What question did this study set out to answer?

This study aims to develop a machine learning approach to quantify pain-related behaviors in chlorine-exposed rats.

May 20, 2026American Journal of Respiratory and Critical Care Medicine0 citations

B30-15 Evaluation of Pain and Physical Discomfort in Chlorine Exposed Rats Using a Machine Learning Based Measurement Approach

GJG JadhavUniversity of Alabama at Birmingham SGS GuptaUniversity of Alabama at Birmingham WNW NasserUniversity of Alabama at Birmingham

Key Points

This study aims to develop a machine learning approach to quantify pain-related behaviors in chlorine-exposed rats.
Employed machine learning with DeepLabCut to analyze facial landmarks in video recordings of rats.
Quantified eyelid distance and palpebral fissure width as measures of orbital tightening.
Administered buprenorphine to evaluate its analgesic effect on chlorine-induced discomfort.
Significant reduction in eyelid distance and palpebral fissure width in chlorine-exposed rats (p<0.05).
Buprenorphine administration significantly reduced orbital tightening effects caused by chlorine exposure.
Developed a quantitative grimace scale that enables objective pain assessment in preclinical settings.

Abstract

Abstract Rationale Inhalation of noxious chemicals like chlorine induces extreme distress, pain, and irritation of the exposed individual, yet methods to evaluate the pain-related behavioral response are absent. It is also unknown whether analgesics can be used to alleviate pain and physical discomfort induced by inhalation of noxious chemicals. The grimace scale (GS), which evaluates facial expression features such as orbital tightening (OT), serves as a valuable indicator for pain and distress in animals. However, conventional GS approaches are labor-intensive, prone to subjectivity, and lack quantitative precision. Methods In this study, we employed machine learning with DeepLabCut to annotate key facial landmarks in video recordings of rats exposed to chlorine. Focusing on the superior and inferior eyelid margins, as well as the medial and lateral canthi, we quantified eyelid distance and palpebral fissure width as measures of OT. Rigorous inclusion and exclusion criteria for annotated images were established to ensure accurate and reproducible quantification. We administered an opioid drug i.e. buprenorphine to assess its analgesic effect, and we validated quantitative grimace scale (qGS) in rats subjected to chlorine gas exposure. Results With the help of sheltering tube method, we observed a significant reduction in eyelid distance and palpebral fissure width in chlorine exposed rats compared to baseline control animals not exposed to nociceptive stimuli. Administration of an opioid analgesic buprenorphine significantly reduced the orbital tightening caused by chlorine as measured by this method. Conclusions This study establishes a robust, quantitative method for assessing orbital tightening in chlorine exposed rats using DeepLabCut, offering a scalable and objective tool for assessing pain induced by inhalation of noxious chemicals in preclinical research. This study also suggests that opioids can alleviate pain and physical discomfort induced by inhalation of noxious chemicals, providing a new therapeutic strategy for managing the respiratory hazard of noxious chemicals. This abstract is funded by: National Institutes of Health Office of the Director (NIH OD), U01ES033263

Ask AI

Helpful

Bookmark

View Full Paper