Cocaine: Excitatory effects on sensorimotor reactivity measured with acoustic startle

✍ Scribed by Michael Davis

• Book ID: 104771348
• Publisher: Springer
• Year: 1985
• Tongue: English
• Weight: 691 KB
• Volume: 86
• Category: Article
• ISSN: 0033-3158
• DOI: 10.1007/bf00431680

✦ Synopsis

Cocaine (2.5-10 mg/kg) caused a dose-related increase in the amplitude of the acoustic startle reflex in rats. In contrast, procaine (5 40 mg/kg) caused a dose-related decrease in startle, indicating that the effects of cocaine could not be ascribed to its local anesthetic effects. Cocaine's excitatory effects were blocked by pretreatment with haloperidol (0.5 mg/kg) but not by cyproheptadine or prazosin. The excitatory effects of cocaine (10 mg/kg) were markedly attenuated by pretreatment with reserpine (5 rag/ kg 24 and 18 h earlier) but not by c~-methyl-p-tyrosine (100 mg/kg 1 h earlier). In contrast, comparably sized excitatory effects of d-amphetamine were blocked by a-methylp-tyrosine and greatly enhanced by pretreatment with reserpine. Neither pretreatment blocked excitatory effects of apomorphine on startle. The data indicate that cocaine increases startle by acting through reserpine-sensitive pools of dopamine and provide further support for the conclusion that acoustic startle is enhanced by activation of dopamine receptors.