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Namiki K, Nakai J, Lukowiak K, Ito E. Sleep-like State in Pond Snails Leads to Enhanced Memory Formation. BIOLOGY 2024; 13:336. [PMID: 38785818 PMCID: PMC11117650 DOI: 10.3390/biology13050336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/01/2024] [Accepted: 05/10/2024] [Indexed: 05/25/2024]
Abstract
To test the hypothesis that a sleep-like quiescent state enhances memory consolidation in the pond snail Lymnaea stagnalis, we interposed a period in which snails experienced either a quiescent, sleeping state or an active, non-sleeping state following escape behavior suppression learning (EBSL). During EBSL training, the number of escapes made by a snail from a container was significantly suppressed using an external aversive stimulus (punishment). After training, the snails were divided into two groups. One group of snails was allowed to move freely and to experience a sleep-like quiescent state for 3 h in distilled water. The other group was stimulated with a sucrose solution every 10 min to keep them active (i.e., non-sleeping). In the memory test, escape behavior was suppressed in the group that experienced the quiescent state, whereas the suppression was not observed in snails that were kept active. Additionally, the latency of the first escape in the memory test was shorter in the snails kept active than in those that experienced the quiescent state. Together, these data are consistent with the hypothesis that a sleep-like quiescent state enhances EBSL memory consolidation in L. stagnalis.
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Affiliation(s)
- Kengo Namiki
- Department of Biology, Waseda University, Tokyo 162-8480, Japan; (K.N.); (J.N.)
| | - Junko Nakai
- Department of Biology, Waseda University, Tokyo 162-8480, Japan; (K.N.); (J.N.)
| | - Ken Lukowiak
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada;
| | - Etsuro Ito
- Department of Biology, Waseda University, Tokyo 162-8480, Japan; (K.N.); (J.N.)
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Song H, Xie C, Dong M, Zhang Y, Huang H, Han Y, Liu Y, Wei L, Wang X. Effects of ambient UVB light on Pacific oyster Crassostrea gigas mantle tissue based on multivariate data. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 274:116236. [PMID: 38503101 DOI: 10.1016/j.ecoenv.2024.116236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 03/07/2024] [Accepted: 03/15/2024] [Indexed: 03/21/2024]
Abstract
Ambient ultraviolet radiation (UVB) from solar and artificial light presents serious environmental risks to aquatic ecosystems. The Pacific oyster, Crassostrea gigas, perceives changes in the external environment primarily through its mantle tissue, which contains many nerve fibers and tentacles. Changes within the mantles can typically illustrate the injury of ambient UVB. In this study, a comprehensive analysis of phenotypic, behavioral, and physiological changes demonstrated that extreme UVB radiation (10 W/m²) directly suppressed the behavioral activities of C. gigas. Conversely, under ambient UVB radiation (5 W/m²), various physiological processes exhibited significant alterations in C. gigas, despite the behavior remaining relatively unaffected. Using mathematical model analysis, the integrated analysis of the full-length transcriptome, proteome, and metabolome showed that ambient UVB significantly affected the metabolic processes (saccharide, lipid, and protein metabolism) and cellular biology processes (autophagy, apoptosis, oxidative stress) of the C. gigas mantle. Subsequently, using Procrustes analysis and Pearson correlation analysis, the association between multi-omics data and physiological changes, as well as their biomarkers, revealed the effect of UVB on three crucial biological processes: activation of autophagy signaling (key factors: Ca2+, LC3B, BECN1, caspase-7), response to oxidative stress (reactive oxygen species, heat shock 70, cytochrome c oxidase), and recalibration of energy metabolism (saccharide, succinic acid, translation initiation factor IF-2). These findings offer a fresh perspective on the integration of multi-data from non-model animals in ambient UVB risk assessment.
