Oxytocin enhances the prolactin response to vasoactive intestinal polypeptide in healthy women.
OBJECTIVE
To establish whether oxytocin modifies the stimulatory effect of vasoactive intestinal polypeptide (VIP) on prolactin secretion in healthy women.


METHODS
Controlled clinical study.


METHODS
Healthy women in an academic research environment.


METHODS
Seven healthy women (aged 24-32 years) were tested on the 22nd day of two consecutive normal menstrual cycles.


METHODS
Vasoactive intestinal polypeptide (4 pmol x kg(-1) x min(-1) in 50 mL of normal saline infused i.v. for 60 minutes) was administered in either the presence or absence of concurrent treatment with oxytocin (2 IU injected plus 0.07 IU/min infused for 60 minutes).


METHODS
Serum prolactin levels.


RESULTS
The administration of VIP induced a significant increase in serum prolactin levels, with a mean peak response 1.6 times higher than baseline at 45 minutes after injection. In the presence of oxytocin, the prolactin response to VIP was significantly higher, with a mean peak response 2 times higher than baseline.


CONCLUSIONS
These data suggest that in healthy women, oxytocin facilitates the regulation of the stimulating effect of VIP on prolactin secretion.
Chiodera
P
P
Department of Internal Medicine, School of Medicine, University of Parma, Italy.
Volpi
R
R
Capretti
L
L
Coiro
V
V
D000328:Adult; D000704:Analysis of Variance; D004357:Drug Synergism; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008597:Menstrual Cycle / Q000502:physiology; D010121:Oxytocin / Q000494:pharmacology*; D011388:Prolactin / Q000378:metabolism*; D012016:Reference Values; D014660:Vasoactive Intestinal Peptide / Q000009:adverse effects / Q000494:pharmacology*
D014660:Vasoactive Intestinal Peptide; D010121:Oxytocin; D011388:Prolactin