Good article but please note this at the end:

These findings contradict the well-accepted idea of high prolactin levels being linked to men's sexual issues. The results of this study suggest that the hormone could have a positive impact in initiating or stabilizing male sexual behavior. The study does not prove a cause-and-effect relationship between prolactin and sexual functioning. The researchers speculate that low prolactin reflects a change in the levels of signaling chemicals in the brain that are responsible for regulating sexual behavior. Also, poorer physical and mental health could be an underlying reason for low prolactin and a lower sex drive, said the researchers.

Another study on prolactin levels found that participants between the ages of 65 and 70 who were married, physically healthy, and had no psychopathology or marital problems, had decreased libido when their levels of the hormone were high. Mild hyperprolactinaemia in aging men may possibly be associated with decreased sexual desire and frequency of sexual activity as suggested in this study.

The two studies provide contrasting findings of prolactin levels and its effects on male sexual behavior which may lead to the possibility of conducting further studies to further examine this indirect relationship.