title: Short-term treatment with metformin suppresses toll like receptors (TLRs) activity in isoproterenol-induced myocardial infarction in rat: are AMPK and TLRs connected?
abstract: AMP-activated protein kinase (AMPK) is a key sensor of cellular energy. The activation of AMPK by metformin prevents cardiac remodeling after myocardial infarction (MI). Besides, the innate immune response through TLRs is activated during MI. In the present study, the effects of short-term treatment with metformin on TLRs activity and its relation with AMPK in isoproterenol-induced MI were assessed in rats. To induce MI, a subcutaneous injection of isoproterenol was given to Wistar rats for two consecutive days. Metformin (25, 50, and 100mg/kg) was orally administered to rats twice daily for two days. Interstitial fibrosis was dose-dependently attenuated in the treated groups in comparison to the MI group (score: 1.25 ± 0.28 with 100 mg/kg metformin versus 3.5 ± 0.28; P<0.001). Further, metformin reduced TLR-dependent inflammatory cytokines as indexed by reduced myocardial levels of TNFα (maximum 68%; P<0.001) and IL6 (maximum 84%; P<0.001) as well as by reduced myocardial MPO activity (25%; P<0.01). It was found that the level of phosphorylated AMPK was significantly upregulated by 165% (P<0.001) when treated with 100 mg/kg of metformin, but not with 25 and 50mg/kg. This was associated with a remarkable suppression of TLR4 expression and reduction of protein level of TLRs adapter protein, MyD88 (P<0.01) in the infarcted myocardium. These results suggest that AMPK activation by metformin and the subsequent suppression of TLRs activity could be considered as a target in protecting the infarcted heart, which may indicate a link between AMPK and TLRs.
authors.affiliation: Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Soraya
authors.forename: Safar
authors.initials: S
authors.lastname: Farajnia
authors.forename: Sajjad
authors.initials: S
authors.lastname: Khani
authors.forename: Maryam
authors.initials: M
authors.lastname: Rameshrad
authors.forename: Arash
authors.initials: A
authors.lastname: Khorrami
authors.forename: Armita
authors.initials: A
authors.lastname: Banani
authors.forename: Nasrin
authors.initials: N
authors.lastname: Maleki-Dizaji
authors.forename: Alireza
authors.initials: A
authors.lastname: Garjani
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000318:Adrenergic beta-Agonists / Q000633:toxicity; D000818:Animals; D005786:Gene Expression Regulation / Q000187:drug effects; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D007545:Isoproterenol / Q000633:toxicity*; D008297:Male; D008687:Metformin / Q000008:administration & dosage / Q000494:pharmacology*; D009203:Myocardial Infarction / Q000139:chemically induced*; D010766:Phosphorylation; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000318:Adrenergic beta-Agonists; D007004:Hypoglycemic Agents; D015850:Interleukin-6; D051193:Toll-Like Receptors; D008687:Metformin; D055372:AMP-Activated Protein Kinases; D007545:Isoproterenol