Bardoxolone methyl prevents high-fat diet-induced alterations in prefrontal cortex signalling molecules involved in recognition memory

Abstract Objectives This project investigated the capacity of dietary (-)-epicatechin (EC) to mitigate hippocampal inflammation and impaired memory in high fat diet (HFD)-fed mice. Methods Healthy 6 weeks old male C57BL/6J mice (10 mice/group) were fed for 13 weeks either: a control diet (10% total calories from fat), a high fat diet (60% total calories from lard fat), or the control and high fat diets supplemented with 20 mg EC/kg body weight. Between weeks 10 and 12 of the dietary intervention, object recognition memory was evaluated by the novel object recognition task and short-term spatial memory by the object location memory task, and the Morris Water Maze. After 13 weeks on the dietary treatments, mice were euthanized, and brain tissues and blood were collected. Hippocampus was isolated, flash-frozen in liquid nitrogen, and stored at −80°C. Metabolic endotoxemia was assessed by measuring plasma lipopolysaccharide (LPS) levels. Gene expressions related to inflammation (Toll-like receptor 4 (TLR4) and tumor necrosis factor-α (TNF-α)), activation of microglia (ionized calcium-binding adapter molecule 1 (Iba-1)), and oxidative stress (NADPH oxidase 4 (NOX4)) were analyzed in the hippocampus with RT-qPCR. Results After 13 weeks on the dietary treatments, HFD-fed mice developed obesity, endotoxemia, and showed increased parameters of hippocampal inflammation, i.e., high mRNA levels of TLR4, Iba-1, and NOX4. While not affecting body weight gain, EC supplementation prevented all other HFD-induced changes. Impaired recognition memory was observed in HFD-fed mice, which was prevented by EC supplementation. Neither HFD consumption nor EC supplementation affected mouse spatial memory. Conclusions EC supplementation prevented short-term recognition memory in HFD-induced obese mice, which could be in part due to the capacity of EC to mitigate metabolic endotoxemia and associated hippocampal inflammation and oxidative stress. Funding Sources HA Jastro Shields Award.

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Consumption of a High-Fat Diet Alters Perineuronal Nets in the Prefrontal Cortex

Neural Plasticity ◽

10.1155/2018/2108373 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 7

Author(s):

P. M. Dingess ◽

J. H. Harkness ◽

M. Slaker ◽

Z. Zhang ◽

S. S. Wulff ◽

...

Keyword(s):

Prefrontal Cortex ◽

Weight Gain ◽

High Fat Diet ◽

Spine Density ◽

Structural Adaptation ◽

High Fat ◽

Perineuronal Net ◽

Key Factor ◽

Ad Libitum ◽

Induced Changes

A key factor in the development of obesity is the overconsumption of fatty foods, which, in addition to facilitating weight gain, alters neuronal structures within brain reward circuitry. Our previous work demonstrates that sustained consumption of a high-fat diet (HFD) attenuates spine density in the prefrontal cortex (PFC). Whether HFD promotes structural adaptation among inhibitory cells of the PFC is presently unknown. One structure of interest is the perineuronal net (PNN), a specialized extracellular matrix surrounding, primarily, parvalbumin-containing GABAergic interneurons. PNNs contribute to synaptic stabilization, protect against oxidative stress, regulate the ionic microenvironment within cells, and modulate regional excitatory output. To examine diet-induced changes in PNNs, we maintained rats on one of three dietary conditions for 21 days: ad libitum chow, ad libitum 60% high fat (HF-AL), or limited-access calorically matched high fat (HF-CM), which produced no significant change in weight gain or adiposity with respect to chow controls. The PNN “number” and intensity were then quantified in the prelimbic (PL-PFC), infralimbic (IL-PFC), and ventral orbitofrontal cortex (OFC) using Wisteria floribunda agglutinin (WFA). Our results demonstrated that fat exposure, independent of weight gain, induced a robust decrease in the PNN intensity in the PL-PFC and OFC and a decrease in the PNN number in the OFC.

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PPARg Dysfunction in the Medial Prefrontal Cortex Mediates High-Fat Diet-Induced Depression

10.21203/rs.3.rs-1144403/v1 ◽

2021 ◽

Author(s):

Cong-Cong Fu ◽

Xin-Yi Zhang ◽

Liu Xu ◽

Hui-Xian Huang ◽

Shuang Xu ◽

...

Keyword(s):

