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Vaasjo LO, Miller MW. A conserved gastropod withdrawal circuit in Biomphalaria glabrata, an intermediate host for schistosomiasis. J Neurophysiol 2024; 131:903-913. [PMID: 38478883 DOI: 10.1152/jn.00390.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 05/18/2024] Open
Abstract
Neuronal signals mediated by the biogenic amine serotonin (5-HT) underlie critical survival strategies across the animal kingdom. This investigation examined serotonin-like immunoreactive neurons in the cerebral ganglion of the panpulmonate snail Biomphalaria glabrata, a major intermediate host for the trematode parasite Schistosoma mansoni. Five neurons comprising the cerebral serotonergic F (CeSF) cluster of B. glabrata shared morphological characteristics with neurons that contribute to withdrawal behaviors in numerous heterobranch species. The largest member of this group, designated CeSF-1, projected an axon to the tentacle, a major site of threat detection. Intracellular recordings demonstrated repetitive activity and electrical coupling between the bilateral CeSF-1 cells. In semi-intact preparations, the CeSF-1 cells were not responsive to cutaneous stimuli but did respond to photic stimuli. A large FMRF-NH2-like immunoreactive neuron, termed C2, was also located on the dorsal surface of each cerebral hemiganglion near the origin of the tentacular nerve. C2 and CeSF-1 received coincident bouts of inhibitory synaptic input. Moreover, in the presence of 5-HT they both fired rhythmically and in phase. As the CeSF and C2 cells of Biomphalaria share fundamental properties with neurons that participate in withdrawal responses in Nudipleura and Euopisthobranchia, our observations support the proposal that features of this circuit are conserved in the Panpulmonata.NEW & NOTEWORTHY Neuronal signals mediated by the biogenic amine serotonin underlie critical survival strategies across the animal kingdom. This investigation identified a group of serotonergic cells in the panpulmonate snail Biomphalaria glabrata that appear to be homologous to neurons that mediate withdrawal responses in other gastropod taxa. It is proposed that an ancient withdrawal circuit has been highly conserved in three major gastropod lineages.
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Affiliation(s)
- Lee O Vaasjo
- Institute of Neurobiology and Department of Anatomy & Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
| | - Mark W Miller
- Institute of Neurobiology and Department of Anatomy & Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
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2
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Gribkova ED, Lee CA, Brown JW, Cui J, Liu Y, Norekian T, Gillette R. A common modular design of nervous systems originating in soft-bodied invertebrates. Front Physiol 2023; 14:1263453. [PMID: 37854468 PMCID: PMC10579582 DOI: 10.3389/fphys.2023.1263453] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 09/12/2023] [Indexed: 10/20/2023] Open
Abstract
Nervous systems of vertebrates and invertebrates show a common modular theme in the flow of information for cost-benefit decisions. Sensory inputs are incentivized by integrating stimulus qualities with motivation and memory to affect appetitive state, a system of homeostatic drives, and labelled for directionality. Appetitive state determines action responses from a repertory of possibles and transmits the decision to a premotor system that frames the selected action in motor arousal and appropriate postural and locomotion commands. These commands are then sent to the primary motor pattern generators controlling the motorneurons, with feedback at each stage. In the vertebrates, these stages are mediated by forebrain pallial derivatives for incentive and directionality (olfactory bulb, cerebral cortex, pallial amygdala, etc.) interacting with hypothalamus (homeostasis, motivation, and reward) for action selection in the forebrain basal ganglia, the mid/hindbrain reticular formation as a premotor translator for posture, locomotion, and arousal state, and the spinal cord and cranial nuclei as primary motor pattern generators. Gastropods, like the predatory sea slug Pleurobranchaea californica, show a similar organization but with differences that suggest how complex brains evolved from an ancestral soft-bodied bilaterian along with segmentation, jointed skeletons, and complex exteroceptors. Their premotor feeding network combines functions of hypothalamus and basal ganglia for homeostasis, motivation, presumed reward, and action selection for stimulus approach or avoidance. In Pleurobranchaea, the premotor analogy to the vertebrate reticular formation is the bilateral "A-cluster" of cerebral ganglion neurons that controls posture, locomotion, and serotonergic motor arousal. The A-cluster transmits motor commands to the pedal ganglia analogs of the spinal cord, for primary patterned motor output. Apparent pallial precursors are not immediately evident in Pleurobranchaea's central nervous system, but a notable candidate is a subepithelial nerve net in the peripheral head region that integrates chemotactile stimuli for incentive and directionality. Evolutionary centralization of its computational functions may have led to the olfaction-derived pallial forebrain in the ancestor's vertebrate descendants and their analogs in arthropods and annelids.
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Affiliation(s)
- Ekaterina D. Gribkova
- Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Colin A. Lee
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Jeffrey W. Brown
- Stanson Toshok Center for Brain Function and Repair, Rosalind Franklin University of Medicine and Science, North Chicago, IL, United States
| | - Jilai Cui
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Yichen Liu
- Department of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Tigran Norekian
- Whitney Laboratory for Marine Biosciences, University of Florida, St. Augustine, FL, United States
| | - Rhanor Gillette
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Department of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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Paoli M, Macri C, Giurfa M. A cognitive account of trace conditioning in insects. CURRENT OPINION IN INSECT SCIENCE 2023; 57:101034. [PMID: 37044245 DOI: 10.1016/j.cois.2023.101034] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/03/2023] [Accepted: 04/05/2023] [Indexed: 05/07/2023]
Abstract
Trace conditioning is a form of Pavlovian learning in which the conditioned stimulus (CS) and the unconditioned stimulus (US) are separated by a temporal gap. Insects learn trace associations of variable nature (appetitive, aversive) and involving CSs of different sensory modalities (olfactory, visual). The accessibility of the insect neural system in behaving animals allowed identifying neural processes driving trace conditioning: the existence of prolonged neural responses to the CS after stimulus offset and the anticipation of US responses during the free-stimulus gap. Specific brain structures, such as the mushroom bodies seem to be allocated to this learning form. Here, we posit that a further component facilitating trace conditioning in insects relates to neuromodulatory mechanisms underlying enhanced attention. We thus propose a model based on different types of mushroom-body neurons, which provides a cognitive account of trace conditioning in insects.
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Affiliation(s)
- Marco Paoli
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, 31062 Toulouse cedex 9, France
| | - Catherine Macri
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, 31062 Toulouse cedex 9, France
| | - Martin Giurfa
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, 31062 Toulouse cedex 9, France; Institut Universitaire de France (IUF), Paris, France.
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AI protein structure prediction-based modeling and mutagenesis of a protostome receptor and peptide ligands reveal key residues for their interaction. J Biol Chem 2022; 298:102440. [PMID: 36049520 PMCID: PMC9562341 DOI: 10.1016/j.jbc.2022.102440] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 11/24/2022] Open
Abstract
The protostome leucokinin (LK) signaling system, including LK peptides and their G protein-coupled receptors, has been characterized in several species. Despite progress in this area, molecular mechanisms governing LK peptide-receptor interactions remain to be elucidated. Previously, we identified a precursor protein for Aplysia leucokinin-like peptides (ALKs) that contains the greatest number of amidated peptides among LK precursors in all species identified so far. Here, we identified the first ALK receptor from Aplysia, ALKR. We used cell-based IP1 activation assays to demonstrate that the two ALK peptides with the most copies, ALK1 and ALK2, activated ALKR with high potencies. Other endogenous ALK-derived peptides bearing the FXXWX-amide motif also activated ALKR to various degrees. Our examination of cross-species activity of ALKs with the Anopheles LKR was consistent with a critical role for the FXXWX-amide motif in receptor activity. Furthermore, we showed, through alanine substitution of ALK1, the highly conserved phenylalanine (F), tryptophan (W), and C-terminal amidation were each essential for receptor activation. Finally, we used an AI-based protein structure prediction server (Robetta) and Autodock Vina to predict the ligand-bound conformation of ALKR. Our model predicted several interactions (i.e., hydrophobic interactions, hydrogen bonds, and amide-pi stacking) between ALK peptides and ALKR, and several of our substitution and mutagenesis experiments were consistent with the predicted model. In conclusion, our results provide important information defining the possible interactions between ALK peptides and their receptors. The workflow utilized here may be useful for studying other ligand-receptor interactions for a neuropeptide signaling system, particularly in protostomes.
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Ågmo A, Laan E. Sexual incentive motivation, sexual behavior, and general arousal: Do rats and humans tell the same story? Neurosci Biobehav Rev 2022; 135:104595. [PMID: 35231490 DOI: 10.1016/j.neubiorev.2022.104595] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/28/2022] [Accepted: 02/24/2022] [Indexed: 12/13/2022]
Abstract
Sexual incentive stimuli activate sexual motivation and heighten the level of general arousal. The sexual motive may induce the individual to approach the incentive, and eventually to initiate sexual acts. Both approach and the ensuing copulatory interaction further enhance general arousal. We present data from rodents and humans in support of these assertions. We then suggest that orgasm is experienced when the combined level of excitation surpasses a threshold. In order to analyze the neurobiological bases of sexual motivation, we employ the concept of a central motive state. We then discuss the mechanisms involved in the long- and short-term control of that state as well as those mediating the momentaneous actions of sexual incentive stimuli. This leads to an analysis of the neurobiology behind the interindividual differences in responsivity of the sexual central motive state. Knowledge is still fragmentary, and many contradictory observations have been made. Nevertheless, we conclude that the basic mechanisms of sexual motivation and the role of general arousal are similar in rodents and humans.
