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Loh MK, Stickling C, Schrank S, Hanshaw M, Ritger AC, Dilosa N, Finlay J, Ferrara NC, Rosenkranz JA. Liposaccharide-induced sustained mild inflammation fragments social behavior and alters basolateral amygdala activity. Psychopharmacology (Berl) 2023; 240:647-671. [PMID: 36645464 DOI: 10.1007/s00213-023-06308-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 01/02/2023] [Indexed: 01/17/2023]
Abstract
RATIONALE Conditions with sustained low-grade inflammation have high comorbidity with depression and anxiety and are associated with social withdrawal. The basolateral amygdala (BLA) is critical for affective and social behaviors and is sensitive to inflammatory challenges. Large systemic doses of lipopolysaccharide (LPS) initiate peripheral inflammation, increase BLA neuronal activity, and disrupt social and affective measures in rodents. However, LPS doses commonly used in behavioral studies are high enough to evoke sickness syndrome, which can confound interpretation of amygdala-associated behaviors. OBJECTIVES AND METHODS The objectives of this study were to find a LPS dose that triggers mild peripheral inflammation but not observable sickness syndrome in adult male rats, to test the effects of sustained mild inflammation on BLA and social behaviors. To accomplish this, we administered single doses of LPS (0-100 μg/kg, intraperitoneally) and measured open field behavior, or repeated LPS (5 μg/kg, 3 consecutive days), and measured BLA neuronal firing, social interaction, and elevated plus maze behavior. RESULTS Repeated low-dose LPS decreased BLA neuron firing rate but increased the total number of active BLA neurons. Repeated low-dose LPS also caused early disengagement during social bouts and less anogenital investigation and an overall pattern of heightened social caution associated with reduced gain of social familiarity over the course of a social session. CONCLUSIONS These results provide evidence for parallel shifts in social interaction and amygdala activity caused by prolonged mild inflammation. This effect of inflammation may contribute to social symptoms associated with comorbid depression and chronic inflammatory conditions.
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Affiliation(s)
- Maxine K Loh
- Discipline of Cellular and Molecular Pharmacology, Department of Foundational Sciences and Humanities, Chicago Medical School, Rosalind Franklin University of Medicine and Science, IL, 60064, North Chicago, USA.,Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Courtney Stickling
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Sean Schrank
- Discipline of Cellular and Molecular Pharmacology, Department of Foundational Sciences and Humanities, Chicago Medical School, Rosalind Franklin University of Medicine and Science, IL, 60064, North Chicago, USA.,Discipline of Neuroscience, Department of Foundational Sciences and Humanities, Chicago Medical School, Rosalind Franklin University of Medicine and Science, IL, North Chicago, USA
| | - Madison Hanshaw
- Discipline of Cellular and Molecular Pharmacology, Department of Foundational Sciences and Humanities, Chicago Medical School, Rosalind Franklin University of Medicine and Science, IL, 60064, North Chicago, USA.,Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Alexandra C Ritger
- Discipline of Cellular and Molecular Pharmacology, Department of Foundational Sciences and Humanities, Chicago Medical School, Rosalind Franklin University of Medicine and Science, IL, 60064, North Chicago, USA.,Discipline of Neuroscience, Department of Foundational Sciences and Humanities, Chicago Medical School, Rosalind Franklin University of Medicine and Science, IL, North Chicago, USA
| | - Naijila Dilosa
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Joshua Finlay
- Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Nicole C Ferrara
- Discipline of Cellular and Molecular Pharmacology, Department of Foundational Sciences and Humanities, Chicago Medical School, Rosalind Franklin University of Medicine and Science, IL, 60064, North Chicago, USA.,Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - J Amiel Rosenkranz
- Discipline of Cellular and Molecular Pharmacology, Department of Foundational Sciences and Humanities, Chicago Medical School, Rosalind Franklin University of Medicine and Science, IL, 60064, North Chicago, USA. .,Center for Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA.
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