Relationship between melatonin rhythms and visual loss in the blind.
Melatonin rhythms were assessed in 49 registered blind individuals by measurement of the urinary metabolite of melatonin, 6-sulfatoxymelatonin (aMT6s). Subjects had different causes of visual loss and were classified as having light perception or better (LP; n = 19) or having no perception of light (NPL; n = 30). Subjects collected four-hourly urine samples (eight-hourly overnight) for 48 h at weekly intervals for 3-5 weeks. The majority of LP subjects (14 of 19) had normally entrained aMT6s rhythms (mean acrophase range, 2.4-6.2 h), 4 were abnormally entrained to 24 h (mean acrophase range, 8.9-1.0 h), and 1 was unclassified. Conversely, most NPL subjects had abnormal rhythms (23 of 30), the incidence of which was greater in uni- and bilaterally enucleated subjects. The majority of NPL subjects (17 of 30) had free-running aMT6s rhythms period range, 24.13-24.79 h), 5 were abnormally entrained to 24 h (acrophase range, 7.2-20.6 h), and 1 was unclassified. Output (micrograms of aMT6s per 24 h) and amplitude (micrograms per h) of aMT6s production did not vary between LP and NPL subjects (mean 24-h output +/- SD, 12.7 +/- 7.5 and 9.4 +/- 6.4 micrograms aMT6s/24 h, respectively; mean amplitude +/- SD, 0.6 +/- 0.4 and 0.5 +/- 0.3 microgram/h, respectively). These results indicate that a higher proportion of NPL subjects have abnormal melatonin rhythms compared to those with LP.
Lockley
S W
SW
Chronobiology Laboratory, School of Biological Sciences, University of Surrey, United Kingdom. s.lockley@surrey.ac.uk
Skene
D J
DJ
Arendt
J
J
Tabandeh
H
H
Bird
A C
AC
Defrance
R
R
D000328:Adult; D000368:Aged; D001766:Blindness / Q000652:urine*; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000031:analogs & derivatives* / Q000652:urine*; D008875:Middle Aged; D012890:Sleep; D014796:Visual Perception
C054513:6-sulfatoxymelatonin; D008550:Melatonin