title: Long-Term Consumption of High-Fat Diet in Rats: Effects on Microglial and Astrocytic Morphology and Neuronal Nitric Oxide Synthase Expression.
abstract: Obesity in humans is associated with cognitive decline and elevated risk of neurodegenerative diseases of old age. Variations of high-fat diet are often used to model these effects in animal studies. However, we previously reported improvements in markers of memory and learning, as well as larger hippocampi and higher metabolite concentrations in Wistar rats fed high-fat, high-carbohydrate diet (HFCD, 60 % energy from fat, 28 % from carbohydrates) for 1 year; this diet leads to mild ketonemia (Setkowicz et al. in PLoS One 10:e0139987, 2015). In the present study, we follow up on this cohort to assess glial morphology and expression of markers related to gliosis. Twenty-five male Wistar rats were kept on HFCD and twenty-five on normal chow. At 12 months of age, the animals were sacrificed and processed for immunohistochemical staining for astrocytic (glial fibrillary acidic protein), microglial (Iba1), and neuronal (neuronal nitric oxide synthetase, nNOS) markers in the hippocampus. We have found changes in immunopositive area fraction and cellular complexity, as studied by a simplified Sholl procedure. To our knowledge, this study is the first to apply this methodology to the study of glial cells in HFCD animals. GFAP and Iba1 immunoreactive area fraction in the hippocampi of HFCD-fed rats were decreased, while the mean number of intersections (an indirect measure of cell complexity) was decreased in GFAP-positive astrocytes, but not in Iba1-expressing microglia. At the same time, nNOS expression was lowered after HFCD in both the cortex and the hippocampus.
authors.affiliation: Department of Neuroanatomy, Jagiellonian University, Gronostajowa 9, 30-387, Kraków, Poland. kinga.gzielo@uj.edu.pl.
authors.forename: Kinga
authors.initials: K
authors.lastname: Gzielo
authors.affiliation: Department of Neuroanatomy, Jagiellonian University, Gronostajowa 9, 30-387, Kraków, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Kielbinski
authors.affiliation: Department of Neuroanatomy, Jagiellonian University, Gronostajowa 9, 30-387, Kraków, Poland.
authors.forename: Jakub
authors.initials: J
authors.lastname: Ploszaj
authors.affiliation: Department of Neuroanatomy, Jagiellonian University, Gronostajowa 9, 30-387, Kraków, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Janeczko
authors.affiliation: Military Institute of Aviation Medicine, Krasinskiego 54, 01-755, Warsaw, Poland.
authors.forename: Stefan P
authors.initials: SP
authors.lastname: Gazdzinski
authors.affiliation: Department of Neuroanatomy, Jagiellonian University, Gronostajowa 9, 30-387, Kraków, Poland.
authors.forename: Zuzanna
authors.initials: Z
authors.lastname: Setkowicz
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000201:enzymology*; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002452:Cell Count; D048430:Cell Shape; D059305:Diet, High-Fat; D004797:Enzyme-Linked Immunosorbent Assay; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism; D017628:Microglia / Q000166:cytology* / Q000201:enzymology*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism*; D017208:Rats, Wistar
chemical_list: C100745:Aif1 protein, rat; D002135:Calcium-Binding Proteins; D005904:Glial Fibrillary Acidic Protein; D008840:Microfilament Proteins; D052248:Nitric Oxide Synthase Type I
keywords: Astrocyte; High-fat diet; Hippocampus; Microglia; Sholl analysis; nNOS