Effects of fluoxetine on changes of pain sensitivity in chronic stress model rats

• Published in: Neuroscience letters Vol. 651; pp. 16 - 20
• Main Authors: Lian, Yan-Na, Chang, Jin-Long, Lu, Qi, Wang, Yi, Zhang, Ying, Zhang, Feng-Min
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 09.06.2017
• Subjects: Animals; Antidepressive Agents, Second-Generation - administration & dosage; Disease Models, Animal; Fluoxetine - administration & dosage; Hyperalgesia; Hypoalgesia; Inflammation - complications; Male; Nociception - drug effects; Pain; Pain - complications; Pain - physiopathology; Pain - psychology; Pain Measurement; Pain Threshold - drug effects; Rats, Sprague-Dawley; Serotonin; Serotonin Uptake Inhibitors - administration & dosage; Stress; Stress, Psychological - complications; Stress, Psychological - physiopathology; Stress, Psychological - psychology; Pain; Serotonin; Hypoalgesia; Stress; Hyperalgesia
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2017.04.062

•Fluoxetine facilitates hypoalgesia in thermal and inflammatory pain and induced mechanical hyperalgesia.•Fluoxetine aggravates stress-induced analgesia on thermal and inflammatory pain but not on mechanical pain.•5-HT system may be involved in changes of pain sensitivity after chronic stress exposure. Exposure to stress could facilitate or inhibit pain responses (stress-induced hyperalgesia or hypoalgesia, respectively). Fluoxetine is a selective serotonin (5-HT) reuptake inhibitor antidepressant. There have been contradictory reports on whether fluoxetine produces antinociceptive effects. The purpose of this study was to elucidate changes in pain sensitivity after chronic stress exposure, and the effects of fluoxetine on these changes. We measured thermal, mechanical, and formalin-induced acute and inflammatory pain by using the tail-flick, von Frey, and formalin tests respectively. The results showed that rats exposed to chronic stress exhibited thermal and formalin-induced acute and inflammatory hypoalgesia and transient mechanical hyperalgesia. Furthermore, fluoxetine promoted hypoalgesia in thermal and inflammatory pain and induced mechanical hyperalgesia. Our results indicate that the 5-HT system could be involved in hypoalgesia of thermal and inflammatory pain and induce transient mechanical hyperalgesia after stress exposure.