CORRELATION OF BRAIN LEVELS OF DRUGS WITH BEHAVIORAL EFFECTS

¹ Laboratory of Psychopharmacology, Departments of Pharmacology and Psychology, Indiana University, Bloomington, Indiana

Physiologic disposition studies of H³-damphetamine in rats indicate high degrees of localization in all tissues except fat, with tissue/plasma levels >1 maintained for >8 hr. Similar studies of pentobarbital-2-C¹⁴ show moderate localization in fat, kidney and liver, also maintained for >8 hr. The effects of d-amphetamine on a variety of behavioral tasks indicate a differential sensitivity to the drug; minimal effective brain levels range from 0.40 µg/g for continuous avoidance to 5.0 µg/g in a straightaway escape response. In contrast, pentobarbital has a relatively uniform sensitivity; minimal effective brain levels are in the range 1.0 to 1.2 µg/ g for all behavioral tests.