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Phase-Response Curves to Melatonin

By clock on August 12, 2007.

NBM found an excellent online article (which I have seen before but I forgot) depicting Phase-Response Curves (PRC) to injections of melatonin in humans, rodents and lizards.

i-9a75d14c85618ecff2f8964bb2ca0bf6-melatonin PRCs.gif

Note how the shape is roughly opposite to that of a PRC to light pulses, i.e., at phases at which light elicits phase-delays, melatonin produces advances and vice versa:

i-ffb38d9dcbdd11cc953e2fea7150ff18-melatonin-light-PRC small.jpg

The lizard PRC was actually constructed in our lab, about ten years before I joined. The article, though, gives the wrong reference to this:

Underwood, H. and M. Harless (1985). "Entrainment of the circadian activity rhythm of a lizard to melatonin injections." Physiology & Behavior 35(2): 267-70.

In that paper, lizards were entrained by daily melatonin injections. The PRC was reported in a different paper the following year:

H Underwood (1986) Circadian Rhythms in Lizards: Phase Response Curve for Melatonin, Journal of Pineal Research 3 (2), 187-196.

Update: an alert reader sends a better figure, taken from this freely available recent paper:

i-a43ada0288d40b8998e1b71e1e56ad5c-human PRC light and melatonin.jpg

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chronobiology
Clock Tutorials
Rhythmic Human

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Thanks! Finally that superimposed version which I've only read about, not seen before.
Now wouldn't it be nice if all studies were online in full text, not just those tantalizing abstracts??
;-)