NICOTINE IS MORE EFFICIENT THAN COTININE AT PASSING THE BLOOD-BRAIN-BARRIER IN RATS

1. Nicotine and its main metabolite, cotinine, were reported to have d istinct behavioral activities in mammals. 2. In this study, cotinine w as synthesized without detectable nicotine contamination to compare th e ability of nicotine and cotinine to pass the blood-brain barrier (BB B) in rats. 3. The alkaloids were extracted from plasma and brain tiss ues by methanol, identified by thin-layer chromatography, and quantifi ed by high-pressure liquid chromatography and radioimmunoassays. 4. Co nsistently, the three methods showed that the passage of cotinine was time, route of administration, and dose dependent and that nicotine wa s more efficient than cotinine to pass the BBB. 5. The results suggest that these alkaloids may have central activities that probably result from their actions at distinct molecular levels.