Effects of low-dose ionising radiation on pituitary adenoma: Is there a role for l-type calcium channel?

Abstract

Pituitary adenomas constitute about 6-18% of brain tumours in adults. Activation of voltage gated calcium currents can account for growth hormone oversecretion in some GH-secreting pituitary adenomas that produce an acromegaly appearance and increase mortality. Ca 2+ ions, as mediators of intracellular signalling, are crucial for the development of apoptosis. However, the role of [Ca 2+] in the development of apoptosis is ambiguous. In this study, the effects of low-dose ionising gamma radiation ( 60Co) on rat pituitary adenoma cells survival and proliferation and the role of calcium channels on the apoptosis radio-induced were evaluated. Doses as low as 3 Gy were found to inhibit GH3 cell proliferation. Even though there was a significant number of live cells,168 hours following irradiation, they were not able to proliferate. The results indicate that the blockade of extracellular calcium influx through these channels does not interfere in the radiation-induced apoptosis in GH3 cells.