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Affiliation(s)
- Anders Ågmo
- Department of Psychology, University of Tromsø, Norway.
| | - Ellen Laan
- Department of Sexology and Psychosomatic Gynaecology, Amsterdam UMC, University of Amsterdam, The Netherlands
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6
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Identification of an allatostatin C signaling system in mollusc Aplysia. Sci Rep 2022; 12:1213. [PMID: 35075137 PMCID: PMC8786951 DOI: 10.1038/s41598-022-05071-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 01/06/2022] [Indexed: 02/06/2023] Open
Abstract
Neuropeptides, as pervasive intercellular signaling molecules in the CNS, modulate a variety of behavioral systems in both protostomes and deuterostomes. Allatostatins are neuropeptides in arthropods that inhibit the biosynthesis of juvenile hormones. Based on amino acid sequences, they are divided into three different types in arthropods: allatostatin A, allatostatin B, allatostatin C. Allatostatin C (AstC) was first isolated from Manduca sexta, and it has an important conserved feature of a disulfide bridge formed by two cysteine residues. Moreover, AstC appears to be the ortholog of mammalian somatostatin, and it has functions in common with somatostatin, such as modulating feeding behaviors. The AstC signaling system has been widely studied in arthropods, but minimally studied in molluscs. In this study, we seek to identify the AstC signaling system in the marine mollusc Aplysia californica. We cloned the AstC precursor from the cDNA of Aplysia. We predicted a 15-amino acid peptide with a disulfide bridge, i.e., AstC, using NeuroPred. We then cloned two putative allatostatin C-like receptors and through NCBI Conserved Domain Search we found that they belonged to the G protein-coupled receptor (GPCR) family. In addition, using an inositol monophosphate 1 (IP1) accumulation assay, we showed that Aplysia AstC could activate one of the putative receptors, i.e., the AstC-R, at the lowest EC50, and AstC without the disulfide bridge (AstC') activated AstC-R with the highest EC50. Moreover, four molluscan AstCs with variations of sequences from Aplysia AstC but with the disulfide bridge activated AstC-R at intermediate EC50. In summary, our successful identification of the Aplysia AstC precursor and its receptor (AstC-R) represents the first example in molluscs, and provides an important basis for further studies of the AstC signaling system in Aplysia and other molluscs.
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Abstract
The serotonergic modulation of feeding behaviour has been intensively studied in several invertebrate groups, including Arthropoda, Annelida, Nematoda and Mollusca. These studies offer comparative information on feeding regulation across divergent phyla and also provide general insights into the neural control of feeding. Specifically, model invertebrates are ideal for parsing feeding behaviour into component parts and examining the underlying mechanisms at the levels of biochemical pathways, single cells and identified neural circuitry. Research has found that serotonin is crucial during certain phases of feeding behaviour, especially movements directly underlying food intake, but inessential during other phases. In addition, while the serotonin system can be manipulated systemically in many animals, invertebrate model organisms also allow manipulations at the level of single cells and molecules, revealing limited and precise serotonergic actions. The latter highlight the importance of local versus global modulatory effects of serotonin, a potentially significant consideration for drug and pesticide design.
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Affiliation(s)
- Ann Jane Tierney
- Neuroscience Program, Psychological and Brain Sciences, Colgate University, Hamilton, NY, USA
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8
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Watson WH, Nash A, Lee C, Patz MD, Newcomb JM. The Distribution and Possible Roles of Small Cardioactive Peptide in the Nudibranch Melibe leonina. Integr Org Biol 2020; 2:obaa016. [PMID: 33791559 PMCID: PMC7671164 DOI: 10.1093/iob/obaa016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The neuropeptide small cardioactive peptide (SCP) plays an integrative role in exciting various motor programs involved in feeding and locomotion in a number of gastropod species. In this study, immunohistochemistry, using monoclonal antibodies against SCPB, was used to localize SCPB-like-immunoreactive neurons in the central nervous system, and map their connections to various tissues, in the nudibranch, Melibe leonina. Approximately 28-36 SCPB-like-immunoreactive neurons were identified in the M. leonina brain, as well as one large neuron in each of the buccal ganglia. The neuropil of the pedal ganglia contained the most SCPB-like-immunoreactive varicosities, although only a small portion of these were due to SCPB-like-immunoreactive neurons in the same ganglion. This suggests that much of the SCPB-like immunoreactivity in the neuropil of the pedal ganglia was from neurons in other ganglia that projected through the pedal-pedal connectives or the connectives from the cerebral and pleural ganglia. We also observed extensive SCPB innervation along the length of the esophagus. Therefore, we investigated the impact of SCPB on locomotion in intact animals, as well as peristaltic contractions of the isolated esophagus. Injection of intact animals with SCPB at night led to a significant increase in crawling and swimming, compared to control animals injected with saline. Furthermore, perfusion of isolated brains with SCPB initiated expression of the swim motor program. Application of SCPB to the isolated quiescent esophagus initiated rhythmic peristaltic contractions, and this occurred in preparations both with and without the buccal ganglia being attached. All these data, taken together, suggest that SCPB could be released at night to arouse animals and enhance the expression of both feeding and swimming motor programs in M. leonina.
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Affiliation(s)
- W H Watson
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - A Nash
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - C Lee
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - M D Patz
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - J M Newcomb
- Department of Biology and Health Science, New England College, Henniker, NH 03242, USA
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Conserved Serotonergic Background of Experience-Dependent Behavioral Responsiveness in Zebrafish ( Danio rerio). J Neurosci 2020; 40:4551-4564. [PMID: 32350040 DOI: 10.1523/jneurosci.2178-19.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 03/17/2020] [Accepted: 03/20/2020] [Indexed: 01/28/2023] Open
Abstract
Forming effective responses to threatening stimuli requires the adequate and coordinated emergence of stress-related internal states. Such ability depends on early-life experiences and, in connection, the adequate formation of neuromodulatory systems, particularly serotonergic signaling. Here, we assess the serotonergic background of experience-dependent behavioral responsiveness using male and female zebrafish (Danio rerio). For the first time, we have characterized a period during behavioral metamorphosis in which zebrafish are highly reactive to their environment. Absence of social stimuli during this phase established by isolated rearing fundamentally altered the behavioral phenotype of postmetamorphic zebrafish in a challenge-specific manner, partially due to reduced responsiveness and an inability to develop stress-associated arousal state. In line with this, isolation differentially affected whole-brain serotonergic signaling in resting and stress-induced conditions, an effect that was localized in the dorsal pallium and was negatively associated with responsiveness. Administration of the serotonin receptor 1A partial agonist buspirone prevented the isolation-induced serotonin response to novelty in the level of the whole brain and the forebrain as well, without affecting catecholamine levels, and rescued stress-induced arousal along with challenge-induced behaviors, which together indicates functional connection between these changes. In summary, there is a consistent negative association between behavioral responsiveness and serotonergic signaling in zebrafish, which is well recognizable through the modifying effects of developmental perturbation and pharmacological manipulations as well. Our results imply a conserved serotonergic mechanism that context-dependently modulates environmental reactivity and is highly sensitive to experiences acquired during a specific early-life time window, a phenomenon that was previously only suggested in mammals.SIGNIFICANCE STATEMENT The ability to respond to challenges is a fundamental factor in survival. We show that zebrafish that lack appropriate social stimuli in a sensitive developmental period show exacerbated alertness in nonstressful conditions while failing to react adequately to stressors. This shift is reflected inversely by central serotonergic signaling, a system that is implicated in numerous mental disorders in humans. Serotonergic changes in brain regions modulating responsivity and behavioral impairment were both prevented by the pharmacological blockade of serotonergic function. These results imply a serotonergic mechanism in zebrafish that transmits early-life experiences to the later phenotype by shaping stress-dependent behavioral reactivity, a phenomenon that was previously only suggested in mammals. Zebrafish provide new insights into early-life-dependent neuromodulation of behavioral stress-responses.
