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Wongsaengchan C, McCafferty DJ, Lennox K, Nager RG, McKeegan DEF. Non-invasive assessment of positive affective state using infra-red thermography in rats. Anim Welf 2023; 32:e66. [PMID: 38510988 PMCID: PMC10951672 DOI: 10.1017/awf.2023.87] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 07/27/2023] [Accepted: 08/16/2023] [Indexed: 03/22/2024]
Abstract
With recent increased focus on positive welfare in animal welfare science, there is demand for objective positive welfare indicators. It is unclear whether changes in body surface temperature can be used to non-invasively identify and quantify positive states in mammals. We recorded continuous measurements of tail surface temperature using infra-red thermography (IRT) and concurrent behavioural observations in male and female Wistar rats (Rattus norvegicus). If tail surface temperature can differentiate between positive and negative experiences, we expect a qualitatively different response compared to negative experiences. Three groups of rats were presented with increasing magnitudes of food rewards (neutral/none, one and three rewards). The rats were placed in an arena to which they were habituated and filmed for 30 s before and 30 min after exposure to different rewards. Tail temperature initially decreased from the pre-reward baseline and subsequently returned towards baseline temperature. The overall pattern of the change was the same as for rats subjected to negative stimuli in previous studies. Nevertheless, dynamic changes in tail temperature, specifically the rate of recovery and the behavioural response (exploration), differed between neutral and rewarded rats but failed to distinguish reward magnitude. Sex differences were found in both thermal and behavioural responses, unrelated to reward magnitudes. Female rats exhibited a greater initial response with a slower recovery than male rats, emphasising the value of using of both sexes in animal welfare research. This study improves our understanding of the effects of positive emotions induced by food reward on peripheral body temperature and behaviour.
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Affiliation(s)
- Chanakarn Wongsaengchan
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, GlasgowG12 8QQ, UK
- School of Psychology & Neuroscience, University of St Andrews, St Andrews, KY16 9JP, UK
| | - Dominic J McCafferty
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, GlasgowG12 8QQ, UK
| | - Katie Lennox
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, GlasgowG12 8QQ, UK
| | - Ruedi G Nager
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, GlasgowG12 8QQ, UK
| | - Dorothy EF McKeegan
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, GlasgowG12 8QQ, UK
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Domínguez-Oliva A, Hernández-Ávalos I, Olmos-Hernández A, Villegas-Juache J, Verduzco-Mendoza A, Mota-Rojas D. Thermal Response of Laboratory Rats ( Rattus norvegicus) during the Application of Six Methods of Euthanasia Assessed by Infrared Thermography. Animals (Basel) 2023; 13:2820. [PMID: 37760220 PMCID: PMC10526081 DOI: 10.3390/ani13182820] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/28/2023] [Accepted: 09/01/2023] [Indexed: 09/29/2023] Open
Abstract
Refinement is one of the principles aiming to promote welfare in research animals. The techniques used during an experimental protocol, including euthanasia selection, must prevent and minimize suffering. Although the current euthanasia methods applied to laboratory rodents are accepted, the controversial findings regarding the potential stress/distress they can cause is a field of research. The objective was to assess the thermal response of Wistar rats during various euthanasia methods using infrared thermography (IRT) to determine the method that prevents or diminishes the stress response and prolonged suffering. Pentobarbital (G1), CO2 (G2), decapitation (G3), isoflurane (G4), ketamine + xylazine (G5), and ketamine + CO2 (G6) were evaluated at five evaluation times with IRT to identify changes in the surface temperature of four anatomical regions: ocular (T°ocu), auricular (T°ear), interscapular (T°dor), and caudal (T°tai). Significant differences (p < 0.05) were found in G2 and G4, registering temperature increases from the administration of the drug to the cessation of respiratory rate and heart rate. Particularly, isoflurane showed a marked thermal response in T°ocu, T°ear, T°dor, and T°tai, suggesting that, in general, inhalant euthanasia methods induce stress in rats and that isoflurane might potentially cause distress, an effect that must be considered when deciding humane euthanasia methods in laboratory rodents.