Prefrontal Cortex ◽

Medial Prefrontal Cortex ◽

Knockout Mice ◽

High Fat Diet ◽

Peroxisome Proliferator ◽

Obese Mice ◽

High Fat ◽

Peroxisome Proliferator Activated Receptor ◽

Increased Risk ◽

Bidirectional Association

Abstract ObjectiveEpidemiological studies suggest a bidirectional association between depression and obesity; however, the biological mechanisms that link the development of depression to a metabolic disorder remain unclear. Even though nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) agonists show anti-depressive effect, and high-fat diet-(HFD)-induced PPARγ dysfunction is involved in the pathogenesis of metabolic disorders, the neuronal PPARg has never been studied in HFD-induced depression. Thus, we aimed to investigate the effect of neuronal PPARγ on depressive-like behaviors in HFD-induced obese mice. MethodsWe fed male C57BL/6J mice with HFD to generate obese mice and conducted a series of behavioral tests to assess the effects of HFD feeding on depression. We generated neuron-specific PPARγ knockout mice (NKO) to determine whether neuronal PPARg deficiency was correlated with depressive-like behaviors. To further prove whether PPARγ in the medial prefrontal cortex (mPFC) neurons is involved in depressive-like behaviors, we applied AAV- CaMKIIa-Cre approach to specifically knockout PPARγ in the mPFC neurons of LoxP mice and used AAV-syn-PPARγ vectors to overexpress PPARγ in the mPFC neurons of NKO mice. ResultsWe observed a low mPFC PPARγ level and an increase in depressive-like behaviors in the HFD-fed mice. Moreover, neuronal-specific PPARγ deficiency in mice induced depressive-like behaviors, which could be abolished by imipramine. Furthermore, overexpressing PPARg in the mPFC reversed the depressive-like behaviors in HFD-fed mice as well as in neuronal-specific PPARγ knockout mice. ConclusionsThese results implicate that dysregulation of neuronal PPARγ in the mPFC may contribute to an increased risk for depression in obese populations.

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Examination of BDNF Treatment on BACE1 Activity and Acute Exercise on Brain BDNF Signaling

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2021.665867 ◽

2021 ◽

Vol 15 ◽

Author(s):

Bradley J. Baranowski ◽

Grant C. Hayward ◽

Daniel M. Marko ◽

Rebecca E. K. MacPherson

Keyword(s):

Prefrontal Cortex ◽

Direct Effect ◽

High Fat Diet ◽

Beta Amyloid ◽

Treadmill Running ◽

Pathological Feature ◽

High Fat ◽

Acute Bout ◽

Exercise Induced ◽

Bace1 Activity

Perturbations in metabolism results in the accumulation of beta-amyloid peptides, which is a pathological feature of Alzheimer’s disease. Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) is the rate limiting enzyme responsible for beta-amyloid production. Obesogenic diets increase BACE1 while exercise reduces BACE1 activity, although the mechanisms are unknown. Brain-derived neurotropic factor (BDNF) is an exercise inducible neurotrophic factor, however, it is unknown if BDNF is related to the effects of exercise on BACE1. The purpose of this study was to determine the direct effect of BDNF on BACE1 activity and to examine neuronal pathways induced by exercise. C57BL/6J male mice were assigned to either a low (n = 36) or high fat diet (n = 36) for 10 weeks. To determine the direct effect of BDNF on BACE1, a subset of mice (low fat diet = 12 and high fat diet n = 12) were used for an explant experiment where the brain tissue was directly treated with BDNF (100 ng/ml) for 30 min. To examine neuronal pathways activated with exercise, mice remained sedentary (n = 12) or underwent an acute bout of treadmill running at 15 m/min with a 5% incline for 120 min (n = 12). The prefrontal cortex and hippocampus were collected 2-h post-exercise. Direct treatment with BDNF resulted in reductions in BACE1 activity in the prefrontal cortex (p < 0.05), but not the hippocampus. The high fat diet reduced BDNF content in the hippocampus; however, the acute bout of exercise increased BDNF in the prefrontal cortex (p < 0.05). These novel findings demonstrate the region specific differences in exercise induced BDNF in lean and obese mice and show that BDNF can reduce BACE1 activity, independent of other exercise-induced alterations. This work demonstrates a previously unknown link between BDNF and BACE1 regulation.

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Effects of Metabolic Programming on Juvenile Play Behavior and Gene Expression in the Prefrontal Cortex of Rats

Developmental Neuroscience ◽

10.1159/000444015 ◽

2016 ◽

Vol 38 (2) ◽

pp. 96-104 ◽

Cited By ~ 6

Author(s):

Harleen Hehar ◽

Irene Ma ◽

Richelle Mychasiuk

Keyword(s):

Gene Expression ◽

Prefrontal Cortex ◽

Caloric Restriction ◽

High Fat Diet ◽

Developmental Trajectories ◽

Metabolic Programming ◽

Play Behavior ◽

High Fat ◽

Social Emotional ◽

Induced Changes

Early developmental processes, such as metabolic programming, can provide cues to an organism, which allow it to make modifications that are predicted to be beneficial for survival. Similarly, social play has a multifaceted role in promoting survival and fitness of animals. Play is a complex behavior that is greatly influenced by motivational and reward circuits, as well as the energy reserves and metabolism of an organism. This study examined the association between metabolic programming and juvenile play behavior in an effort to further elucidate insight into the consequences that early adaptions have on developmental trajectories. The study also examined changes in expression of four genes (Drd2, IGF1, Opa1, and OxyR) in the prefrontal cortex known to play significant roles in reward, bioenergetics, and social-emotional functioning. Using four distinct variations in developmental programming (high-fat diet, caloric restriction, exercise, or high-fat diet combined with exercise), we found that dietary programming (high-fat diet vs. caloric restriction) had the greatest impact on play behavior and gene expression. However, exercise also induced changes in both measures. This study demonstrates that metabolic programming can alter neural circuits and bioenergetics involved in play behavior, thus providing new insights into mechanisms that allow programming to influence the evolutionary success of an organism.

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