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Bacqué-Cazenave J, Bharatiya R, Barrière G, Delbecque JP, Bouguiyoud N, Di Giovanni G, Cattaert D, De Deurwaerdère P. Serotonin in Animal Cognition and Behavior. Int J Mol Sci 2020; 21:ijms21051649. [PMID: 32121267 PMCID: PMC7084567 DOI: 10.3390/ijms21051649] [Citation(s) in RCA: 143] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/25/2020] [Accepted: 02/25/2020] [Indexed: 12/20/2022] Open
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) is acknowledged as a major neuromodulator of nervous systems in both invertebrates and vertebrates. It has been proposed for several decades that it impacts animal cognition and behavior. In spite of a completely distinct organization of the 5-HT systems across the animal kingdom, several lines of evidence suggest that the influences of 5-HT on behavior and cognition are evolutionary conserved. In this review, we have selected some behaviors classically evoked when addressing the roles of 5-HT on nervous system functions. In particular, we focus on the motor activity, arousal, sleep and circadian rhythm, feeding, social interactions and aggressiveness, anxiety, mood, learning and memory, or impulsive/compulsive dimension and behavioral flexibility. The roles of 5-HT, illustrated in both invertebrates and vertebrates, show that it is more able to potentiate or mitigate the neuronal responses necessary for the fine-tuning of most behaviors, rather than to trigger or halt a specific behavior. 5-HT is, therefore, the prototypical neuromodulator fundamentally involved in the adaptation of all organisms across the animal kingdom.
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Affiliation(s)
- Julien Bacqué-Cazenave
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
| | - Rahul Bharatiya
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
- Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, University of Cagliari, 09100 Cagliari, Italy
| | - Grégory Barrière
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
| | - Jean-Paul Delbecque
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
| | - Nouhaila Bouguiyoud
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
| | - Giuseppe Di Giovanni
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, MSD 2080 Msida, Malta;
- School of Biosciences, Neuroscience Division, Cardiff University, Cardiff CF24 4HQ, UK
| | - Daniel Cattaert
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
- Correspondence: (D.C.); (P.D.D.)
| | - Philippe De Deurwaerdère
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
- Correspondence: (D.C.); (P.D.D.)
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Hunger and satiety determine foraging decissions in land snails: Evidence from the invasive species Theba pisana. Behav Processes 2019; 164:230-236. [PMID: 31095990 DOI: 10.1016/j.beproc.2019.05.013] [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: 01/20/2019] [Revised: 05/05/2019] [Accepted: 05/12/2019] [Indexed: 11/20/2022]
Abstract
The foraging behaviour of gastropod molluscs usually involves complex decisions that provide a model for the study of high-order cognitive processes. Land snails tested for food-finding in the laboratory, however, have shown an invariable feeding pattern: novel foods are mostly missed (i.e. just found by chance) whilst familiar foods, due to a type of conditioned attraction, are always located and ingested. This effect, known as Food-attraction conditioning, has led to the conclusion that, regardless of their hunger level, land snails are both willing to eat anything at any moment and also blind to the odours of novel foods. An alternative account of these findings emerges from the fact that the snails are usually tested whilst in a moderate state of hunger, so that they benefit from feeding on known foods but not from taking the risk of feeding on those that are unknown. The present experiments suggest that it is the case. Snails of the invasive species Theba pisana were tested for food-finding according to their seasonal cycle in a laboratory located in their native Mediterranean region. Subjects collected at the beginning of their aestivation period succeed in locating novel food items after being deprived for a long period (45 days), but ignored a conditioned food when they were sated with this food at the end of their lethargy. The results allow us to conclude that the feeding behaviour of snails is the product of a complex cost-benefit analysis in which their motivational state and the stimuli they perceive (and the memory of such stimuli), are evaluated. Finally, we anticipate that these results will be of use in increasing the efficiency of current baits employed for the protection of crops.
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12
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Automated behavioural analysis reveals the basic behavioural repertoire of the urochordate Ciona intestinalis. Sci Rep 2019; 9:2416. [PMID: 30787329 PMCID: PMC6382837 DOI: 10.1038/s41598-019-38791-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/09/2019] [Indexed: 12/17/2022] Open
Abstract
Quantitative analysis of animal behaviour in model organisms is becoming an increasingly essential approach for tackling the great challenge of understanding how activity in the brain gives rise to behaviour. Here we used automated image-based tracking to extract behavioural features from an organism of great importance in understanding the evolution of chordates, the free-swimming larval form of the tunicate Ciona intestinalis, which has a compact and fully mapped nervous system composed of only 231 neurons. We analysed hundreds of videos of larvae and we extracted basic geometric and physical descriptors of larval behaviour. Importantly, we used machine learning methods to create an objective ontology of behaviours for C. intestinalis larvae. We identified eleven behavioural modes using agglomerative clustering. Using our pipeline for quantitative behavioural analysis, we demonstrate that C. intestinalis larvae exhibit sensory arousal and thigmotaxis. Notably, the anxiotropic drug modafinil modulates thigmotactic behaviour. Furthermore, we tested the robustness of the larval behavioural repertoire by comparing different rearing conditions, ages and group sizes. This study shows that C. intestinalis larval behaviour can be broken down to a set of stereotyped behaviours that are used to different extents in a context-dependent manner.
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13
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Brown JW, Schaub BM, Klusas BL, Tran AX, Duman AJ, Haney SJ, Boris AC, Flanagan MP, Delgado N, Torres G, Rolón-Martínez S, Vaasjo LO, Miller MW, Gillette R. A role for dopamine in the peripheral sensory processing of a gastropod mollusc. PLoS One 2018; 13:e0208891. [PMID: 30586424 PMCID: PMC6306152 DOI: 10.1371/journal.pone.0208891] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 11/27/2018] [Indexed: 11/26/2022] Open
Abstract
Histological evidence points to the presence of dopamine (DA) in the cephalic sensory organs of multiple gastropod molluscs, suggesting a possible sensory role for the neurotransmitter. We investigated the sensory function of DA in the nudipleuran Pleurobranchaea californica, in which the central neural correlates of sensation and foraging behavior have been well characterized. Tyrosine hydroxylase-like immunoreactivity (THli), a signature of the dopamine synthetic pathway, was similar to that found in two other opisthobranchs and two pulmonates previously studied: 1) relatively few (<100) THli neuronal somata were observed in the central ganglia, with those observed found in locations similar to those documented in the other snails but varying in number, and 2) the vast majority of THli somata were located in the peripheral nervous system, were associated with ciliated, putative primary sensory cells, and were highly concentrated in chemotactile sensory organs, giving rise to afferent axons projecting to the central nervous system. We extended these findings by observing that applying a selective D2/D3 receptor antagonist to the chemo- and mechanosensory oral veil-tentacle complex of behaving animals significantly delayed feeding behavior in response to an appetitive stimulus. A D1 blocker had no effect. Recordings of the two major cephalic sensory nerves, the tentacle and large oral veil nerves, in a deganglionated head preparation revealed a decrease of stimulus-evoked activity in the former nerve following application of the same D2/D3 antagonist. Broadly, our results implicate DA in sensation and engender speculation regarding the foraging-based decisions the neurotransmitter may serve in the nervous system of Pleurobranchaea and, by extension, other gastropods.
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Affiliation(s)
- Jeffrey W. Brown
- Program in Biophysics and Computational Biology, University of Illinois, Urbana, Illinois, United States of America
- College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- * E-mail:
| | - Brittany M. Schaub
- School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Bennett L. Klusas
- School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Andrew X. Tran
- School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Alexander J. Duman
- School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Samantha J. Haney
- School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Abigail C. Boris
- School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Megan P. Flanagan
- School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Nadia Delgado
- Institute of Neurobiology and Department of Anatomy & Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico, United States of America
| | - Grace Torres
- Institute of Neurobiology and Department of Anatomy & Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico, United States of America
| | - Solymar Rolón-Martínez
- Institute of Neurobiology and Department of Anatomy & Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico, United States of America
| | - Lee O. Vaasjo
- Institute of Neurobiology and Department of Anatomy & Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico, United States of America
| | - Mark W. Miller
- Institute of Neurobiology and Department of Anatomy & Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico, United States of America
| | - Rhanor Gillette
- Program in Biophysics and Computational Biology, University of Illinois, Urbana, Illinois, United States of America
- School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- Department of Molecular & Integrative Physiology and the Neuroscience Program, University of Illinois, Urbana, Illinois, United States of America
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14
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Stratmann P, Albu-Schäffer A, Jörntell H. Scaling Our World View: How Monoamines Can Put Context Into Brain Circuitry. Front Cell Neurosci 2018; 12:506. [PMID: 30618646 PMCID: PMC6307502 DOI: 10.3389/fncel.2018.00506] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 12/06/2018] [Indexed: 12/12/2022] Open
Abstract
Monoamines are presumed to be diffuse metabotropic neuromodulators of the topographically and temporally precise ionotropic circuitry which dominates CNS functions. Their malfunction is strongly implicated in motor and cognitive disorders, but their function in behavioral and cognitive processing is scarcely understood. In this paper, the principles of such a monoaminergic function are conceptualized for locomotor control. We find that the serotonergic system in the ventral spinal cord scales ionotropic signals and shows topographic order that agrees with differential gain modulation of ionotropic subcircuits. Whereas the subcircuits can collectively signal predictive models of the world based on life-long learning, their differential scaling continuously adjusts these models to changing mechanical contexts based on sensory input on a fast time scale of a few 100 ms. The control theory of biomimetic robots demonstrates that this precision scaling is an effective and resource-efficient solution to adapt the activation of individual muscle groups during locomotion to changing conditions such as ground compliance and carried load. Although it is not unconceivable that spinal ionotropic circuitry could achieve scaling by itself, neurophysiological findings emphasize that this is a unique functionality of metabotropic effects since recent recordings in sensorimotor circuitry conflict with mechanisms proposed for ionotropic scaling in other CNS areas. We substantiate that precision scaling of ionotropic subcircuits is a main functional principle for many monoaminergic projections throughout the CNS, implying that the monoaminergic circuitry forms a network within the network composed of the ionotropic circuitry. Thereby, we provide an early-level interpretation of the mechanisms of psychopharmacological drugs that interfere with the monoaminergic systems.