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Affiliation(s)
- Adriana Domínguez-Oliva
- Master in Science Program “Maestría en Ciencias Agropecuarias”, Xochimilco Campus, Universidad Autónoma Metropolitana, Mexico City 04960, Mexico
- Neurophysiology of Pain, Behavior and Assessment of Welfare in Domestic Animals, DPAA, Xochimilco Campus, Universidad Autónoma Metropolitana (UAM), Mexico City 04960, Mexico
| | - Ismael Hernández-Ávalos
- Clinical Pharmacology and Veterinary Anesthesia, Biological Sciences Department, Facultad de Estudios Superiores Cuautitlán, Universidad Nacional Autónoma de México, Cuautitlán Izcalli 54714, Mexico
| | - Adriana Olmos-Hernández
- Division of Biotechnology—Bioterio and Experimental Surgery, Instituto Nacional de Rehabilitación-Luis Guillermo Ibarra Ibarra (INR-LGII), Mexico City 14389, Mexico
| | - Juan Villegas-Juache
- Bioterio and Experimental Surgery, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City 14080, Mexico
| | - Antonio Verduzco-Mendoza
- Division of Biotechnology—Bioterio and Experimental Surgery, Instituto Nacional de Rehabilitación-Luis Guillermo Ibarra Ibarra (INR-LGII), Mexico City 14389, Mexico
| | - Daniel Mota-Rojas
- Neurophysiology of Pain, Behavior and Assessment of Welfare in Domestic Animals, DPAA, Xochimilco Campus, Universidad Autónoma Metropolitana (UAM), Mexico City 04960, Mexico
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Wongsaengchan C, McCafferty DJ, Evans NP, McKeegan DEF, Nager RG. Body surface temperature of rats reveals both magnitude and sex differences in the acute stress response. Physiol Behav 2023; 264:114138. [PMID: 36871696 DOI: 10.1016/j.physbeh.2023.114138] [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: 06/07/2022] [Revised: 02/09/2023] [Accepted: 02/24/2023] [Indexed: 03/07/2023]
Abstract
Understanding how biological markers of stress relate to stressor magnitude is much needed and can be used in welfare assessment. Changes in body surface temperature can be measured using infrared thermography (IRT) as a marker of a physiological response to acute stress. While an avian study has shown that changes in body surface temperature can reflect the intensity of acute stress, little is known about surface temperature responses to stressors of different magnitudes and its sex-specificity in mammals, and how they correlate with hormonal and behavioural responses. We used IRT to collect continuous surface temperature measurements of tail and eye of adult male and female rats (Rattus norvegicus), for 30 minutes after exposure to one of three stressors (small cage, encircling handling or rodent restraint cone) for one minute, and cross-validated the thermal response with plasma corticosterone (CORT) and behavioural assessment. To obtain individual baseline temperatures and thermal responses to stress, rats were imaged in a test arena (to which they were habituated) for 30 seconds before and 30 minutes after being exposed to the stressor. In response to the three stressors, tail temperature initially decreased and then recovered to, or overshot the baseline temperature. Tail temperature dynamics differed between stressors; being restrained in the small cage was associated with the smallest drop in temperature, in male rats, and the fastest thermal recovery, in both sexes. Increases in eye temperature only distinguished between stressors early in the response and only in females. The post stressor increase in eye temperature was greater in the right eye of males and the left eye of females. In both sexes encircling may have been associated with the fastest increase in CORT. These results were in line with observed behavioural changes, with greater movement in rats exposed to the small cage and higher immobility after encircling. The female tail and eye temperature, as well as the CORT concentrations did not return to pre-stressor levels in the observation period, in conjunction with the greater occurrence of escape-related behaviours in female rats. These results suggest that female rats are more vulnerable to acute restraint stress compared to male rats and emphasise the importance of using both sexes in future investigations of stressor magnitude. This study demonstrates that acute stress induced changes in mammalian surface temperature measured with IRT relate to the magnitude of restraint stress, indicate sex differences and correlate with hormonal and behavioural responses. Thus, IRT has the potential to become a non-invasive method of continuous welfare assessment in unrestrained mammals.