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Affiliation(s)
- Hongce Song
- School of Agriculture, Ludong University, Yantai City, Shandong Province 264025, China
| | - Chaoyi Xie
- School of Agriculture, Ludong University, Yantai City, Shandong Province 264025, China
| | - Meiyun Dong
- School of Agriculture, Ludong University, Yantai City, Shandong Province 264025, China
| | - Yuxuan Zhang
- School of Agriculture, Ludong University, Yantai City, Shandong Province 264025, China
| | - Haifeng Huang
- School of Agriculture, Ludong University, Yantai City, Shandong Province 264025, China
| | - Yijing Han
- School of Agriculture, Ludong University, Yantai City, Shandong Province 264025, China
| | - Yaqiong Liu
- School of Agriculture, Ludong University, Yantai City, Shandong Province 264025, China
| | - Lei Wei
- School of Agriculture, Ludong University, Yantai City, Shandong Province 264025, China.
| | - Xiaotong Wang
- School of Agriculture, Ludong University, Yantai City, Shandong Province 264025, China.
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Chikamoto N, Fujimoto K, Nakai J, Totani Y, Hatakeyama D, Ito E. Expression Level Changes in Serotonin Transporter are Associated with Food Deprivation in the Pond Snail Lymnaea stagnalis. Zoolog Sci 2023; 40:382-389. [PMID: 37818887 DOI: 10.2108/zs230027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 06/21/2023] [Indexed: 10/13/2023]
Abstract
In the pond snail Lymnaea stagnalis, serotonin (5-HT) plays an important role in feeding behavior and its associated learning (e.g., conditioned taste aversion: CTA). The 5-HT content in the central nervous system (CNS) fluctuates with changes in the nutritional status, but it is also expected to be influenced by changes in the serotonin transporter (SERT) expression level. In the present study, we identified SERT in Lymnaea and observed its localization in 5-HTergic neurons, including the cerebral giant cells (CGCs) in the cerebral ganglia and the pedal A cluster neurons and right and left pedal dorsal 1 neurons in the pedal ganglia by in situ hybridization. Real-time PCR revealed that the SERT mRNA expression level was lower under severe food deprivation than under mild food deprivation in the whole CNS as well as in a single CGC. These results inversely correlated with previous data that the 5-HT content in the CNS was higher in the severely food-deprived state than in the mildly food-deprived state. Furthermore, in single CGCs, we observed that the 5-HT level was significantly increased in the severely food-deprived state compared with the mildly food-deprived state. Our present findings suggest that changes in the SERT expression level associated with food deprivation may affect 5-HT signaling, probably contributing to learning and memory mechanisms in Lymnaea.
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Affiliation(s)
- Nozomi Chikamoto
- Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan
| | - Kanta Fujimoto
- Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan
| | - Junko Nakai
- Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan
| | - Yuki Totani
- Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan
| | - Dai Hatakeyama
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan
| | - Etsuro Ito
- Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan,
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Chikamoto N, Fujimoto K, Nakai J, Namiki K, Hatakeyama D, Ito E. Genes Upregulated by Operant Conditioning of Escape Behavior in the Pond Snail Lymnaea stagnalis. Zoolog Sci 2023; 40:375-381. [PMID: 37818886 DOI: 10.2108/zs230032] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 06/13/2023] [Indexed: 10/13/2023]
Abstract
The pond snail Lymnaea stagnalis is capable of learning by both classical conditioning and operant conditioning. Although operant conditioning related to escape behavior with punishment has been examined by some research groups, the molecular mechanisms are not known. In the present study, we examined changes in the expression levels of cAMP-response element binding protein 1 (CREB1), CREB2, CREB-binding protein (CBP), and monoamine oxidase (MAO) in the Lymnaea central nervous system (CNS) using real-time PCR following operant conditioning of escape behavior. CREB1 and CREB2 are transcription factors involved in long-term memory in Lymnaea; CBP is a coactivator with CREB1; and MAO is a degrading enzyme for monoamines (e.g., serotonin) with important roles in learning and memory in Lymnaea. In operant conditioning, the punishment cohort, in which snails escaping from the container encountered aversive KCl, exhibited significantly fewer escape attempts than the control cohort, in which snails escaping from the container encountered distilled water, during both the training and memory test periods. After the operant conditioning, CREB1 and CREB2 were upregulated, and the ratio of CREB1/CREB2 was also increased, suggesting that the operant conditioning of escape behavior involves these factors. MAO was also upregulated, suggesting that the content of monoamines such as serotonin in the CNS decreased. The upregulated genes identified in the present study will help to further elucidate learning and memory mechanisms in Lymnaea.
