Deleterious effects of fungizone on growth hormone and prolactin secretion by cultured GH₃ cells

The rates at which growth hormone (GH) and prolactin (PRL) are spontaneously secreted from a rat pituitary tumor cell line (GH₃) were significantly reduced when these cells were maintained in medium containing 2.5 μg/ml Fungizone (Fz). The reduction in hormone secretion was not immediately reversed by removal of Fz during perifusion, but after 3 wk in control medium, secretory rates approached the pre-Fz treatment levels. In plated cells, secretion of GH was reduced by Fz in a dose-dependent manner, whereas PRL secretion was significantly reduced only by the highest concentration (2.5 μg/ml) of Fz. We concluded that Fz is not an acceptable medium constituent for the long-term culture of GH₃ cells. However, because its effects are reversible, its short-term use as a decontaminating agent might eliminate the necessity for reinitiating the culture of cells whose secretory behavior must be followed in long-term protocols.