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.
Lipo-oxytocin-1
Lipo-oxytocin-1 (LOT-1) is a synthetic peptide and derivative of oxytocin that acts as an agonist of the oxytocin receptor. The lipidation strategy was applied to oxytocin to create a new peptide with improved pharmacokinetics. LOT-1 consists of oxytocin conjugated with two palmitoyl groups. After adjusting for molecular weight (LOT-1 is ~1.5x the weight of oxytocin), oxytocin and LOT-1 are equipotent. In addition, LOT-1 appears to have a significantly longer duration of effect relative to that of oxytocin. It has yet to be determined whether LOT-1 possesses improved blood-brain-barrier permeability relative to oxytocin.