Physiological disposition of Β-phenylethylamine, 2,4,5-trimethoxyphenylethylamine, 2,3,4,5,6-pentamethoxyphenylethylamine and Β-hydroxymescaline in rat brain, liver and plasma

Abstract

Hydroxymescaline (HM) and Β-phenylethylamine (PEA) affected the conditioned-avoidance responses (CAR) in rats after i.p. injection of 100 mg/kg and 40 mg/kg, respectively. The fates of these two compounds and of 2,3,4,5,6-pentamethoxyphenylethylamine (PMPEA), a behaviorally active mescaline derivative, and of 2,4,5-trimethoxyphenylethylamine (TMPEA), a behaviorally inactive compound, were studied in rats. All compounds are quickly absorbed and distributed after i.p. injection and are also quickly removed from brain, liver and plasma. The compounds cross the blood-brain barrier differently and TMPEA could not be detected in the CNS explaining, perhaps, its lack of behavioral activity. A comparison of the minimal doses (Μmoles/kg) of these compounds which affect the CAR in rats is: PMPEA (10)>mescaline (60)>PEA (240)>HM (420). In contrast, a comparison of minimal brain levels necessary to affect the CAR reveals the following relationship (nmoles/g) PMPEA (1.8)>mescaline (2.4)>Hm=PEA (40). It is suggested that SAR studies with psychoactive compounds should not be based on injected doses but on actual brain levels at periods of abnormal behavior.