Pineal photoreceptors rhythmically secrete melatonin.
Individual pineal cells secrete melatonin with a circadian period, reducing a vertebrate circadian system to the level of a single cell [Brain Res., 627 (1993) 141-146]. In the present study, dissociated pineal cells were identified as melatonin-secreting by a reverse hemolytic plaque assay (RHPA) and all melatonin-secreting cells were immuno-positive when analyzed for the photoreceptor protein S-antigen. The results are the first direct evidence that isolated photoreceptor cells secrete melatonin and taken together with our previous findings indicate that single pineal cells contain: (1) a circadian oscillator; (2) a photoreceptive capacity; and (3) the ability to secrete melatonin rhythmically.
Pickard
G E
GE
Department of Psychiatry, University of Pennsylvania School of Medicine, Philadelphia 19104-6141.
Tang
W X
WX
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology; D006462:Hemolytic Plaque Technique; D007150:Immunohistochemistry; D008116:Lizards; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000276:immunology / Q000378:metabolism*; D010870:Pineal Gland / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure
D008550:Melatonin