Abstract
The cellular localization of tritiated norepinephrine (H3-NE) injected into the cerebral ventricular system was studied by electron-microscopic autoradiography. The distribution of autoradiographic grains in control and drug-pretreated (reserpine and desmethylimipramine) animals was compared. In the controls, intraventricular injection of H3-NE resulted in intense autoradiographic activity over nerve endings and axons in the hypothalamus and caudate nucleus. Hypothalamic endings with autoradiographic activity also usually contained some dense-core (granular) vesicles. Reserpine (2 mg/kg i.v.) given 2 hr prior to the H3-NE almost completely abolished the autoradiographic activity. However, the dense-core vesicles were unchanged in number or electron density. Forty-eight hours after reserpine treatment there was considerable recovery of the ability of endings to retain the H3-NE and the pattern of localization of autoradiographic activity was almost identical to the controls. For example, in the hypothalamus, grains were again over endings with dense-core vesicles. Pretreatment with desmethylimipramine (20 mg/kg) also did not alter the normal cellular patterns of localization. These results suggest that certain nerve endings (e.g., in hypothalamus and caudate) can accumulate the H3-NE given via the ventricular route. The rapid return in the ability of nerve endings to retain H3-NE 48 hr after reserpine is correlated with gross behavioral recovery.
Footnotes
- Received November 1, 1966.
- Accepted January 25, 1967.
- © 1967 by The Williams & Wilkins Company
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