Figure 2
From: Relationship between nocturnal serotonin surge and melatonin onset in rodent pineal gland
Circadian profiles of pineal 5-HT and melatonin secretion from multiple outbred SD and Wistar rats. A. Entrained profiles of 5-HT (upper panel) and melatonin (lower panel) secretion from 6 SD rats. All data points were normalized to the nocturnal peak values of each circadian cycle. Each rat is represented by a different color. 5-HT and melatonin secretion from the same rat is shown in the same color. B. Secretory activities of 5-HT (upper panel) and melatonin (lower panel) from 8 Wistar rats. C. Comparison of 5-HT (upper panel) and melatonin (lower panel) secretion profiles from SD (red) and Wistar (green) rats. D. Phase angle difference in MT-on is independent of pineal mechanisms. Norepinephrine (NE, 20 uM) was infused directly into the pineal gland of the rats ID2263 (pink) and ID2269 (blue) for 3.5 hrs (11:00 h-14:30 h; blue shaded area). Data for melatonin secretion were normalized to the nocturnal maximum of the first night.