Effects of anxiety drugs on the modification of the acoustic startle reflex by noise gaps.
The acoustic startle reflex was modified by presenting gaps (0-30 ms) in a continuous noise (70 dB) before the startle eliciting stimulus. The effects of midazolam (0.4-1.8 mg/kg, IP), DMCM (0.1-0.4 mg/kg, IP), buspirone (5-20 mg/kg, PO), 8-OH-DPAT (0.5-8 mg/kg, IP), and clonidine (0.009-0.08 mg/kg, IP) on startle amplitudes (reflecting sensorimotor reactivity) on the one hand, and on gap inhibition of the startle reflex (a measure of temporal acuity) on the other hand, were investigated. The results showed that midazolam and clonidine attenuated sensorimotor reactivity dose-dependently. DMCM had no systematic effect on sensorimotor reactivity. Buspirone and 8-OH-DPAT increased sensorimotor reactivity dose dependently. Furthermore, midazolam and clonidine did not affect the neuronal systems underlying inhibition of the startle reflex. In contrast, DMCM and buspirone increased inhibition dose-dependently, and 8-OH-DPAT first increased and then decreased inhibition of the startle reflex. The possibility that drug-induced behavior affected the startle reflex was discussed.
Department of Psychopharmacology, University of Utrecht, The Netherlands.
T H
TH
Hijzen
H J
HJ
Rijnders
J L
JL
Slangen
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000161:Acoustic Stimulation; D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D002065:Buspirone / Q000494:pharmacology; D002243:Carbolines / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology; D008297:Male; D008874:Midazolam / Q000494:pharmacology; D051381:Rats; D012022:Reflex, Acoustic / Q000187:drug effects*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
D014151:Anti-Anxiety Agents; D002243:Carbolines; D013764:Tetrahydronaphthalenes; C034818:methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D003000:Clonidine; D008874:Midazolam; D002065:Buspirone