[Inhibition of harmaline induced tremor by L-threo-3, 4-dihydroxyphenylserine, an L-norepinephrine precursor].
Effect of 3, 4-dihydroxyphenylserine (DOPS), a norepinephrine precurosr, on harmaline tremor was investigated in mice to elucidate the role of norepinephrine in the genesis of tremor. 1) Spontaneous motor activity was inhibited by L-threo-DOPS (200 mg/kg i.p.). 2) Tremor induced by harmaline (5 and 7 mg/kg i.p.) was enhanced by alpha-methyl-p-tyrosone (200 mg/kg i.p.). 3) The development and duration of tremor induced by harmaline (10 mg/kg i.p.) were inhibited significantly in a dose dependent manner by L-threo-DOPS (50, 70, 100, 150 and 200 mg/kg i.p.), but neither by D-threo-DOPS (200 mg/kg i.p.) nor DL-erythro-DOPS (200 mg/kg i.p.). 4) L-threo-DOPS (200 mg/kg i.-.) had no effect on the development of tremor induced by tremorine (5 and 10 mg/kg i.p.), while lacrimation and diarrhea caused by tremorine was markedly inhibited. 5) Administration of harmaline (10 mg/kg i.p.) produced an increase in brain 5-hydroxytryptamine content but not in that of norepinephrine. Administration of L-threo-DOPS (100 mg/kg i.p.) increased the norepinephrine content but not the 5-hydroxytryptamine content in the brain. Inhibition of harmaline tremor induced by L-threo-DOPS is attributed to the L-norepinephrine converted from L-threo-DOPS and the involvement of a noradrenergic mechanism in harmaline tremor has to be considered.
D000470:Alkaloids / Q000037:antagonists & inhibitors*; D000818:Animals; D001923:Brain Chemistry; D015103:Droxidopa / Q000494:pharmacology*; D004357:Drug Synergism; D006246:Harmaline / Q000037:antagonists & inhibitors*; D007536:Isomerism; D008124:Locomotion / Q000187:drug effects; D008297:Male; D051379:Mice; D009638:Norepinephrine / Q000032:analysis; D012694:Serine / Q000031:analogs & derivatives*; D012701:Serotonin / Q000032:analysis; D014202:Tremor / Q000139:chemically induced*; D014203:Tremorine / Q000037:antagonists & inhibitors; D014443:Tyrosine / Q000494:pharmacology
D000470:Alkaloids; D012701:Serotonin; D014443:Tyrosine; D012694:Serine; D006246:Harmaline; D015103:Droxidopa; D014203:Tremorine; D009638:Norepinephrine