Effects of stressful procedures as ether anesthesia and intracranial injections on amino acid incorporation into brain protein.

Ether anesthesia elevates plasma corticosterone levels considerably and interferes severely with the incorporation of centrally applied [3 H] leucine into brain protein. Only minor changes in leucine incorporation are observed in conscious rats with an implanted cannula in the third brain ventricle as compared to noncannulated controls. Injection through this cannula can be regarded as a minor stressful procedure comparable to subcutaneous injection both causing moderate elevations in plasma corticosterone levels. Injection through the cannula per se did not affect the leucine incorporation. In studies which require local application of the radioactive precursor, it is therefore recommended to avoid ether anesthesia and to use a preimplanted cannula in the brain ventricular system.