Serotonin Stimulates Adenosine 3', 5'-Monophosphate Accumulation in Parathyroid Adenoma

The effect of serotonin on cAMP accumulation in parathyroid adenoma tissue from patients with primary hyperparathyroidism was studied in vitro. Incubation with 1CT5 Mserotonin elicited a marked increase (of 90-150%) in cAMP content in slices of parathyroid adenoma tissue. This stimulatory effect of serotonin was already apparent after 2 min of incubation;stimulation by serotonin was dose dependent, with the highest stimulation being achieved at 10~4 M serotonin. These rotonin antagonists, methylsergide and cinanserin, in concentrations equimolar to serotonin completely blocked the stimulatory effect of serotonin on cAMP increase. The serotonincontent in surgically removed parathyroid adenoma tissue, as determined by fluorometric assay, was 6.4 ± 1.2 pmol/mg wet wt (~0.8 x 10~5 M). The present observations demonstrate that parathyroid adenoma tissue has a high content of serotonin, and serotonin stimulates cAMP accumulation in this tissue. Sincec AMP acts as a mediator of parathyroid hormone (PTH) release, our results suggest that serotonin could be one of the factor sregulating PTH secretion and/or contributing to PTH hypersecretionin various forms of primary hyperparathyroidism.