Autoradiographic localization of [14C]8-S-adenosyl-L-homocysteine in rat brain.

Following intracarotid injection of [14C]8-S-adenosyl-L-homocysteine ( [14C]SAH) in the rat, radioactivity was localized by autoradiographic detection in the circumventricular organs, such as the pineal gland, choroid plexuses and area postrema, which lie outside the blood-brain barrier. HPLC analysis indicated a decrease of [14C]SAH radioactivity in these structures from 1 to 45 min, after injection. These results are discussed and related to the known pharmacological properties of SAH.