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Ouaidat S, Amaral IM, Monteiro DG, Harati H, Hofer A, El Rawas R. Orexins/Hypocretins: Gatekeepers of Social Interaction and Motivation. Int J Mol Sci 2024; 25:2609. [PMID: 38473854 DOI: 10.3390/ijms25052609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/12/2024] [Accepted: 02/20/2024] [Indexed: 03/14/2024] Open
Abstract
Ever since the discovery of the brain's orexin/hypocretin system, most research was directed toward unveiling its contribution to the normal functioning of individuals. The investigation of reward-seeking behaviors then gained a lot of attention once the distribution of orexinergic neurons was revealed. Here, we discuss findings on the involvement of orexins in social interaction, a natural reward type. While some studies have succeeded in defining the relationship between orexin and social interaction, the controversy regarding its nature (direct or inverse relation) raises questions about what aspects have been overlooked until now. Upon examining the literature, we identified a research gap concerning conditions influencing the impact of orexins on social behavior expression. In this review, we introduce a number of factors (e.g., stress, orexin's source) that must be considered while studying the role of orexins in social interaction. Furthermore, we refer to published research to investigate the stage at which orexins affect social interaction and we highlight the nucleus accumbens (NAc) shell's role in social interaction and other rewarding behaviors. Finally, the underlying orexin molecular pathway influencing social motivation in particular illnesses is proposed. We conclude that orexin's impact on social interaction is multifactorial and depends on specific conditions available at a time.
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Affiliation(s)
- Sara Ouaidat
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, Medical University Innsbruck, 6020 Innsbruck, Austria
- Neuroscience Research Center, Faculty of Medical Sciences, Lebanese University, Beirut P.O. Box 1533, Lebanon
| | - Inês M Amaral
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Diogo G Monteiro
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Hayat Harati
- Neuroscience Research Center, Faculty of Medical Sciences, Lebanese University, Beirut P.O. Box 1533, Lebanon
| | - Alex Hofer
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Rana El Rawas
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, Medical University Innsbruck, 6020 Innsbruck, Austria
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Toyoshima M, Yamada K. Enhanced social motivation in briefly isolated male rats. IBRO Neurosci Rep 2023; 15:203-208. [PMID: 37767188 PMCID: PMC10520927 DOI: 10.1016/j.ibneur.2023.08.2195] [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: 06/26/2023] [Revised: 08/09/2023] [Accepted: 08/30/2023] [Indexed: 09/29/2023] Open
Abstract
Loneliness and anxiety are associated with psychiatric disorders in humans. Although brief social isolation in adult rats and mice has been proposed as a rodent model of loneliness, its socioemotional characteristics are not well known. In this study, we evaluated the social and emotional behaviors of adult male rats subjected to brief social isolation. Isolated rats frequently showed sniffing behavior toward empty cylinders where conspecifics had previously existed, as well as conspecifics themselves. Furthermore, social motivation correlated with anxiety levels, as indicated by the elevated plus-maze test performance in isolated but not in non-isolated rats. These results suggest that high social motivation is associated with anxiety in briefly isolated rats.
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Affiliation(s)
- Michimasa Toyoshima
- Institute of Psychology and Behavioral Neuroscience, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
- JSPS Research Fellow, Japan Society for the Promotion of Science, Chiyoda, Tokyo 102-0083, Japan
| | - Kazuo Yamada
- Institute of Psychology and Behavioral Neuroscience, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
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Augier G, Schwabl V, Lguensat A, Atudorei M, Iyere OC, Solander SE, Augier E. Wistar rats choose alcohol over social interaction in a discrete-choice model. Neuropsychopharmacology 2022; 48:1098-1107. [PMID: 36587185 PMCID: PMC10209174 DOI: 10.1038/s41386-022-01526-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 12/19/2022] [Accepted: 12/21/2022] [Indexed: 01/01/2023]
Abstract
Animal models of substance use disorders have been criticized for their limited translation. One important factor behind seeking and taking that has so far been largely overlooked is the availability of alternative non-drug rewards. We recently reported that only about 15% of outbred Wistar rats will choose alcohol over a sweet solution of saccharin. It was also shown using a novel operant model of choice of drugs over social rewards that social interaction consistently attenuates self-administration and incubation of craving for stimulants and opioids. Whether this is also true for alcohol and choice of alcohol over a sweet reward translates to social rewards is currently unknown. We therefore evaluated choice between alcohol and a social reward in different experimental settings in both male and female Wistar rats. We found, in contrast to prior work that employed discrete choice of drugs vs. social reward, that rats almost exclusively prefer alcohol over social interaction, irrespective of the nature of the social partner (cagemate vs. novel rat), the length of interaction, housing conditions and sex. Alcohol choice was reduced when the response requirement for alcohol was increased. However, rats persisted in choosing alcohol, even when the effort required to obtain it was 10-16 times higher (for females and males respectively) than the one for the social reward. Altogether, these results indicate that the social choice model may not generalize to alcohol, pointing to the possibility that specific interactions between alcohol and social reward, not seen when a sweet solution is used as an alternative to the drug, may play a crucial role in alcohol vs. social choice experiments.
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Affiliation(s)
- Gaëlle Augier
- Center for Social and Affective Neuroscience, BKV, Augier lab, Linköping University, Linköping, 58185, Sweden
| | - Veronika Schwabl
- Center for Social and Affective Neuroscience, BKV, Augier lab, Linköping University, Linköping, 58185, Sweden
| | - Asmae Lguensat
- Center for Social and Affective Neuroscience, BKV, Augier lab, Linköping University, Linköping, 58185, Sweden
| | - Mihai Atudorei
- Center for Social and Affective Neuroscience, BKV, Augier lab, Linköping University, Linköping, 58185, Sweden
| | - Osamudiamen Consoler Iyere
- Center for Social and Affective Neuroscience, BKV, Augier lab, Linköping University, Linköping, 58185, Sweden
| | - Sandra Eriksson Solander
- Center for Social and Affective Neuroscience, BKV, Augier lab, Linköping University, Linköping, 58185, Sweden
| | - Eric Augier
- Center for Social and Affective Neuroscience, BKV, Augier lab, Linköping University, Linköping, 58185, Sweden.
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