Oxytocin
It has been shown that oxytocin differentially affects males and females. Females who are administered oxytocin are overall faster in responding to socially relevant stimuli than males who received oxytocin. Additionally, after the administration of oxytocin, females show increased amygdala activity in response to threatening scenes; however, males do not show increased amygdala activation. This phenomenon can be explained by looking at the role of gonadal hormones, specifically estrogen, which modulate the enhanced threat processing seen in females. Estrogen has been shown to stimulate the release of oxytocin from the hypothalamus and promote receptor binding in the amygdala.
Sexual desire and intimate relationships
Much like the opioids mentioned above, the neuropeptide oxytocin has been shown to be extremely affective in the conditioning effects involved in the formation of stable preferences for places, stimuli and other beings. Studies have shown that women specifically not only show greater sensitivity to the release of oxytocin during sexual activity than men, but it has been suggested a correlation exists between oxytocin release and orgasm intensity, which may explain why women generally associate stronger interconnectivity between love and sexual desire.