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D Zivanovic

Publications and source records attributed to D Zivanovic.

11 recordsLinked to original sources
PubMed1976

Tremorogenic effects of intracaudate d-amphetamine and their suppression by dopamine.

Pronounced tremors were produced in unanesthetized cats following intracaudate (I.C.) injections of either d-amphetamine (15 mug), dl-methamphetamine (20 mug), l-amphetamine (48 mug) or 3-methoxytyramine (68-120 mug). Yet, a series of other chemically and pharmacologically related phenylethylamines, including dopamine (90 mug), were not tremorogenic even at substantially higher doses. The d-amphetamine tremors developed rapidly, failed to exhibit tachyphylaxis to repeated challenging doses (15 mug) and were not influenced by pretreatment with alpha-methyl-p-tyrosine. They also developed independently of local acetylcholine activity as evidenced by the inability of cholinergic antagonists (scopolamine and hemicholinium) to interfere with the tremors. Significant qualitative differences were found between the I.C. effects of d-amphetamine (15 mug) and dopamine (15-90 mug): d-amphetamine further increased the intensity of ongoing tremors induced by physostigmine (111 mug I.C.), whereas, dopamine readily inhibited the latter. When superimposed, I.C. dopamine was equally effective in suppressing d-amphetamine tremor activity. The results emphasize the selective tremorogenic actions of d-amphetamine and call attention to the contrasting stabilizing role of dopamine. This would suggest that two types of adrenergic receptor sites are operative in the caudate in neuroregulation of involuntary movements.

Amphetamines↗
PubMed1975

Contrasting local effects of MAO inhibitors on caudate tremor activities.

Hindlimb tremor was produced in chronic cats by intracaudate microinjection of the monoamine oxidase (MAO) inhibitors tranylcypromine and harmaline throughout a range of doses (150-385 mug). Pargyline, however, was non-tremorgenic within the same range, suggesting that interference with MAO is not sufficient in itself to elicit tremor. Tranylcypromine tremors differed from those of harmaline by exhibiting a slower onset, longer duration and susceptibility to antagonism by hemicholinium. In contrast, ongoing cholinergic tremors following intracaudate physostigmine were variably suppressed by all three MAO inhibitors at comparable dose levels (175-200 mug); pargyline produced the most complete suppression. These results indicate that MAO inhibitors can modify tremor activities in a differential manner dependent both on the functional state of the caudate nucleus and on the ability of cartain MAO inhibitors to exert other local actions.

Alkaloids↗