Early evening prolactin rise in women with regular cycles.
Prolactin concentrations were measured in hourly integrated blood samples collected over 24 h in normally cyclic women during the follicular (N = 8) and the luteal (N = 7) phases of the menstrual cycle. Prolactin concentrations were increased during the evening in all the subjects when compared with the rest of the day-time wake-period. This rise was unrelated to sleep, and peak concentrations were seen at 20:00 h. During the luteal phase the magnitude of this evening rise of prolactin was significantly greater (P less than 0.02 at 19:00 h and P less than 0.001 at 20:00 h) when compared with the follicular phase, and was only slightly smaller than the magnitude of the sleep-induced prolactin rise. It is therefore suggested that there may be an intrinsic rhythm in prolactin secretion apart from the sleep-induced rise.
D000328:Adult; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008597:Menstrual Cycle; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D012636:Secretory Rate; D012890:Sleep
D011388:Prolactin