| Abstract: | The concentrations of dopamine (DA), dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were measured in the striatum of rats after i.p. injection of dipropyl-2-aminotetralin and the four positional isomers of monohydroxy-dipropyl-2-aminotetralin. All compounds except 8-OH dipropylaminotetralin caused a decrease in DOPAC- and HVA-concentrations. In addition, 5-OH-dipropylaminotetralin produced a small elevation in DA concentrations. In contrast, 7-OH dipropylaminotetralin, in doses of 100 mumol/kg and more, decreased DA to 50% and initially increased HVA and DOPAC to about 200%, after which the concentrations of the metabolites fell to 30% or less. The 5-OH isomer was found to be the most potent compound, decreasing HVA concentrations to 70% at a dose of 0.14 mumol/kg. The potencies are compared to those of catechol-group containing DA-agonists such as apomorphine and N,N-dipropyl-5,6-dihydroxy-2-aminotetralin. In addition, a comparison is made with reported behavioural data. It is suggested that the more active N-alkylated 2-aminotetralins have a conformation which corresponds to that of the alpha rotamer of dopamine. |
