NEUROTROPHIN EXPRESSION MODULATED BY GLUCOCORTICOIDS AND ESTROGEN IN IMMORTALIZED HIPPOCAMPAL-NEURONS

We have used reverse transcription followed by polymerase chain reacti on amplification to investigate changes in expression of nerve growth factor (NGF) mRNA in immortalized hippocampal neurons after treatment with the glucocorticoids dexamethasone and corticosterone, the glucoco rticoid antagonist RU38486, and the gonadal steroids progesterone and 17-beta oestradiol. We found that NGF mRNA levels rise after applicati on of either dexamethasone or corticosterone, and that this rise is pr evented by the antagonist. Thus, neurotrophin expression is modulated by the physiological glucocorticoid and is mediated by type II glucoco rticoid receptors. Progesterone has no effect, while 17-beta oestradio l suppresses NGF mRNA in a postnatally-derived cell line but does not change levels in an embryonic line. An increase in neurotrophin expres sion is therefore not a general response to steroid hormone applicatio n, and may be a specific defence against the presence of metabolically endangering glucocorticoids.