Inflammation in peripheral tissues is implicated as a key mediator of insulin resistance and other metabolic consequences of obesity. Recent studies show that a similar inflammatory process also occurs in the hypothalamus, and that this process, unlike inflammation in peripheral tissues, is a potential cause (and not just a consequence) of obesity and associated metabolic impairment. These effects of hypothalamic inflammation are mediated in part via impaired neuronal responses to the hormones insulin and leptin, key signals in the central control of both energy homeostasis and insulin sensitivity. Our novel findings that hypothalamic proinflammatory cytokine expression occurs within just 24 h of the onset of high-fat (HF) feeding, an effect that coincides with a marked increase of caloric intake, and that both parameters are gradually return to normal over the subsequent week suggest a link between neuronal inflammatory responses and the hyperphagic response to a HF diet. Coincident with these early responses, microglia (the macrophage of the brain) accumulate in the arcuate nucleus (ARC, a key hypothalamic area for sensing input from insulin and leptin) - but not other brain areas. These and other observations strongly suggest that interactions between hypothalamic neurons and microglia are determinants of weight gain during HF feeding. Further, acute reversal of hypothalamic inflammation fully reverses systemic insulin resistance induced by 3 wk of HF feeding. Here, we propose studies to determine the time course over which hypothalamic microglia and neurons respond to HF feeding, and whether the response of microglia, neurons, or both cell types is required for this inflammation. We will also identify mechanisms underlying microglial accumulation in the ARC during HF feeding, and determine whether disruption of this microglial response predisposes to obesity. Lastly, we will investigate the mechanism whereby hypothalamic inflammatory signaling induced by HF feeding causes insulin resistance. These studies will clarify how interactions between hypothalamic neurons and microglia influence weight gain and metabolic impairment induced by HF feeding, which will inform our understanding of the pathogenesis of both obesity and insulin resistance and facilitate the discovery of new approaches to the treatment and prevention of these disorders.

Public Health Relevance

This proposal focuses on mechanisms whereby high-fat feeding causes obesity and insulin resistance, both of which are major public health problems worldwide. Growing evidence implicates inflammation in peripheral tissues as a major cause of insulin resistance and other metabolic consequences of obesity. During high-fat feeding, inflammation also occurs in the hypothalamus, a key brain area for the control of both body weight and glucose metabolism. Unlike inflammation in peripheral tissues, hypothalamic inflammation is implicated as a cause (and not just a consequence) of both obesity and insulin resistance. By clarifying the mechanisms underlying these effects of hypothalamic inflammation, our studies will advance our understanding of obesity pathogenesis and its links to metabolic dysfunction, and identify new potential targets for the treatment of these conditions.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
Project #
Application #
Study Section
Integrative Physiology of Obesity and Diabetes Study Section (IPOD)
Program Officer
Abraham, Kristin M
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Washington
Internal Medicine/Medicine
Schools of Medicine
United States
Zip Code
van Praag, Henriette; Fleshner, Monika; Schwartz, Michael W et al. (2014) Exercise, energy intake, glucose homeostasis, and the brain. J Neurosci 34:15139-49
Morton, Gregory J; Kaiyala, Karl J; Foster-Schubert, Karen E et al. (2014) Carbohydrate feeding dissociates the postprandial FGF19 response from circulating bile acid levels in humans. J Clin Endocrinol Metab 99:E241-5
Gao, Yuanqing; Ottaway, Nickki; Schriever, Sonja C et al. (2014) Hormones and diet, but not body weight, control hypothalamic microglial activity. Glia 62:17-25
Berkseth, Kathryn E; Guyenet, Stephan J; Melhorn, Susan J et al. (2014) Hypothalamic gliosis associated with high-fat diet feeding is reversible in mice: a combined immunohistochemical and magnetic resonance imaging study. Endocrinology 155:2858-67
Rojas, J M; Schwartz, M W (2014) Control of hepatic glucose metabolism by islet and brain. Diabetes Obes Metab 16 Suppl 1:33-40
Morton, Gregory J; Meek, Thomas H; Schwartz, Michael W (2014) Neurobiology of food intake in health and disease. Nat Rev Neurosci 15:367-78
Berkseth, Kathryn E; Schur, Ellen; Schwartz, Michael W (2013) A role for natriuretic peptides in the central control of energy balance? Diabetes 62:1379-81
Thaler, Joshua P; Guyenet, Stephan J; Dorfman, Mauricio D et al. (2013) Hypothalamic inflammation: marker or mechanism of obesity pathogenesis? Diabetes 62:2629-34
Matsen, Miles E; Thaler, Joshua P; Wisse, Brent E et al. (2013) In uncontrolled diabetes, thyroid hormone and sympathetic activators induce thermogenesis without increasing glucose uptake in brown adipose tissue. Am J Physiol Endocrinol Metab 304:E734-46
Schwartz, Michael W; Baskin, Denis G (2013) Leptin and the brain: then and now. J Clin Invest 123:2344-5

Showing the most recent 10 out of 18 publications