[The effects of light exposure on plasma concentrations of melatonin, LH, FSH and prolactin in women].
The effects of light exposure on plasma concentrations of melatonin, LH, FSH and prolactin were studied in 11 normal cycling women during their follicular phases. Blood samples were obtained via an indwelling venous catheter every 10 min. for 2.5 hours starting at 9:30 and 21:30h. For the blood samplings taken at night, six women were kept in a dark room and were permitted to sleep. Their blood samples were obtained using a flashlight (5-10 lux) without their rest being disturbed. However, the other five women were exposed to light (3,000 lux at eye level) and awakened from 22:40 to 24:00h. Plasma melatonin concentrations in the morning decreased from 48.7 +/- 11.6 pg/ml at 9:30h to 24.7 +/- 4.0 pg/ml at 12:00h. On the other hand, plasma melatonin concentrations at night increased from 65.4 +/- 9.6 pg/ml at 21:30h to 138.2 +/- 28.6 pg/ml at 24:00h. The pulsatile LH secretion was changed from the type of "high frequency, low amplitude" in the morning to the type of "low frequency, high amplitude" at night. Nocturnal FSH concentrations were lower than diurnal ones, but nocturnal prolactin concentrations were higher than diurnal ones. Nocturnal concentrations of melatonin were suppressed 40 min. after the light exposure (from 117.4 +/- 11.4 pg/ml at 22:40h to 74.6 +/- 13.9 pg/ml at 23:20h). On the the other hand, the light exposure increased plasma prolactin concentrations from 10.9 +/- 4.1 ng/ml at 22:40h to 17.0 +/- 4.4 ng/ml at 22:50h, maintained those higher levels for 20 min. and decreased them gradually after 23:20h. With the light exposure, mean values of nocturnal LH concentrations were increased from 11.9 +/- 1.5 mIU/ml before exposure to 14.2 +/- 1.8 mIU/ml after exposure, and those of FSH were also increased from 5.9 +/- 0.4 mIU/ml to 6.3 +/- 0.4 mIU/ml. These results showed that the secretion of melatonin, as well as LH, FSH and prolactin had daily rhythms and that melatonin and prolactin showed different responses to light exposure, suggesting different control mechanisms for the secretion of those two hormones.
Miyauchi
F
F
Yamaguchi University School of Medicine.
Nanjo
K
K
Kato
H
H
Sasaki
T
T
Yonezawa
M
M
Tsukada
Y
Y
D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D005498:Follicular Phase / Q000502:physiology*; D006801:Humans; D008027:Light; D007986:Luteinizing Hormone / Q000097:blood*; D008550:Melatonin / Q000097:blood*; D011388:Prolactin / Q000097:blood*
D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D008550:Melatonin