No evidence for prolactin's involvement in the post-ejaculatory refractory period

Area of Science:

• Behavioral Endocrinology
• Neuroendocrinology
• Reproductive Biology

Background:

• The post-ejaculatory refractory period is a common phenomenon across species, characterized by decreased sexual activity after ejaculation.
• Prolactin, a pituitary hormone released during ejaculation, has been hypothesized to play a key role in establishing this refractory period.
• Existing data on prolactin's involvement is controversial, necessitating further investigation.

Purpose of the Study:

• To investigate the role of prolactin in sexual activity and the post-ejaculatory refractory period in male mice.
• To determine if prolactin release during copulation influences sexual behavior or the duration of the refractory period.

Main Methods:

• Utilized two distinct strains of house mouse (wild-derived and laboratory) with differing sexual performance.
• Measured prolactin release during sexual behavior in male mice.
• Employed a pharmacological approach to acutely manipulate prolactin levels, either by mimicking or inhibiting its release.

Main Results:

• Confirmed prolactin release in male mice during sexual behavior.
• Demonstrated that acute pharmacological manipulation of prolactin levels did not affect sexual activity.
• Showed that inhibiting prolactin release did not shorten the post-ejaculatory refractory period.

Conclusions:

• Provided compelling evidence refuting the hypothesis that prolactin released during copulation is involved in establishing the post-ejaculatory refractory period.
• Suggests that other neuroendocrine mechanisms likely regulate the refractory period.
• Highlights the importance of using distinct animal models to resolve controversial findings in behavioral endocrinology.