Phytohemagglutinin alters cell morphology and decreases prolactin production in GH cells

Phytohemagglutinin (PHA) produced morphological and functional alterations in a clonal strain of rat pituitary tumor cells (GH4C1). Addition of PHA (2-5 micrograms/ml) results in a decrease in the proportion of elongated cells from 20% in control cell cultures to less than 10% in the presence of PHA. This effect can be observed after exposure of cells to PHA for 2-3 h and requires 4 days to be reversed after removing PHA from the culture medium. A specialized cell function, the production of the peptide hormone prolactin (PRL), is also affected by PHA treatment. Exposure of cells to 2 micrograms/ml PHA results in greater than 50% inhibition of PRL production. The above effects of PHA occur without any apparent alteration in total protein per culture dish, the rate of protein synthesis or the overall growth characteristics of the cells.