Parathyroid hormone secretion by brain and pituitary of sheep.

The secretion of immunoreactive PTH by different brain regions and pituitary of sheep was studied in vitro. Separate tissue samples of gyrus, internal capsule, basal ganglia, cerebellum, and pituitary were incubated in culture medium with low, normal, and high Calcium (Ca)(0.7 mM, 1.2 mM and 2.4 mM) concentrations. PTH release in medium containing low Ca were observed by all samples. The concentrations increased in the fifth and sixth hour from 100% (1st hour basis value) up to 300%. The PTH release showed an inverse relationship to the Ca concentration in the culture medium. To induce any significant decrease in medium concentrations of PTH, 1.25(OH)2D (100 ng/ml) was added to the culture medium. This effect could be reversed by DB-cAMP. Our results indicate that secretion of immunoreactive PTH by brain and pituitary of sheep may occur in vitro. The secretion depends on the content of Ca, 1.25(OH)2D, and DB-cAMP.