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Affiliation(s)
- Philipp Stratmann
- Sensor Based Robotic Systems and Intelligent Assistance Systems, Department of Informatics, Technical University of Munich, Garching, Germany
- German Aerospace Center (DLR), Institute of Robotics and Mechatronics, Weßling, Germany
| | - Alin Albu-Schäffer
- Sensor Based Robotic Systems and Intelligent Assistance Systems, Department of Informatics, Technical University of Munich, Garching, Germany
- German Aerospace Center (DLR), Institute of Robotics and Mechatronics, Weßling, Germany
| | - Henrik Jörntell
- Neural Basis of Sensorimotor Control, Department of Experimental Medical Science, Lund University, Lund, Sweden
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15
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Zhang G, Yuan WD, Vilim FS, Romanova EV, Yu K, Yin SY, Le ZW, Xue YY, Chen TT, Chen GK, Chen SA, Cropper EC, Sweedler JV, Weiss KR, Jing J. Newly Identified Aplysia SPTR-Gene Family-Derived Peptides: Localization and Function. ACS Chem Neurosci 2018. [PMID: 29543430 DOI: 10.1021/acschemneuro.7b00513] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
When individual neurons in a circuit contain multiple neuropeptides, these peptides can target different sets of follower neurons. This endows the circuit with a certain degree of flexibility. Here we identified a novel family of peptides, the Aplysia SPTR-Gene Family-Derived peptides (apSPTR-GF-DPs). We demonstrated apSPTR-GF-DPs, particularly apSPTR-GF-DP2, are expressed in the Aplysia CNS using immunohistochemistry and MALDI-TOF MS. Furthermore, apSPTR-GF-DP2 is present in single projection neurons, e.g., in the cerebral-buccal interneuron-12 (CBI-12). Previous studies have demonstrated that CBI-12 contains two other peptides, FCAP/CP2. In addition, CBI-12 and CP2 promote shortening of the protraction phase of motor programs. Here, we demonstrate that FCAP shortens protraction. Moreover, we show that apSPTR-GF-DP2 also shortens protraction. Surprisingly, apSPTR-GF-DP2 does not increase the excitability of retraction interneuron B64. B64 terminates protraction and is modulated by FCAP/CP2 and CBI-12. Instead, we show that apSPTR-GF-DP2 and CBI-12 increase B20 excitability and B20 activity can shorten protraction. Taken together, these data indicate that different CBI-12 peptides target different sets of pattern-generating interneurons to exert similar modulatory actions. These findings provide the first definitive evidence for SPTR-GF's role in modulation of feeding, and a form of molecular degeneracy by multiple peptide cotransmitters in single identified neurons.
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Affiliation(s)
- Guo Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210046, China
| | - Wang-ding Yuan
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210046, China
| | - Ferdinand S. Vilim
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, United States
| | - Elena V. Romanova
- Beckman Institute for Advanced Science and Technology and Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Ke Yu
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210046, China
| | - Si-yuan Yin
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210046, China
| | - Zi-wei Le
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210046, China
| | - Ying-yu Xue
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210046, China
| | - Ting-ting Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210046, China
| | - Guo-kai Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210046, China
| | - Song-an Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210046, China
| | - Elizabeth C. Cropper
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, United States
| | - Jonathan V. Sweedler
- Beckman Institute for Advanced Science and Technology and Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Klaudiusz R. Weiss
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, United States
| | - Jian Jing
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210046, China
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, United States
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16
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Checco JW, Zhang G, Yuan WD, Yu K, Yin SY, Roberts-Galbraith RH, Yau PM, Romanova EV, Jing J, Sweedler JV. Molecular and Physiological Characterization of a Receptor for d-Amino Acid-Containing Neuropeptides. ACS Chem Biol 2018. [PMID: 29543428 PMCID: PMC5962930 DOI: 10.1021/acschembio.8b00167] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
![]()
Neuropeptides
in several animals undergo an unusual post-translational
modification, the isomerization of an amino acid residue from the l-stereoisomer to the d-stereoisomer. The resulting d-amino acid-containing peptide (DAACP) often displays biological
activity higher than that of its all-l-residue analogue,
with the d-residue being critical for function in many cases.
However, little is known about the full physiological roles played
by DAACPs, and few studies have examined the interaction of DAACPs
with their cognate receptors. Here, we characterized the signaling
of several DAACPs derived from a single neuropeptide prohormone, the Aplysia californica achatin-like neuropeptide precursor
(apALNP), at their putative receptor, the achatin-like neuropeptide
receptor (apALNR). We first used quantitative polymerase chain reaction
and in situ hybridization experiments to demonstrate
receptor (apALNR) expression throughout the central
nervous system; on the basis of the expression pattern, we identified
novel physiological functions that may be mediated by apALNR. To gain
insight into ligand signaling through apALNR, we created a library
of native and non-native neuropeptide analogues derived from apALNP
(the neuropeptide prohormone) and evaluated them for activity in cells
co-transfected with apALNR and the promiscuous Gα
subunit Gα-16. Several of these neuropeptide
analogues were also evaluated for their ability to induce circuit
activity in a well-defined neural network associated with feeding
behavior in intact ganglia from Aplysia. Our results
reveal the specificity of apALNR and provide strong evidence that
this receptor mediates diverse physiological functions throughout
the central nervous system. Finally, we show that some native apALNP-derived
DAACPs exhibit enhanced stability toward endogenous proteases, suggesting
that the d-residues in these DAACPs may increase the peptide
lifetime, in addition to influencing receptor specificity, in the
nervous system. Ultimately, these studies provide insight into signaling
at one of the few known DAACP-specific receptors and advance our understanding
of the roles that l- to d-residue isomerization
play in neuropeptide signaling.
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Affiliation(s)
- James W. Checco
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Guo Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, China
| | - Wang-ding Yuan
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, China
| | - Ke Yu
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, China
| | - Si-yuan Yin
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, China
| | - Rachel H. Roberts-Galbraith
- Department of Cell and Developmental Biology, Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Peter M. Yau
- Roy J. Carver Biotechnology Center, Protein Sciences Facility, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Elena V. Romanova
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Jian Jing
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, China
| | - Jonathan V. Sweedler
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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17
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Katz PS. Phylogenetic plasticity in the evolution of molluscan neural circuits. Curr Opin Neurobiol 2016; 41:8-16. [PMID: 27455462 DOI: 10.1016/j.conb.2016.07.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 06/17/2016] [Accepted: 07/13/2016] [Indexed: 01/06/2023]
Abstract
Recent research on molluscan nervous systems provides a unique perspective on the evolution of neural circuits. Molluscs evolved large, encephalized nervous systems independently from other phyla. Homologous body-patterning genes were re-specified in molluscs to create a plethora of body plans and nervous system organizations. Octopuses, having the largest brains of any invertebrate, independently evolved a learning circuit similar in organization and function to the mushroom body of insects and the hippocampus of mammals. In gastropods, homologous neurons have been re-specified for different functions. Even species exhibiting similar, possibly homologous behavior have fundamental differences in the connectivity of the neurons underlying that behavior. Thus, molluscan nervous systems provide clear examples of re-purposing of homologous genes and neurons for neural circuits.
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Affiliation(s)
- Paul S Katz
- Neuroscience Institute, Georgia State University, PO Box 5030, Atlanta, GA 30302-5030, USA.
