Cognitive dysfunction associated with diabetic ketoacidosis in rats

Acute and chronic neuroinflammation is triggered by diabetic ketoacidosis in a rat model

INTRODUCTION

Cognitive decline is common in patients with type 1 diabetes and has been attributed to the effects of chronic hyperglycemia and severe hypoglycemia. Diabetic ketoacidosis (DKA) has only recently been suspected to be involved in causing cognitive decline. We hypothesized that DKA triggers both acute and chronic neuroinflammation, contributing to brain injury.

RESEARCH METHODS AND DESIGN

We measured concentrations of cytokines, chemokines and matrix metalloproteinases (MMP) in serum and brain tissue lysates in juvenile rats during and after DKA (during acute DKA, 24 hours and 7 days after DKA), and compared these to healthy controls and hyperglycemic controls. We also measured cytokine, chemokine and MMP concentrations in serum and brain tissue of adult rats (70 days) that had experienced DKA as juveniles and compared these measurements to those of adult diabetic rats without exposure to DKA.

RESULTS

During acute DKA in the juvenile rats, serum concentrations of CCL3, tumor necrosis factor (TNF)-α, interleukin (IL)-1ß and MMP-9 were significantly increased. Serum concentrations of IL-2 and IL-17A increased 7 days after DKA recovery. In brain tissue lysates, concentrations of CCL3, CCL5, interferon (IFN)-γ and MMP-9 were significantly elevated during acute DKA. In adult rats that had DKA as juveniles (28 days previously), serum concentrations of IL-1ß and brain concentrations of IL-10 and IL-12p70 were elevated in comparison to diabetic rats without prior DKA. Composite scores for highly correlated cytokines and chemokines (mean z-scores for IL-10, IL-1ß, TNF-α, IL-17A, IFN-γ, CXCL-1 and CCL5) were also significantly elevated in adult rats with prior DKA.

CONCLUSIONS

These data confirm that DKA causes acute systemic inflammation and neuroinflammation in a rat model. Importantly, the neuroinflammatory response triggered by DKA is long-lasting, suggesting the possibility that DKA-induced chronic neuroinflammation could contribute to long-term cognitive decline in individuals with diabetes.

Recurrent diabetic ketoacidosis and cognitive function among older adults with type 1 diabetes: findings from the Study of Longevity in Diabetes

INTRODUCTION

Diabetic ketoacidosis (DKA) is a serious complication of diabetes. DKA is associated with poorer cognition in children with type 1 diabetes (T1D), but whether this is the case in older adults with T1D is unknown. Given the increasing life expectancy in T1D, understanding the role of DKA on brain health in older adults is crucial.

RESEARCH DESIGN AND METHODS

We examined the association of DKA with cognitive function in 714 older adults with T1D from the Study of Longevity in Diabetes. Participants self-reported lifetime exposure to DKA resulting in hospitalization; DKA was categorized into 0 hospitalization, 1 hospitalization or ≥2 hospitalizations (recurrent DKA). Global and domain-specific cognition (language, executive function/psychomotor speed, episodic memory and simple attention) were assessed. The association of DKA with cognitive function was evaluated via linear and logistic regression models.

RESULTS

Twenty-eight percent of participants (mean age=67 years; mean age at diagnosis=28 years; average duration of diabetes=39 years) reported a lifetime history of DKA resulting in hospitalization (18.5% single DKA; 9.7% recurrent DKA). In fully adjusted models, those with recurrent DKA had lower global cognitive function (β=-0.13; 95% CI -0.22 to 0.02) and lower scores on the executive function/psychomotor speed domain (β=-0.34; 95% CI -0.51 to 0.17). Individuals with recurrent DKA were also more likely to have the lowest level of cognitive function on the executive function/psychomotor speed domain (defined as 1.5 SD below the population mean; OR=3.26, 95% CI 1.43 to 7.42).

