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Inada K. Neurobiological mechanisms underlying oxytocin-mediated parental behavior in rodents. Neurosci Res 2024:S0168-0102(24)00052-X. [PMID: 38642676 DOI: 10.1016/j.neures.2024.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 03/29/2024] [Accepted: 04/07/2024] [Indexed: 04/22/2024]
Abstract
Parental behavior is essential for mammalian offspring to survive. Because of this significance, elucidating the neurobiological mechanisms that facilitate parental behavior has received strong interest. Decades of studies utilizing pharmacology and molecular biology have revealed that in addition to its facilitatory effects on parturition and lactation, oxytocin (OT) promotes the expression of parental behavior in rodents. Recent studies have also described the modulation of sensory processing by OT and the interaction of the OT system with other brain regions associated with parental behavior. However, the precise neurobiological mechanisms underlying the facilitation of caregiving behaviors by OT remain unclear. In this Review, I summarize the findings from rats and mice with a view toward integrating past and recent progress. I then review recent advances in the understanding of the molecular, cellular, and circuit mechanisms of OT-mediated parental behavior. Based on these observations, I propose a hypothetical model that would explain the mechanisms underlying OT-mediated parental behavior. Finally, I conclude by discussing some major remaining questions and propose potential future research directions.
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Affiliation(s)
- Kengo Inada
- RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
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Perkinson MR, Kirchner MK, Zhang M, Augustine RA, Stern JE, Brown CH. α-Melanocyte-stimulating hormone inhibition of oxytocin neurons switches to excitation in late pregnancy and lactation. Physiol Rep 2022; 10:e15226. [PMID: 35312181 PMCID: PMC8935534 DOI: 10.14814/phy2.15226] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 06/14/2023] Open
Abstract
Oxytocin is secreted into the periphery by magnocellular neurons of the hypothalamic supraoptic and paraventricular nuclei (SON and PVN) to trigger uterine contraction during birth and milk ejection during suckling. Peripheral oxytocin secretion is triggered by action potential firing, which is regulated by afferent input activity and by feedback from oxytocin secreted into the extracellular space from magnocellular neuron somata and dendrites. A prominent input to oxytocin neurons arises from proopiomelanocortin neurons of the hypothalamic arcuate nucleus that secrete an alpha-melanocyte-stimulating hormone (α-MSH), which inhibits oxytocin neuron firing in non-pregnant rats by increasing somato-dendritic oxytocin secretion. However, α-MSH inhibition of oxytocin neuron firing is attenuated in mid-pregnancy and somato-dendritic oxytocin becomes auto-excitatory in late-pregnancy and lactation. Therefore, we hypothesized that attenuated α-MSH inhibition of oxytocin neuron firing marks the beginning of a transition from inhibition to excitation to facilitate peripheral oxytocin secretion for parturition and lactation. Intra-SON microdialysis administration of α-MSH inhibited oxytocin neuron firing rate by 33 ± 9% in non-pregnant rats but increased oxytocin neuron firing rate by 37 ± 12% in late-pregnant rats and by 28 ± 10% in lactating rats. α-MSH-induced somato-dendritic oxytocin secretion measured ex vivo with oxytocin receptor-expressing "sniffer" cells, was of similar amplitude in PVN slices from non-pregnant and lactating rats but longer-lasting in slices from lactating rats. Hence, α-MSH inhibition of oxytocin neuron activity switches to excitation over pregnancy while somato-dendritic oxytocin secretion is maintained, which might enhance oxytocin neuron excitability to facilitate the increased peripheral secretion that is required for normal parturition and milk ejection.
