Research Spotlights October 2017

Research Spotlights October 2017

High-fat diet increases pain behaviors in rats regardless of obesity status

Poor diet, not obesity, appears to increase pain behavior in rats according to a new study funded by NINDS, NIAMS, and NIDDK.  The study revealed a high-fat diet increased pain behavior in two rat models of local inflammation regardless of obesity induced changes in weight and body fat.

Long-Evans and Sprague-Dawley rats were fed either a low-fat or high-fat diet for 6 weeks, after which one of two pain models, dorsal root ganglion (DRG) inflammation or complete Freund’s adjuvant (CFA) paw inflammation, was implemented.  Pain behaviors and paw swelling were measured at baseline and continued for 2 weeks after pain model implementation.  Behaviors included mechanical and cold allodynia (i.e., pain produced by normally non-painful stimuli) and spontaneous guarding behavior.

Both Long-Evans and Sprague-Dawley rats fed a high-fat diet prior to DRG inflammation displayed significant increases in guarding behavior and cold and mechanical allodynia.  In addition, CFA inflammation in rats fed a high-fat diet resulted in significantly greater paw swelling and mechanical and cold allodynia.  Interestingly, however, the high-fat diet only induced obesity in the Long-Evans rats suggesting the high-fat diet, not obesity, increased pain behavior.

Song Z, Xie W, Chen S, Strong JA, Print MS, Wang JI, Shareef AF, Ulrich-Lai YM, Zhang JM. 2017. High-fat diet increases pain behaviors in rats with or without obesity. Sci Rep 7(1):10350

Income, not healthy food access, drives cardiovascular risk in food desert residents

A new study funded by NHLBI reveals that increased cardiovascular disease (CVD) risk is related to a person’s individual income over and above the income level of their neighborhood or the availability of healthy foods in their neighborhood.

The study included 1,421 metropolitan Atlanta residents who participated in the Eliminate Health Disparities study or the Predictive Health study. Researchers analyzed participants’ demographic data, metabolic profiles, oxidative stress markers, arterial stiffness, and high-sensitivity C-reactive protein (hs-CRP) levels. Results revealed food desert residents had a significantly higher prevalence of hypertension, smoking rates, body mass index, fasting glucose, CVD risk, and hs-CRP levels than those not residing in a food desert.

Income, however, was found to predict CVD risk independent of access to healthy foods.  Among low income individuals, there was no significant difference in CVD risk between those residing in a food desert compared to those with access to healthy foods in their neighborhood. CVD risk was also lower in high income individuals living in low income areas or areas with poor food access when compared to lower income residents of similar areas. These findings provide insights into the socioeconomic factors contributing to CVD risk in urban setting and suggest that factors associated with an individual’s income may be more influential in developing CVD than the income and healthy food access of the neighborhoods in which they live.

Kelli HM, Hammadah M, Ahmed H, Ko YA, Samman-Tahhan A, Awad M, Patel K, Mohammed K, Sperling LS, Pemu P, Vaccarino V, Lewis T, Taylor H, Martin G, Gibbons GH, Quyyumi AA. 2017. Association between living in food deserts and cardiovascular risk. Circa Cardiovasc Quall Outcomes 10(9): e003532.

Adolescent victimization exacerbates the influence of loneliness on sleep quality in young adults

Lack of social connectedness predicts poor health outcomes in a dose-response manner. Consequently, people who endure chronic loneliness early in life may endure poorer health over time. This is the focus of a new NICHD-funded study suggesting that self-reported loneliness or childhood maltreatment is associated with overall poorer sleep quality and daytime dysfunction in young adults.

Researchers used data from the Environmental Risk Longitudinal Twin Study, a cohort of 2,232 twins born in England and Wales in 1994 -1995. The investigators used reliable and valid items to measure loneliness and sleep and controlled for covariates including social isolation, psychopathology, employment status, and parenting an infant. The authors examined twin differences to control for unmeasured genetic and shared environmental factors.

The study found that self-reported feelings of loneliness were associated with poorer sleep quality and daytime dysfunction. The association between loneliness and poor sleep quality was significantly greater in youth who experienced childhood maltreatment or victimization during adolescence. These findings suggest that childhood experiences of loneliness and mistreatment may have long-term and enduring impacts on sleep quality.

Matthews T, Danese A, Gregory AM, Caspi A, Moffitt TE, Arseneault L. 2017. Sleeping with one eye open: Loneliness and sleep quality in young adults. Psychol Med 47(12): 2177-86.

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