Melatonin was measured by radioimmunoassay in homogenates of pineal glands from quail (Coturnix coturnix japonica) kept under different photoperiods and in darkness. Under 8-, 12- and 16-h daylengths melatonin levels were increased during the dark period, the duration of the increase depending on the duration of the dark period. As the daylength was increased the peak occurred closer to lights-off, reflecting the more rapid melatonin rise under the longer photoperiods. The pineal melatonin rhythm continued in darkness with an amplitude relative to that seen under a light/dark cycle of slightly less than one-half after 2 days in darkness and one-third after 6 days in darkness. The corresponding average periods of the rhythm were 25·5 h and 25·7 h. These results show that there is a circadian rhythm of melatonin in the pineal gland of the quail which is entrained by light/dark cycles and which continues in darkness.
J. Endocr. (1985) 107, 317–324
Journal of Endocrinology is committed to supporting researchers in demonstrating the impact of their articles published in the journal.
The two types of article metrics we measure are (i) more traditional full-text views and pdf downloads, and (ii) Altmetric data, which shows the wider impact of articles in a range of non-traditional sources, such as social media.
More information is on the Reasons to publish page.
|Sept 2018 onwards||Past Year||Past 30 Days|
|Full Text Views||1||1||0|