Interaction between Atropine and Hexobarbital in the Abstinence after Chronic Barbital Treatments in the Rat
After chronic treatments with barbital a decreased sensitivity to hexobarbital can be observed in rats. Such a decreased sensitivity is usually called tolerance and it can be detected for at least 60 days after the end of a 50 week long barbital treatment (8). There is a positive relation between the duration of the treatment and the duration of the tolerance found in the abstinence (2). Spontaneous convulsions during abstinence are usually regarded as a sign that physical dependence has been induced by the treatment. The frequency of the spontaneous convulsions also seems to depend on the duration of barbital treatment and can be recorded at least for the first five weeks of abstinence after 50 weeks of barbital treatment (8). Since convulsions can decrease tolerance to hexobarbital a relation seems to exist between these two variables (3). Thus, long term treatments with barbital can induce changes in the CNS indicating increased escitation which lasts for a long time during the abstinence. Several changes in brain cholinergic mechanisms, indicating increased activity, have also been found during abstinence (Nordberg and Wahlstrom, this volume) and these changes might be related to the tolerance and physical dependence described above (6).
KeywordsLasting Effect Brain Weight Physical Dependence Cholinergic Activity Cholinergic Mechanism
Unable to display preview. Download preview PDF.