In-vitro uptake and metabolism of [3H]-5-hydroxytryptamine in the pineal glands of the rabbit, rat and hamster. A comparative study with the use of autoradiography, chromatography and liquid-scintillation counting.

Pineal glands of rat, rabbit and hamster were incubated during day or night in Merlis' fluid containing [3H]-5-hydroxytryptamine (=[3H]-HT) by the use of a 20-min pulse with or without postincubation in "cold" medium for 15, 30, 45 or 60 min. (1) Selective autoradiographic labeling was observed in sympathetic nerve terminals; this reaction was missing after bilateral surgical removal of the superior cervical ganglia. In contrast, a scarce and diffuse labeling was found in pinealocytes (Pi) and interstitial cells (IC) of both untreated and ganglionectomized animals.