Park S, Kim DS, Kang S, Moon NR. β-Amyloid-induced cognitive dysfunction impairs glucose homeostasis by increasing insulin resistance and decreasing β-cell mass in non-diabetic and diabetic rats.
Metabolism 2013;
62:1749-60. [PMID:
24050268 DOI:
10.1016/j.metabol.2013.08.007]
[Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 08/13/2013] [Accepted: 08/13/2013] [Indexed: 01/12/2023]
Abstract
OBJECTIVE
β-Amyloid accumulation in the brain may impair glucose homeostasis in both the brain and peripheral tissues. The present study investigated whether β-amyloid deposition in the hippocampus impairs glucose homeostasis by altering insulin sensitivity, glucose-stimulated insulin secretion or β-cell mass.
METHODS
Male rats were divided into two groups: a non-diabetic sham group and a diabetic partial pancreatectomized (Px) group. Each group was then subdivided into three treatment groups that received intra-CA1 infusions of β-amyloid (25-35; AMY), β-amyloid (35-25; RAMY; non-plaque forming), or saline at a rate of 3.6 nmol/day for 14 days.
RESULTS
After 4weeks, cognitive function measured by passive avoidance and water maze tests was impaired in non-diabetic rats that received AMY compared with rats that received saline or RAMY. Furthermore, diabetes exacerbated cognitive dysfunction in AMY-infused rats. This was associated with the hyperphosphorylation of tau as a result of attenuated insulin signaling (pAkt→pGSK) through decreased phosphorylation of cAMP responding element binding protein in the hippocampus of non-diabetic and diabetic rats. AMY exacerbated whole-body and hepatic insulin resistance in non-diabetic and diabetic rats. However, AMY potentiated glucose-stimulated insulin secretion in non-diabetic and diabetic rats, but caused decreased β-cell mass via increased β-cell apoptosis and decreased β-cell proliferation. As a result, glucose homeostasis was maintained by potentiating insulin secretion in diabetic rats, but may not be sustainable with further decreases in β-cell mass.
CONCLUSION
Cognitive dysfunction attributable to β-amyloid accumulation in the hippocampus might be related to disturbed glucose homeostasis due to increased insulin resistance and decreased β-cell mass.
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