Behavioral responses of mGluR3-KO mice to the lipopolysaccharide-induced innate inflammatory reaction.

Mira Lainiola, Anni-Maija Linden, Teemu Aitta-Aho

Pharmacology, biochemistry, and behavior 2020 Mar

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Acute lipopolysaccharide (LPS) administration induces innate inflammatory signalling and produces sickness reaction characterized by reduced drinking, eating and reduced locomotor exploration, as well as emotional changes indicating increased helplessness/despair. LPS administration has been used to model behavioral and emotional responses to inflammatory reactions. Our aim was to find out whether the lack of metabotropic glutamate receptor 3 (mGluR3) in the knockout (KO) mice affects behavioral effects of LPS in vivo, as mGluR3 may have a role in inflammatory signalling. After LPS (1 mg/kg, i.p.) administration, we compared wild-type (WT) and mGluR3-KO mice for differences in gross appearance and locomotion at 3- and 6-h time points, anxiety-like behavior in the light-dark test at 24-h, depression-like behavior in the tail-suspension test at 25-h, and in the forced-swim test at 48-h time points. Body weight and water consumption were monitored. Based on behavioral scorings at the 3-h and 6-h time points, the mGluR3-KO mice reacted to LPS in a similar way as the WT mice. LPS-induced reductions in the body weight or water consumption did not differ between genotypes. Interestingly, LPS-induced reductions in the body temperature were significantly enhanced in male and female mGluR3-KO mice at 6-h and 3-h time points, respectively. In the light-dark anxiety-test the saline-treated mGluR3-KOs showed increased anxiolytic-like behaviors compared to the saline-treated WT mice. LPS treatment significantly reduced the KO entries to the light compartment to the same level as WT mice given saline. Total locomotion was significantly reduced in both genotypes by LPS. In the despair models, no genotype difference was observed after saline or LPS, neither had LPS treatment any significant effect on immobility. Although changes in glutamatergic neurotransmission may partly mediate effects of systemic LPS administration, mGluR3 appears not to be crucial in behavioral responses to acute activation of innate immune system. Copyright © 2020 Elsevier Inc. All rights reserved.

Citation

Mira Lainiola, Anni-Maija Linden, Teemu Aitta-Aho. Behavioral responses of mGluR3-KO mice to the lipopolysaccharide-induced innate inflammatory reaction. Pharmacology, biochemistry, and behavior. 2020 Mar;190:172852