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Batabyal A, Wiley B, Matsuoka H, Komatsuzaki Y, Lukowiak K. Sensory input from osphradium is involved in fluoride detection that alters feeding and memory phenotype in Lymnaea stagnalis. Behav Brain Res 2024; 472:115148. [PMID: 39004230 DOI: 10.1016/j.bbr.2024.115148] [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: 03/28/2024] [Revised: 06/07/2024] [Accepted: 06/21/2024] [Indexed: 07/16/2024]
Abstract
Fluoride (F-) exposure in organisms remains a significant concern due to its widespread presence and potential health implications. Investigating its detection and subsequent effects on behaviour in aquatic organisms like Lymnaea stagnalis provides valuable insights. Our study focused on elucidating the sensory pathways involved in F- detection and its impact on feeding and memory formation. We explored two potential detection mechanisms: direct flow across the integument onto neurons; and sensory input to the central nervous system (CNS) via the osphradium-osphradial ganglion-osphradial nerve pathway (snails use this system for olfactory sensation of multiple compounds). Injection of F- into snails did not alter feeding behaviour or central neuronal activity, suggesting that internalization might not be the primary detection mode. In contrast, severing the osphradial nerve abolished F-'s suppressive effects on feeding and memory formation, implicating the osphradial pathway in F- sensing and behavioural changes. This finding supports the idea that osphradial nerve signaling mediates the behavioural effects of F-. Our study underscores the importance of sensory pathways in F- detection and behavioural modulation in L. stagnalis. Understanding these mechanisms could provide critical insights into how organisms respond to and adapt to environmental chemical stressors like F-.
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Affiliation(s)
- Anuradha Batabyal
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Canada; Department of Physical and Natural Sciences, FLAME University, India.
| | - Bevin Wiley
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Canada
| | - Hideki Matsuoka
- Department of Physics, College of Science and Technology, Nihon University, Japan
| | | | - Ken Lukowiak
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Canada
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2
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Hollings J, Kagan D, Batabyal A, Lukowiak K. How to reduce fear in a snail: Take an aspirin, call me in the morning. Comp Biochem Physiol C Toxicol Pharmacol 2024; 284:109978. [PMID: 39094989 DOI: 10.1016/j.cbpc.2024.109978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 06/17/2024] [Accepted: 07/14/2024] [Indexed: 08/04/2024]
Abstract
Aspirin (Acetylsalicylic acid, ASA), one of the widely used non-steroid anti-inflammatory drugs can easily end up in sewage effluents and thus it becomes necessary to investigate the effects of aspirin on behaviour of aquatic organisms. Previous studies in mammals have shown ASA to alter fear and anxiety-like behaviours. In the great pond snail Lymnaea stagnalis, ASA has been shown to block a 'sickness state' induced by lipopolysaccharide injection which upregulates immune and stress-related genes thus altering behavioural responses. In Lymnaea, eliciting physiological stress may enhance memory formation or block its retrieval depending on the stimulus type and intensity. Here we examine whether ASA will alter two forms of associative-learning memory in crayfish predator-experienced Lymnaea when ASA exposure accompanies predator-cue-induced stress during the learning procedure. The two trainings procedures are: 1) operant conditioning of aerial respiration; and 2) a higher form of learning, called configural learning, which here is dependent on evoking a fear response. We show here that ASA alone does not alter homeostatic aerial respiration, feeding behaviour or long-term memory (LTM) formation of operantly conditioned aerial respiration. However, ASA blocked the enhancement of LTM formation normally elicited by training snails in predator cue. ASA also blocked configural learning, which makes use of the fear response elicited by the predator cue. Thus, ASA alters how Lymnaea responds cognitively to predator detection.
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Affiliation(s)
- Jasper Hollings
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Diana Kagan
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Anuradha Batabyal
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada; Department of Physical and Natural Sciences, FLAME University, Pune, India
| | - Ken Lukowiak
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada.
