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Pineal N-acetyltransferase activity: effect of sympathetic stimulation
Science (New York, N.Y.)
|August 27, 1971
Summary
Sympathetic nerve stimulation increases pineal N-acetyltransferase activity. However, activity returns to baseline even with continued stimulation, explaining circadian rhythms in blinded animals.
Area of Science:
- Neuroscience
- Chronobiology
- Biochemistry
Background:
- The pineal gland regulates circadian rhythms.
- N-acetyltransferase is a key enzyme in melatonin synthesis.
- Sympathetic nervous system input influences pineal gland function.
Purpose of the Study:
- To investigate the effect of sympathetic stimulation on pineal N-acetyltransferase activity.
- To understand the mechanism behind the persistence of circadian rhythms in the absence of light cues.
Main Methods:
- Stimulation of preganglionic sympathetic fibers to the superior cervical ganglia in animal models.
- Measurement of pineal N-acetyltransferase activity over time.
Main Results:
- Sympathetic stimulation caused a rapid increase in pineal N-acetyltransferase activity.
- Enzyme activity returned to baseline levels despite continued nerve stimulation.
- This decrease occurred irrespective of whether stimulation was maintained.
Conclusions:
- The ability of pineal N-acetyltransferase activity to decrease during sustained stimulation is crucial.
- This regulatory mechanism likely explains the persistence of circadian rhythms in blinded animals.
- Suggests a feedback or desensitization process within the sympathetic-pineal pathway.