A serum-free culture of the neurons in the septal, preoptic, and hypothalamic region. Effects of triiodothyronine and estradiol

Serial modifications of Bottenstein and Sato' serum-free hormone-supplemented medium resulted in a new promising medium (1 : 1 mixture of L15 and MCDB 104 containing several supplements) for culturing neonatal rat brain cells. This medium favored the morphological and biochemical differentiation of the neurons, including particular types of cholinergic and cholinoceptive neurons, obtained enzymatically from the septum, preoptic area, and hypothalamus. On the other hand, the growth of non-neuronal cells was markedly suppressed in this medium. Therefore, their effects on the neurons are minimized in this culture. Effects of triiodothyronine (T3) and estradiol (E2) on the activities of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE), synthetic and degradative enzymes for acetylcholine, respectively, were examined in this culture. The optimal concentrations of T3 and E2 for AChE activity were around 1 nM and 10 pM, respectively. However, E2 appeared to be somewhat inhibitory at higher concentrations. Although the activity of ChAT was maximum around 10 pM of E2, the ChAT activity increased as the concentration of T3 was increased to 100 nM.