BACKGROUND: Defining the impact of diabetes and related risk factors on brain cognitive function is critically important for patients with diabetes. AIMS: To investigate the alterations in hippocampal serine/threonine kinases signaling in the early phase of type 1 and type 2 diabetic rats. METHODS: Early experimental diabetes mellitus was induced in rats with streptozotocin or streptozotocin/high fat. Changes in the phosphorylation of proteins were determined by immunoblotting and immunohistochemistry. RESULTS: Our data showed a pronounced decrease in the phosphorylation of Ca(2+) /calmodulin-dependent protein kinase II (CaMKII) in the hippocampi of both type 1 and type 2 diabetic rats compared with age-matched control rats. Unexpectedly, we found a significant increase in the phosphorylation of synapsin I (Ser 603) and GluR1 (Ser 831) in the same experiment. In addition, aberrant changes in hippocampal protein kinase C (PKC) and protein kinase A (PKA) signaling in type 1 and type 2 diabetic rats were also found. Moreover, PP1α and PP2A protein levels were decreased in the hippocampus of type 1 diabetic rats, but significantly up-regulated in type 2 diabetic rats. CONCLUSIONS: The disturbance of CaMKII/PKA/PKC phosphorylation in the hippocampus is an early change that may be associated with the development and progression of diabetes-related cognitive dysfunction.
BACKGROUND: Defining the impact of diabetes and related risk factors on brain cognitive function is critically important for patients with diabetes. AIMS: To investigate the alterations in hippocampal serine/threonine kinases signaling in the early phase of type 1 and type 2 diabeticrats. METHODS: Early experimental diabetes mellitus was induced in rats with streptozotocin or streptozotocin/high fat. Changes in the phosphorylation of proteins were determined by immunoblotting and immunohistochemistry. RESULTS: Our data showed a pronounced decrease in the phosphorylation of Ca(2+) /calmodulin-dependent protein kinase II (CaMKII) in the hippocampi of both type 1 and type 2 diabeticrats compared with age-matched control rats. Unexpectedly, we found a significant increase in the phosphorylation of synapsin I (Ser 603) and GluR1 (Ser 831) in the same experiment. In addition, aberrant changes in hippocampal protein kinase C (PKC) and protein kinase A (PKA) signaling in type 1 and type 2 diabeticrats were also found. Moreover, PP1α and PP2A protein levels were decreased in the hippocampus of type 1 diabeticrats, but significantly up-regulated in type 2 diabeticrats. CONCLUSIONS: The disturbance of CaMKII/PKA/PKC phosphorylation in the hippocampus is an early change that may be associated with the development and progression of diabetes-related cognitive dysfunction.