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Close relation between hypothalamic and cardiac norepinephrine during stress and its role in acute myocardial
Insights
Stress-induced norepinephrine depletion in the brain and heart is blocked by pargyline and imipramine. Other drugs like chlorpromazine and lithium showed varied effects on norepinephrine levels in different organs during stress and anoxia.
Area of Science:
- Neuropharmacology
- Stress Physiology
Background:
- Stress significantly impacts neurotransmitter levels, particularly norepinephrine.
- Understanding the differential effects of pharmacological agents on norepinephrine regulation is crucial.
Purpose of the Study:
- To investigate the effects of various drugs on norepinephrine levels in different organs under stress.
- To examine norepinephrine uptake and levels in cardiac tissue during anoxia.
Main Methods:
- Administering pargyline, imipramine, chlorpromazine, and lithium to assess their impact on stress-induced norepinephrine changes.
- Measuring norepinephrine levels in hypothalamus, heart, spleen, and adrenals.
- Evaluating the uptake of H3-norepinephrine in isolated guinea-pig atria under anoxic conditions.
Main Results:
- Pargyline and imipramine prevented norepinephrine decrease in hypothalamus and heart, but not spleen or adrenals.
- Chlorpromazine and lithium specifically prevented norepinephrine decrease in the spleen.
- Anoxia increased H3-norepinephrine uptake in isolated atria, while reoxygenation caused a >50% decrease in norepinephrine levels.
Conclusions:
- Pargyline and imipramine exhibit protective effects on norepinephrine in central and cardiac tissues during stress.
- Chlorpromazine and lithium demonstrate organ-specific modulation of norepinephrine levels.
- Cardiac norepinephrine levels are highly sensitive to oxygen availability, with significant depletion during reoxygenation after anoxia.
Abstract:
The decrease of the norepinephrine levels in hypothalamus and heart caused by stress is prevented by pargyline and imipramine. Such a decrease in spleen and adrenals is not affected. Chlorpromazine and lithium only prevented the norepinephrine decrease in the spleen. The uptake of H3norepinephrine by isolated atria of guinea-pig increases during anoxia; the change to a normal oxygen situation decreases these norepinephrine levels by more than 50%.