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A flavonoid, quercetin, is capable of enhancing long-term memory formation if encountered at different times in the learning, memory formation, and memory recall continuum. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2021; 208:253-265. [PMID: 34820709 DOI: 10.1007/s00359-021-01522-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/26/2021] [Accepted: 11/03/2021] [Indexed: 02/07/2023]
Abstract
A major extrinsic factor influencing memory and neuro-cognitive performances across taxa is diet. Studies from vertebrates have shown the effects of a flavonoid rich diet on cognitive performance, but the mechanism underlying this action is still poorly understood. A common and abundant flavonoid present in numerous food substances is quercetin (Q). The present study provides the first support for Q-modulated enhancement of cognitive function in an invertebrate model, the pond snail Lymnaea stagnalis, after an operant conditioning procedure. We found that when snails were exposed to Q 3 h before or after a single 0.5 h training session, which typically results in memory lasting ~ 3 h, they formed a long-term memory (LTM) lasting for at least 24 h. Additionally, we assessed the effects of the combined presentation of a single reinforcing stimulus (at 24 h post-training or 24 h before training) and Q-exposure on both LTM formation and reconsolidation. That is, when applied within 3 h of critical periods of memory, Q regulates four different phases: (1) acquisition (i.e., a learning event), (2) consolidation processes after acquisition, (3) memory recall, and (4) memory reconsolidation. In all these phases Q-exposure enhanced LTM persistence.
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Abstract
Gastropod diversity is substantial in marine and freshwater habitats, and many aquatic slugs and snails use olfactory cues to guide their navigation behaviour. Examples include finding prey or avoiding predators based on kairomones, or finding potential mates using pheromones. Here, I review the diversity of navigational behaviours studied across the major aquatic taxa of gastropods. I then synthesize evidence for the different theoretical navigation strategies the animals may use. It is likely that gastropods regularly use either chemotaxis or odour-gated rheotaxis (or both) during olfactory-based navigation. Finally, I collate the patchwork of research conducted on relevant proximate mechanisms that could produce navigation behaviours. Although the tractability of several gastropod species for neurophysiological experimentation has generated some valuable insight into how turning behaviour is triggered by contact chemoreception, there remain many substantial gaps in our understanding for how navigation relative to more distant odour sources is controlled in gastropods. These gaps include little information on the chemoreceptors and mechanoreceptors (for detecting flow) found in the peripheral nervous system and the central (or peripheral) processing circuits that integrate that sensory input. In contrast, past studies do provide information on motor neurons that control the effectors that produce crawling (both forward locomotion and turning). Thus, there is plenty of scope for further research on olfactory-based navigation, exploiting the tractability of gastropods for neuroethology to better understand how the nervous system processes chemosensory input to generate movement towards or away from distant odour sources.
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Affiliation(s)
- Russell C Wyeth
- Biology Department, St Francis Xavier University, 2321 Notre Dame Avenue, Antigonish, NS, Canada B2G 2W5
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Sunada H, Watanabe T, Hatakeyama D, Lee S, Forest J, Sakakibara M, Ito E, Lukowiak K. Pharmacological effects of cannabinoids on learning and memory in Lymnaea. ACTA ACUST UNITED AC 2018; 220:3026-3038. [PMID: 28855319 DOI: 10.1242/jeb.159038] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 06/07/2017] [Indexed: 12/22/2022]
Abstract
Cannabinoids are hypothesized to play an important role in modulating learning and memory formation. Here, we identified mRNAs expressed in Lymnaeastagnalis central nervous system that encode two G-protein-coupled receptors (Lymnaea CBr-like 1 and 2) that structurally resemble mammalian cannabinoid receptors (CBrs). We found that injection of a mammalian CBr agonist WIN 55,212-2 (WIN 55) into the snail before operant conditioning obstructed learning and memory formation. This effect of WIN 55 injection persisted for at least 4 days following its injection. A similar obstruction of learning and memory occurred when a severe traumatic stimulus was delivered to L. stagnalis In contrast, injection of a mammalian CBr antagonist AM 251 enhanced long-term memory formation in snails and reduced the duration of the effects of the severe traumatic stressor on learning and memory. Neither WIN 55 nor AM 251 altered normal homeostatic aerial respiratory behaviour elicited in hypoxic conditions. Our results suggest that putative cannabinoid receptors mediate stressful stimuli that alter learning and memory formation in Lymnaea This is also the first demonstration that putative CBrs are present in Lymnaea and play a key role in learning and memory formation.
