title: Prolactin secretory rhythm in women: immediate and long-term alterations after sexual contact.
abstract: BACKGROUND
  Prolactin (PRL) is one of the most versatile hormones in the mammalian body, affecting reproductive, sexual and other functions. In rats, mating or vaginocervical stimulation activates a characteristic PRL secretory pattern for several days, which is essential for successful reproduction. Although the underlying mechanisms appear to be different, PRL is also crucial for human fertility. We have detected a PRL increase in women induced by sexual intercourse. Extending these findings, the current study aimed at analyzing the PRL secretory rhythm after sexual contact, in order to elucidate whether human females also show long-term alterations of the PRL secretory pattern.
  
  
  METHODS
  In a pilot study, serial blood samples were taken from women (n= 7) in mid-cycle to assess changes in PRL secretory rhythm induced by sexual intercourse, during a period of 32 h.
  
  
  RESULTS
  Compared with control condition, sexual intercourse with orgasm induced not only the well-established immediate PRL increase of ~300% but also an additional PRL elevation around noon of the next day (P< 0.05). These fluctuations were measured on top of the regular circadian rhythm of PRL, manifested as a surge early in the morning.
  
  
  CONCLUSIONS
  We are able to demonstrate a long-term change in the PRL secretory rhythm after sexual intercourse with orgasm in females, suggesting memory effects. We hypothesize that the additionally secreted PRL could be beneficial for decidualization and implantation. Further studies with more participants are required to investigate in detail the implications of such effects on reproductive success in humans.
authors.affiliation: Division of Clinical Psychology, Department of Psychiatry, Social Psychiatry and Psychotherapy,  Hannover Medical School, Hannover,  Germany.
authors.forename: Tillmann H C
authors.initials: TH
authors.lastname: Kruger
authors.forename: Brigitte
authors.initials: B
authors.lastname: Leeners
authors.forename: Eva
authors.initials: E
authors.lastname: Naegeli
authors.forename: Sandra
authors.initials: S
authors.lastname: Schmidlin
authors.forename: Manfred
authors.initials: M
authors.lastname: Schedlowski
authors.forename: Uwe
authors.initials: U
authors.lastname: Hartmann
authors.forename: Marcel
authors.initials: M
authors.lastname: Egli
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D003075:Coitus / Q000502:physiology*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008183:Luteal Phase / Q000378:metabolism; D009948:Orgasm / Q000502:physiology; D010865:Pilot Projects; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D013997:Time Factors
chemical_list: D011388:Prolactin