European Journal of Pharmacology, 44 (1977) 391--395 © Elsevier/North-Holland Biomedical Press Short communication EFFECTS OF AMPHETAMINE ON BRAIN BIOGENIC AMINES IN ISOLATED AND AGGREGATED RATS FRANCOIS LOKIEC, CHRISTIAN JACQUOT, JEAN R. RAPIN and YVES COHEN Laboratoire de Pharmacodynamie, ERA CNRS 627, Facultd de Pharmacie, F. 92290 Chdtenay-Malabry, France Received 27 May 1977, accepted 2 June 1977 391 F. LOKIEC, C. JACQUOT, J.R. RAPIN and Y. COHEN, Effects of amphetamine on brain biogenic amines in iso- lated and aggregated rats, European J. Pharmacol. 44 (1977) 391--395. d- and 1-amphetamine were injected (15 mg/kg i.p.) into isolated or aggregated rats. Both d- and 1-forms decreased the noradrenaline levels of brain areas in isolated and in aggregated rats, d-Amphetamine decreased 5-hydroxytryptamine (5-HT) and 5-hydroxyindolacetic acid (5-HIAA) levels in aggregated rats only. 1-Ampheta- mine induced no change in 5-HT and 5-HIAA levels. The greater sensitivity of aggregated rats to d-amphetamine can be ascribed to a change in 5-HT metabolism rather t~han to a modification of noradrenaline levels. Isolated and aggregated rats d-Amphetamine 1-Amphetamine 5-HT 5-HIAA 1. Introduction The group of d-amphetamine (Gunn and Gurd, 1940) is a complex phenomenon parti- ally related to hyperexcitability, increased motor activity and hyperthermia (Menon and Dandiya, 1967) all of which are controlled by biogenic amines, catecholamines (CA)and 5-hydroxytryptamine (5-HT) (Reid, 1970). The rat, which is sensitive to group toxicity, can be used for experiments involving the study of amphetamine effects. The levoisomer is less active than the dextro form of amphe- tamine (Moore, 1964). We thus undertook an analysis of the biochemical modifications brought about by application of d- or 1-am- phetamine to various noradrenergic areas in both isolated and aggregated rats. The areas which control the above-mentioned phenom- ena are the cortex, hypothalamus and medulla oblongata-pons. 2. Materials and methods 2.1. Animal treatments Adult male albino rats (200--300g) received 15 mg/kg i.p. of d- or 1-amphetamine and were then divided into two groups. The rats were either isolated after the injection and placed in opaque 0.1 m 2 polypropylene cages or were aggregated in groups of five in the same cages. The animals from both groups were sacrificed by cervical dislocation and decapitation 10 and 45 min after injection of the drug. These times were chosen as a func- tion of the kinetics of elimination of the drug (Brodie et al., 1970). The brain was rapidly removed and dissected in the cold (Glowinski and Iversen, 1966). The cortex, hypothalamus and medulla oblongata-pons were isolated, weighed and homogenized in 10 ml of 0.4 N perchloric acid reagent containing 5 g of sodi- um metabisulphite and 5 g of disodium EDTA/1. Assays were carried out with the supernatant obtained after centrifugation. 5