Involvement of norepinephrine in startle arousal after acute and chronic d-amphetamine administration.
Treatment with d-amphetamine produced a dose-dependent increase in startle amplitude in response to a buzzer. This increase appeared to be a reflection of a sensitization effect, i.e., enhanced responsivity as a function of repeated stimulus presentations. Treatment with alpha-methyl-p-tyrosine, which reduced whole brain concentrations of dopamine (DA) and norepinephrine (NE), or treatment with FLA-63, which reduced only NE, antagonized the effects of d-amphetamine on the startle reflex, suggesting a role of NE in this behavior. Startle amplitude was also reduced following chronic d-amphetamine treatment. The effect of d-amphetamine on startle was found to be independent of changes in drug-induced locomotor excitation. The data of the present investigation, together with earlier reports, suggests that tolerance occurs to those behaviors that involve a noradrenergic component.
D000818:Animals; D005406:Bis(4-Methyl-1-Homopiperazinylthiocarbonyl)disulfide / Q000494:pharmacology; D003913:Dextroamphetamine / Q000494:pharmacology*; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology; D051379:Mice; D009638:Norepinephrine / Q000502:physiology*; D013216:Reflex, Startle / Q000187:drug effects*; D013997:Time Factors
D008781:Methyltyrosines; D005406:Bis(4-Methyl-1-Homopiperazinylthiocarbonyl)disulfide; D003913:Dextroamphetamine; D009638:Norepinephrine