Effects of 8-OH-DPAT, lisuride and some ergot-related compounds on the acoustic startle response in the rat.
Five ergot-related compounds were examined for their effects on the acoustic startle response in the rat. The startle amplitude and the startle latency were registered. 8-Hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT; 0.5-8 mg/kg) and lisuride (0.05-0.8 mg/kg) were found to enhance the startle amplitude, while the mainly DA receptor active ergot derivatives pergolide (0.2-0.8 mg/kg), bromocriptine (5-20 mg/kg) and LY 141865 (5-20 mg/kg) had no, or even the reverse, effect. All five compounds caused a prolongation of the startle latency. The increased startle amplitude caused by 8-OH-DPAT (2 mg/kg) and lisuride (0.2 mg/kg) was successfully antagonized by the 5-HT receptor antagonist methiothepin (0.1 mg/kg) but not by metergoline (1 mg/kg). 5-Hydroxy-L-tryptophan (L-5-HTP; 12.5-50 mg/kg), administered to pargyline- and benserazide-pretreated animals, was included for comparison. The serotonin precursor caused a marked increase in the startle amplitude and a shortening of the startle latency.
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D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology; D004873:Ergolines / Q000494:pharmacology*; D008090:Lisuride / Q000494:pharmacology; D008297:Male; D008711:Metergoline / Q000494:pharmacology; D008719:Methiothepin / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology*; D010479:Pergolide; D019257:Quinpirole; D051381:Rats; D011919:Rats, Inbred Strains; D013216:Reflex, Startle / Q000187:drug effects*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology*
D004873:Ergolines; D009281:Naphthalenes; D013764:Tetrahydronaphthalenes; D008711:Metergoline; D019257:Quinpirole; D010479:Pergolide; D001971:Bromocriptine; D008719:Methiothepin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D008090:Lisuride