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Affiliation(s)
- Michael R. Perkinson
- Brain Health Research CentreUniversity of OtagoDunedinAotearoa New Zealand
- Centre for NeuroendocrinologyUniversity of OtagoDunedinAotearoa New Zealand
- Department of PhysiologyUniversity of OtagoDunedinAotearoa New Zealand
| | - Matthew K. Kirchner
- Center for Neuroinflammation and Cardiometabolic DiseasesGeorgia State UniversityAtlantaGeorgiaUSA
| | - Meng Zhang
- Center for Neuroinflammation and Cardiometabolic DiseasesGeorgia State UniversityAtlantaGeorgiaUSA
| | - Rachael A. Augustine
- Brain Health Research CentreUniversity of OtagoDunedinAotearoa New Zealand
- Centre for NeuroendocrinologyUniversity of OtagoDunedinAotearoa New Zealand
- Department of PhysiologyUniversity of OtagoDunedinAotearoa New Zealand
| | - Javier E. Stern
- Center for Neuroinflammation and Cardiometabolic DiseasesGeorgia State UniversityAtlantaGeorgiaUSA
| | - Colin H. Brown
- Brain Health Research CentreUniversity of OtagoDunedinAotearoa New Zealand
- Centre for NeuroendocrinologyUniversity of OtagoDunedinAotearoa New Zealand
- Department of PhysiologyUniversity of OtagoDunedinAotearoa New Zealand
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Abstract
Prolactin (PRL) released from lactotrophs of the anterior pituitary gland in response to the suckling by the offspring is the major hormonal signal responsible for stimulation of milk synthesis in the mammary glands. PRL secretion is under chronic inhibition exerted by dopamine (DA), which is released from neurons of the arcuate nucleus of the hypothalamus into the hypophyseal portal vasculature. Suckling by the young activates ascending systems that decrease the release of DA from this system, resulting in enhanced responsiveness to one or more PRL-releasing hormones, such as thyrotropin-releasing hormone. The neuropeptide oxytocin (OT), synthesized in magnocellular neurons of the hypothalamic supraoptic, paraventricular, and several accessory nuclei, is responsible for contracting the myoepithelial cells of the mammary gland to produce milk ejection. Electrophysiological recordings demonstrate that shortly before each milk ejection, the entire neurosecretory OT population fires a synchronized burst of action potentials (the milk ejection burst), resulting in release of OT from nerve terminals in the neurohypophysis. Both of these neuroendocrine systems undergo alterations in late gestation that prepare them for the secretory demands of lactation, and that reduce their responsiveness to stimuli other than suckling, especially physical stressors. The demands of milk synthesis and release produce a condition of negative energy balance in the suckled mother, and, in laboratory rodents, are accompanied by a dramatic hyperphagia. The reduction in secretion of the adipocyte hormone, leptin, a hallmark of negative energy balance, may be an important endocrine signal to hypothalamic systems that integrate lactation-associated food intake with neuroendocrine systems.
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Affiliation(s)
- William R Crowley
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah Health Sciences Center, Salt Lake City, Utah
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Teng BL, Nonneman RJ, Agster KL, Nikolova VD, Davis TT, Riddick NV, Baker LK, Pedersen CA, Jarstfer MB, Moy SS. Prosocial effects of oxytocin in two mouse models of autism spectrum disorders. Neuropharmacology 2013; 72:187-96. [PMID: 23643748 DOI: 10.1016/j.neuropharm.2013.04.038] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 03/23/2013] [Accepted: 04/22/2013] [Indexed: 12/17/2022]
Abstract
Clinical evidence suggests that oxytocin treatment improves social deficits and repetitive behavior in autism spectrum disorders (ASDs). However, the neuropeptide has a short plasma half-life and poor ability to penetrate the blood-brain barrier. In order to facilitate the development of more bioavailable oxytocinergic compounds as therapeutics to treat core ASD symptoms, small animal models must be validated for preclinical screens. This study examined the preclinical utility of two inbred mouse strains, BALB/cByJ and C58/J, that exhibit phenotypes relevant to core ASD symptoms. Mice from both strains were intraperitoneally administered oxytocin, using either acute or sub-chronic regimens. Acute oxytocin did not increase sociability in BALB/cByJ; however, sub-chronic oxytocin had significant prosocial effects in both BALB/cByJ and C58/J. Increased sociability was observed 24 h following the final oxytocin dose in BALB/cByJ, while prosocial effects of oxytocin emerged 1-2 weeks post-treatment in C58/J. Furthermore, acute oxytocin decreased motor stereotypy in C58/J and did not induce hypoactivity or anxiolytic-like effects in an open field test. This study demonstrates that oxytocin administration can attenuate social deficits and repetitive behavior in mouse models of ASD, dependent on dose regimen and genotype. These findings provide validation of the BALB/cByJ and C58/J models as useful platforms for screening novel drugs for intervention in ASDs and for elucidating the mechanisms contributing to the prosocial effects of oxytocin.
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Affiliation(s)
- Brian L Teng
- Carolina Institute for Developmental Disabilities, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA.