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Affiliation(s)
- Nozomi Chikamoto
- Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan
| | - Kanta Fujimoto
- Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan
| | - Junko Nakai
- Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan
| | - Kengo Namiki
- Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan
| | - Dai Hatakeyama
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan
| | - Etsuro Ito
- Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan,
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Nakai J, Namiki K, Fujimoto K, Hatakeyama D, Ito E. FOXO in Lymnaea: Its Probable Involvement in Memory Consolidation. BIOLOGY 2023; 12:1201. [PMID: 37759600 PMCID: PMC10525164 DOI: 10.3390/biology12091201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 08/29/2023] [Accepted: 08/31/2023] [Indexed: 09/29/2023]
Abstract
Food deprivation activates forkhead box O (FOXO), a transcription factor downstream of insulin receptors. In the pond snail Lymnaea stagnalis, insulin signaling and food deprivation improve memory consolidation following conditioned taste aversion (CTA) learning. We investigated the subcellular localization of FOXO in Lymnaea and changes in its expression levels following food deprivation, CTA learning, and insulin administration. Immunohistochemistry revealed that Lymnaea FOXO (LymFOXO) was located in the central nervous system (CNS) neuronal cytoplasm in food-satiated snails but was mainly in neuronal nuclei in food-deprived snails. Following CTA acquisition, LymFOXO translocated to the nuclei in food-satiated snails and remained in the nuclei in food-deprived snails. Contrary to our expectations, insulin administered to the CNS did not induce LymFOXO translocation into the nuclei in food-satiated snails. Real-time PCR was used to quantify LymFOXO mRNA levels, its target genes, and insulin signaling pathway genes and revealed that LymFOXO mRNA was upregulated in food-deprived snails compared to food-satiated snails. Insulin applied to isolated CNSs from food-satiated snails increased LymFOXO compared to vehicle-treated samples. Food deprivation prepares FOXO to function in the nucleus and enhances CTA learning in snails. Insulin application did not directly affect LymFOXO protein localization. Thus, insulin administration may stimulate pathways other than the LymFOXO cascade.
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Affiliation(s)
- Junko Nakai
- Department Biology, Waseda University, Tokyo 162-8480, Japan; (J.N.); (K.N.); (K.F.)
| | - Kengo Namiki
- Department Biology, Waseda University, Tokyo 162-8480, Japan; (J.N.); (K.N.); (K.F.)
| | - Kanta Fujimoto
- Department Biology, Waseda University, Tokyo 162-8480, Japan; (J.N.); (K.N.); (K.F.)
| | - Dai Hatakeyama
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan;
| | - Etsuro Ito
- Department Biology, Waseda University, Tokyo 162-8480, Japan; (J.N.); (K.N.); (K.F.)