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18
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Yang CY, Yu K, Wang Y, Chen SA, Liu DD, Wang ZY, Su YN, Yang SZ, Chen TT, Livnat I, Vilim FS, Cropper EC, Weiss KR, Sweedler JV, Jing J. Aplysia Locomotion: Network and Behavioral Actions of GdFFD, a D-Amino Acid-Containing Neuropeptide. PLoS One 2016; 11:e0147335. [PMID: 26796097 PMCID: PMC4721866 DOI: 10.1371/journal.pone.0147335] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Accepted: 01/01/2016] [Indexed: 12/02/2022] Open
Abstract
One emerging principle is that neuromodulators, such as neuropeptides, regulate multiple behaviors, particularly motivated behaviors, e.g., feeding and locomotion. However, how neuromodulators act on multiple neural networks to exert their actions remains poorly understood. These actions depend on the chemical form of the peptide, e.g., an alternation of L- to D- form of an amino acid can endow the peptide with bioactivity, as is the case for the Aplysia peptide GdFFD (where dF indicates D-phenylalanine). GdFFD has been shown to act as an extrinsic neuromodulator in the feeding network, while the all L-amino acid form, GFFD, was not bioactive. Given that both GdFFD/GFFD are also present in pedal neurons that mediate locomotion, we sought to determine whether they impact locomotion. We first examined effects of both peptides on isolated ganglia, and monitored fictive programs using the parapedal commissural nerve (PPCN). Indeed, GdFFD was bioactive and GFFD was not. GdFFD increased the frequency with which neural activity was observed in the PPCN. In part, there was an increase in bursting spiking activity that resembled fictive locomotion. Additionally, there was significant activity between bursts. To determine how the peptide-induced activity in the isolated CNS is translated into behavior, we recorded animal movements, and developed a computer program to automatically track the animal and calculate the path of movement and velocity of locomotion. We found that GdFFD significantly reduced locomotion and induced a foot curl. These data suggest that the increase in PPCN activity observed in the isolated CNS during GdFFD application corresponds to a reduction, rather than an increase, in locomotion. In contrast, GFFD had no effect. Thus, our study suggests that GdFFD may act as an intrinsic neuromodulator in the Aplysia locomotor network. More generally, our study indicates that physiological and behavioral analyses should be combined to evaluate peptide actions.
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Affiliation(s)
- Chao-Yu Yang
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Ke Yu
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Ye Wang
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Song-An Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Dan-Dan Liu
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Zheng-Yang Wang
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Yan-Nan Su
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Shao-Zhong Yang
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Ting-Ting Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Itamar Livnat
- Beckman Institute for Advanced Science and Technology and Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Ferdinand S. Vilim
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Elizabeth C. Cropper
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Klaudiusz R. Weiss
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Jonathan V. Sweedler
- Beckman Institute for Advanced Science and Technology and Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Jian Jing
- State Key Laboratory of Pharmaceutical Biotechnology, Collaborative Innovation Center of Chemistry for Life Sciences, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail:
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19
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Identified Serotonin-Releasing Neurons Induce Behavioral Quiescence and Suppress Mating in Drosophila. J Neurosci 2016; 35:12792-812. [PMID: 26377467 DOI: 10.1523/jneurosci.1638-15.2015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Animals show different levels of activity that are reflected in sensory responsiveness and endogenously generated behaviors. Biogenic amines have been determined to be causal factors for these states of arousal. It is well established that, in Drosophila, dopamine and octopamine promote increased arousal. However, little is known about factors that regulate arousal negatively and induce states of quiescence. Moreover, it remains unclear whether global, diffuse modulatory systems comprehensively affecting brain activity determine general states of arousal. Alternatively, individual aminergic neurons might selectively modulate the animals' activity in a distinct behavioral context. Here, we show that artificially activating large populations of serotonin-releasing neurons induces behavioral quiescence and inhibits feeding and mating. We systematically narrowed down a role of serotonin in inhibiting endogenously generated locomotor activity to neurons located in the posterior medial protocerebrum. We identified neurons of this cell cluster that suppress mating, but not feeding behavior. These results suggest that serotonin does not uniformly act as global, negative modulator of general arousal. Rather, distinct serotoninergic neurons can act as inhibitory modulators of specific behaviors. SIGNIFICANCE STATEMENT An animal's responsiveness to external stimuli and its various types of endogenously generated, motivated behavior are highly dynamic and change between states of high activity and states of low activity. It remains unclear whether these states are mediated by unitary modulatory systems globally affecting brain activity, or whether distinct neurons modulate specific neuronal circuits underlying particular types of behavior. Using the model organism Drosophila melanogaster, we find that activating large proportions of serotonin-releasing neurons induces behavioral quiescence. Moreover, distinct serotonin-releasing neurons that we genetically isolated and identified negatively affect aspects of mating behavior, but not food uptake. This demonstrates that individual serotoninergic neurons can modulate distinct types of behavior selectively.
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20
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Andrianov VV, Bogodvid TK, Deryabina IB, Golovchenko AN, Muranova LN, Tagirova RR, Vinarskaya AK, Gainutdinov KL. Modulation of defensive reflex conditioning in snails by serotonin. Front Behav Neurosci 2015; 9:279. [PMID: 26557063 PMCID: PMC4615812 DOI: 10.3389/fnbeh.2015.00279] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 10/02/2015] [Indexed: 01/24/2023] Open
Abstract
Highlights Daily injection of serotonin before a training session accelerated defensive reflex conditioning in snails.Daily injection of 5-hydroxytryptophan before a training session in snails with a deficiency of serotonin induced by the "neurotoxic" analog of serotonin 5,7-dihydroxytryptamine, restored the ability of snails to learn.After injection of the "neurotoxic" analogs of serotonin 5,6- and 5,7-dihydroxytryptamine as well as serotonin, depolarization of the membrane and decrease of the threshold potential of premotor interneurons was observed. We studied the role of serotonin in the mechanisms of learning in terrestrial snails. To produce a serotonin deficit, the "neurotoxic" analogs of serotonin, 5,6- or 5,7-dihydroxytryptamine (5,6/5,7-DHT) were used. Injection of 5,6/5,7-DHT was found to disrupt defensive reflex conditioning. Within 2 weeks of neurotoxin application, the ability to learn had recovered. Daily injection of serotonin before a training session accelerated defensive reflex conditioning and daily injections of 5-HTP in snails with a deficiency of serotonin induced by 5,7-DHT restored the snail's ability to learn. We discovered that injections of the neurotoxins 5,6/5,7-DHT as well as serotonin, caused a decrease in the resting and threshold potentials of the premotor interneurons LPa3 and RPa3.
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Affiliation(s)
- Vyatcheslav V. Andrianov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal UniversityKazan, Russia
- Group of Biophysics, Zavoisky Physical-Technical Institute, Russian Academy of SciencesKazan, Russia
| | - Tatiana K. Bogodvid
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal UniversityKazan, Russia
- Department of Biomedical Sciences, Volga Region State Academy of Physical Culture, Sport and TourismKazan, Russia
| | - Irina B. Deryabina
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal UniversityKazan, Russia
| | - Aleksandra N. Golovchenko
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal UniversityKazan, Russia
| | - Lyudmila N. Muranova
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal UniversityKazan, Russia
| | - Roza R. Tagirova
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal UniversityKazan, Russia
| | - Aliya K. Vinarskaya
- Laboratory of Cellular Neurobiology of Learning, Institute of High Nerve Activity and Neurophysiology, Russian Academy of SciencesMoscow, Russia
| | - Khalil L. Gainutdinov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal UniversityKazan, Russia
- Group of Biophysics, Zavoisky Physical-Technical Institute, Russian Academy of SciencesKazan, Russia
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21
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Functional Characterization of a Vesicular Glutamate Transporter in an Interneuron That Makes Excitatory and Inhibitory Synaptic Connections in a Molluscan Neural Circuit. J Neurosci 2015; 35:9137-49. [PMID: 26085636 DOI: 10.1523/jneurosci.0180-15.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Understanding circuit function requires the characterization of component neurons and their neurotransmitters. Previous work on radula protraction in the Aplysia feeding circuit demonstrated that critical neurons initiate feeding via cholinergic excitation. In contrast, it is less clear how retraction is mediated at the interneuronal level. In particular, glutamate involvement was suggested, but was not directly confirmed. Here we study a suspected glutamatergic retraction interneuron, B64. We used the representational difference analysis (RDA) method to successfully clone an Aplysia vesicular glutamate transporter (ApVGLUT) from B64 and from a glutamatergic motor neuron B38. Previously, RDA was used to characterize novel neuropeptides. Here we demonstrate its utility for characterizing other types of molecules. Bioinformatics suggests that ApVGLUT is more closely related to mammalian VGLUTs than to Drosophila and Caenorhabditis elegans VGLUTs. We expressed ApVGLUT in a cell line, and demonstrated that it indeed transports glutamate in an ATP and proton gradient-dependent manner. We mapped the ApVGLUT distribution in the CNS using in situ hybridization and immunocytochemistry. Further, we demonstrated that B64 is ApVGLUT positive, supporting the idea that it is glutamatergic. Although glutamate is primarily an excitatory transmitter in the mammalian CNS, B64 elicits inhibitory PSPs in protraction neurons to terminate protraction and excitatory PSPs in retraction neurons to maintain retraction. Pharmacological data indicated that both types of PSPs are mediated by glutamate. Thus, glutamate mediates the dual function of B64 in Aplysia. More generally, our systematic approaches based on RDA may facilitate analyses of transmitter actions in small circuits with identifiable neurons.