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Ferri SL, Flanagan-Cato LM. Oxytocin and dendrite remodeling in the hypothalamus. Horm Behav 2012; 61:251-8. [PMID: 22326383 PMCID: PMC3312999 DOI: 10.1016/j.yhbeh.2012.01.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 01/13/2012] [Accepted: 01/14/2012] [Indexed: 10/14/2022]
Abstract
For most people, their quality of life depends on their successful interdependence with others, which requires sophisticated social cognition, communication, and emotional bonds. Across the lifespan, new bonds must be forged and maintained, and conspecific menaces must be managed. The dynamic nature of the human social landscape suggests ongoing specific alterations in neural circuitry across several brain systems to subserve social behavior. To discover the biological mechanisms that contribute to normal social activities, animal models of social behavior have been developed. One valuable model system has been female rat sexual behavior, which is governed by cyclic variation of ovarian hormones. This behavior is modulated by the neuropeptide oxytocin (OT) through its actions in the hypothalamic ventromedial nucleus (VMH). The fluctuation of this behavior is associated with dendrite remodeling, like several other examples of behavioral plasticity. This review compares hormone-induced plasticity in the VMH with other examples of dendrite plasticity across the mammalian nervous system, namely the neurobehavioral paradigms of environmental enrichment, chronic stress, and incentive sensitization, which affect the neocortex, hippocampal formation, and ventral striatum, respectively. This comparison suggests that the effects of ovarian hormones on VMH neurons in rats, given the simple dendritic arbor and short time course for dendrite remodeling, provide a dual opportunity for mechanistic and functional studies that will shed light on i) the neural actions of OT that regulate social behavior and, ii) behaviorally relevant dendrite regulation in a variety of brain structures. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.
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Affiliation(s)
- Sarah L Ferri
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Lee SK, Lee S, Shin SY, Ryu PD, Lee SY. Single cell analysis of voltage-gated potassium channels that determines neuronal types of rat hypothalamic paraventricular nucleus neurons. Neuroscience 2012; 205:49-62. [PMID: 22245500 DOI: 10.1016/j.neuroscience.2011.12.031] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 11/16/2011] [Accepted: 12/19/2011] [Indexed: 10/14/2022]
Abstract
The hypothalamic paraventricular nucleus (PVN), a site for the integration of both the neuroendocrine and autonomic systems, has heterogeneous cell composition. These neurons are classified into type I and type II neurons based on their electrophysiological properties. In the present study, we investigated the molecular identification of voltage-gated K+ (Kv) channels, which determines a distinctive characteristic of type I PVN neurons, by means of single-cell reverse transcription-polymerase chain reaction (RT-PCR) along with slice patch clamp recordings. In order to determine the mRNA expression profiles, firstly, the PVN neurons of male rats were classified into type I and type II neurons, and then, single-cell RT-PCR and single-cell real-time RT-PCR analysis were performed using the identical cell. The single-cell RT-PCR analysis revealed that Kv1.2, Kv1.3, Kv1.4, Kv4.1, Kv4.2, and Kv4.3 were expressed both in type I and in type II neurons, and several Kv channels were co-expressed in a single PVN neuron. However, we found that the expression densities of Kv4.2 and Kv4.3 were significantly higher in type I neurons than in type II neurons. Taken together, several Kv channels encoding A-type K+ currents are present both in type I and in type II neurons, and among those, Kv4.2 and Kv4.3 are the major Kv subunits responsible for determining the distinct electrophysiological properties. Thus these 2 Kv subunits may play important roles in determining PVN cell types and regulating PVN neuronal excitability. This study further provides key molecular mechanisms for differentiating type I and type II PVN neurons.
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Affiliation(s)
- S K Lee
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Korea
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Wang YF, Hatton GI. Burst firing of oxytocin neurons in male rat hypothalamic slices. Brain Res 2005; 1032:36-43. [PMID: 15680939 DOI: 10.1016/j.brainres.2004.10.046] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2004] [Indexed: 11/20/2022]
Abstract
Burst firing and single spike activity play different roles in the modulation of local neuronal circuit activity and neurosecretion. In hypothalamic oxytocin (OT) neurons in vivo, burst firing is associated with pulsatile secretion of OT in the milk ejection reflex, and can be observed in slices from both immature and lactating rats in vitro. Whether OT neurons from male rats also possess burst firing capability is still an open question. To examine this possibility, whole-cell patch clamp recordings were made in supraoptic nucleus OT neurons in brain slices from male rats. In low Ca(2+) medium, the alpha(1)-adrenoceptor agonist, phenylephrine evoked bursts that were highly similar to those from lactating rats in vivo and in vitro: explosive onset, short-duration, quickly reaching peak firing rate and displaying an exponential decay in returning to the pre-burst rate. During bursts, spike durations increased, and spike amplitudes decreased, while riding on an arc of depolarization around peak rate. In comparison to those from lactating rats in vitro, the rising phase of male bursts was more rapid, the decay phase was slower, and the rising phase of the spike after hyperpolarization was faster. No significant differences, however, were seen in burst characteristics that are most important in determining the amount of peptide release: burst amplitudes (the number of spikes in a burst), firing frequency within bursts or peak firing rate. Thus, we conclude that OT neurons in males are capable of burst firing highly similar to that seen in lactating rats.