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Affiliation(s)
- Hiroshi Sunada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada T2N 4N1.,Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
| | - Takayuki Watanabe
- Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 060-0811, Japan
| | - Dai Hatakeyama
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
| | - Sangmin Lee
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Jeremy Forest
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Manabu Sakakibara
- School of High-Technology for Human Welfare, Tokai University, Numazu, Shizuoka 410-0321, Japan
| | - Etsuro Ito
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan .,Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan
| | - Ken Lukowiak
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada T2N 4N1
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Tan R, Lukowiak K. Combining Factors That Individually Enhance Memory in Lymnaea. THE BIOLOGICAL BULLETIN 2018; 234:37-44. [PMID: 29694801 DOI: 10.1086/697197] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
When applied individually, thermal stress (1 hour at 30 °C) and (-)epicatechin (a flavonol found in green tea, e.g.) each enhance long-term memory formation following operant conditioning of Lymnaea aerial respiratory behavior. Snails demonstrate enhanced long-term memory formation when trained in epicatechin-treated pond water or when placed in 30 °C pond water for 1 hour, 1 hour prior to training in pond water. We ask here whether the combined application of epicatechin + thermal stress enhances long-term memory retention length beyond the maximal lengths of the individual factors alone. We report that the applied combination of epicatechin + thermal stress has a synergistic memory-enhancing effect; that is, when the two are applied in combination, memory persists longer than when either is applied alone. We then ask whether quercetin, a heat shock protein blocker, will affect the memory enhancement produced by the combined treatment of thermal stress and epicatechin. We report that quercetin does not decrease the memory enhancement of epicatechin, but it does decrease the memory enhancement by thermal stress; and it also decreases the memory persistence of snails exposed to both treatments in combination.
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Rothwell CM, Spencer GE, Lukowiak K. The effect of rearing environment on memory formation. J Exp Biol 2018; 221:jeb.180521. [DOI: 10.1242/jeb.180521] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 03/27/2018] [Indexed: 11/20/2022]
Abstract
Lymnaea stagnalis is a well-studied model system for determining how changes in the environment influence associative learning and memory formation. For example, some wild strains of Lymnaea, collected from separate geographic locations show superior memory-forming abilities compared to others. Here, we have studied memory formation in two laboratory-bred Lymnaea strains, derived from the same original population in The Netherlands. The two strains were reared in two different laboratories at the University of Calgary (C-strain) and at Brock University (B-strain) for many years and were found to differ in their memory-forming ability. Specifically, the C-strain required only two training sessions to form long-term memory (LTM) whereas the B-strain required four sessions to form LTM. Additionally, the LTM formed by the B-strain persisted for a shorter amount of time than the memory formed by the C-strain. Thus, despite being derived from the same original population, the C- and B-strains have developed different memory-forming abilities. Next, we raised the two strains from embryos ‘Away’ from home (i.e. in the other laboratory) over two generations and assessed their memory-forming abilities. The B-strain reared and maintained at the University of Calgary demonstrated improved memory-forming ability within a single generation, while the C-strain reared at Brock University retained their normal LTM forming ability across two subsequent generations. This suggests that local environmental factors may contribute to the behavioural divergence observed between these two laboratory-bred strains.
