Authors
Abstract
Introduction: It is well recognized that gender and race differences play a role in pain sensitivity, pain perception, response to analgesic drug and prevalence of certain chronic pain disorders. In this study investigated gender and strain-related differences in the effect of food deprivation on formalin induced nociceptive behaviors in rats.
Methods: This study was done in Qazvin University of Medical Sciences 8 groups of rats (220-300gr). Groups 1 and 2: Effect formalin-induced nociceptive behaviours in male and female Sprague-Dawley rats. Groups 3 and 4: Effect formalin-induced nociceptive behaviours in male and female Wistar rats. Groups 5 and 6: Effect of food deprivation on formalin-induced nociceptive behaviours in male and female Sprague-Dawley rats. Groups 7 and 8: Effect of food deprivation on formalin-induced nociceptive behaviours in male and female Wistar rats. Food was withdrawn 48 h (short-term food deprivation) prior to performing the formalin test, but water continued to be available ad libitum. The formalin (50 μL, 2%) was injected into hind plantar paw. Immediately after the formalin injection, pain behaviors recorded for 90 minutes.
Results: There is significant difference between male and female control Sprague-Dawley rats during phase 2B. Although interphase in male rats is more than female ones, but the phase 2B in female rats is more than male ones and phase 2 finished with delay in Sprague-Dawley race. There are no significant differences between male and female control Wistar rats during formalin test. Following 48-h food deprivation, male and female rats exhibited enhanced nociceptive behaviors in response to formalin injection during phase 1, the interphase, phase 2. In contrast, 48 h food deprivation had significant effect on formalin-evoked nociceptive behaviors in phase 2B for male Wistar and in interphase and phase 2B for female rats.
Conclusion: The present study demonstrates the existence of gender and strain-related differences in rats in the development and maintenance of inflammatory hyperalgesia. Also, these differences observed following food deprivation.
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