SEX-HORMONE MODULATION OF NEURAL DEVELOPMENT IN-VITRO

The sex hormonal milieu during human and primate development is though t to influence adult cognition, perception, and behavior. Similarly in the rat, the neonatal sex hormonal milieu dictates adult behavior, as well as patterns of neural organization within the CNS. Specifically, estrogen and androgen alter neurite outgrowth, neuritic spine develop ment, and synaptogenesis in the limbic system and spinal cord. To exam ine specific molecular/cellular effects of sex hormones on neurons, in vitro models were developed, using the PC12 cell line. Wild-type cell s (PC12-WT) were stably transfected either with an expression vector c oding for the human estrogen receptor (ER), androgen receptor (AR), or with a control vector. Resultant crones were isolated, screened for i ncorporation of vector and expression of ER or AR mRNA and protein, an d analyzed for morphologic responses to estrogen and androgen, respect ively. PC12WT, NEO9 (ER-negative, AR-negative), SER8 (ER-positive, AR- negative), and AR8 (ER-negative, AR-positive) cells were exposed to ne rve growth factor and graded doses of estradiol or dihydrotestosterone (DHT) for 2 days. In SER8 cells, estradiol led to dose-dependent incr eases in the frequency of neurite outgrowth, spine development, and in terneuritic connectivity. Estradiol increased the frequency of gap jun ction frequency and length, and functional dye-coupling in SER8 cells. Conversely, in AR8 cells, DHT induced a dose-dependent increase in me an neurite length, branch order, and neuritic held area, while neurite branch segment length and soma area were unaffected. These results su ggest that SER8 and AR8 cells in vitro recapitulate various sex hormon al effects on neurons in vivo. Estrogen and androgen appear to induce inherent neural morphologic programs in which androgen increases neuri te arborization and the receptive held of individual cells, increasing the likelihood for intercellular communication, while estrogen actual ly induces this communication, in the form of spines, synapses, and ga p junctions. Thus estrogen and androgen act in different but complemen tary ways to modulate neural development and organization. (C) 1994 Ac ademic Press, Inc.