Abstract
BackgroundThis feasibility study established an experimental protocol to evaluate brain activation patterns using fluorodeoxyglucose positron emission tomography ((18F)FDG-PET) during volume-induced voiding and isovolumetric bladder contractions in rats.MethodsFemale Sprague-Dawley rats were anaesthetized with urethane and underwent either volume-induced voiding cystometry or isovolumetric cystometry and simultaneous functional PET brain imaging after injection of (18F)FDG in the tail vein. Brain glucose metabolism in both groups was compared to their respective control conditions (empty bladder). Relative glucose metabolism images were anatomically standardized to Paxinos space and analysed voxel-wise using Statistical Parametric Mapping 12 (SPM12).ResultsDuring volume-induced voiding, glucose hypermetabolism was observed in the insular cortex while uptake was decreased in a cerebellar cluster and the dorsal midbrain. Relative glucose metabolism during isovolumetric bladder contractions increased in the insular and cingulate cortices and decreased in the cerebellum.ConclusionsOur findings demonstrate that volume-induced voiding as well as isovolumetric bladder contractions in rats provokes changes in brain metabolism, including activation of the insular and cingulate cortices, which is consistent with their role in the mapping of bladder afferent activity. These findings are in line with human studies. Our results provide a basis for further research into the brain control of the lower urinary tract in small laboratory animals.
Highlights
This feasibility study established an experimental protocol to evaluate brain activation patterns using fluorodeoxyglucose positron emission tomography ((18F)FDG-PET) during volume-induced voiding and isovolumetric bladder contractions in rats
Since technological advancements have made it possible to study the supraspinal control of the bladder and urethra using PET and functional magnetic resonance imaging (fMRI), increasing interest has been focused on the brain control of the lower urinary tract (LUT) and its relationship with lower urinary tract dysfunction (LUTd)
Our findings are complementary with previous neuroanatomical and electrophysiological studies and human and rat brain imaging studies [7, 8, 19, 26]. In this feasibility study, we show that (18F)FDG-PET brain imaging is a valuable technique to study the supraspinal control of the LUT in rats
Summary
This feasibility study established an experimental protocol to evaluate brain activation patterns using fluorodeoxyglucose positron emission tomography ((18F)FDG-PET) during volume-induced voiding and isovolumetric bladder contractions in rats. Storage of urine and micturition are controlled by a complex neural circuitry, located in the brain, spinal cord and peripheral ganglia and nerves [1]. It has become clear that the brain plays a crucial role in normal voiding control and is involved in lower urinary tract dysfunction (LUTd). The brain does not merely initiate micturition by activating efferent signalling. The advent of brain imaging techniques such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) has encouraged research into the brain control of the bladder. Neuroanatomical and electrophysiological studies show that they play a role in the mapping of visceral
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