A NEW way to look at an old test: Transforming the void spot assay (VSA) into a diagnostic tool

摘要

Lower urinary tract (LUT) pathologies present in almost all cases with the clinical manifestations of altered voiding behavior, symptoms that include frequency, urgency, nocturia, incontinence, and dribbling. To study urinary pathologies using mouse models, as well as the efficacy of a given treatment or intervention, the voluntary voiding behavior of mice must be addressed. The void spot assay (VSA) is an increasingly common method used in the field that is simple, inexpensive, and noninvasive (Chen et al., 2017; Sugino et al., 2008). The first VSA ever performed—to the best of the author's knowledge—is the one reported by Desjardins et al. (1973), where the investigators studied the urination patterns of male mice according to their social rank. In this study, the investigators placed a filter paper on the floor of a mouse cage and examined the urine marks deposited using ultraviolet light after an overnight test. Since then, researchers have used this approach, with slight modifications, to assess the voiding behavior of mice under a wide variety of conditions and disease models (Chen et al., 2017; Keil et al., 2016; Liu et al., 2019; Sugino et al., 2008). Although technically simple, proper analysis and correct interpretation of the results are not trivial (Bjorling et al., 2015; Wegner et al., 2018). Most of the researchers in the field have focused their attention on parameters that include the total number of void spots in a specific time window (frequency of urination), the total size and the frequency distribution of the size of the void spots, and the region where the urine is deposited (corners versus center) which may be related to urinary continence, and compared these parameters between a control and a treated or disease group (Liu et al., 2019; Rajandram et al., 2016; Sugino et al., 2008).