Dependency on sex and stimulus quality of nociceptive behavior in a conscious visceral pain rat model

• Published in: Neuroscience letters Vol. 746; p. 135667
• Main Authors: López-Gómez, L., López-Tofiño, Y., Abalo, R.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 16.02.2021
• Subjects: Animals; Colorectal sensitivity; Consciousness - physiology; Disease Models, Animal; Estrogens; Female; Male; Nociception - physiology; Pain Measurement - methods; Pain Measurement - psychology; Phasic stimulation; Physical Stimulation - adverse effects; Rats; Rats, Wistar; Sex; Sex Characteristics; Tonic stimulation; Visceral pain; Visceral Pain - physiopathology; Visceral Pain - psychology; OVX; Phasic stimulation; GI; Visceral pain; CRD; Tonic stimulation; Estrogens; Sex; IBS; Colorectal sensitivity
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2021.135667

•Sex and type of mechanical stimulation strongly influence visceral pain.•Responses to tonic stimuli are less intense compared to those to phasic stimuli.•Sex influences the responses to phasic but not to tonic stimulation.•Visceral pain behavior may depend on abdominal musculature composition features.•Estrogens modulate the different pathways activated by tonic and phasic stimuli. Visceral pain may be influenced by many factors. The aim of this study was to analyze the impact of sex and quality of intracolonic mechanical stimulus on the behavioral manifestations of visceral pain in a preclinical model. Male and female young adult Wistar rats were sedated, and a 5 cm long latex balloon was inserted into the colon. Sedation was reverted and behavior was recorded. The pressure of the intracolonic balloon was gradually increased using a sphygmomanometer. Visceral sensitivity was measured as abdominal contractions in response to mechanical intracolonic stimulation. Two different types of stimulation were used: tonic and phasic. Phasic stimulation consisted of repeating several times (3x) the same short stimulus (20 s) within a 5 min interval allowing a 1 min break between individual stimuli. For tonic stimulation the stimulus was maintained throughout the whole 5 min interval. Both phasic and tonic stimulation produced a pressure-dependent increase of abdominal contractions. The abdominal response was more intense under phasic than under tonic stimulation, but with differences depending on the sex of the animals: females exhibited more contractions than males and of similar duration at all pressures, whereas duration of contractions pressure-dependently increased in males. The duration of tonically stimulated contractions was lower and not sex- or pressure-dependent. In the rat, responses to colonic distension depend on the quality of the stimulus, which also produces sex-dependent differences that must be taken into account in the development of models of pathology and visceral pain treatments.