Viability of estrogen and lithium‐treated primary brain cell cultures following glutamate insult and NR1 mRNA expression of pretreated cultures

Abstract

Glutamate is an excitatory neurotransmitter that facilitates calcium influx, and excess calcium influx is detrimental to brain cells. Excitotoxicity is implicated in many neurological diseases and estrogen (E2) and lithium can influence excitotoxicity inversely: E2 facilitates calcium influx, while lithium impedes this influx. We harvested cortical and hippocampal cells of C57BL/6J fetal mice and pre‐treated for 48 hours with E2, lithium or combined E2/lithium. Cultures were then exposed to a toxic level of glutamate (100μM). Cell viability using fluorescein diacetate/propidium iodide assay revealed that only lithium pretreatment increased viability of cortical cultures and combined pretreatment did not. All pretreated hippocampal cultures reduced cell viability. Total RNA was also isolated from pre‐treated cultures and reverse transcribed. cDNA was then amplified via PCR using a glutamate receptor subunit (NR1), neuron and glia gene‐specific primers. Combined E2/lithium treatment reduced NR1 mRNA expression for both culture types. Additionally, these cultures expressed increased glial fibrillary acidic protein (GFAP) mRNA while neurofilament‐heavy chain (NF‐H) mRNA was low. Our data suggest lithium may protect against glutamate insult, but combined doses of E2 and lithium interfere with/prevent protection against glutamate excitotoxicity and NR1 mRNA expression among these cultures.