Figure 5.

α-Adrenergic signaling promotes 5-HT release in vivo. (A) 5-HT release and melatonin (MT) output both are elevated by norepinephrine (NE, 20 μM) between 3 p.m. and 7 p.m., and 5-HT and melatonin levels were monitored before, during, and after the drug infusion by using microdialysis on-line with HPLC-FD. (B) Norepinephrine in the presence of β-blocker elevates 5-HT secretion. β-Adrenergic blocker propranolol (PROP, 20 μM) and norepinephrine (NE, 20 μM) were infused directly into the pineal between 3 p.m. and 7 p.m. 5-HT and melatonin levels were assayed as described in A. Similar results were obtained with other tested rats (n = 4).