Evaluation of the nociceptive threshold and inflammatory markers in rats after induction of pulmonary emphysema by elastase in the phasic, inflammatory and neuropathic pain models

HIGHLIGHTS

This is a study about a disease that is on the rise in Brazil and in the world. It is estimated that in Brazil about 30 thousand deaths/year occur due to chronic obstructive pulmonary disease (COPD), being the fifth leading cause of death.

Animals with COPD induced by tracheal elastase instillation have elevated levels of inflammatory markers.

Animals with COPD show altered responses to noxious stimuli, suggesting influence of inflammatory markers on nociceptive perception.

ABSTRACT

BACKGROUND AND OBJECTIVES:

Chronic obstructive pulmonary disease (COPD) is characterized by airflow obstruction, although it compromises the lungs, it also produces significant systemic consequences. The objective of this study was to analyze the relationship between pro-inflammatory cytokines and nociceptive threshold in rats with porcine pancreatic elastase-induced COPD.

METHODS

144 animals were randomly distributed into 3 different models: nociceptive phasic pain at tail-flick test (TF), inflammatory pain in the Freund’s complete adjuvant model (CFA) and neuropathic pain in the sciatic nerve constriction model (CCI). 21 days after tracheal instillation of elastase the COPD was established, and the nociceptive threshold was evaluated at different times.

RESULTS:

The animals with COPD in TF had a shorter latency time and higher levels of IL-1b, IL-6 and TNF-alpha cytokines. In the CFA and CCI model, the animals with COPD showed an increase in the mechanical hyperalgesia and the levels of IL-1b, IL-6 and TNF-alpha were greater in plasma up to 24 hours.

CONCLUSION:

Animals with COPD have higher levels of pro-inflammatory cytokines and reduced nociceptive thresholds, suggesting a relationship between COPD and increased nociception.

Keywords:
Chronic obstructive pulmonary disease; Pain; Pulmonary disease