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. 2023 Jan 26;24(3):2422.
doi: 10.3390/ijms24032422.

Rodent Animal Models of Endometriosis-Associated Pain: Unmet Needs and Resources Available for Improving Translational Research in Endometriosis

Miguel A Tejada  1 , Carles Antunez  1 , Paulina Nunez-Badinez  2 , Bianca De Leo  3 , Philippa T Saunders  4 , Katy Vincent  5 , Antonio Cano  1   6 , Jens Nagel  2 , Raul Gomez  1   7
Affiliations

Rodent Animal Models of Endometriosis-Associated Pain: Unmet Needs and Resources Available for Improving Translational Research in Endometriosis

Miguel A Tejada et al. Int J Mol Sci. .

Abstract

Chronic pain induced by endometriosis is a maladaptive pain experienced by half of women with this disease. The lack of pharmacological treatments suitable for the long-term relief of endometriosis-associated pain, without an impact on fertility, remains an urgent unmet need. Progress has been slowed by the absence of a reproducible rodent endometriosis model that fully replicates human physiopathological characteristics, including pain symptoms. Although pain assessment in rodents is a complicated task requiring qualified researchers, the choice of the behavioral test is no less important, since selecting inappropriate tests can cause erroneous data. Pain is usually measured with reflex tests in which hypersensitivity is evaluated by applying a noxious stimulus, yet this ignores the associated emotional component that could be evaluated via non-reflex tests. We conducted a systematic review of endometriosis models used in rodents and the number of them that studied pain. The type of behavioral test used was also analyzed and classified according to reflex and non-reflex tests. Finally, we determined the most used reflex tests for the study of endometriosis-induced pain and the main non-reflex behavioral tests utilized in visceral pain that can be extrapolated to the study of endometriosis and complement traditional reflex tests.

Keywords: endometriosis models; pain; reflex and non-reflex test.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flowchart of manuscript selection. The left column represents the total number of articles that studied endometriosis in rodents, while the right column shows the total number of articles that studied pain in rodent models of endometriosis.
Figure 2
Figure 2
Endometriosis models in rodents. Schematic representation of homologous (A) and heterologous (B) endometriosis models. (C) Percentage of articles reporting homologous vs. heterologous disease induction in these two main models of endometriosis from 931 papers reviewed.
Figure 3
Figure 3
Preclinical model of endometriosis and pain. (A) Number of research articles that evaluated pain compared to all articles studying endometriosis in rodents. (B) Percentage of research articles that evaluated endometriosis-associated pain using reflex vs. non-reflex tests.
Figure 4
Figure 4
Behavioral tests used to assess endometriosis pain. Most frequent types of reflex (A) and non-reflex (B) tests used for evaluation of endometriosis-induced pain in rodent models.
See this image and copyright information in PMC

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