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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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Fodor I, Svigruha R, Bozsó Z, Tóth GK, Osugi T, Yamamoto T, Satake H, Pirger Z. Functional characterization and related evolutionary implications of invertebrate gonadotropin-releasing hormone/corazonin in a well-established model species. Sci Rep 2021; 11:10028. [PMID: 33976353 PMCID: PMC8113230 DOI: 10.1038/s41598-021-89614-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 04/29/2021] [Indexed: 11/09/2022] Open
Abstract
In vertebrates, gonadotropin-releasing hormone (GnRH) peptide is the central mediator of reproduction. Homologous peptides have previously also been identified in molluscan species. However, emerging evidence suggests that these molecules might serve diverse regulatory functions and proposes to consider them as corazonin (CRZ). We previously isolated the full-length cDNA of the invGnRH/CRZ peptide (termed ly-GnRH/CRZ) in the well-established invertebrate model species, the great pond snail Lymnaea stagnalis; however, its predicted functions remain to be verified. In this study, we first confirmed the presence of the deduced active peptide from the central nervous system of L. stagnalis. Further, we performed in vivo and in vitro studies to explore the functions of ly-GnRH/CRZ. Injection of sexually mature specimens with synthetic active peptide had an inhibitory effect on locomotion and an acceleratory effect on egg-laying, but had no effect on feeding. The previously predicted modulatory effect of ly-GnRH/CRZ was supported by its identified co-localization with serotonin on the surface of the heart atria. Lastly, we demonstrated not only the presence of ly-GnRH/CRZ in the penial complex but also that ly-GnRH/CRZ-containing neurons project to the efferent penis nerve, suggesting ly-GnRH/CRZ may directly modulate the motor output of this peripheral tissue. Overall, our findings strongly support that ly-GnRH/CRZ is a multifunctional neuropeptide. These results contribute to the understanding of the GnRH superfamily and, more broadly, disciplines such as comparative endocrinology and neurobiology.
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Affiliation(s)
- István Fodor
- NAP Adaptive Neuroethology, Balaton Limnological Research Institute, Eötvös Loránd Research Network (ELKH), Klebelsberg Kuno u. 3., Tihany, 8237, Hungary
| | - Réka Svigruha
- NAP Adaptive Neuroethology, Balaton Limnological Research Institute, Eötvös Loránd Research Network (ELKH), Klebelsberg Kuno u. 3., Tihany, 8237, Hungary
| | - Zsolt Bozsó
- Department of Medical Chemistry, University of Szeged, Szeged, Hungary
| | - Gábor K Tóth
- Department of Medical Chemistry, University of Szeged, Szeged, Hungary
| | - Tomohiro Osugi
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika, Souraku, Kyoto, 619-0284, Japan
| | - Tatsuya Yamamoto
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika, Souraku, Kyoto, 619-0284, Japan
| | - Honoo Satake
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika, Souraku, Kyoto, 619-0284, Japan
| | - Zsolt Pirger
- NAP Adaptive Neuroethology, Balaton Limnological Research Institute, Eötvös Loránd Research Network (ELKH), Klebelsberg Kuno u. 3., Tihany, 8237, Hungary.
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