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Fujimoto K, Totani Y, Nakai J, Chikamoto N, Namiki K, Hatakeyama D, Ito E. Identification of Putative Molecules for Adiponectin and Adiponectin Receptor and Their Roles in Learning and Memory in Lymnaea stagnalis. BIOLOGY 2023; 12:biology12030375. [PMID: 36979067 PMCID: PMC10045044 DOI: 10.3390/biology12030375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 02/20/2023] [Accepted: 02/25/2023] [Indexed: 03/02/2023]
Abstract
Adiponectin enhances insulin sensitivity, which improves cognition in mammals. How adiponectin affects the mechanism’s underlying cognition, however, remains unknown. We hypothesized that experiments using the pond snail Lymnaea stagnalis, which has long been used in learning and memory studies and in which the function of insulin-like peptides affect learning and memory, could clarify the basic mechanisms by which adiponectin affects cognition. We first identified putative molecules of adiponectin and its receptor in Lymnaea. We then examined their distribution in the central nervous system and changes in their expression levels when hemolymph glucose concentrations were intentionally decreased by food deprivation. We also applied an operant conditioning protocol of escape behavior to Lymnaea and examined how the expression levels of adiponectin and its receptor changed after the conditioned behavior was established. The results demonstrate that adiponectin and adiponectin’s receptor expression levels were increased in association with a reduced concentration of hemolymph glucose and that expression levels of both adiponectin and insulin-like peptide receptors were increased after the conditioning behavior was established. Thus, the involvement of the adiponectin-signaling cascade in learning and memory in Lymnaea was suggested to occur via changes in the glucose concentrations and the activation of insulin.
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Affiliation(s)
- Kanta Fujimoto
- Department of Biology, Waseda University, Tokyo 162-8480, Japan
| | - Yuki Totani
- Department of Biology, Waseda University, Tokyo 162-8480, Japan
| | - Junko Nakai
- Department of Biology, Waseda University, Tokyo 162-8480, Japan
| | | | - Kengo Namiki
- Department of Biology, Waseda University, Tokyo 162-8480, Japan
| | - Dai Hatakeyama
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan
| | - Etsuro Ito
- Department of Biology, Waseda University, Tokyo 162-8480, Japan
- Graduate Institute of Medicine, School of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Correspondence:
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Nakai J, Chikamoto N, Fujimoto K, Totani Y, Hatakeyama D, Dyakonova VE, Ito E. Insulin and Memory in Invertebrates. Front Behav Neurosci 2022; 16:882932. [PMID: 35558436 PMCID: PMC9087806 DOI: 10.3389/fnbeh.2022.882932] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 04/04/2022] [Indexed: 11/17/2022] Open
Abstract
Insulin and insulin-like peptides (ILP) help to maintain glucose homeostasis, whereas insulin-like growth factor (IGF) promotes the growth and differentiation of cells in both vertebrates and invertebrates. It is sometimes difficult to distinguish between ILP and IGF in invertebrates, however, because in some cases ILP has the same function as IGF. In the present review, therefore, we refer to these peptides as ILP/IGF signaling (IIS) in invertebrates, and discuss the role of IIS in memory formation after classical conditioning in invertebrates. In the arthropod Drosophila melanogaster, IIS is involved in aversive olfactory memory, and in the nematode Caenorhabditis elegans, IIS controls appetitive/aversive response to NaCl depending on the duration of starvation. In the mollusk Lymnaea stagnalis, IIS has a critical role in conditioned taste aversion. Insulin in mammals is also known to play an important role in cognitive function, and many studies in humans have focused on insulin as a potential treatment for Alzheimer’s disease. Although analyses of tissue and cellular levels have progressed in mammals, the molecular mechanisms, such as transcriptional and translational levels, of IIS function in cognition have been far advanced in studies using invertebrates. We anticipate that the present review will help to pave the way for studying the effects of insulin, ILPs, and IGFs in cognitive function across phyla.
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Affiliation(s)
- Junko Nakai
- Department of Biology, Waseda University, Tokyo, Japan
| | | | | | - Yuki Totani
- Department of Biology, Waseda University, Tokyo, Japan
| | - Dai Hatakeyama
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Varvara E. Dyakonova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia
| | - Etsuro Ito
- Department of Biology, Waseda University, Tokyo, Japan
- Graduate Institute of Medicine, School of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
- *Correspondence: Etsuro Ito
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