CONCLUSIONS

Among 714 older adults with T1D, recurrent DKA was associated with lower global cognitive function, lower scores on the executive function/psychomotor speed domain and 3.3 times greater risk of having the lowest level of cognitive function in our sample on the executive function/psychomotor speed domain. These findings suggest that recurrent DKA may negatively impact the brain health of older patients with T1D and highlight the importance of DKA prevention.

n-3 Fatty Acid and Its Metabolite 18-HEPE Ameliorate Retinal Neuronal Cell Dysfunction by Enhancing Müller BDNF in Diabetic Retinopathy

Diabetic retinopathy (DR) is a widespread vision-threatening disease, and neuroretinal abnormality should be considered as an important problem. Brain-derived neurotrophic factor (BDNF) has recently been considered as a possible treatment to prevent DR-induced neuroretinal damage, but how BDNF is upregulated in DR remains unclear. We found an increase in hydrogen peroxide (H₂O₂) in the vitreous of patients with DR. We confirmed that human retinal endothelial cells secreted H₂O₂ by high glucose, and H₂O₂ reduced cell viability of MIO-M1, Müller glia cell line, PC12D, and the neuronal cell line and lowered BDNF expression in MIO-M1, whereas BDNF administration recovered PC12D cell viability. Streptozocin-induced diabetic rats showed reduced BDNF, which is mainly expressed in the Müller glia cell. Oral intake of eicosapentaenoic acid ethyl ester (EPA-E) ameliorated BDNF reduction and oscillatory potentials (OPs) in electroretinography (ERG) in DR. Mass spectrometry revealed an increase in several EPA metabolites in the eyes of EPA-E-fed rats. In particular, an EPA metabolite, 18-hydroxyeicosapentaenoic acid (18-HEPE), induced BDNF upregulation in Müller glia cells and recovery of OPs in ERG. Our results indicated diabetes-induced oxidative stress attenuates neuroretinal function, but oral EPA-E intake prevents retinal neurodegeneration via BDNF in Müller glia cells by increasing 18-HEPE in the early stages of DR.

Cognitive Dysfunction in Type 1 Diabetes Mellitus

CONTEXT

We have summarized key studies assessing the epidemiology, mechanisms, and consequences of cognitive dysfunction (CD) in type 1 diabetes.

EVIDENCE SYNTHESIS

In a number of studies, the severity of CD in type 1 diabetes was affected by the age of onset and duration, and the presence of proliferative retinopathy and autonomic neuropathy. Diabetes-related CD has been observed, not only in adults, but also in children and adolescents. Most neuroimaging studies of patients with type 1 diabetes did not show any differences in whole brain volumes; however, they did reveal selective deficits in gray matter volume or density within the frontal, posterior, and temporal cortex and subcortical gray matter. Studies of middle-age adults with long-standing type 1 diabetes using diffusion tensor imaging have demonstrated partial lesions in the white matter and decreased fractional anisotropy in posterior brain regions. The mechanisms underlying diabetes-related CD are very complex and include factors related to diabetes per se and to diabetes-related cardiovascular disease and microvascular dysfunction, including chronic hyperglycemia, hypoglycemia, macro- and microvascular disease, and increased inflammatory cytokine expression. These mechanisms might contribute to the development and progression of both vascular dementia and Alzheimer disease.

CONCLUSIONS

Higher rates of CD and faster progression in type 1 diabetes can be explained by both the direct effects of altered glucose metabolism on the brain and diabetes-related cardiovascular disease. Because the presence and progression of CD significantly worsens the quality of life of patients with diabetes, further multidisciplinary studies incorporating the recent progress in both neuroimaging and type 1 diabetes management are warranted to investigate this problem.

Brain injury markers: S100 calcium-binding protein B, neuron-specific enolase and glial fibrillary acidic protein in children with diabetic ketoacidosis

BACKGROUND

To investigate serum levels of brain injury markers in diabetic ketoacidosis (DKA) and the relation of these markers with clinical and radiological findings of brain injury and laboratory results.

METHODS

Twenty-nine patients with DKA, 30 with type 1 diabetes mellitus (T1DM), and 35 healthy children were included. Clinical and laboratory findings, and the Glasgow Coma Scale (GCS) were recorded. In the DKA group, neuron-specific enolase (NSE), S100 calcium-binding protein B (S100B) and glial fibrillary acidic protein (GFAP) levels were measured at baseline and 6 and 12 hours after treatment. Magnetic resonance imaging was performed in the DKA group to demonstrate any brain injury.

RESULTS

No clinical or radiological findings of brain injury were found in any of the patients with DKA. In the DKA group, S100B was significantly higher than the healthy control and T1DM groups, while GFAP and NSE levels were not different from controls and T1DM patients. No significant differences were found in GFAP, NSE and S100B levels according to severity of DKA, diabetes duration and GCS.

