AN IN-VITRO MODEL FOR THE EFFECTS OF ANDROGEN ON NEURONS EMPLOYING ANDROGEN RECEPTOR-TRANSFECTED PC12 CELLS

Androgen alters neurite outgrowth, synaptic organization, and cell sur vival in various portions of the brain and spinal cord. However, exami nation of the specific effects of androgen on neurons in vivo has been difficult. Previously, an in vitro model for the effects of estrogen on neurons was developed and characterized, using an estrogen receptor (ER)-transfected PC12 rat pheochromocytoma cell line. This model demo nstrated estrogenic regulation of neurite outgrowth, spine formation, and gap junction formation. Similarly, an in vitro model for the effec ts of androgen on neurons is now described. Wildtype cells (PC12-WT) w ere stably transfected with an expression vector coding for the full-l ength cDNA for the human androgen receptor (AR). Resultant clones were isolated, screened for incorporation of vector and expression of AR m RNA and protein, and analyzed for morphologic responses to androgen. P C12-WT, NE09 (ER-negative, AR-negative), SER8 (ER-positive, AR-negativ e), and AR8 (ER-negative, AR-positive) cells were exposed to 10 ng/ml nerve growth factor (NGF), along with 0-10(-7) M dihydrotestosterone ( DHT) for 2 days. AR8 cells demonstrated an androgen dose-dependent inc rease in mean neurite length, branch order, and neurite field area, wh ereas neurite branch segment length and soma area were not affected by androgen. PC12-WT, NE09, and SER8 cells exhibited no alterations in c ell morphology with DHT exposure. Because of the synergistic effects o f DHT and NGF, the regulation of NGF receptor mRNA by DHT was evaluate d; however, no significant induction of either trkA or p75 mRNA expres sion by androgen was documented. The results suggest that in AR-positi ve PC12 cells, androgen acts additively with NGF to increase neurite o utgrowth; but androgen effects are mediated specifically through branc hing and arborization. These responses are similar to developmental st udies of androgen effects in vivo. Thus, androgen appears to induce an inherent neural morphologic program in AR-containing cells, which inc reases the receptive field of these cells, increasing the likelihood f or interneural communication, although not promoting communication its elf. These cell lines will provide a unique in vitro system for studyi ng mechanisms of androgen-neuron interactions. (C) 1994 Academic Press , Inc.