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Affiliation(s)
- Chanakarn Wongsaengchan
- School of Psychology & Neuroscience, University of St Andrews, St Andrews, KY16 9JP, United Kingdom
| | - Dominic J McCafferty
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Scottish Centre for Ecology and the Natural Environment, Rowardennan, G63 0AW, United Kingdom
| | - Neil P Evans
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Jarrett Building, Glasgow, G61 1QH, United Kingdom
| | - Dorothy E F McKeegan
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Jarrett Building, Glasgow, G61 1QH, United Kingdom
| | - Ruedi G Nager
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, United Kingdom.
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Osada K, Kujirai R, Hosono A, Tsuda M, Ohata M, Ohta T, Nishimori K. Repeated exposure to kairomone-containing coffee odor improves abnormal olfactory behaviors in heterozygous oxytocin receptor knock-in mice. Front Behav Neurosci 2023; 16:983421. [PMID: 36817409 PMCID: PMC9930907 DOI: 10.3389/fnbeh.2022.983421] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 12/16/2022] [Indexed: 02/04/2023] Open
Abstract
The oxytocin receptor (OXTR) knockout mouse is a model of autism spectrum disorder, characterized by abnormalities in social and olfactory behaviors and learning. Previously, we demonstrated that OXTR plays a crucial role in regulating aversive olfactory behavior to butyric acid odor. In this study, we attempted to determine whether coffee aroma affects the abnormal olfactory behavior of OXTR-Venus knock-in heterozygous mice [heterozygous OXTR (±) mice] using a set of behavioral and molecular experiments. Four-week repeated exposures of heterozygous OXTR (±) mice to coffee odor, containing three kairomone alkylpyrazines, rescued the abnormal olfactory behaviors compared with non-exposed wild-type or heterozygous OXTR (±) mice. Increased Oxtr mRNA expression in the olfactory bulb and amygdala coincided with the rescue of abnormal olfactory behaviors. In addition, despite containing the kairomone compounds, both the wild-type and heterozygous OXTR (±) mice exhibited a preference for the coffee odor and exhibited no stress-like increase in the corticotropin-releasing hormone, instead of a kairomone-associated avoidance response. The repeated exposures to the coffee odor did not change oxytocin and estrogen synthetase/receptors as a regulator of the gonadotropic hormone. These data suggest that the rescue of abnormal olfactory behaviors in heterozygous OXTR (±) mice is due to the coffee odor exposure-induced OXTR expression.
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Affiliation(s)
- Kazumi Osada
- Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan,*Correspondence: Kazumi Osada,
| | - Riyuki Kujirai
- Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Akira Hosono
- Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Masato Tsuda
- Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Motoko Ohata
- Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Tohru Ohta
- The Research Institute of Health Science, Health Sciences University of Hokkaido, Tobetsu, Japan
| | - Katsuhiko Nishimori
- Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
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Blenkuš U, Gerós AF, Carpinteiro C, Aguiar PDC, Olsson IAS, Franco NH. Non-Invasive Assessment of Mild Stress-Induced Hyperthermia by Infrared Thermography in Laboratory Mice. Animals (Basel) 2022; 12:177. [PMID: 35049799 PMCID: PMC8773026 DOI: 10.3390/ani12020177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 12/31/2021] [Accepted: 01/09/2022] [Indexed: 11/16/2022] Open
Abstract
Stress-induced hyperthermia (SIH) is a physiological response to acute stressors in mammals, shown as an increase in core body temperature, with redirection of blood flow from the periphery to vital organs. Typical temperature assessment methods for rodents are invasive and can themselves elicit SIH, affecting the readout. Infrared thermography (IRT) is a promising non-invasive alternative, if shown to accurately identify and quantify SIH. We used in-house developed software ThermoLabAnimal 2.0 to automatically detect and segment different body regions, to assess mean body (Tbody) and mean tail (Ttail) surface temperatures by IRT, along with temperature (Tsc) assessed by reading of subcutaneously implanted PIT-tags, during handling-induced stress of pair-housed C57BL/6J and BALB/cByJ mice of both sexes (N = 68). SIH was assessed during 10 days of daily handling (DH) performed twice per day, weekly voluntary interaction tests (VIT) and an elevated plus maze (EPM) at the end. To assess the discrimination value of IRT, we compared SIH between tail-picked and tunnel-handled animals, and between mice receiving an anxiolytic drug or vehicle prior to the EPM. During a 30 to 60 second stress exposure, Tsc and Tbody increased significantly (p < 0.001), while Ttail (p < 0.01) decreased. We did not find handling-related differences. Within each cage, mice tested last consistently showed significantly higher (p < 0.001) Tsc and Tbody and lower (p < 0.001) Ttail than mice tested first, possibly due to higher anticipatory stress in the latter. Diazepam-treated mice showed lower Tbody and Tsc, consistent with reduced anxiety. In conclusion, our results suggest that IRT can identify and quantify stress in mice, either as a stand-alone parameter or complementary to other methods.