CONCLUSION

NSE and GFAP levels do not increase in DKA patients without overt brain injury. Elevated levels of S100B, which is also synthesized from non-neuronal tissues, might arise from peripheral sources. A lack of concurrent increase in serum levels of these brain injury markers might result from the yet intact blood brain barrier or a true absence of neuronal damage. In order to reveal subclinical brain injury related to DKA, there is a need for studies concurrently assessing neurocognitive functions.

Diabetic ketoacidosis in juvenile rats is associated with reactive gliosis and activation of microglia in the hippocampus

BACKGROUND

Type 1 diabetes may be associated with structural and functional alterations in the brain. The role of diabetic ketoacidosis (DKA) in causing these alterations has not been well explored.

METHODS

We used immunohistochemical staining to investigate cellular alterations in brain specimens from juvenile rats with DKA before, during, and after treatment with insulin and saline, and compared these to samples from diabetic rats and normal controls.

RESULTS

Glial fibrillary acidic protein (GFAP) staining intensity was increased in the hippocampus during DKA and increased further during insulin/saline treatment. Twenty-four and 72 h after treatment, hippocampal GFAP intensity declined but remained above control levels. There were no significant changes in GFAP intensity in the cortex or striatum. OX42 staining intensity was increased during untreated DKA and increased further during insulin/saline treatment in the hippocampus and cortex. NeuN staining intensity was decreased after DKA treatment in the striatum but not in other regions.

CONCLUSIONS

DKA causes inflammatory changes in the brain including reactive gliosis and activation of microglia. These findings are present during untreated DKA, but intensify during insulin/saline treatment. The hippocampus was disproportionately affected, consistent with previous studies showing deficits in hippocampal functions in rats after DKA recovery and decreased memory capacity in children with a history of DKA.

Biomarkers and genetics of brain injury risk in diabetic ketoacidosis: A pilot study

Diabetic ketoacidosis (DKA) is the primary cause of death for children with diabetes, especially when complicated by cerebral edema. Central nervous system (CNS) involvement is common, however the mechanism of, and predictors of CNS dysfunction/injury are largely unknown. In this observational pilot study, blood was collected from pediatric DKA patients at three time points (consent, 12 hr and 24 hr after beginning treatment), to test genetic markers, ribonucleic acid expression and plasma biomarkers reflecting inflammation (tumor necrosis factor-alpha [TNF-α], interleukin-6 [IL-6]) and cerebral dysfunction and/or possible injury (S100β, glial fibrillary acidic protein [GFAP]). Thirty patients were enrolled in the study. The average age was 11.3 yr, 73% were new onset diabetes and 53% were female. Forty percent exhibited abnormal mentation (Glasgow Coma Scale <15), consistent with CNS dysfunction. IL-6 and TNF-α were elevated in plasma, suggesting systemic inflammation. GFAP was measurable in 45% of patients and correlated positively with GCS. Only two patients had detectable levels of S100β. In conclusion, children with DKA often present with evidence of acute neurologic dysfunction or injury. We have demonstrated the feasibility of exploring genetic and biochemical markers of potential importance in the pathophysiology of CNS dysfunction and/or possible injury in DKA. We have identified IL-6, TNF-α and GFAP as potentially important markers for further exploration. A larger, follow-up study will help to better understand the extent and type of CNS injury in DKA as well as the mechanism underlying this dysfunction/injury.

Insulin treatment prevents the increase in D-serine in hippocampal CA1 area of diabetic rats

PURPOSE

Diabetes is a high risk factor for dementia. Employing a diabetic rat model, the present study was designed to determine whether the content of D-serine (D-Ser) in hippocampus is associated with the impairment of spatial learning and memory ability.

METHODS

Diabetes was induced by a single intravenous injection of streptozotocin (STZ). The insulin treatment began 3 days after STZ injection.

RESULTS

We found that both water maze learning and hippocampal CA1 long-term potentiation (LTP) were impaired in diabetic rats. The contents of glutamate, D-Ser, and serine racemase in the hippocampus of diabetic rats were significantly higher than those in the control group. Insulin treatment prevented the STZ-induced impairment in water maze learning and hippocampal CA1-LTP in diabetic rats and also maintained the contents of glutamate, D-Ser, and serine racemase at the normal range in hippocampus.