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Affiliation(s)
- Yu-Feng Wang
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
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Cunningham JT, Penny ML, Murphy D. Cardiovascular regulation of supraoptic neurons in the rat: synaptic inputs and cellular signals. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2004; 84:183-96. [PMID: 14769435 DOI: 10.1016/j.pbiomolbio.2003.11.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The supraoptic nucleus of the hypothalamus contains a population of neurons that project to the posterior pituitary where they release peptides into systemic circulation. The system has two main secretory products--vasopressin and oxytocin. The main systemic affects of vasopressin are related to body fluid homeostasis while circulating oxytocin is involved in parturition and lactation. The circulating levels of both hormones are, to a large part, determined by the electrical activity of the supraoptic neurons and other neurosecretory cells, which is in turn determined by synaptic inputs. More recent work suggests that there may be other dimensions to the cellular response of supraoptic neurons to these synaptic inputs. For example, it has been demonstrated that supraoptic neurons alter their synthesis of vasopressin and oxytocin in response to prolonged stimulation and that the morphology of cells in the supraoptic nucleus and its number of synaptic inputs change with the physiological conditions of the animal. These responses would appear to require some type of activity-dependent set of cellular signals. Candidates for such signals include members of the AP-1 transcription factor family whose expression in neurons has been linked to synaptic stimulation. This review will describe the effects of cardiovascular-related stimuli on the expression of different members of the AP-1 family in the supraoptic nucleus.
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Affiliation(s)
- J Thomas Cunningham
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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Ragnauth AK, Goodwillie A, Brewer C, Muglia LJ, Pfaff DW, Kow LM. Vasopressin stimulates ventromedial hypothalamic neurons via oxytocin receptors in oxytocin gene knockout male and female mice. Neuroendocrinology 2004; 80:92-9. [PMID: 15528951 DOI: 10.1159/000081844] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Accepted: 08/09/2004] [Indexed: 11/19/2022]
Abstract
A wealth of neuropharmacological data demonstrates that oxytocin (OT) actions in the mammalian forebrain support a wide variety of affiliative behaviors and repress aggressive behaviors. Based on that literature, it was expected that reproductive and affiliative behaviors would be vastly decreased and aggression markedly increased in OT gene knockout (OTKO) mice. The initial publications reporting the behaviors of these mice did not include such phenotypes. Here, we compared single-unit activities recorded from the ventromedial hypothalamus in tissue slices of male and female OTKO mice and their wild-type littermate to test two hypotheses about OT functional genomics. First, we proposed that in OTKO mice, a very similar 9-amino-acid neuropeptide, arginine vasopressin (a likely gene duplication product), can 'cross over' and compensate for the lack of OT. This hypothesis was confirmed in both males and females. Further, we proposed that because of the lifelong absence of OT in OTKO, OT receptors would be more sensitive to OT in the knockout animals. We tested this idea in males and found that it was correct. Thus, an answer to the 'OTKO paradox' is put forth, with implications for OT-sensitive behaviors in a variety of species.
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Affiliation(s)
- André K Ragnauth
- Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10021, USA
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Abstract
During the female reproductive cycle, hypothalamic oxytocin (OT) neurons undergo sharp changes in excitability. In lactating mammals, bursts of electrical activity of OT neurons result in the release of large amounts of OT in the bloodstream, which causes milk ejection. One hypothesis is that OT neurons regulate their own firing activity and that of nearby OT neurons by somatodendritic release of OT. In this study, we show that OT neuron activity strongly reduces inhibitory synaptic transmission to these neurons. This effect is blocked by antagonists of both adenosine and OT receptors and is mimicked by OT application. Inhibition of soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex formation by tetanus toxin completely blocked the stimulation-induced reduction in inhibitory input, as did the calcium chelator BAPTA. During lactation, the readily releasable pool of secretory vesicles in OT cell bodies was doubled, and calcium currents were upregulated. This resulted in an increased inhibition of GABAergic synaptic transmission by somatodendritic release during lactation compared with the adult virgin stage. These results demonstrate that somatodendritic release is augmented during lactation, which is a novel form of plasticity to change the strength of synaptic transmission.
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