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Affiliation(s)
- Cailin M. Rothwell
- Hotchkiss Brain Institute, Cumming School and Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada
| | - Gaynor E. Spencer
- Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario, L2S 3A1, Canada
| | - Ken Lukowiak
- Hotchkiss Brain Institute, Cumming School and Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada
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Mitchell MD, Bairos-Novak KR, Ferrari MCO. Mechanisms underlying the control of responses to predator odours in aquatic prey. J Exp Biol 2017; 220:1937-1946. [DOI: 10.1242/jeb.135137] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
ABSTRACT
In aquatic systems, chemical cues are a major source of information through which animals are able to assess the current state of their environment to gain information about local predation risk. Prey use chemicals released by predators (including cues from a predator's diet) and other prey (such as alarm cues and disturbance cues) to mediate a range of behavioural, morphological and life-history antipredator defences. Despite the wealth of knowledge on the ecology of antipredator defences, we know surprisingly little about the physiological mechanisms that control the expression of these defensive traits. Here, we summarise the current literature on the mechanisms known to specifically mediate responses to predator odours, including dietary cues. Interestingly, these studies suggest that independent pathways may control predator-specific responses, highlighting the need for greater focus on predator-derived cues when looking at the mechanistic control of responses. Thus, we urge researchers to tease apart the effects of predator-specific cues (i.e. chemicals representing a predator's identity) from those of diet-mediated cues (i.e. chemicals released from a predator's diet), which are known to mediate different ecological endpoints. Finally, we suggest some key areas of research that would greatly benefit from a more mechanistic approach.
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Affiliation(s)
- Matthew D. Mitchell
- Department of Biomedical Sciences, WCVM, University of Saskatchewan, Saskatoon, SK, Canada S7N 5B4
| | | | - Maud C. O. Ferrari
- Department of Biomedical Sciences, WCVM, University of Saskatchewan, Saskatoon, SK, Canada S7N 5B4
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Domenici P, Torres R, Manríquez PH. Effects of elevated carbon dioxide and temperature on locomotion and the repeatability of lateralization in a keystone marine mollusc. J Exp Biol 2017; 220:667-676. [DOI: 10.1242/jeb.151779] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 11/29/2016] [Indexed: 01/18/2023]
Abstract
ABSTRACT
Recent work has shown that the behaviour of marine organisms can be affected by elevated PCO2, although little is known about the effect of multiple stressors. We therefore investigated the effect of elevated PCO2 and temperature on locomotion and behaviour during prey searching in the marine gastropod Concholepas concholepas, a predator characteristic of the southeastern Pacific coast. Movement duration, decision time, route finding and lateralization were measured using a T-maze tank with a prey positioned behind a barrier. Four treatments, representing present day and near-future scenarios of ocean acidification and warming were used in rearing the individuals for 6 months. Regardless of the treatment, no significant differences were found in relative and absolute lateralization before and after exposure for 6 months. However, relative lateralization was not repeatable for animals tested after 6 months at elevated PCO2 at both experimental temperatures, whereas it was repeatable in individuals kept at the present day level of PCO2. We suggest that these effects may be related to a behavioural malfunction caused by elevated PCO2. Movement duration, decision time and route finding were not repeatable. However, movement duration and decision time increased and route finding decreased in elevated PCO2 (at 15°C), suggesting that elevated PCO2 has negative effects on the locomotor and sensory performance of C. concholepas in the presence of a prey odour, thereby decreasing their ability to forage efficiently.
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Affiliation(s)
- Paolo Domenici
- CNR-IAMC - Istituto per l′Ambiente Marino Costiero, Localita Sa Mardini, Torregrande, Oristano 09170, Italy
| | - Rodrigo Torres
- Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Coyhaique 5950000, Chile
- Centro de Investigación: Dinámica de Ecosistemas marinos de Altas Latitudes (IDEAL), Punta Arenas 6200000, Chile
| | - Patricio H. Manríquez
- Laboratorio de Ecología y Conducta de la Ontogenia Temprana (LECOT), Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Coquimbo 1780000, Chile
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Knezevic B, Komatsuzaki Y, de Freitas E, Lukowiak K. A flavanoid component of chocolate quickly reverses an imposed memory deficit. ACTA ACUST UNITED AC 2016; 219:816-23. [PMID: 26823103 DOI: 10.1242/jeb.130765] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 12/30/2015] [Indexed: 01/27/2023]
Abstract
The ability to remember is influenced by environmental and lifestyle factors, such as stress and diet. A flavanol contained in chocolate, epicatechin (Epi), has been shown to enhance long-term memory (LTM) formation in Lymnaea. Combining two stressors (low-calcium pond water and crowding) blocks learning and all forms of memory; that is, this combination of environmentally relevant stressors creates a memory-unfriendly state. We tested the hypothesis that Epi will immediately reverse the memory-unfriendly state, i.e. that snails in the memory-deficit state when trained in Epi will immediately become competent to learn and form memory. We found that Epi not only reverses the memory-deficit state but also further enhances LTM formation. Thus, a naturally occurring bioactive plant compound can overcome a memory-unfriendly state. This supports the idea that bioactive substances may mitigate memory-making deficits that, for example, occur with ageing.
