Brain regional and adrenal monoamine concentrations and behavioral responses to stress in alcohol-preferring AA and alcohol-avoiding ANA rats

The concentrations of monoamines, precursors and metabolites in various brain regions and the levels of catecholamines in the adrenal glands were determined from naive rats of the AA and ANA lines, and from ones immediately after an escapable shock test. The brain determinations were made with a new step-gradient ion-pair elution method on a reversed phase column and coulometric detection. Several significant differences were observed in the amine concentrations, largely confirming and extending the findings made before the genetic revitalization of the lines: in particular, the AAs, unlike other alcohol-preferring rodents, had higher 5-hydroxytryptamine concentrations. The AA rats tended to have smaller changes than the ANAs in brain aminergic systems and had significantly less change in adrenal epinephrine and dopamine levels after the shock test. The AAs were consistently found to be less active than ANAs in this shock test and in a warm-water swim test, but whether this was a cause or an effect of their brain and adrenal changes could not be determined. Our behavioral results might suggest a reduced reaction of the alcohol-preferring rats to aversive stimulation.