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Chu X, Gagnidze K, Pfaff D, Ågmo A. Estrogens, androgens and generalized behavioral arousal in gonadectomized female and male C57BL/6 mice. Physiol Behav 2015; 147:255-63. [PMID: 25936820 DOI: 10.1016/j.physbeh.2015.04.053] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 04/27/2015] [Accepted: 04/28/2015] [Indexed: 01/18/2023]
Abstract
General arousal has been operationally defined as an enhanced motor activity and enhanced intensity of response to sensory stimuli. Even though the effects of gonadal hormones on mating behavior have been much studied, their potential effect on generalized arousal, as defined above, has never been evaluated. In the present study we employed a thoroughly validated assay of general arousal to determine the effects of estradiol (E) and testosterone (T) in gonadectomized female and male mice, respectively. The steroids were administered in three different ways: A fast-acting, water soluble preparation given intraperitoneally, an oil solution given subcutaneously, and an oil solution in a subcutaneous Silastic capsule. Motor activity and responses to sensory stimuli were recorded for 24h, 91h, and seven days following hormone administration, respectively. All measures of arousal varied according to the day/night cycle. The water soluble steroid preparation had no reliable effect. When the same doses of estradiol and testosterone were administered subcutaneously in an oil vehicle no effect of either treatment on arousal was observed. The subcutaneously implanted capsule containing estradiol or testosterone had a delayed effect on motor activity in females (four to seven days) but no effect in males. The long time required by the gonadal hormones for affecting arousal would be consistent with, but does not prove, a genomic action. The limited effects of E and T in our arousal assay suggest to us that the strongest actions of these hormones on arousal occur in the context of sequences of responses to sexually relevant stimuli.
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Affiliation(s)
- Xi Chu
- Department of Psychology, University of Tromsø, 9037 Tromsø, Norway.
| | - Khatuna Gagnidze
- Laboratory of Neurobiology and Behavior, The Rockefeller University, NY, USA
| | - Donald Pfaff
- Laboratory of Neurobiology and Behavior, The Rockefeller University, NY, USA
| | - Anders Ågmo
- Department of Psychology, University of Tromsø, 9037 Tromsø, Norway
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Woods IG, Schoppik D, Shi VJ, Zimmerman S, Coleman HA, Greenwood J, Soucy ER, Schier AF. Neuropeptidergic signaling partitions arousal behaviors in zebrafish. J Neurosci 2014; 34:3142-60. [PMID: 24573274 PMCID: PMC3935080 DOI: 10.1523/jneurosci.3529-13.2014] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 01/01/2014] [Accepted: 01/07/2014] [Indexed: 11/21/2022] Open
Abstract
Animals modulate their arousal state to ensure that their sensory responsiveness and locomotor activity match environmental demands. Neuropeptides can regulate arousal, but studies of their roles in vertebrates have been constrained by the vast array of neuropeptides and their pleiotropic effects. To overcome these limitations, we systematically dissected the neuropeptidergic modulation of arousal in larval zebrafish. We quantified spontaneous locomotor activity and responsiveness to sensory stimuli after genetically induced expression of seven evolutionarily conserved neuropeptides, including adenylate cyclase activating polypeptide 1b (adcyap1b), cocaine-related and amphetamine-related transcript (cart), cholecystokinin (cck), calcitonin gene-related peptide (cgrp), galanin, hypocretin, and nociceptin. Our study reveals that arousal behaviors are dissociable: neuropeptide expression uncoupled spontaneous activity from sensory responsiveness, and uncovered modality-specific effects upon sensory responsiveness. Principal components analysis and phenotypic clustering revealed both shared and divergent features of neuropeptidergic functions: hypocretin and cgrp stimulated spontaneous locomotor activity, whereas galanin and nociceptin attenuated these behaviors. In contrast, cart and adcyap1b enhanced sensory responsiveness yet had minimal impacts on spontaneous activity, and cck expression induced the opposite effects. Furthermore, hypocretin and nociceptin induced modality-specific differences in responsiveness to changes in illumination. Our study provides the first systematic and high-throughput analysis of neuropeptidergic modulation of arousal, demonstrates that arousal can be partitioned into independent behavioral components, and reveals novel and conserved functions of neuropeptides in regulating arousal.
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Affiliation(s)
- Ian G. Woods
- Department of Biology, Ithaca College, Ithaca, New York 14850, and
- Department of Molecular and Cellular Biology and
| | | | | | | | - Haley A. Coleman
- Department of Biology, Ithaca College, Ithaca, New York 14850, and
| | - Joel Greenwood
- Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138
| | - Edward R. Soucy
- Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138
| | - Alexander F. Schier
- Department of Molecular and Cellular Biology and
- Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138
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Bai L, Livnat I, Romanova EV, Alexeeva V, Yau PM, Vilim FS, Weiss KR, Jing J, Sweedler JV. Characterization of GdFFD, a D-amino acid-containing neuropeptide that functions as an extrinsic modulator of the Aplysia feeding circuit. J Biol Chem 2013; 288:32837-51. [PMID: 24078634 DOI: 10.1074/jbc.m113.486670] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During eukaryotic translation, peptides/proteins are created using L-amino acids. However, a D-amino acid-containing peptide (DAACP) can be produced through post-translational modification via an isomerase enzyme. General approaches to identify novel DAACPs and investigate their function, particularly in specific neural circuits, are lacking. This is primarily due to the difficulty in characterizing this modification and due to the limited information on neural circuits in most species. We describe a multipronged approach to overcome these limitations using the sea slug Aplysia californica. Based on bioinformatics and homology to known DAACPs in the land snail Achatina fulica, we targeted two predicted peptides in Aplysia, GFFD, similar to achatin-I (GdFAD versus GFAD, where dF stands for D-phenylalanine), and YAEFLa, identical to fulyal (YdAEFLa versus YAEFLa), using stereoselective analytical methods, i.e. MALDI MS fragmentation analysis and LC-MS/MS. Although YAEFLa in Aplysia was detected only in an all L-form, we found that both GFFD and GdFFD were present in the Aplysia CNS. In situ hybridization and immunolabeling of GFFD/GdFFD-positive neurons and fibers suggested that GFFD/GdFFD might act as an extrinsic modulator of the feeding circuit. Consistent with this hypothesis, we found that GdFFD induced robust activity in the feeding circuit and elicited egestive motor patterns. In contrast, the peptide consisting of all L-amino acids, GFFD, was not bioactive. Our data indicate that the modification of an L-amino acid-containing neuropeptide to a DAACP is essential for peptide bioactivity in a motor circuit, and thus it provides a functional significance to this modification.
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Affiliation(s)
- Lu Bai
- From the Beckman Institute for Advanced Science and Technology and Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
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Evolution of consciousness: phylogeny, ontogeny, and emergence from general anesthesia. Proc Natl Acad Sci U S A 2013; 110 Suppl 2:10357-64. [PMID: 23754370 DOI: 10.1073/pnas.1301188110] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Are animals conscious? If so, when did consciousness evolve? We address these long-standing and essential questions using a modern neuroscientific approach that draws on diverse fields such as consciousness studies, evolutionary neurobiology, animal psychology, and anesthesiology. We propose that the stepwise emergence from general anesthesia can serve as a reproducible model to study the evolution of consciousness across various species and use current data from anesthesiology to shed light on the phylogeny of consciousness. Ultimately, we conclude that the neurobiological structure of the vertebrate central nervous system is evolutionarily ancient and highly conserved across species and that the basic neurophysiologic mechanisms supporting consciousness in humans are found at the earliest points of vertebrate brain evolution. Thus, in agreement with Darwin's insight and the recent "Cambridge Declaration on Consciousness in Non-Human Animals," a review of modern scientific data suggests that the differences between species in terms of the ability to experience the world is one of degree and not kind.
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Starling MJ, Branson N, Cody D, McGreevy PD. Conceptualising the Impact of Arousal and Affective State on Training Outcomes of Operant Conditioning. Animals (Basel) 2013; 3:300-17. [PMID: 26487403 PMCID: PMC4494394 DOI: 10.3390/ani3020300] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/25/2013] [Accepted: 03/28/2013] [Indexed: 11/16/2022] Open
Abstract
Simple Summary This article discusses the impacts of arousal and emotional state on training animals using methods based on reward and punishment. Three-dimensional graphs are provided to offer a visual means to illustrate how arousal and emotional state may influence the effectiveness of reward and punishment depending on the behaviour being trained. Dogs and horses are used to illustrate this with reference to commonly trained behaviours in a predatory and a prey animal. Abstract Animal training relies heavily on an understanding of species-specific behaviour as it integrates with operant conditioning principles. Following on from recent studies showing that affective states and arousal levels may correlate with behavioural outcomes, we explore the contribution of both affective state and arousal in behavioural responses to operant conditioning. This paper provides a framework for assessing how affective state and arousal may influence the efficacy of operant training methods. It provides a series of three-dimensional conceptual graphs as exemplars to describing putative influences of both affective state and arousal on the likelihood of dogs and horses performing commonly desired behaviours. These graphs are referred to as response landscapes, and they highlight the flexibility available for improving training efficacy and the likely need for different approaches to suit animals in different affective states and at various levels of arousal. Knowledge gaps are discussed and suggestions made for bridging them.
