Abstract
Sex differences in the response to nociceptive stimuli have long been recognized in many species. For example, in rats, females are more sensitive to formalin-induced nociceptive stimuli than males, as revealed by behavioral test. However, the neural mechanism for sex differences in the response to nociceptive stimuli was still unclear. In the previous study, we showed that females were more sensitive to formalin-induced nociceptive stimuli than males, as revealed by behavioral test. We looked for a possible sex difference in the response of the brain to formalin-induced nociceptive stimuli by checking the expression of phosphorylated cAMP response element-binding protein (pCREB) as a marker of neural activity. We found that, in the bed nucleus of the stria terminalis lateral subdivision (BSTL), the number of cells expressing pCREB was increased 5-10 min after formalin injection in female rats but not in male rats. In the present study, we examined the function of CREB in the BSTL. We found that the expression of a dominant negative form of CREB (mCREB) using adenovirus vector, significantly attenuated the response to formalin only in females but not in males, suggesting that CREB in the BSTL play a role for controlling pain-related behavior only in females. [J Physiol Sci. 2008;58 Suppl:S165]