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Affiliation(s)
- Bogdan Knezevic
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1
| | - Yoshimasa Komatsuzaki
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1
| | - Emily de Freitas
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1
| | - Ken Lukowiak
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1
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12
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Dodd SX, Lukowiak K. Sequential exposure to a combination of stressors blocks memory reconsolidation in Lymnaea. J Exp Biol 2015; 218:923-30. [PMID: 25617463 DOI: 10.1242/jeb.114876] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Stress alters the formation of long-term memory (LTM) in Lymnaea. When snails are exposed to more than one stressor, however, how the memory is altered becomes complicated. Here, we investigated how multiple stressors applied in a specific pattern affect an aspect of memory not often studied in regards to stress - reconsolidation. We hypothesized that the application of a sequence of stressors would block the reconsolidation process. Reconsolidation occurs following activation of a previously formed memory. Sequential crowding and handling were used as the stressors to block reconsolidation. When the two stressors were sequentially presented immediately following memory activation, reconsolidation was blocked. However, if the sequential presentation of the stressors was delayed for 1 h after memory activation, reconsolidation was not blocked. That is, LTM was observed. Finally, presentation of either stressor alone did not block reconsolidation. Thus, stressors can block reconsolidation, which may be preferable to pharmacological manipulations.
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Affiliation(s)
- Shawn Xavier Dodd
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1
| | - Ken Lukowiak
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1
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Lukowiak K, Sunada H, Teskey M, Lukowiak K, Dalesman S. Environmentally relevant stressors alter memory formation in the pond snail Lymnaea. J Exp Biol 2014; 217:76-83. [DOI: 10.1242/jeb.089441] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Stress alters adaptive behaviours such as learning and memory. Stressors can either enhance or diminish learning, memory formation and/or memory recall. We focus attention here on how environmentally relevant stressors alter learning, memory and forgetting in the pond snail, Lymnaea stagnalis. Operant conditioning of aerial respiration causes associative learning that may lead to long-term memory (LTM) formation. However, individual ecologically relevant stressors, combinations of stressors, and bio-active substances can alter whether or not learning occurs or memory forms. While the behavioural memory phenotype may be similar as a result of exposure to different stressors, how each stressor alters memory formation may occur differently. In addition, when a combination of stressors are presented it is difficult to predict ahead of time what the outcome will be regarding memory formation. Thus, how combinations of stressors act is an emergent property of how the snail perceives the stressors.
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Affiliation(s)
- Ken Lukowiak
- Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, AB, Canada, T2N 4N1
| | - Hiroshi Sunada
- Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, AB, Canada, T2N 4N1
| | - Morgan Teskey
- Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, AB, Canada, T2N 4N1
| | - Kai Lukowiak
- Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, AB, Canada, T2N 4N1
| | - Sarah Dalesman
- Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, AB, Canada, T2N 4N1
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Knezevic B, Lukowiak K. A flavonol, epicatechin, reverses the suppressive effects of a stressor on LTM formation. J Exp Biol 2014; 217:4004-9. [DOI: 10.1242/jeb.110726] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Abstract
Learning and subsequent memory formation are influenced by both environmental and lifestyle factors, such as stress and diet. Epicatechin, a plant flavonol found in cocoa, red wine, and green tea enhances long term memory formation (LTM) in Lymnaea; while an ecologically relevant stressor, low calcium pond water, suppress LTM formation. We tested the hypothesis that epicatechin overcomes the suppressive effects of the stressor on LTM formation in the continued presence of the stressor. Snails trained in low calcium pond water exhibit learning but not LTM. Epicatechin (15 mg/L) in control pond water enhances LTM formation. When epicatechin was added to the low calcium pond water an enhanced LTM similar to that seen in control pond water was observed. Thus, a naturally occurring bioactive plant compound was able to overcome the suppressive effects of an ecologically relevant stressor on LTM formation.
