Send to

Choose Destination
Neuron. 1997 Jul;19(1):91-102.

Molecular dissection of two distinct actions of melatonin on the suprachiasmatic circadian clock.

Author information

Laboratory of Developmental Chronobiology, Massachusetts General Hospital and Harvard Medical School, Boston 02114, USA.


The pineal hormone melatonin elicits two effects on the suprachiasmatic nuclei (SCN): acute neuronal inhibition and phase-shifting. Melatonin evokes its biological effects through G protein-coupled receptors. Since the Mel1a melatonin receptor may transduce the major neurobiological actions of melatonin in mammals, we examined whether it mediates both melatonin effects on SCN function by using mice with targeted disruption of the Mel1a receptor. The Mel1a receptor accounts for all detectable, high affinity melatonin binding in mouse brain. Functionally, this receptor is necessary for the acute inhibitory action of melatonin on the SCN. Melatonin-induced phase shifts, however, are only modestly altered in the receptor-deficient mice; pertussis toxin still blocks melatonin-induced phase shifts in Mel1a receptor-deficient mice. The other melatonin receptor subtype, the Mel1b receptor, is expressed in mouse SCN, implicating it in the phase-shifting response. The results provide a molecular basis for two distinct, mechanistically separable effects of melatonin on SCN physiology.

[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center