Fig. 8.
5-HT2C receptors sensitize NE-induced melatonin and NAS secretion in pinealocytes. (A) Schematic of a single pineal strip in one well of a 96-well plate. Strips were incubated individually in M199 for 6 h and then in M199 containing different drugs for another 6 h. Next, 0.2 μM NE was used to activate adrenergic receptors, and RS was used to block 5-HT2C receptors. After each 6-h incubation, the solutions were collected and used to measure melatonin (B), 5-HT (C), and NAS (D) levels by UPLC/MS. (E) Normalized levels of secreted melatonin (green), 5-HT (red), and NAS (black) after further application of 5-HT with NE were measured as a positive control. The green dotted line indicates the basal melatonin secretion. When exogenous 5-HT was added to the bath, it was not possible to measure endogenous 5-HT secretion. Fold increases relative to the baseline incubation in M199 were compared using a t test. **P < 0.01 and *P < 0.05.