title: Alpha-lipoic acid does not alter stress protein response to acute exercise in diabetic brain.
abstract: Heat shock proteins (HSPs) are molecular chaperones which may act protective in cerebrovascular insults and peripheral diabetic neuropathy. We hypothesized that alpha-lipoic acid (LA), a natural thiol antioxidant, may enhance brain HSP response in diabetes. Rats with or without streptozotocin-induced diabetes were treated with LA or saline for 8 weeks. Half of the rats were subjected to exhaustive exercise to investigate HSP induction, and the brain tissue was analyzed. Diabetes increased constitutive HSC70 mRNA, and decreased HSP90 and glucose-regulated protein 75 (GRP75) mRNA without affecting protein levels. Exercise increased HSP90 protein and mRNA, and also GRP75 and heme oxygenase-1 (HO-1) mRNA only in non-diabetic animals. LA had no significant effect on brain HSPs, although LA increased HSC70 and HO-1 mRNA in diabetic animals and decreased HSC70 mRNA in non-diabetic animals. Eukaryotic translation elongation factor-2, essential for protein synthesis, was decreased by diabetes and suggesting a mechanism for the impaired HSP response related to translocation of the nascent chain during protein synthesis. LA supplementation does not offset the adverse effects of diabetes on brain HSP mRNA expression. Diabetes may impair HSP translation through elongation factors related to nascent chain translocation and subsequent responses to acute stress.
authors.affiliation: Institute of Biomedicine, Physiology, University of Eastern Finland, Kuopio, Finland.
authors.forename: Jani
authors.initials: J
authors.lastname: Lappalainen
authors.forename: Zekine
authors.initials: Z
authors.lastname: Lappalainen
authors.forename: Niku K J
authors.initials: NK
authors.lastname: Oksala
authors.forename: David E
authors.initials: DE
authors.lastname: Laaksonen
authors.forename: Savita
authors.initials: S
authors.lastname: Khanna
authors.forename: Chandan K
authors.initials: CK
authors.lastname: Sen
authors.forename: Mustafa
authors.initials: M
authors.lastname: Atalay
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis*; D018841:HSP90 Heat-Shock Proteins / Q000096:biosynthesis*; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis*; D010805:Physical Conditioning, Animal; D005082:Physical Exertion; D051381:Rats; D017208:Rats, Wistar; D008063:Thioctic Acid / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D008565:Membrane Proteins; C018551:glucose-regulated proteins; D008063:Thioctic Acid