Fig. 9.   Demonstration that nicotine damages the developing brain at dose levels that do not compromise growth or general development (Navarro et al., 1989b; Seidler et al., 1992b; Slotkin, 1992). Administration of 2 mg/kg/day to pregnant rats, which simulates plasma levels of nicotine found in moderate smokers, results in normal body and brain region weights in the offspring. Nevertheless, cell damage (elevated ornithine decarboxylase activity [ODC]), cell loss (reduced DNA content) and synaptic hypoactivity (subnormal norepinephrine [NE] turnover) are still fully evident.