The Unmet Needs for Studying Chronic Pelvic/Visceral Pain Using Animal Models

Abstract

The different definitions of chronic pelvic/visceral pain used by international societies have changed over the years. These differences have a great impact on the way researchers study chronic pelvic/visceral pain. Recently, the role of systemic changes, including the role of the central nervous system, in the perpetuation and chronification of pelvic/visceral pain has gained weight. Consequently, researchers are using animal models that resemble those systemic changes rather than using models that are organ- or tissue-specific. In this review, we discuss the advantages and disadvantages of using bladder-centric and systemic models, enumerating some of the central nervous system changes and pain-related behaviors occurring in each model. We also present some drawbacks when using animal models and pain-related behavior tests and raise questions about possible, yet to be demonstrated, investigator-related bias. We also suggest new approaches to study chronic pelvic/visceral pain by refining existing animal models or using new ones.

Keywords: animal model; chronic primary bladder pain syndrome; endometriosis pain syndrome.

Figure 1

Illustrative image of pain mapping in women with endometriosis (grey dots, adapted from [12]) and CPBPS (black dots, adapted from [11]), regardless of the reported intensity of the pain.

Figure 2

Possible refinement strategies to improve the study of chronic pelvic/visceral pain using animal models or animals that naturally develop EPS or CPBPS.