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Harris A.P.,University Center for Cardiovascular Science | Harris A.P.,University of Edinburgh | Lennen R.J.,University Center for Cardiovascular Science | Brydges N.M.,University of Cardiff | And 12 more authors.
Genes, Brain and Behavior | Year: 2016

Brain-derived neurotrophic factor (BDNF) signaling is implicated in the etiology of many psychiatric disorders associated with altered emotional processing. Altered peripheral (plasma) BDNF levels have been proposed as a biomarker for neuropsychiatric disease risk in humans. However, the relationship between peripheral and central BDNF levels and emotional brain activation is unknown. We used heterozygous BDNF knockdown rats (BDNF+/-) to examine the effects of genetic variation in the BDNF gene on peripheral and central BDNF levels and emotional brain activation as assessed by awake functional magnetic resonance imaging (fMRI). BDNF+/- and control rats were trained to associate a flashing light (conditioned stimulus; CS) with foot-shock, and brain activation in response to the CS was measured 24h later in awake rats using fMRI. Central and peripheral BDNF levels were decreased in BDNF+/- rats compared with control rats. Activation of fear circuitry (amygdala, periaqueductal gray, granular insular) was seen in control animals; however, activation of this circuitry was absent in BDNF+/- animals. Behavioral experiments confirmed impaired conditioned fear responses in BDNF+/- rats, despite intact innate fear responses. These data confirm a positive correlation [r=0.86, 95% confidence interval (0.55, 0.96); P=0.0004] between peripheral and central BDNF levels and indicate a functional relationship between BDNF levels and emotional brain activation as assessed by fMRI. The results demonstrate the use of rodent fMRI as a sensitive tool for measuring brain function in preclinical translational studies using genetically modified rats and support the use of peripheral BDNF as a biomarker of central affective processing. BDNF+/- rats exhibit impaired amygdala activation during a learned fear-associated task using awake functional magnetic resonance imaging. © 2016 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society. Source

Tura O.,University of Edinburgh | Skinner E.M.,University of Edinburgh | Barclay R.,University of Edinburgh | Barclay R.,University Center for Cardiovascular Science | And 10 more authors.
Stem Cells | Year: 2013

A decade of research has sought to identify circulating endothelial progenitor cells (EPC) in order to harness their potential for cardiovascular regeneration. Endothelial outgrowth cells (EOC) most closely fulfil the criteria for an EPC, but their origin remains obscure. Our aim was to identify the source and precursor of EOC and to assess their regenerative potential compared to mature endothelial cells. EOC are readily isolated from umbilical cord blood (6/6 donors) and peripheral blood mononuclear cells (4/6 donors) but not from bone marrow (0/6) or peripheral blood following mobilization with granulocyte-colony stimulating factor (0/6 donors). Enrichment and depletion of blood mononuclear cells demonstrated that EOC are confined to the CD341CD1332CD1461 cell fraction. EOC derived from blood mononuclear cells are indistinguishable from mature human umbilical vein endothelial cells (HUVEC) by morphology, surface antigen expression, immunohistochemistry, real-time polymerase chain reaction, proliferation, and functional assessments. In a subcutaneous sponge model of angiogenesis, both EOC and HUVEC contribute to de novo blood vessel formation giving rise to a similar number of vessels (7.0 6 2.7 vs. 6.6 6 3.7 vessels, respectively, n 5 9). Bone marrow-derived outgrowth cells isolated under the same conditions expressed mesenchymal markers rather than endothelial cell markers and did not contribute to blood vessels in vivo. In this article, we confirm that EOC arise from CD341CD1332CD1461 mononuclear cells and are similar, if not identical, to mature endothelial cells. Our findings suggest that EOC do not arise from bone marrow and challenge the concept of a bone marrowderived circulating precursor for endothelial cells. © 2012 AlphaMed Press. Source

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