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Affiliation(s)
- Melissa J Starling
- Faculty of Veterinary Science, University of Sydney, Sydney NSW 2006, Australia.
| | - Nicholas Branson
- Deakin Research, Deakin University, Geelong VIC 3217, Australia.
| | - Denis Cody
- Indice Ecotech Pty Ltd., East Richmond VIC 3121, Australia.
| | - Paul D McGreevy
- Faculty of Veterinary Science, University of Sydney, Sydney NSW 2006, Australia.
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Functional differentiation of a population of electrically coupled heterogeneous elements in a microcircuit. J Neurosci 2013; 33:93-105. [PMID: 23283325 DOI: 10.1523/jneurosci.3841-12.2013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Although electrical coupling is present in many microcircuits, the extent to which it will determine neuronal firing patterns and network activity remains poorly understood. This is particularly true when the coupling is present in a population of heterogeneous, or intrinsically distinct, circuit elements. We examine this question in the Aplysia californica feeding motor network in five electrically coupled identified cells, B64, B4/5, B70, B51, and a newly identified interneuron B71. These neurons exhibit distinct activity patterns during the radula retraction phase of motor programs. In a subset of motor programs, retraction can be flexibly extended by adding a phase of network activity (hyper-retraction). This is manifested most prominently as an additional burst in the radula closure motoneuron B8. Two neurons that excite B8 (B51 and B71) and one that inhibits it (B70) are active during hyper-retraction. Consistent with their near synchronous firing, B51 and B71 showed one of the strongest coupling ratios in this group of neurons. Nonetheless, by manipulating their activity, we found that B51 preferentially acted as a driver of B64/B71 activity, whereas B71 played a larger role in driving B8 activity. In contrast, B70 was weakly coupled to other neurons and its inhibition of B8 counteracted the excitatory drive to B8. Finally, the distinct firing patterns of the electrically coupled neurons were fine-tuned by their intrinsic properties and the largely chemical cross-inhibition between some of them. Thus, the small microcircuit of the Aplysia feeding network is advantageous in understanding how a population of electrically coupled heterogeneous neurons may fulfill specific network functions.
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Delgado N, Vallejo D, Miller MW. Localization of serotonin in the nervous system of Biomphalaria glabrata, an intermediate host for schistosomiasis. J Comp Neurol 2013; 520:3236-55. [PMID: 22434538 DOI: 10.1002/cne.23095] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The digenetic trematode Schistosoma mansoni that causes the form of schistosomiasis found in the Western Hemisphere requires the freshwater snail Biomphalaria glabrata as its primary intermediate host. It has been proposed that the transition from the free-living S. mansoni miracidium to parasitic mother sporocyst depends on uptake of biogenic amines, e.g. serotonin, from the snail host. However, little is known about potential sources of serotonin in B. glabrata tissues. This investigation examined the localization of serotonin-like immunoreactivity (5HTli) in the central nervous system (CNS) and peripheral tissues of B. glabrata. Emphasis was placed on the cephalic and anterior pedal regions that are commonly the sites of S. mansoni miracidium penetration. The anterior foot and body wall were densely innervated by 5HTli fibers but no peripheral immunoreactive neuronal somata were detected. Within the CNS, clusters of 5HTli neurons were observed in the cerebral, pedal, left parietal, and visceral ganglia, suggesting that the peripheral serotonergic fibers originate from the CNS. Double-labeling experiments (biocytin backfill × serotonin immunoreactivity) of the tentacular nerve and the three major pedal nerves (Pd n. 10, Pd n. 11, and Pd n. 12) disclosed central neurons that project to the cephalopedal periphery. Overall, the central distribution of 5HTli neurons suggests that, as in other gastropods, serotonin regulates the locomotion, reproductive, and feeding systems of Biomphalaria. The projections to the foot and body wall indicate that serotonin may also participate in defensive, nociceptive, or inflammation responses. These observations identify potential sources of host-derived serotonin in this parasite-host system. Inc.
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Affiliation(s)
- Nadia Delgado
- Institute of Neurobiology, and Department of Anatomy & Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico 00901
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29
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Abstract
During waking behavior, animals adapt their state of arousal in response to environmental pressures. Sensory processing is regulated in aroused states, and several lines of evidence imply that this is mediated at least partly by the serotonergic system. However, there is little information directly showing that serotonergic function is required for state-dependent modulation of sensory processing. Here we find that zebrafish larvae can maintain a short-term state of arousal during which neurons in the dorsal raphe modulate sensory responsiveness to behaviorally relevant visual cues. After a brief exposure to water flow, larvae show elevated activity and heightened sensitivity to perceived motion. Calcium imaging of neuronal activity after flow revealed increased activity in serotonergic neurons of the dorsal raphe. Genetic ablation of these neurons abolished the increase in visual sensitivity during arousal without affecting baseline visual function or locomotor activity. We traced projections from the dorsal raphe to a major visual area, the optic tectum. Laser ablation of the tectum demonstrated that this structure, like the dorsal raphe, is required for improved visual sensitivity during arousal. These findings reveal that serotonergic neurons of the dorsal raphe have a state-dependent role in matching sensory responsiveness to behavioral context.
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Origins of arousal: roles for medullary reticular neurons. Trends Neurosci 2012; 35:468-76. [PMID: 22626543 DOI: 10.1016/j.tins.2012.04.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 04/18/2012] [Accepted: 04/23/2012] [Indexed: 01/12/2023]
Abstract
The existence of a primitive CNS function involved in the activation of all vertebrate behaviors, generalized arousal (GA), has been proposed. Here, we provide an overview of the neuroanatomical, neurophysiological and molecular properties of reticular neurons within the nucleus gigantocellularis (NGC) of the mammalian medulla, and propose that the properties of these neurons equip them to contribute powerfully to GA. We also explore the hypothesis that these neurons may have evolved from the Mauthner cell in the medulla of teleost fish, although NGC neurons have a wider range of action far beyond the specific escape network served by Mauthner cells. Understanding the neuronal circuits that control and regulate GA is central to understanding how motivated behaviors such as hunger, thirst and sexual behaviors arise.
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Balog G, Voronezhskaya EE, Hiripi L, Elekes K. Organization of the serotonergic innervation of the feeding (buccal) musculature during the maturation of the pond snail Lymnaea stagnalis: a morphological and biochemical study. J Comp Neurol 2012; 520:315-29. [PMID: 21674495 DOI: 10.1002/cne.22693] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The serotonergic innervation of the buccal musculature responsible for feeding (radula protraction) was investigated during the maturation of the pond snail, Lymnaea stagnalis L., applying light and electron microscopic immunohistochemistry and biochemical approaches. According to epifluorescence and laser confocal microscopy, the first 5-HT-like-immunoreactive (5-HTLIR) processes appeared on the surface of the musculature at the postmetamorphic E80% embryonic stage. Until hatching, the innervation continued to increase in density, showing axon arborizations with projections into the deeper muscle levels. An adult-like pattern of 5-HTLIR innervation appeared at P2-P3 juvenile stages. At the ultrastructural level, close (16-20 nm) but mostly unspecialized neuromuscular contacts were formed by both unlabeled and 5-HTLIR axon profiles from the E80% embryonic stage. Labeled processes were also found located relatively far from the muscle cells. An HPLC assay showed a gradual increase of the 5-HT level in the buccal mass during development. The buccal mass was characterized by a single-component high-affinity 5-HT uptake system, and 5-HT release could be evoked by 100 mM K(+) and blocked in Ca(2+) -free medium. It is suggested that 5-HT plays a wide modulatory role in the peripheral feeding system and is also involved in the functional maturation of the muscle system.
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Affiliation(s)
- Gábor Balog
- Department of Experimental Zoology, Balaton Limnological Research Institute, Hungarian Academy of Sciences, H-8237 Tihany, Hungary
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32
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Coordination of distinct motor structures through remote axonal coupling of projection interneurons. J Neurosci 2011; 31:15438-49. [PMID: 22031890 DOI: 10.1523/jneurosci.3741-11.2011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Complex behaviors often require coordinated movements of dissimilar motor structures. The underlying neural mechanisms are poorly understood. We investigated cycle-by-cycle coordination of two dissimilar feeding structures in Aplysia californica: the external lips and the internal radula. During feeding, the lips open while the radula protracts. Lip and radula motoneurons are located in the cerebral and buccal ganglia, respectively, and radula motoneurons are controlled by a well characterized buccal central pattern generator (CPG). Here, we examined whether the three electrically coupled lip motoneurons C15/16/17 are controlled by the buccal CPG or by a previously postulated cerebral CPG. Two buccal-cerebral projection interneurons, B34 and B63, which are part of the buccal CPG and mediate radula protraction, monosynaptically excite C15/16/17. Recordings from the B34 axon in the cerebral ganglion demonstrate its direct electrical coupling with C15/16/17, eliminating the need for a cerebral CPG. Moreover, when the multifunctional buccal CPG generates multiple forms of motor programs due to the activation of two inputs, the command-like neuron CBI-2 and the esophageal nerve (EN), C15/16 exhibit activity patterns that are distinct from C17. These distinct activity patterns result from combined activity of B34 and B63 and their differential excitation of C15/16 versus C17. In more general terms, we identified neuronal mechanisms that allow a single CPG to coordinate the phasing and activity of remotely located motoneurons innervating distinct structures that participate in the production of different motor outputs. We also demonstrated that axodendritic electrical coupling by projection interneurons plays a pivotal role in coordinating activity of these remotely located neurons.
