GutMap: A New Interface for Analysing Regional Motility Patterns in ex vivo Mouse Gastrointestinal Preparations

Abstract

Different regions of the gastrointestinal tract have specific functions and thus distinct motility patterns. Motility is primarily regulated by the enteric nervous system (ENS), an intrinsic network of neurons located within the gut wall. Under physiological conditions, the ENS is influenced by the central nervous system (CNS). However, by using ex vivo organ bath experiments, ENS regulation of gut motility can also be studied in the absence of CNS influences. The current technique enables the characterisation of small intestinal, caecal, and colonic motility patterns using an ex vivo organ bath and video imaging protocol. This approach is combined with the novel edge detection script GutMap, available in MATLAB, that functions across Windows and Mac platforms. Dissected intestinal segments are cannulated in an organ bath containing physiological saline with a camera mounted overhead. Video recordings of gut contractions are then converted to spatiotemporal heatmaps and analysed using the GutMap software interface. Using data analysed from the heatmaps, parameters of contractile patterns (including contraction propagation frequency and velocity as well as gut diameter) at baseline and in the presence of drugs/treatments/genetic mutations can be compared. Here, we studied motility patterns of female mice at baseline and in the presence of a nitric oxide synthase inhibitor ( N ω-Nitro-L-arginine; NOLA) (nitric oxide being the main inhibitory neurotransmitter of gut motility) to showcase the application of GutMap. This technique is suitable for application to a broad range of animal models of clinical disorders to understand underlying biological pathways contributing to gastrointestinal dysfunction. Key features • Enhanced video imaging analysis of gut contractility in rodents using a novel software interface. • New edge detection algorithm to accurately contour curvatures of the gastrointestinal tract. • Allows for output of high-resolution spatiotemporal heatmaps across Windows and Mac platforms. • Edge detection and analysis method makes motility measurements accessible in different gut regions including the caecum and stomach.

Faster Gastrointestinal Transit, Reduced Small Intestinal Smooth Muscle Tone and Dysmotility in the Nlgn3R451C Mouse Model of Autism

“…In this study, we compared regional gastrointestinal motility patterns in the small intestine using an enhanced software interface in MATLAB, including a novel edge detection algorithm for the video imaging of gut contractile activity in fresh tissue preparations [54]. Although the development of the software interface and optimization of experimental conditions (including the level of applied pressure to the lumen of the gastrointestinal tissue sample) improved our ability to record and analyse motility patterns in the mouse jejunum and ileum, the interpretation of these complex small intestinal motility patterns continues to be developed.…”

“…We identified that the level of applied intraluminal pressure is a critical element for the successful recordings of small intestinal motility patterns. This approach, combined with the development of enhanced edge detection software for analysis of the rodent gut contractions in ex vivo preparations [54], enabled a more accurate comparison of motility parameters across experimental groups.…”

“…In the ileum, however, the PCC duration was shorter and a corresponding increase in quiescence was also identified in Nlgn3 R451C mice (Figure 4E,F, Table 1). To characterise motility patterns in small intestines from wild-type and Nlgn3 R451C mice, we used the enhanced edge detection interface in MATLAB (GutMap, available on request Abo-Shaban et al, 2023 [54]). Specifically, we selected three anatomical locations (proximal, mid and distal) in each small intestinal preparation and measured changes in the gut width over a 15 min recording duration.…”

“…Spatiotemporal heatmaps in the colon and small intestine, respectively, were generated using in-house software (Scribble v2. 10 [53]) or the GutMap MATLAB software interface [54]. A subset of these datasets were analyzed using both Scribble v2.10 and GutMap and yielded identical results.…”