Effects of gender and gonadal hormones on nociceptive responses to intraplantar carrageenan in the rat

The effects of gender and gonadal hormones on nociceptive responses to intraplantar carrageenan in the rat were investigated. A plantar analgesic meter was used to measure carrageenan-induced changes in paw withdrawal latency (PWL) values, and von Frey monofilaments were used to assess changes in paw withdrawal threshold (PWT) values in response to tactile-evoked (mechanical) stimuli. The data revealed that PWL values were significantly greater in gonadally-intact females than in gonadally-intact males, and this response was abolished by surgical gonadectomies. Gonadally-intact as well as gonadectomized male and female rats also exhibited significant carrageenan-induced decreases in PWT, but neither sex- nor gonadectomy-related differences were detected in the development of mechanical allodynia. These findings demonstrate that intraplantar carrageenan induces nociceptive behaviors in rats that are differentially affected by sex and gonadal hormones. (C) 2003 Published by Elsevier Ireland Ltd.