THE ESTROGEN NEUROTROPHIN CONNECTION DURING NEURAL DEVELOPMENT - IS COLOCALIZATION OF ESTROGEN-RECEPTORS WITH THE NEUROTROPHINS AND THEIR RECEPTORS BIOLOGICALLY RELEVANT/

Estrogen enhances neurite growth within the developing rodent forebrai n, Estrogen receptor mRNA is co-expressed with the mRNAs for the neuro trophins and their receptors, Estrogen may act independently, by alter ing growth-related genes directly, but may interact additionally with growth factors (neurotrophins) and their receptors (trks). Estrogen ma y also act permissively to facilitate neurotrophin actions by genomic cross-talk with neurotrophin regulatory pathways whose nuclear end poi nts may be the same estrogen-responsive genes. Differential and recipr ocal regulation of estrogen and nerve growth factor (NGF) receptor gen e expression by their ligands suggests that estrogen and the neurotrop hins may influence each other's actions by regulating receptor/ligand availability or by reciprocal regulation at the level of gene transcri ption or signal transduction. Steroid/neurotrophin interactions may st imulate the synthesis of proteins required for neuronal differentiatio n, survival and maintenance of function.