Pioglitazone ameliorates memory deficits in streptozotocin-induced diabetic mice by reducing brain β-amyloid through PPARγ activation
Abstract
Li-ping LIU1, #, Tian-hua YAN2, #, Li-ying JIANG2, Wei HU1, Meng HU2, Chao WANG2, Qian ZHANG1, Yan LONG2, Jiang-qing WANG1, Yong-qi LI2, Mei HU2, Hao HONG2, *
1Department of Pharmacy, the Second Hospital Affiliated to Anhui Medical University, Hefei 230031, China; 2Department of Pharmacology, China Pharmaceutical University, Nanjing 210009, China
Aim: To examine the effects of pioglitazone, a PPARγ agonist, on memory performance and brain amyloidogenesis in streptozotocin (STZ)-induced diabetic mice.
Methods: ICR male mice were injected with STZ (150 mg/kg, iv) to induce experimental diabetes. Pioglitazone (9 and 18 mg·kg-1·d-1, po) was administered for 6 weeks. Passive avoidance and Morris water maze (MWM) tests were used to evaluate cognitive function. The blood glucose and serum insulin levels were detected using the glucose oxidase method and an ELISA assay, respectively. β-amyloid (Aβ), β-amyloid precursor protein (APP), β-amyloid precursor protein cleaving enzyme 1 (BACE1), NF-κB p65, the receptor for advanced glycation end products (RAGE) and PPARγ in the brains were analyzed using Western blotting assays.
Results: The STZ-induced diabetic mice characterized by hyperglycemia and hypoinsulinemia performed poorly in both the passive avoidance and MWM tests, accompanied by increased Aβ1–40/Aβ1–42, APP, BACE1, NF-κB p65 and RAGE levels and decreased PPARγ level in the hippocampus and cortex. Chronic pioglitazone treatment significantly ameliorated the memory deficits of STZ-induced diabetic mice, and suppressed expression of APP, BACE1, RAGE and NF-κB p65, and activated PPARγ in the hippocampus and cortex. However, pioglitazone did not significantly affect blood glucose and insulin levels.
Conclusion: Pioglitazone ameliorates memory deficits in STZ-induced diabetic mice by reducing brain Aβ level via activation of PPARγ, which is independent of its effects on blood glucose and insulin levels. The results suggest that pioglitazone may be used for treating the cognitive dysfunction in type 1 diabetes mellitus.
Keywords: diabetes mellitus; pioglitazone; learning memory; hippocampus; cortex; PPARγ; β-amyloid; BACE1; NF-κB; receptor for advanced glycation end products; APP
This work was supported, in part, by the Natural Science Foundation of Anhui Province, China (No 1208085MH164).
# These authors contributed equally to this work.
* To whom correspondence should be addressed.
E-mail haohongchina@hotmail.com
Received 2012-10-18 Accepted 2013-01-02
Keywords:
1Department of Pharmacy, the Second Hospital Affiliated to Anhui Medical University, Hefei 230031, China; 2Department of Pharmacology, China Pharmaceutical University, Nanjing 210009, China
Aim: To examine the effects of pioglitazone, a PPARγ agonist, on memory performance and brain amyloidogenesis in streptozotocin (STZ)-induced diabetic mice.
Methods: ICR male mice were injected with STZ (150 mg/kg, iv) to induce experimental diabetes. Pioglitazone (9 and 18 mg·kg-1·d-1, po) was administered for 6 weeks. Passive avoidance and Morris water maze (MWM) tests were used to evaluate cognitive function. The blood glucose and serum insulin levels were detected using the glucose oxidase method and an ELISA assay, respectively. β-amyloid (Aβ), β-amyloid precursor protein (APP), β-amyloid precursor protein cleaving enzyme 1 (BACE1), NF-κB p65, the receptor for advanced glycation end products (RAGE) and PPARγ in the brains were analyzed using Western blotting assays.
Results: The STZ-induced diabetic mice characterized by hyperglycemia and hypoinsulinemia performed poorly in both the passive avoidance and MWM tests, accompanied by increased Aβ1–40/Aβ1–42, APP, BACE1, NF-κB p65 and RAGE levels and decreased PPARγ level in the hippocampus and cortex. Chronic pioglitazone treatment significantly ameliorated the memory deficits of STZ-induced diabetic mice, and suppressed expression of APP, BACE1, RAGE and NF-κB p65, and activated PPARγ in the hippocampus and cortex. However, pioglitazone did not significantly affect blood glucose and insulin levels.
Conclusion: Pioglitazone ameliorates memory deficits in STZ-induced diabetic mice by reducing brain Aβ level via activation of PPARγ, which is independent of its effects on blood glucose and insulin levels. The results suggest that pioglitazone may be used for treating the cognitive dysfunction in type 1 diabetes mellitus.
Keywords: diabetes mellitus; pioglitazone; learning memory; hippocampus; cortex; PPARγ; β-amyloid; BACE1; NF-κB; receptor for advanced glycation end products; APP
This work was supported, in part, by the Natural Science Foundation of Anhui Province, China (No 1208085MH164).
# These authors contributed equally to this work.
* To whom correspondence should be addressed.
E-mail haohongchina@hotmail.com
Received 2012-10-18 Accepted 2013-01-02