ABSTRACT
Introduction: Adolescence is an important stage of maturation for various brain structures. It is during this time therefore that the brain may be more vulnerable to environmental factors such as diet that may influence mood and memory. Diets high in fat and sugar (termed a cafeteria diet) during adolescence have been shown to negatively impact upon cognitive performance, which may be reversed by switching to a standard diet during adulthood. Consumption of a cafeteria diet increases both peripheral and central levels of interleukin-1β (IL-1β), a pro-inflammatory cytokine which is also implicated in cognitive impairment during the ageing process. It is unknown whether adolescent exposure to a cafeteria diet potentiates the negative effects of IL-1β on cognitive function during adulthood.
Methods: Male Sprague-Dawley rats consumed a cafeteria diet during adolescence after which time they received a lentivirus injection in the hippocampus to induce chronic low-grade overexpression of IL-1β. After viral integration, metabolic parameters, circulating and central pro-inflammatory cytokine levels, and cognitive behaviours were assessed.
Results: Our data demonstrate that rats fed the cafeteria diet exhibit metabolic dysregulations in adulthood, which were concomitant with low-grade peripheral and central inflammation. Overexpression of hippocampal IL-1β in adulthood impaired spatial working memory. However, adolescent exposure to a cafeteria diet, combined with or without hippocampal IL-1β in adulthood did not induce any lasting cognitive deficits when the diet was replaced with a standard diet in adulthood. Discussion: These data demonstrate that cafeteria diet consumption during adolescence induces metabolic and inflammatory changes, but not behavioural changes in adulthood.
Acknowledgements
We thank Dr. Gerard Moloney, Suzanne Crotty and Tara Foley for technical assistance.
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No potential conflict of interest was reported by the author(s).
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Notes on contributors
Sarah Nicolas
Sarah Nicolas is a Postdoctoral researcher in the Dept. of Anatomy & Neuroscience, University College Cork, Ireland. Her research focuses on how lifestyle factors such as exercise and diet interact with the gut-brain axis to promote brain health across life.
Ciarán S. Ó. Léime
Ciarán S. Ó. Léime obtained his PhD in 2017 in the Dept. of Anatomy & Neuroscience, University College Cork, Ireland. He now works as a technical process lead within the medical device industry in Ireland.
Alan E. Hoban
Alan E. Hoban is a senior technical officer in the School of Biomolecular and Biomedical Science, University College Dublin where he also teaches in the Neuroscience and Pharmacology departments. His research to date has focused primarily on the role of the gut microbiota on brain and behaviour. In particular, his main interest is how the gut microbiota influences central nervous system myelination.
Cara M. Hueston
Cara M. Hueston obtained her PhD in Behavioral Neuroscience from Binghamton University where she studied the impact of hormones on neuroinflammation. She now works as a Pre-Clinical Research Support Officer for APC Microbiome Ireland where she works on numerous projects exploring the role of the microbiome in heath and disease.
John F. Cryan
John F. Cryan is Professor and Chair, Dept. of Anatomy & Neuroscience, University College Cork, Ireland and is also a Principal Investigator at APC Microbiome Ireland. Prof. Cryan’s current research is focused on understanding the interaction between brain, gut & microbiome and how it applies to stress, psychiatric and immune-related disorders at key time-windows across the lifespan.
Yvonne M. Nolan
Yvonne M. Nolan is a Senior Lecturer, Funded Investigator in APC Microbiome Ireland and Science Foundation Ireland Investigator in University College Cork, Ireland. She leads a research team investigating how lifestyle factors such as exercise, diet and stress throughout the life course impact upon memory and mood. The role of hippocampal neurogenesis, inflammation and the gut microbiome in mediating these effects is the mechanistic focus of her research.