Related Experiment Videos
Locus coeruleus involvement in the learning of classically conditioned bradycardia
1Vollum Institute, Oregon Health Sciences University, Portland 97201.
Summary
Opioid agonists impair heart-rate conditioned responses by inhibiting locus coeruleus (LC) neurons. This effect on cardiovascular learning was reversed by naltrexone, confirming the LC
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Cardiovascular Physiology
Background:
- Opioid agonists are known to inhibit locus coeruleus (LC) neuronal activity.
- The LC plays a crucial role in central noradrenergic pathways.
Purpose of the Study:
- To investigate the role of the LC in the development of conditioned cardiovascular responses.
- To determine if opioid-induced inhibition of LC neurons affects heart rate (HR) conditioned responses (CR).
Main Methods:
- Microinjections of the mu-opioid agonist DAMGO into the LC of rats.
- Assessment of the development of HR CRs following LC microinjections.
- Administration of naltrexone pretreatment to assess reversibility.
- Control microinjections into adjacent brain structures.
Main Results:
- Bilateral microinjections of DAMGO into the LC significantly impaired the development of HR CRs.
- The inhibitory effect of DAMGO on HR CR development was reversed by naltrexone.
- Microinjections of DAMGO into nearby structures did not affect HR CR development.
Conclusions:
- Central noradrenergic activity mediated by the LC is critical for learning and retention of conditioned cardiovascular responses.
- The LC is a key neural substrate for associative learning involving autonomic functions.