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15
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Combining stressors that individually impede long-term memory blocks all memory processes. PLoS One 2013; 8:e79561. [PMID: 24223180 PMCID: PMC3819272 DOI: 10.1371/journal.pone.0079561] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 09/24/2013] [Indexed: 12/25/2022] Open
Abstract
The effects of stress on memory are typically assessed individually; however, in reality different stressors are often experienced simultaneously. Here we determined the effect that two environmentally relevant stressors, crowding and low calcium availability, have on memory and neural activity following operant conditioning of aerial respiration in the pond snail, Lymnaea stagnalis. We measured aerial breathing behaviour and activity of a neuron necessary for memory formation, right pedal dorsal 1 (RPeD1), in the central pattern generator (CPG) that drives aerial respiration in untrained animals, and assessed how these traits changed following training. In naïve animals both crowding and combined stressors significantly depressed burst activity in RPeD1 which correlated with a depression in aerial breathing behaviour, whereas low calcium availability had no effect on RPeD1 activity. Following training, changes in burst activity in RPeD1 correlated with behavioural changes, decreasing relative to their naïve state at 3 h and 24 h in control conditions when both intermediate-term memory (ITM: 3 h) and long-term memory (LTM: 24 h) are formed, at 3 h but not 24 h when exposed to individual stressors when only ITM is formed, and did not change in combined stressors (i.e. when no memory is formed). Additionally, we also found that Lymnaea formed short-term memory (STM: 10 min) in the presence of individual stressors or under control conditions, but failed to do so in the presence of combined stressors. Our data demonstrate that by combining stressors that individually block LTM only we can block all memory processes. Therefore the effects of two stressors with similar individual affects on memory phenotype may be additive when experienced in combination.
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Manríquez PH, Jara ME, Mardones ML, Navarro JM, Torres R, Lardies MA, Vargas CA, Duarte C, Widdicombe S, Salisbury J, Lagos NA. Ocean acidification disrupts prey responses to predator cues but not net prey shell growth in Concholepas concholepas (loco). PLoS One 2013; 8:e68643. [PMID: 23844231 PMCID: PMC3700904 DOI: 10.1371/journal.pone.0068643] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 05/30/2013] [Indexed: 12/22/2022] Open
Abstract
Background Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. Methodology/Principal Findings The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716±12 and 1036±14 µatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388±8 µatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. Conclusions and Significance These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.
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Affiliation(s)
- Patricio H Manríquez
- Instituto de Ciencias Marinas y Limnológicas, Laboratorio de Ecología y Conducta de la Ontogenia Temprana and Laboratorio Costero de Recursos Acuáticos de Calfuco. Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.
