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K Ornstein

Publications and source records attributed to K Ornstein.

5 recordsLinked to original sources
PubMed1987

Biochemical and radioautographic evidence for dopaminergic afferents of the locus coeruleus originating in the ventral tegmental area.

The dopamine (DA) content of the locus coeruleus (LC) and the uptake of tritiated DA in the presence of desmethylimipramine into fresh vibratome sections of the LC-area were determined in control rats and in rats whose ventral tegmental area (VTA) had been destroyed by local application of 6-hydroxydopamine (6-OHDA). Destruction of the VTA reduced the DA content and the number of dopaminergic fibers visualized by radioautography in the LC area. This indicates that the DA containing afferents of the LC originate, at least partly, in the VTA.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

The morphogenesis of stereotyped behavior induced by the dopamine receptor agonist apomorphine in the laboratory rat.

The seemingly unrelated stereotyped locomotor "acts" reported in the literature to be produced by apomorphine in rats are shown to be composites, whose form and sequence are determined by the particular values of a few component variables which form a common denominator in each of the behaviors. Three variables, continuous snout contact, forward progression and turning, account for much of the behavior. In the course of the drug's action these emerge in succession and vary in amount, the latter two successively reaching a peak and subsiding. The interaction between forward progression and turning yields in sequence, forward walking, circling, revolving, tight pivoting and finally side-to-side movements of the forequarters around the relatively stationary hindquarters. Later behaviors in this list are gradually incorporated into the sequence as earlier ones are eliminated. The course of change in forward progression and turning is also reflected in changes in the sequence and in the direction of stepping of each of the four legs. The order in which the behavior unfolds under the drug is opposite to that manifested in ontogeny and in recovery from lateral hypothalamic damage, suggesting that at the particular high dose used, apomorphine is acting not only to activate the behavior but also to shut it down.

Animals↗
PubMed1977

Interaction between morphine and reinforcing lateral hypothalamic stimulation.

The interaction between morphine and lateral hypothalamic self-stimulation in rats was investigated in three experiments. In nonaddicted animals injections of moderate doses of morphine (8 mg/kg) resulted in a short-lasting increase in the self-stimulation threshold. Injections of low doses (2 mg/kg) did not alter the self-stimulation threshold significantly. In addicted animals self-stimulation thresholds were significantly lower 2 h compared to 22 h after injection of 200 mg/kg morphine hydrochloride (calculated as the salt). A 16 mg/kg injection of morphine in non-addicted rats suppressed self-stimulation. However, when the animals were administered noncontingent priming stimulation and were hand-shaped toward the lever whenever they left it, they continued to lever-press throughout the entire 90-min postinjection testing period. The animals that were neither primed nor shaped (and therefore remained unstimulated), however, showed a significantly better recovery when tested 90 min after the injection; i.e., their response rate was higher than that of the primed and shaped animals, which were engaged in bar-pressing throughout the entire testing procedure.

Animals↗