Browsing by Subject "Mice"
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Item Antigen presenting cells In the retina(2010-10) Lehmann, UteThe presence and activity of dendritic cells (DC) in retina is controversial. This is in part due to the limited number of DC in the retina and the small number of reliable DC markers. In addition, functions ascribed to DC in other parts of the body are thought to be done by microglia in the central nervous system. CD11c is the cellular marker most associated with DC. In order to study the nature of retinal DC, transgenic mice that express green fluorescent protein (GFP) on the CD11c promoter were used to visualize, quantify, and characterize DC in both quiescent and injured retinas. In the quiescent retina it was found that compared to the number of neurons and microglial cells there were relatively few DC located in the nerve fiber layer and the outer plexiform layer. Upon retinal injury by either optic nerve crush or exposure to continuous bright light, the numbers of DC increased significantly and translocated to retinal layers associated with the injury. Surprisingly, the retinas of the eyes contralateral to the optic nerve crush also showed a significant increase in DC. The potential origin of the DC in retina was examined using a chimeric mouse paradigm. Most of the retinal DC were found to originate from circulating precursors, and a smaller number from a local progenitor cell population. This study suggests that retinal DC are a previously overlooked population, distinct from microglia, and may be important in the injury response and maintenance of homeostasis in the retina.Item Changes in endocannabinoid signaling contribute to the anti-hyperalgesic effect of URB597 in a murine model of persistent inflammation.(2011-09) Lindberg, Amy ElizabethModulation of endocannabinoid neurotransmission has a therapeutic benefit in the treatment of inflammatory pain. Studies in this thesis investigated endocannabinoid signaling in a murine model of persistent, peripheral inflammation. Specifically, the ability of URB597, an inhibitor of fatty acid amide hydroxylase (FAAH), which degrades the endogenous cannabinoid anandamide, to reduce mechanical hyperalgesia associated with inflammation was determined. The first study tested whether local injection of URB597 dose-dependently reduced mechanical hyperalgesia associated with persistent inflammation. Inflammation was induced by injection of Complete Freund's Adjuvant (CFA) in the hind paw of mice and mechanical hyperalgesia was determined using a series of von Frey filaments. The first part of the study resolved that local injection of URB597 dose-dependently reduced mechanical hyperalgesia associated with persistent inflammation and decreased mechanical sensitivity in naïve mice. However, injection of URB597 did not result in increased endocannabinoid content in the plantar skin ipsilateral to the injection as would be expected based on the known mechanism of action of URB597. The second and third studies investigated the effect of inflammation on levels of FAAH, endocannabinoids and cannabinoid (CB)-1 receptor in naïve and CFA-injected mice to understand the neurochemistry underlying the anti-hyperalgesic effect of URB597. Levels FAAH mRNA decreased and enzyme activity trended toward a decrease in the plantar skin of the inflamed hind paw compared to tissue from naïve mice, but inflammation did not alter level of anandamide in plantar skin ipsilateral to the injections. In contrast, an increase in FAAH mRNA was accompanied by a decrease in the level of anandamide in dorsal root ganglia (DRGs) ipsilateral to the inflamed hind paw compared to naïve mice. In addition, there is an upregulation of functional CB1 receptors in DRGs ipsilateral to the inflamed hind paw in CFA-injected mice compared to DRGs from naïve mice. Together, these data support a model in which reduced synthesis of AEA in the primary afferent neurons may contribute to the mechanical hyperalgesia associated with peripheral inflammation, and upregulation of CB1 receptors on the primary afferent neurons affected by inflammation may be a compensatory response to decreased basal activation of AEA.Item In Vivo Tumor Reduction in Mice(2014) Ronayne, Conor T.; Mereddy, Venkatram R.Item Principles of Computer Numerical Controlled Machining Applied to Small Research Animal Microsurgical Procedures(2017-12) Rynes, MathewThe palette of tools available for systems neuroscientists to measure and manipulate the brain during behavioral experiments has exploded in the last decade. Implementing these tools, from electrical to optical sensors require the removal of bone tissue without damage to the underlying brain tissue. This is typically a delicate procedure as the skulls of commonly used inbred mouse strains are very thin (~80-500 μm above the mice dorsal cortex). However, with increasing complexity, these microsurgical procedures have become art forms. It takes many months to become skilled at performing these operations. Automating some of the tissue removal processes would potentially enable more precise procedures to be performed. Here, we introduce the ‘Craniobot’, a microsurgery platform, assembled with off-the- shelf components, that combines automated skull surface profiling with a CNC milling machine to perform a variety of microsurgical procedures in mice. The Craniobot utilizes a low force contact sensor that can accurately measure the surface of the skull across the whole dorsal skull with a precision of 2.4 ± 8.5 µm and this information can be used to perform milling operations with comparable precision. We have used the Craniobot to perform skull thinning, small to large craniotomies, as well as drilling pilot holes for anchoring cranial implants. The system is implemented using open source and customizable machining practices, this approach can be expanded in the future to larger animal models, or for more complex procedures and a more comprehensive part of the pipeline of in vivo neuroscience.Item Sequences of cortical activation states encode search strategies during spatial navigation(2023-05) Rynes, MathewSuccessful goal-directed navigation requires an integration of multiple streams of sensory environments, incorporating those representations into goal-related plans, and actuating those goal-related plans. How this multi-sensory information is processed across the cortex during navigation is not well understood. To investigate this, we recorded cortex-wide calcium dynamics in Thy1-GCamp6f mice (n = 11) using the mini-mScope (Rynes*, Surinach* et al 2021), a head-mounted miniaturized microscope capable of mesoscale calcium imaging of large swathes of the dorsal cortex, in mice solving the Barnes maze. The Barnes maze consists of a single escape hole in the presence of mildly aversive sensory stimuli. Mice learned to successfully navigate to the escape hole predominantly using a random search strategy in early trials, progressing to serial search and spatial search strategies in later tests. A holistic view of the activity across the cortex during a rapid, ethologically relevant spatial learning task revealed neural states indicative of distinct sets of brain-wide circuits being recruited during navigation behaviors. Using an unsupervised algorithm, we clustered cortical activity via k-means clustering into sets of “states” characterized by instantaneous patterns of spatially distributed activity across the FOV of the cortex. We found 5-10 states in each mouse and 7 states across mice. This low-dimensional space allowed the discovery of search strategy-specific spatiotemporal sequences of activity. Trial initiation was marked by repeated macro timescale patterns of state activation with a prolonged duration of activation of states involving high calcium activity in the frontal regions of the cortex occurring shortly after trial initiation. This frontal cortex-activated state coincided with mice approaching the edge of the maze from the center and occurred reliably in nonrandom search strategies. These events were preceded by sequences of state transitions that were distinct for serial and spatial search strategies.