title: Peroxisome proliferator-activated receptor-γ activation with angiotensin II type 1 receptor blockade is pivotal for the prevention of blood-brain barrier impairment and cognitive decline in type 2 diabetic mice.
abstract: We reported previously that an angiotensin II type 1 receptor blocker, telmisartan, improved cognitive decline with peroxisome proliferator-activated receptor-γ activation; however, the detailed mechanisms are unclear. Enhanced blood-brain barrier (BBB) permeability with alteration of tight junctions is suggested to be related to diabetes mellitus. Therefore, we examined the possibility that telmisartan could attenuate BBB impairment with peroxisome proliferator-activated receptor-γ activation to improve diabetes mellitus-induced cognitive decline. Type 2 diabetic mice KKA(y) exhibited impairment of cognitive function, and telmisartan treatment attenuated this. Cotreatment with GW9662, a peroxisome proliferator-activated receptor-γ antagonist, interfered with these protective effects of telmisartan against cognitive function. BBB permeability was increased in both the cortex and hippocampus in KKA(y) mice. Administration of telmisartan attenuated this increased BBB permeability. Coadministration of GW9662 reduced this effect of telmisartan. Significant decreases in expression of tight junction proteins and increases in matrix metalloproteinase expression, oxidative stress, and proinflammatory cytokine production were observed in the brain, and treatment with telmisartan restored these changes. Swollen astroglial end-feet in BBB were observed in KKA(y) mice, and this change in BBB ultrastructure was decreased in telmisartan. These effects of telmisartan were weakened by cotreatment with GW9662. In contrast, administration of another angiotensin II type 1 receptor blocker, losartan, was less effective compared with telmisartan in terms of preventing BBB permeability and astroglial end-foot swelling, and coadministration of GW9662 did not affect the effects of losartan. These findings are consistent with the possibility that, in type 2 diabetic mice, angiotensin II type 1 receptor blockade with peroxisome proliferator-activated receptor-γ activation by telmisartan may help with protection against cognitive decline by preserving the integrity of the BBB.
authors.affiliation: Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University, Graduate School of Medicine, Shitsukawa, Tohon, Ehime, Japan.
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Min
authors.forename: Masaki
authors.initials: M
authors.lastname: Mogi
authors.forename: Masachika
authors.initials: M
authors.lastname: Shudou
authors.forename: Fei
authors.initials: F
authors.lastname: Jing
authors.forename: Kana
authors.initials: K
authors.lastname: Tsukuda
authors.forename: Kousei
authors.initials: K
authors.lastname: Ohshima
authors.forename: Jun
authors.initials: J
authors.lastname: Iwanami
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Horiuchi
mesh_terms: D000704:Analysis of Variance; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology*; D000813:Anilides / Q000494:pharmacology; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D001565:Benzoates / Q000494:pharmacology; D001786:Blood Glucose / Q000032:analysis; D001812:Blood-Brain Barrier / Q000187:drug effects*; D015153:Blotting, Western; D003072:Cognition Disorders / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control*; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000188:drug therapy* / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000188:drug therapy / Q000378:metabolism*; D004195:Disease Models, Animal; D019808:Losartan / Q000494:pharmacology; D008297:Male; D018782:Maze Learning; D051379:Mice; D008810:Mice, Inbred C57BL; D047495:PPAR gamma / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D011897:Random Allocation; D012680:Sensitivity and Specificity; D000077333:Telmisartan
chemical_list: C457499:2-chloro-5-nitrobenzanilide; D047228:Angiotensin II Type 1 Receptor Blockers; D000813:Anilides; D001562:Benzimidazoles; D001565:Benzoates; D001786:Blood Glucose; D047495:PPAR gamma; D019808:Losartan; D000077333:Telmisartan