Amphetamine effects on startle gating in normal women and female rats.
BACKGROUND
Dopamine agonists disrupt prepulse inhibition (PPI) of startle in male rodents. In humans, this is observed only in some studies. We reported that PPI was disrupted by D: -amphetamine in men, but only among those with high basal PPI levels. Here, amphetamine effects on PPI were tested in normal women and female rats.


METHODS
Acoustic startle and PPI were tested in normal women after placebo or 20 mg amphetamine, in a double-blind, crossover design, and in female rats after vehicle or 4.5 mg/kg amphetamine. Rats were from Sprague-Dawley (SD) and Long Evans (LE) strains that differ significantly in gene expression in PPI-regulatory circuitry, including levels of nucleus accumbens (NAC) catechol-O-methyl transferase (COMT) mRNA.


RESULTS
Amphetamine was bioactive in humans based on quantitative autonomic and self-rating measures, but did not significantly change startle magnitude or PPI across all subjects. Amphetamine's effects on PPI in women correlated significantly (p < 0.0008) with placebo PPI levels (reducing PPI only in women whose basal PPI levels exceeded the sample median) and with measures of novelty and sensation seeking. Amphetamine decreased PPI in SD rats that have relatively low NAC COMT gene expression and increased PPI in LE rats that have relatively high NAC COMT gene expression.


CONCLUSIONS
The dopaminergic regulation of PPI in humans is related to basal levels of sensorimotor gating and to specific personality traits in normal men and women. In rats, the effects of amphetamine on PPI differ significantly in strains with low vs. high NAC COMT expression.
Talledo
Jo A
JA
Department of Psychiatry, University of California, San Diego,La Jolla, CA 92093, USA.
Sutherland Owens
Ashley N
AN
Schortinghuis
Tijmen
T
Swerdlow
Neal R
NR
D000328:Adult; D000661:Amphetamine / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000494:pharmacology*; D018592:Cross-Over Studies; D004298:Dopamine / Q000502:physiology; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D009714:Nucleus Accumbens / Q000502:physiology; D011597:Psychomotor Performance / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D020318:Rats, Long-Evans; D017207:Rats, Sprague-Dawley; D013216:Reflex, Startle / Q000187:drug effects* / Q000502:physiology; D013045:Species Specificity
D000697:Central Nervous System Stimulants; D018491:Dopamine Agonists; D000661:Amphetamine; D004298:Dopamine