Total RNA content of brain cells of inbred mice reared under different conditions.

AB/Jena, DBA/2Jena, C57B1/6 Jena inbred mice and ABD2F1- and B6D2F4-hybrid mice either were reared communally and weaned at day 30 or were reared by isolated mothers and weaned at day 21 (I21). On day 50 the total RNA content of pyramidal brain cells of male offspring was determined by cytophotometry. The studied brain areas were the frontal pole of cerebral cortex (FCC) and the CA1 region of the dorsal hippocampus (DHI). The DBA, C57 and ABD2 mice had a reduced FCC and DHI RNA-content under I21-rearing. Under these conditions the AB strain has the highest RNA-content in both substrates. The results call for the awareness of possible genetic influences when studying the effects of environmental enrichment/impoverishing.