We previously reported that interleukin (IL)-6 deficiency potentiates trimethyltin (TMT)-induced convulsive neurotoxicity. The purpose in this study was to investigate the molecular mechanism by which cytokines affect TMT-induced cognitive impairment. To accomplish this, we examined hippocampal changes in Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling in relation to cholinergic parameters after TMT treatment in mice genetically deficient in IL-6 (IL-6-/-), tumor necrosis factor-α (TNF-α-/-), or interferon-γ (IFN-γ-/-). The IL-6-/- mice were the most susceptible to TMT-induced cognitive dysfunction and exhibited significant decreases in JAK2/STAT3 signaling and M1 muscarinic acetylcholine receptor (mAChR) expression, as well as other cholinergic parameters, compared with wild-type (WT) animals. Recombinant IL-6 protein (rIL-6) significantly attenuated these impairments in TMT-treated IL-6-/- mice, whereas an IL-6 receptor antibody potentiated these impairments in TMT-treated WT animals. Inhibition of JAK2 with AG490 or inhibition of cholinergic signaling with the M1 mAChR antagonist dicyclomine counteracted the attenuating effects of rIL-6 on phosphorylated extracellular signal-regulated kinase (ERK) expression, or on cognitive impairment in TMT-treated IL-6-/- mice. However, neither AG490 nor dicyclomine significantly attenuated effects of rIL-6 on acetylcholinesterase values. Our results suggest that activation of JAK2/STAT3 signaling and upregulation of the M1 mAChR are essential components of IL-6-mediated memory improvement against TMT toxicity.
Bibliographical noteFunding Information:
This study was supported by a grant from the Brain Research Center from the 21st Century Frontier Research Program ( 2012k001115 ) funded by the Ministry of Science and Technology, Republic of Korea . This work was, in part, supported by a grant from the Bio & Medical Technology Development Program ( 20120006020 ) through the National Research Foundation funded by the Ministry of Education, Science and Technology, Republic of Korea , and by grants from Ministry of Health Labour and Welfare (MHLW) : Research on Risk of Chemical Substances, and Ministry of Education, Culture, Sports, Science and Technology (MEST): Academic Frontier Project. Jae-Hyung Bach was supported by the BK 21 program.
- Cognitive impairments
- Extracellular signal-regulated kinase
- Interlukin-6 gene
- M1 muscarinic acetylcholine receptor
ASJC Scopus subject areas
- Cell Biology