The effects of anticholinergic and dopaminergic drugs used for Parkinson's disease were studied on the tremor induced by physostigmine (0.3-3.0 mg/kg) in rats. For the measurement of tremor a new electronic device was employed. Atropine (0.3-1.2 mg/kg) and biperiden (0.01-1.0 mg/kg) reduced the physostigmine-induced tremor in a dose-related manner and could abolish it. Biperiden was less potent than atropine. Methylatropine in a dose of 1.2 mg/kg slightly inhibited the tremor. Amantadine (0.3-3.0 mg/kg) reduced the tremor but only to a certain degree. Bromocriptine (0.1-10.0 mg/kg) reduced it in a manner that was not dose-related. Pimozide potentiated the tremor in the dose of 0.2 mg/kg but not in larger doses. At the onset of the tremor, a small decrease in rectal temperature occurred. The hypothermia lasted significantly longer than the tremor. Neither the anticholinergic nor the dopaminergic anti-Parkinson drugs altered the hypothermic effect of physostigmine. The results show that those anti-Parkinson drugs, which act by increasing the dopaminergic activity can counteract the tremor induced by physostigmine. However, these drugs are clearly less active than th anticholinergic anti-Parkinson drugs.
Abslracl:The tremors induced by harmine, LON-954 (N-carbamoyl-2-(2,6-dichlorophenyl)acetamidine hydrochloride) and 5-hydroxytryptophan (5-HTP) were studied in control rats and in rats withdrawn for 1 W 8 hrs from 6 to 9 days' ethanol administration. The frequencies and the intensities of the tremors were determined electronically. In control rats the frequency spectra of the tremors induced by harmine (20 mg/ kg) and LON-954 (10 mg/kg) showed a narrow peak frequency at about 10 Hz. Atropine (1.2 rng/kg) altered neither the frequency nor the intensity of these tremors. 5-HTP (SO mg/kg) when given 3.5 hrs after iproniazid (100 mg/kg) induced tremor with peak frequencies at 6-7 Hz and 12 Hz. In ethanol-withdrawn rats treated with harmine or LON-954 the frequency analysis of tremor revealed a narrow peak frequency at about 12 Hz, which was neither the characteristic frequency of ethanol withdrawal tremor (6 Hz) nor that of harmine or LON-954 (10 Hz). The intensity of both harmine-and LON-954-induced tremor was significantly increased in ethanol-withdrawn rats. The ethanol-withdrawn rats were markedly sensitized to the effect of iproniazidf 5-HTP, shown by deaths. The peak frequencies of this tremor were the same as those in control rats. The results suggest that harmine-induced tremor involves a dopaminergic-5-HT'ergic imbalance and the tremor induced hy LON-954 a dopaminergic-cholinergic imbalance in the brain. The tremor in ethanol-withdrawn rats seems to he mediated by alterations in the activity of the cerebral 5-HT'ergic system.
Key-words:Ethanol withdrawal ~ harmine ~ LON-954 -5-HTPtremorrats. 1 1 3-120. 323, 205-210. 46, 585-589. 6A, 335-346.
Abstracr:The effect of acute and chronic ethanol administration on cerebral 5-hydroxytryptamine (5-HT) and 5hydroxyindoleacetic acid (5-HIAA) concentrations of male Sprague-Dawley and Wistar rats was studied. Acute ethanol administration caused a slight fall (by 13%) in 5-HT concentration and a slight increase (by 10%) in 5-HIAA concentration one hour after administration. In chronically treated rats the whole brain 5-HT concentration was decreased by 9% during ethanol intoxication. This fall was significant in the part of brain containing diencephalon, mesencephalon and telencephalon except cortex (by 23%; P
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