CONCLUSIONS

These results suggest that insulin treatment has a potent protection effect on CA1-LTP, spatial learning and memory ability of the diabetic rats in vivo. Furthermore, insulin may take effect by inhibiting the overactivation of N-methyl-d-aspartate receptors, which play a critical role in neurotoxicity.

Rare complications of pediatric diabetic ketoacidosis

The incidence of type 1 diabetes (T1D) among youth is steadily increasing across the world. Up to a third of pediatric patients with T1D present with diabetic ketoacidosis, a diagnosis that continues to be the leading cause of death in this population. Cerebral edema is the most common rare complication of diabetic ketoacidosis in children. Accordingly, treatment and outcome measures of cerebral edema are vastly researched and the pathophysiology is recently the subject of much debate. Nevertheless, cerebral edema is not the only sequela of diabetic ketoacidosis that warrants close monitoring. The medical literature details various other complications in children with diabetic ketoacidosis, including hypercoagulability leading to stroke and deep vein thrombosis, rhabdomyolysis, pulmonary and gastrointestinal complications, and long-term memory dysfunction. We review the pathophysiology, reported cases, management, and outcomes of each of these rare complications in children. As the incidence of T1D continues to rise, practitioners will care for an increasing number of pediatric patients with diabetic ketoacidosis and should be aware of the various systems that may be affected in both the acute and chronic setting.

Neurological consequences of diabetic ketoacidosis at initial presentation of type 1 diabetes in a prospective cohort study of children

OBJECTIVE

To investigate the impact of new-onset diabetic ketoacidosis (DKA) during childhood on brain morphology and function.

RESEARCH DESIGN AND METHODS

Patients aged 6-18 years with and without DKA at diagnosis were studied at four time points: <48 h, 5 days, 28 days, and 6 months postdiagnosis. Patients underwent magnetic resonance imaging (MRI) and spectroscopy with cognitive assessment at each time point. Relationships between clinical characteristics at presentation and MRI and neurologic outcomes were examined using multiple linear regression, repeated-measures, and ANCOVA analyses.

RESULTS

Thirty-six DKA and 59 non-DKA patients were recruited between 2004 and 2009. With DKA, cerebral white matter showed the greatest alterations with increased total white matter volume and higher mean diffusivity in the frontal, temporal, and parietal white matter. Total white matter volume decreased over the first 6 months. For gray matter in DKA patients, total volume was lower at baseline and increased over 6 months. Lower levels of N-acetylaspartate were noted at baseline in the frontal gray matter and basal ganglia. Mental state scores were lower at baseline and at 5 days. Of note, although changes in total and regional brain volumes over the first 5 days resolved, they were associated with poorer delayed memory recall and poorer sustained and divided attention at 6 months. Age at time of presentation and pH level were predictors of neuroimaging and functional outcomes.

CONCLUSIONS

DKA at type 1 diabetes diagnosis results in morphologic and functional brain changes. These changes are associated with adverse neurocognitive outcomes in the medium term.

Pediatric diabetic ketoacidosis, fluid therapy, and cerebral injury: the design of a factorial randomized controlled trial

Treatment protocols for pediatric diabetic ketoacidosis (DKA) vary considerably among centers in the USA and worldwide. The optimal protocol for intravenous (IV) fluid administration is an area of particular controversy, mainly in regard to possible associations between rates of IV fluid infusion and the development of cerebral edema (CE), the most common and the most feared complication of DKA in children. Theoretical concerns about associations between osmotic fluid shifts and CE have prompted recommendations for conservative fluid infusion during DKA. However, recent data suggest that cerebral hypoperfusion may play a role in cerebral injury associated with DKA. Currently, there are no existing data from prospective clinical trials to determine the optimal fluid treatment protocol for pediatric DKA. The Pediatric Emergency Care Applied Research Network FLUID (FLuid therapies Under Investigation in DKA) study is the first prospective randomized trial to evaluate fluid regimens for pediatric DKA. This 13-center nationwide factorial design study will evaluate the effects of rehydration rate and fluid sodium content on neurological status during DKA treatment, the frequency of clinically overt CE and long-term neurocognitive outcomes following DKA.