Noradrenergic influence on the prepulse inhibition of acoustic startle.
Oral administration of p,p'-1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), a chemical believed to increase neuronal membrane excitability increased the acoustic startle responsiveness of rats. Inhibition of the acoustic startle response with a brief, prepulse white-noise stimulus was evident at 12.5 to 25 mg/kg of p,p'-DDT, but not at 50 mg/kg. Pretreatment of rats with phenoxybenzamine, an adrenergic receptor antagonist, attenuated the effects of 12.5 mg/kg of p,p'-DDT on the acoustic startle reflex, and decreased the maximum magnitude reduction produced by the prepulse stimulus in DDT-exposed rats. These data extend previous work showing that p,p'-DDT augments startle reactivity in rats and is in accord with the existence of an excitatory norepinephrine(NE)-containing pathway modulating motor outflow in the acoustic startle reflex arc.
D000704:Analysis of Variance; D000818:Animals; D003634:DDT / Q000633:toxicity*; D008297:Male; D009638:Norepinephrine / Q000502:physiology*; D010643:Phenoxybenzamine / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D013216:Reflex, Startle / Q000187:drug effects*
D010643:Phenoxybenzamine; D003634:DDT; D009638:Norepinephrine