There has been a great deal of interest in gonadal hormones in the study of pain perception because of the higher sensitivity to pain in females (Berkley, 1997). The influence of gonadal hormones in pain perception has been discussed recently by (Aloisi (2003) and Fillingim and Ness (2000). The peripheral and central mechanisms of how ovarian hormones may influence nociception were presented by both (2003) and (2000). Peripherally, estrogen can influence receptive field properties of primary afferents in the trigeminal and pudental nerves. Centrally, ovarian hormones can influence the levels of neuromodulators and neurotransmitters involved in nociception such as substance P, GABA, glutamate, acetylcholine, b-endorphin, dopamine, serotonin and norepinephrine. They also modulate various other biological and cognitive functions and increase female sensitivity to environmental stimuli (Aloisi, 2003).