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Fruson L, Dalesman S, Lukowiak K. A flavonol present in cocoa [(-)epicatechin] enhances snail memory. ACTA ACUST UNITED AC 2013; 215:3566-76. [PMID: 23014569 DOI: 10.1242/jeb.070300] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Dietary consumption of flavonoids (plant phytochemicals) may improve memory and neuro-cognitive performance, though the mechanism is poorly understood. Previous work has assessed cognitive effects in vertebrates; here we assess the suitability of Lymnaea stagnalis as an invertebrate model to elucidate the effects of flavonoids on cognition. (-)Epicatechin (epi) is a flavonoid present in cocoa, green tea and red wine. We studied its effects on basic snail behaviours (aerial respiration and locomotion), long-term memory (LTM) formation and memory extinction of operantly conditioned aerial respiratory behaviour. We found no significant effect of epi exposure (15 mg l(-1)) on either locomotion or aerial respiration. However, when snails were operantly conditioned in epi for a single 0.5 h training session, which typically results in memory lasting ~3 h, they formed LTM lasting at least 24 h. Snails exposed to epi also showed significantly increased resistance to extinction, consistent with the hypothesis that epi induces a more persistent LTM. Thus training in epi facilitates LTM formation and results in a more persistent and stronger memory. Previous work has indicated that memory-enhancing stressors (predator kairomones and KCl) act via sensory input from the osphradium and are dependent on a serotonergic (5-HT) signalling pathway. Here we found that the effects of epi on LTM were independent of osphradial input and 5-HT, demonstrating that an alternative mechanism of memory enhancement exists in L. stagnalis. Our data are consistent with the notion that dietary sources of epi can improve cognitive abilities, and that L. stagnalis is a suitable model with which to elucidate neuronal mechanisms.
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Affiliation(s)
- Lee Fruson
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada, T2N 4N1
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Teskey ML, Lukowiak KS, Riaz H, Dalesman S, Lukowiak K. What's hot: the enhancing effects of thermal stress on long-term memory formation in Lymnaea stagnalis. J Exp Biol 2012; 215:4322-9. [DOI: 10.1242/jeb.075960] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Summary
The pond snail, Lymnaea stagnalis, naturally inhabits slow flowing, shallow and stagnant environments in the northern temperate zone. Consequently, it will experience wide temperature fluctuations dependent on prevailing weather conditions. We hypothesize that periods of warming act as a thermal stressor to alter memory formation. Snails were exposed to an acute 1h period of 30°C pond water and we determined how memory formation following operant conditioning of aerial respiration was affected. In snails used here (the Dutch strain), a single 0.5h training session (TS) results in intermediate-term (3h) but not long-term memory (LTM). Applying the thermal stressor during training caused memory enhancement (i.e. LTM lasting 24 h). However, the breathing rate also increased in warm water, which might explain the enhanced memory. Therefore, we applied the thermal stressor (1h at 30°C) up to 4h before or 1h after training. This did not alter baseline breathing rate during the period when snails would experience training. However, the thermal stressor weather experienced prior to or following the single TS, resulted in an enhanced memory that persisted up to 48h (i.e. LTM). We conclude that memory enhancement is due to the stress associated with the thermal stimulus.
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Braun MH, Lukowiak K, Karnik V, Lukowiak K. Differences in neuronal activity explain differences in memory forming abilities of different populations of Lymnaea stagnalis. Neurobiol Learn Mem 2011; 97:173-82. [PMID: 22146779 DOI: 10.1016/j.nlm.2011.11.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 11/16/2011] [Accepted: 11/17/2011] [Indexed: 12/20/2022]
Abstract
The ability to learn and form long-term memory (LTM) can enhance an animal's fitness, for example, by allowing them to remember predators, food sources or conspecific interactions. Here we use the pond snail, Lymnaea stagnalis, to assess whether variability between natural populations (i.e., strains) in memory forming capabilities correlates with electrophysiological properties at the level of a single neuron, RPeD1. RPeD1 is a necessary site of LTM formation of aerial respiratory behaviour following operant conditioning. We used strains from two small, separate permanent ponds (TC1 and TC2). A comparison of the two populations showed that the TC1 strain had enhanced memory forming capabilities. Further, the behavioural phenotype of enhanced memory strain was explained, in part, by differences in the electrophysiology of RPeD1. Compared to RPeD1 from the naive TC2 strain, RPeD1 from the TC1 strain has both a decreased resistance and decreased excitability. Moreover, 24h after a single 0.5h training session, those membrane properties, as well as the firing and bursting rate, decrease further in the TC1 strain but not in the TC2 strain. The initial differences in RPeD1 properties in the TC1 strain coupled with their ability to further change these properties with a single training session suggests that RPeD1 neurons from the TC1 strain are "primed" to rapidly form memory.
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Affiliation(s)
- Marvin H Braun
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
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