Interstrain differences in activity pattern, pineal function, and SCN melatonin receptor density of rats

Strain-dependent differences in the melatonin profiles of rats were investigated. The inbred rat strains BH/Ztm, ACI/Ztm, LEW/Ztm were analyzed for diurnal (12:12-h light-dark) wheel running activity, melatonin levels of pineal and plasma glands, urinary 6-sulphatoxymelatonin excretion and melatonin receptor density in the suprachiasmatic nuclei. Results show that melatonin has a long-term stimulating effect on its own receptor density in the suprachiasmatic nuclei.