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Catecholamine uptake in cerebral cortex: adaptive change induced by fighting.
Science (New York, N.Y.)
|June 8, 1973
Summary
Fighting stress alters norepinephrine (NE) brain uptake. Chronic attack lowers NE affinity and increases uptake sites, while acute fights also reduce NE affinity and d-amphetamine sensitivity.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Neuropharmacology
Background:
- The catecholamine uptake process in the brain is crucial for neurotransmitter regulation.
- Stress, particularly social stress like fighting, can significantly impact neurochemical processes.
Purpose of the Study:
- To investigate the effects of fighting-induced stress on the kinetics of catecholamine uptake in the brain.
- To determine how chronic and acute fighting influences norepinephrine (NE) uptake and its inhibition by d-amphetamine.
Main Methods:
- Assessing the kinetics of norepinephrine uptake in cerebral cortical homogenates from mice subjected to different fighting paradigms.
- Measuring apparent Michaelis constant (Km) and maximum velocity (Vmax) for NE uptake.
- Determining the inhibition constant (Ki) for d-amphetamine inhibition of NE uptake.
Main Results:
- Group-caged mice under chronic attack showed increased Km for NE uptake and increased Ki for d-amphetamine inhibition, indicating lowered affinity.
- Male mice after acute intense fights exhibited increased Km and Vmax for NE uptake, suggesting reduced affinity and more uptake sites.
- These changes in NE uptake kinetics were observed 18-20 hours post-fight.
Conclusions:
- Social stress from fighting alters norepinephrine reuptake in the cerebral cortex.
- Fighting stress leads to decreased affinity for norepinephrine reuptake and an increase in the number of available uptake sites.
- Stress-induced changes also result in a lowered affinity for d-amphetamine inhibition of norepinephrine uptake.