Effect of maternal nicotine on the development of sites for [3H]nicotine binding in the fetal brain

The sites for [³H]nicotine binding in fetal brains were examined after administration of nicotine into pregnant rats. Administration of unlabelled nicotine into the pregnant rats increased Bmax values for the sites for [³H]nicotine binding without affecting K_d values in the fetal brains. Treatment with this regimen, however, did not show any significant change in the sites for [³H]quinuclidinyl benzylate (QNB) binding. In addition, treatment with this regimen increased Bmax values of the sites for [³H]nicotine binding in the brains of pregnant rats. α-Bungarotoxin had no effect on the sites for [³H]nicotine binding.It is inferred, therefore, that a similar response is elicited by nicotine binding sites to administered nicotine in both the fetal and maternal brains. Furthermore, a possible effect of nicotine in pregnant rats may be the facilitation of the development of nicotine acetylcholine receptors in the fetal brain.