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Affiliation(s)
- Urša Blenkuš
- Royal (Dick) School of Veterinary Studies, Easter Bush Campus, The University of Edinburgh, Edinburgh EH25 9RG, UK;
- Laboratory Animal Science, i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal;
| | - Ana Filipa Gerós
- Neuroengineering and Computational Neuroscience Group, i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; (A.F.G.); (C.C.); (P.d.C.A.)
- FEUP—Faculdade de Engenharia da Universidade do Porto, 4200-465 Porto, Portugal
| | - Cristiana Carpinteiro
- Neuroengineering and Computational Neuroscience Group, i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; (A.F.G.); (C.C.); (P.d.C.A.)
| | - Paulo de Castro Aguiar
- Neuroengineering and Computational Neuroscience Group, i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; (A.F.G.); (C.C.); (P.d.C.A.)
| | - I. Anna S. Olsson
- Laboratory Animal Science, i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal;
| | - Nuno Henrique Franco
- Laboratory Animal Science, i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal;
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Masuo Y, Satou T, Takemoto H, Koike K. Smell and Stress Response in the Brain: Review of the Connection between Chemistry and Neuropharmacology. Molecules 2021; 26:molecules26092571. [PMID: 33924992 PMCID: PMC8124235 DOI: 10.3390/molecules26092571] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/16/2021] [Accepted: 04/17/2021] [Indexed: 11/24/2022] Open
Abstract
The stress response in the brain is not fully understood, although stress is one of the risk factors for developing mental disorders. On the other hand, the stimulation of the olfactory system can influence stress levels, and a certain smell has been empirically known to have a stress-suppressing effect, indeed. In this review, we first outline what stress is and previous studies on stress-responsive biomarkers (stress markers) in the brain. Subsequently, we confirm the olfactory system and review previous studies on the relationship between smell and stress response by species, such as humans, rats, and mice. Numerous studies demonstrated the stress-suppressing effects of aroma. There are also investigations showing the effects of odor that induce stress in experimental animals. In addition, we introduce recent studies on the effects of aroma of coffee beans and essential oils, such as lavender, cypress, α-pinene, and thyme linalool on the behavior and the expression of stress marker candidates in the brain. The transfer of volatile components into the brain is also discussed while using the results of thyme linalool as an example. These studies may provide a good opportunity to connect chemical research at the molecular level with neuropharmacological approaches in the future.
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Affiliation(s)
- Yoshinori Masuo
- Laboratory of Neuroscience, Department of Biology, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
- Correspondence: ; Tel.: +81-47-472-5257
| | - Tadaaki Satou
- Department of Pharmacognosy, Faculty of Pharmaceutical Sciences, International University of Health and Welfare, 2600-1 Kitakanemaru, Ohtawara, Tochigi 324-8501, Japan;
| | - Hiroaki Takemoto
- Department of Pharmacognosy, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan; (H.T.); (K.K.)
| | - Kazuo Koike
- Department of Pharmacognosy, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan; (H.T.); (K.K.)
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A new stress model by predatory sound produces persistent anxiety-like behaviours in male SD rats but not ICR mice. Appl Anim Behav Sci 2019. [DOI: 10.1016/j.applanim.2019.104843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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