title: 3D analysis of synaptic vesicle density and distribution after acute foot-shock stress by using serial section transmission electron microscopy.
abstract: Behavioural stress has shown to strongly affect neurotransmission within the neocortex. In this study, we analysed the effect of an acute stress model on density and distribution of neurotransmitter-containing vesicles within medial prefrontal cortex. Serial section transmission electron microscopy was employed to compare two groups of male rats: (1) rats subjected to foot-shock stress and (2) rats with sham stress as control group. Two-dimensional (2D) density measures are common in microscopic images and are estimated by following a 2D path in-section. However, this method ignores the slant of the active zone and thickness of the section. In fact, the active zone is a surface in three-dimension (3D) and the 2D measures do not accurately reflect the geometric configuration unless the active zone is perpendicular to the sectioning angle. We investigated synaptic vesicle density as a function of distance from the active zone in 3D. We reconstructed a 3D dataset by estimating the thickness of all sections and by registering all the image sections into a common coordinate system. Finally, we estimated the density as the average number of vesicles per area and volume and modelled the synaptic vesicle distribution by fitting a one-dimensional parametrized distribution that took into account the location uncertainty due to section thickness. Our results showed a clear structural difference in synaptic vesicle density and distribution between stressed and control group with improved separation by 3D measures in comparison to the 2D measures. Our results showed that acute foot-shock stress exposure significantly affected both the spatial distribution and density of the synaptic vesicles within the presynaptic terminal.
authors.affiliation: Computer Science Department, University of Copenhagen, Copenhagen, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Khanmohammadi
authors.affiliation: Computer Science Department, University of Copenhagen, Copenhagen, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Darkner
authors.affiliation: Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
authors.forename: N
authors.initials: N
authors.lastname: Nava
authors.affiliation: Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
authors.forename: J R
authors.initials: JR
authors.lastname: Nyengaard
authors.affiliation: Pharmaceutical Research Center of Excellence, School of Pharmacy, North-West University, Potchefstroom, South Africa.
authors.forename: G
authors.initials: G
authors.lastname: Wegener
authors.affiliation: Laboratory of Neuropsychopharmacology and Functional Neurogenomics - Dipartimento di Scienze Farmacologiche e Biomolecolari and Center of Excellence on Neurodegenerative Diseases, Universita degli Studi di Milano, Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Popoli
authors.affiliation: Computer Science Department, University of Copenhagen, Copenhagen, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Sporring
mesh_terms: D000818:Animals; D001699:Biometry / Q000379:methods*; D004195:Disease Models, Animal; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D046529:Microscopy, Electron, Transmission / Q000379:methods*; D017397:Prefrontal Cortex / Q000473:pathology*; D051381:Rats; D013315:Stress, Psychological; D013572:Synaptic Vesicles / Q000648:ultrastructure*
keywords: Acute foot-shock stress; distribution modelling; image registration; serial section transmission electron microscopy; specimen thickness estimation; synaptic vesicle density