Razi Journal of Medical Sciences

In this research the effect of endogenous sexual hormones on pain perception during the estrus cycle in famale rats has been evaluated, different stages of estrus cycle has been determined by vaginal smears, and the rate of pain responses and susceptibility tests has been determined with formalin and hot plate tests.

In this regard, the increase and decrease of response to pain is an indication of famale sexual hormones activity. Meantime, with the help of ovariectomy we succeeded to increase the rate of LH notably, and as a result, we could succeed in evaluation of LH effect on pain response too. Our results showed that, in respect to female sexual hormones activity the acute and chronic pain decreased during the metestrus cycle and increased in proestrus stage. (Licking time in formalin test during the stage of estrus were 15.74±O.35 seconds in the first step and 75.32±O.35 seconds in the subsequent step, (PMeanwhile these values were 60.75±O.2 and 45.32±O.35 seconds respectively during the proestrus. We could state that as far as the ovariectomy lasts longer, the responses to pain producing factors intensifies.