Expression of glucocorticoid and mineralocorticoid receptors in an immortalized hippocampal neuronal cell line

A clonal cell line of rat embryonic hippocampal origin (H19-7) has been examined for the expression of glucocorticoid receptors (GR) and mineralocorticoid receptors (MR). H19-7 cells grown at 33°C continue to divide, however when grown at 39°C in reduced levels of serum the cells undergo morphological differentiation and express neuronal properties. Immunocytochemistry demonstrated that H19-7 cells express both MR and GR when grown at either 33°C or 39°C. GR mRNA is readily detected in H19-7 cells by RNase protection assay. MR mRNA levels in H19-7 cells are too low to detect by RNase protection, but can be detected by RT-PCR. RT-PCR also demonstrated that H19-7 cells express more GR mRNA than primary hippocampal neurons. Since previous studies have shown that the level of MR mRNA is higher than that of GR mRNA in hippocampal neurons, these studies suggest that H19-7 cells represent hippocampal neurons immortalized at an early stage when the MR system is not yet fully differentiated.