxytocin secretion or change the actions of oxytocin. Here we focus on the diverse stimuli that regulate oxytocin secretion and on the apparent diversity of the roles for oxytocin.
Collapse
Affiliation(s)
- Gareth Leng
- Centre for Integrative Physiology, The University of Edinburgh College of Medicine and Veterinary Sciences, Edinburgh EH8 9XD, United Kingdom
| | | | | |
Collapse
|
29
|
Ozaki Y, Soya A, Nakamura J, Matsumoto T, Ueta Y. Potentiation by angiotensin II of spontaneous excitatory postsynaptic currents in rat supraoptic magnocellular neurones. J Neuroendocrinol 2004; 16:871-9. [PMID: 15584928 DOI: 10.1111/j.1365-2826.2004.01244.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The physiological actions of angiotensin II in the supraoptic (SON) and paraventricular nuclei have been widely demonstrated, including the modulation of firing rate and release of arginine vasopressin and oxytocin. Here, we investigated whether angiotensin II modulates synaptic inputs into the SON. To do this, we measured spontaneous excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs) from rat SON neurones in thin slice preparations using the whole-cell patch-clamp technique. Angiotensin II reversibly increased the frequency of spontaneous EPSCs in a dose-related manner without affecting the amplitude, indicating that angiotensin II potentiated EPSCs via a presynaptic mechanism. Angiotensin II-induced potentiation of EPSCs was unaffected in the presence of tetrodotoxin. On the other hand, angiotensin II did not cause significant effects on IPSCs. The potentiation of EPSCs by angiotensin II was potently suppressed by previous exposure to the angiotensin type 1 (AT1) receptor antagonist, losartan. Our results suggest that angiotensin II potentiates the excitatory synaptic inputs into SON neurones, via the AT1 receptors.
Collapse
Affiliation(s)
- Y Ozaki
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | | | | | | | | |
Collapse
|
30
|
Soldo BL, Giovannucci DR, Stuenkel EL, Moises HC. Ca(2+) and frequency dependence of exocytosis in isolated somata of magnocellular supraoptic neurones of the rat hypothalamus. J Physiol 2003; 555:699-711. [PMID: 14645448 PMCID: PMC1664858 DOI: 10.1113/jphysiol.2003.051136] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In addition to action potential-evoked exocytotic release at neurohypophysial nerve terminals, the neurohormones arginine vasopressin (aVP) and oxytocin (OT) undergo Ca(2+)-dependent somatodendritic release within the supraoptic and paraventricular hypothalamic nuclei. However, the cellular and molecular mechanisms that underlie this release have not been elucidated. In the present study, the whole-cell patch-clamp technique was utilized in combination with high-time-resolved measurements of membrane capacitance (C(m)) and microfluorometric measurements of cytosolic free Ca(2+) concentration ([Ca(2+)](i)) to examine the Ca(2+) and stimulus dependence of exocytosis in the somata of magnocellular neurosecretory cells (MNCs) isolated from rat supraoptic nucleus (SON). Single depolarizing steps (> or =20 ms) that evoked high-voltage-activated (HVA) Ca(2+) currents (I(Ca)) and elevations in intracellular Ca(2+) concentration were accompanied by an increase in C(m) in a majority (40/47) of SON neurones. The C(m) responses were composed of an initial Ca(2+)-independent, transient component and a subsequent, sustained phase of increased C(m) (termed DeltaC(m)) mediated by an influx of Ca(2+), and increased with corresponding prolongation of depolarizing step durations (20-200 ms). From this relationship we estimated the rate of vesicular release to be 1533 vesicles s(-1). Delivery of neurone-derived action potential waveforms (APWs) as stimulus templates elicited I(Ca) and also induced a DeltaC(m), provided APWs were applied in trains of greater than 13 Hz. A train of APWs modelled after the bursting pattern recorded from an OT-containing neurone during the milk ejection reflex was effective in supporting an exocytotic DeltaC(m) in isolated MNCs, indicating that the somata of SON neurones respond to physiological patterns of neuronal activity with Ca(2+)-dependent exocytotic activity.
Collapse
Affiliation(s)
- Brandi L Soldo
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | | | | | | |
Collapse
|