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Jin NG, Crow T. Serotonin regulates voltage-dependent currents in type I(e(A)) and I(i) interneurons of Hermissenda. J Neurophysiol 2011; 106:2557-69. [PMID: 21813747 DOI: 10.1152/jn.00550.2011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Serotonin (5-HT) has both direct and modulatory actions on central neurons contributing to behavioral arousal and cellular-synaptic plasticity in diverse species. In Hermissenda, 5-HT produces changes in intrinsic excitability of different types of identified interneurons in the circumesophageal nervous system. Using whole cell patch-clamp techniques we have examined membrane conductance changes produced by 5-HT that contribute to intrinsic excitability in two identified classes of interneurons, types I(i) and I(eA). Whole cell currents were examined before and after 5-HT application to the isolated nervous system. A 4-aminopyridine-sensitive transient outward K(+) current [I(K(A))], a tetraethylammonium-sensitive delayed rectifier K(+) current [I(K(V))], an inward rectifier K(+) current [I(K(IR))], and a hyperpolarization-activated current (I(h)) were characterized. 5-HT decreased the amplitude of I(K(A)) and I(K(V)) in both type I(i) and I(eA) interneurons. However, differences in 5-HT's effects on the activation-inactivation kinetics were observed in different types of interneurons. 5-HT produced a depolarizing shift in the activation curve of I(K(V)) and a hyperpolarizing shift in the inactivation curve of I(K(A)) in type I(i) interneurons. In contrast, 5-HT produced a depolarizing shift in the activation curve and a hyperpolarizing shift in the inactivation curve of both I(K(V)) and I(K(A)) in type I(eA) interneurons. In addition, 5-HT decreased the amplitude of I(K(IR)) in type I(i) interneurons and increased the amplitude of I(h) in type I(eA) interneurons. These results indicate that 5-HT-dependent changes in I(K(A)), I(K(V)), I(K(IR)), and I(h) contribute to multiple mechanisms that synergistically support modulation of increased intrinsic excitability associated with different functional classes of identified type I interneurons.
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Affiliation(s)
- Nan Ge Jin
- Dept. of Neurobiology and Anatomy, Univ. of Texas Medical School, 6431 Fannin St., Houston, TX 77030, USA
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O'Connell LA, Hofmann HA. Genes, hormones, and circuits: an integrative approach to study the evolution of social behavior. Front Neuroendocrinol 2011; 32:320-35. [PMID: 21163292 DOI: 10.1016/j.yfrne.2010.12.004] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 12/03/2010] [Accepted: 12/09/2010] [Indexed: 12/23/2022]
Abstract
Tremendous progress has been made in our understanding of the ultimate and proximate mechanisms underlying social behavior, yet an integrative evolutionary analysis of its underpinnings has been difficult. In this review, we propose that modern genomic approaches can facilitate such studies by integrating four approaches to brain and behavior studies: (1) animals face many challenges and opportunities that are ecologically and socially equivalent across species; (2) they respond with species-specific, yet quantifiable and comparable approach and avoidance behaviors; (3) these behaviors in turn are regulated by gene modules and neurochemical codes; and (4) these behaviors are governed by brain circuits such as the mesolimbic reward system and the social behavior network. For each approach, we discuss genomic and other studies that have shed light on various aspects of social behavior and its underpinnings and suggest promising avenues for future research into the evolution of neuroethological systems.
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Affiliation(s)
- Lauren A O'Connell
- Institute for Cellular and Molecular Biology, Section of Integrative Biology, University of Texas at Austin, Austin, TX 78705, USA
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35
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Schober J, Weil Z, Pfaff D. How generalized CNS arousal strengthens sexual arousal (and vice versa). Horm Behav 2011; 59:689-95. [PMID: 20950622 DOI: 10.1016/j.yhbeh.2010.10.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 09/23/2010] [Accepted: 10/02/2010] [Indexed: 12/22/2022]
Abstract
Heightened states of generalized CNS arousal are proposed here to facilitate sexual arousal in both males and females. Genetic, pharmacologic and biophysical mechanisms by which this happens are reviewed. Moreover, stimulation of the genital epithelia, as triggers of sex behavior, is hypothesized to lead to a greater generalized arousal in a manner that intensifies sexual motivation. Finally, launched from histochemical studies intended to characterize cells in the genital epithelium, a surprising idea is proposed that links density of innervation with the efficiency of wound healing and with the capacity of that epithelium to stimulate generalized CNS arousal. Thus, bidirectional arousal-related mechanisms that foster sexual behaviors are envisioned as follows: from specific to generalized (as with genital stimulation) and from generalized to specific.
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Affiliation(s)
- Justine Schober
- Laboratory of Neurobiology and Behavior, The Rockefeller University, NY, USA
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Feedforward compensation mediated by the central and peripheral actions of a single neuropeptide discovered using representational difference analysis. J Neurosci 2011; 30:16545-58. [PMID: 21147994 DOI: 10.1523/jneurosci.4264-10.2010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Compensatory mechanisms are often used to achieve stability by reducing variance, which can be accomplished via negative feedback during homeostatic regulation. In principle, compensation can also be implemented through feedforward mechanisms where a regulator acts to offset the anticipated output variation; however, few such neural mechanisms have been demonstrated. We provide evidence that an Aplysia neuropeptide, identified using an enhanced representational difference analysis procedure, implements feedforward compensation within the feeding network. We named the novel peptide "allatotropin-related peptide" (ATRP) because of its similarity to insect allatotropin. Mass spectrometry confirmed the peptide's identity, and in situ hybridization and immunostaining mapped its distribution in the Aplysia CNS. ATRP is present in the higher-order cerebral-buccal interneuron (CBI) CBI-4, but not in CBI-2. Previous work showed that CBI-4-elicited motor programs have a shorter protraction duration than those elicited by CBI-2. Here we show that ATRP shortens protraction duration of CBI-2-elicited ingestive programs, suggesting a contribution of ATRP to the parametric differences between CBI-4-evoked and CBI-2-evoked programs. Importantly, because Aplysia muscle contractions are a graded function of motoneuronal activity, one consequence of the shortening of protraction is that it can weaken protraction movements. However, this potential weakening is offset by feedforward compensatory actions exerted by ATRP. Centrally, ATRP increases the activity of protraction motoneurons. Moreover, ATRP is present in peripheral varicosities of protraction motoneurons and enhances peripheral motoneuron-elicited protraction muscle contractions. Therefore, feedforward compensatory mechanisms mediated by ATRP make it possible to generate a faster movement with an amplitude that is not greatly reduced, thereby producing stability.
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Wu JS, Vilim FS, Hatcher NG, Due MR, Sweedler JV, Weiss KR, Jing J. Composite modulatory feedforward loop contributes to the establishment of a network state. J Neurophysiol 2010; 103:2174-84. [PMID: 20181731 DOI: 10.1152/jn.01054.2009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Feedforward loops (FFLs) are one of many network motifs identified in a variety of complex networks, but their functional role in neural networks is not well understood. We provide evidence that combinatorial actions of multiple modulators may be organized as FFLs to promote a specific network state in the Aplysia feeding motor network. The Aplysia feeding central pattern generator (CPG) receives two distinct inputs-a higher-order interneuron cerebral-buccal interneuron-2 (CBI-2) and the esophageal nerve (EN)-that promote ingestive and egestive motor programs, respectively. EN stimulation elicits a persistent egestive network state, which enables the network to temporarily express egestive programs following a switch of input from the EN to CBI-2. Previous work showed that a modulatory CPG element, B65, is specifically activated by the EN and participates in establishing the egestive state by enhancing activity of egestion-promoting B20 interneurons while suppressing activity and synaptic outputs of ingestion-promoting B40 interneurons. Here a peptidergic contribution is mediated by small cardioactive peptide (SCP). Immunostaining and mass spectrometry show that SCP is present in the EN and is released on EN stimulation. Importantly, SCP directly enhances activity and synaptic outputs of B20 and suppresses activity and synaptic outputs of B40. Moreover, SCP promotes B65 activity. Thus the direct and indirect (through B65) pathways to B20 and B40 from SCPergic neurons constitute two FFLs with one functioning to promote egestive output and the other to suppress ingestive output. This composite FFL consisting of the two combined FFLs appears to be an effective means to co-regulate activity of two competing elements that do not inhibit each other, thereby contributing to establish specific network states.
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Affiliation(s)
- Jin-Sheng Wu
- Dept. of Neuroscience, Mount Sinai School of Medicine, New York, NY 10029, USA
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