Objective: To observe the distribution characters of Evans Blue (EB) exudation spots in the abdominal area in acute intestinal mucosal injury (AIMI) rats by using latitude and longitude grid counting and multivariate statistical analysis and to explore the feasibility of these methods.
Methods: Twenty-four SD rats were randomly divided into blank control, 7.5%, 10%, and 12.5% mustard oil groups (n＝6 rats in each group). The AIMI model was established by mustard oil enema, followed by injection of EB (0.1 mL/100g) into the tail vein. At 5, 10, 15, 20 and 25 h after EB injection, the rats under anesthesia were fixed in supine position for observing and photographing the abdominal subcutaneous EB exudation spots. The H．E. staining was used to observe histopathological changes of colonic mucosa. The longitude and latitude grids of the abdominal region were constructed (by taking the midpoint of the superior sternum as the origin) to determine the position of the blue spots. That the coordinate grids of the two regions can be connected geometrically is termed as "characteristic region". The data were processed by using multivariate statistical analysis.
Results: ① H．E. staining showed edema and inflammatory cell infiltration after colonic enema of different concentrations of mustard oil. ② Clustering analysis indicated that the distribution of exudation points in the "characteristic grid" had no temporal variation trend, and was not related with the concentration of mustard oil (P>0.05). ③ Factor analysis and contour analysis about the exudation spots of EB at 7.5% concentration showed that the "characteristic region Ⅱ" of different factors presented a tendency of time-dependent exudation, i．e. reduction of exudation degree along with time (P<0.05), and it is located near "Tianshu" acupoint. ④At 5 h after injection of EB, the 8 "characteristic regions" presented an EB-concentration-dependent tendency (reduction in exudation degree along with the increase of EB-concentration), among which the exudation degree of region C (near "Tianshu" acupoint) of the abdomen was higher (P<0.05).
Conclusion: The multivariate statistical analysis method can be used to identify the abdominal "characteristic regions" of exudation spots of EB in rats with AIMI, and the characteristic region has acupoint sensitization characteristics related to the time and severity of mucosal injury.
Keywords: Acupoint sensitization; Acute intestinal mucosal injury; Evans Blue exudation; Latitude and longitude grid counting method; Multivariate statistical analysis.