Effects of emotion on oxytocin, prolactin, and ACTH in women
Research on both non-human mammals and humans has raised interest in the role that oxytocin may play in human attachment and attachment-related emotions. This study examined changes in plasma oxytocin, prolactin, and ACTH concentrations in response to laboratory-induced positive and negative emotions related to close, interpersonal relationships. Participants were 32 female volunteers recruited from university communities. During positive emotion induction, oxytocin decreased over time (F(1,3) = 4.41, p < 0.007), prolactin increased (F(1,3) = 4.80, p < 0.004) and ACTH remained constant. During negative emotion induction, prolactin levels increased (F(1,3) = 2.81, p < 0.05), ACTH decreased only after the induction terminated (F(1,3) = 4.02, p < 0.01) and oxytocin remained constant. While oxytocin decreased during positive emotion, this finding contrasted previous research that showed decreases in response to negative emotion. In conclusion, plasma oxytocin levels were not reliably altered by positive or negative emotion induction. While prolactin and ACTH were expected to decrease over time due to diurnal variation, they instead either increased or remained level during emotion induction, or decreased only after the induction. Overall, the degree of change in circulating hormones in response to happy and sad emotions was very small and possibly not functionally significant.