Reduced Cerebrovascular Reactivity and Increased Resting Cerebral Perfusion in Rats Exposed to a Cafeteria Diet
NEUROSCIENCE
Authors: Gomez-Smith, Mariana; Janik, Rafal; Adams, Conner; Lake, Evelyn M.; Thomason, Lynsie A. M.; Jeffers, Matthew S.; Stefanovic, Bojana; Corbett, Dale
Abstract
To better understand the effects of a diet high in fat, sugar, and sodium on cerebrovascular function, Sprague Dawley rats were chronically exposed to a Cafeteria diet. Resting cerebral perfusion and cerebrovascular reactivity was quantified using continuous arterial spin labeling (CASL) magnetic resonance imaging (MRI). In addition, structural changes to the cerebrovasculature and susceptibility to ischemic lesion were examined. Compared to control animals fed standard chow (SD), Cafeteria diet (CAF) rats exhibited increased resting brain perfusion in the hippocampus and reduced cerebrovascular reactivity in response to 10% inspired CO2 challenges in both the hippocampus and the neocortex. CAF rats switched to chow for one month (SWT) exhibited improved resting perfusion in the hippocampus as well as improved cerebrovascular reactivity in the neocortex. However, the diet switch did not correct cerebrovascular reactivity in the hippocampus. These changes were not accompanied by alterations in the structural integrity of the cerebral microvasculature, examined using rat endothelial cell antigen-1 (RECA-1) and immunoglobulin G (IgG) immunostaining. Also, the extent of tissue damage induced by endothelin-1 injection into sensorimotor cortex was not affected by the Cafeteria diet. These results demonstrate that short-term consumption of an ultra-processed diet reduces cerebrovascular reactivity. This effect persists after dietary normalization despite recovery of peripheral symptomatology. (C) 2017 IBRO. Published by Elsevier Ltd. All rights reserved.
Enzymatic digestion improves the purity of harvested cerebral microvessels
JOURNAL OF NEUROSCIENCE METHODS
Authors: Munikoti, Vikram V.; Hoang-Minh, Lan B.; Ormerod, Brandi K.
Abstract
The harvest of intact cerebral microvessel yields could permit the in vitro characterization of mechanisms that underlie numerous vascular-linked central nervous system (CNS) phenomena. Here, we test (1) the effect of mild enzyme digestion on microvessel purity and yield; and then (2) the effect of variable centrifugation and filtration methods on microvessel yields. The brains of female Sprague-Dawley rats (4 weeks-old: n = 38) were removed rapidly and homogenized. In Experiments 1 and 2, brain homogenates were incubated in DMEM or a solution of papain (2.5 U/ml), DNAse I (250 U/ml) and dispase II (1 U/ml) in DMEM for 15 min at 37 degrees C before microvessels were purified using differential (20% Ficoll) and then discontinuous (15/20% Dextran) centrifugation (@3500 x g) and collected with glass bead column filtration. Enzymatic digestion decreased microvessel yields (27 vs. 12k/g tissue; p = 0.053) but increased microvessel purity by decreasing adherent cells (p = 0.002), which included NF-L+ neurons (p < 0.05) and GFAP(+). astrocytes (p < 0.001) and astrocyte endfeet (p < 0.01). After one week in culture, >85% of harvested cells morphologically resembled microvessels and expressed the vascular proteins lectin and/or RECA-1. Finally, microvessels yields decreased when discontinuous centrifugation was omitted or nylon mesh filtration was employed. In summary, we found that digesting brain homogenates enzymatically could improve the purity of harvested microvessels that could be cultured for at least a week. (C) 2012 Elsevier B.V. All rights reserved.