Presence of neuron-specific enolase and somatostatin in human parathyroid tissues

The association of parathyroid abnormalities with apudomas prompted us to examine parathyroid tissues for the presence of neuron-specific enolase and somatostatin. Enolase was present in extracts of 29 out of 29 parathyroid specimens; tissue content was significantly higher in adenoma than in hyperplasia tissues (p < 0.005). Somatostatin was present in 14 of 33 specimens. Immunoreactive somatostatin measured in tissue extracts' fluids coeluted on Sephacryl chromatography along with synthetic somatostatin-14 in studies of two parathyroid carcinoma specimens. Since neuron-specific enolase has been found only in neural and neuroendocrine cells, our results suggest that human parathyroid glands may contain neuroendocrine elements. The differential content of neuron-specific enolase in adenoma versus hyperplasia specimens may be diagnostically useful in selected cases. The significance of the presence of somatostatin in some but not all parathyroid tumors requires further investigation. Taken together with our prior findings of gastrin and pancreatic polypeptide in some human parathyroid glands, we postulate that human parathyroid tumors contain neural crest elements.