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Biomedical subjects

H H Jasper

Publications and source records attributed to H H Jasper.

At least 19 recordsLinked to original sources
PubMed1979

Modulatory role for biogenic amines in the cerebral cortex. Microiontophoretic studies.

In order to investigate the mode of action of biogenic amines in rat cerebral cortex, the unitary activity of spontaneously firing neurons and their excitatory response to acetylcholine (ACh) were examined using microiontophoretic administration of dopamine (DA), noradrenaline (NA) and serotonin (5-HT). The predominant effect of these biogenic amines on the spontaneous activity was a profound and prolonged inhibition of firing (2-4 min), which attained its maximum within 15-120 sec. This response was generally more abrupt in onset and of greater magnitude with NA and 5-HT than with DA. Most units inhibited by DA, NA and 5-HT also showed marked depression of their excitatory response to ACh when pretreated with these biogenic amines. With repetitive administration of ACh, it could be shown that the total duration of inhibition of ACh responses by DA and NA was not as prolonged as the inhibition of the spontaneous firing of the same cells. With 5-HT, the initial ACh responses of many neurons could be completely blocked, and this inhibitory effect lasted as long as the inhibition of spontaneous firing. In view of the anatomical data demonstrating a relative sparsity of monoamine nerve terminals in cerebral cortex, the strong inhibition induced by DA, NA or 5-HT may have reflected slow inactivation of the biogenic amines. However, it could also be indicative of underlying mechanisms of action dependent on metabolic changes. Indeed, the interaction between biogenic amines and ACh might imply a balance between the intracellular pools of cAMP and cGMP is directly or indirectly influenced by the biogenic amines and ACh, respectively. This hypothesis would not exclude other modes of local interaction between DA, NA, 5-HT and ACh, and appears compatible with the modulatory role of biogenic amines in cerebral cortex.

Acetylcholine↗
PubMed1977

Taurine treatment of spontaneous chronic epilepsy in a cat.

Administration of taurine to a cat suffering from naturally occurring chronic (about 3 years) epilepsy caused disappearance of the clinical manifestation of the seizures as well as a marked improvement in the previously grossly abnormal EEG. The treatment consisted of injections of taurine initially, followed by a more prolonged administration of the amino acid by mouth. The combined methods of administration seemed essential for the success of the trial. To date (5 months post-taurine) the animal has suffered only one "grand mal" type seizure which occurred 3 months after the last dose of taurine was administered. Disappearance of the seizures preceded by several weeks the improvement in the EEG. In accordance with previous findings by a number of investigators, the results of this study suggest an immediate depressant action of taurine on hyperexcitable cortical neurons, followed by a more long-lasting, ameliorative influence on cerebral metabolism contributing to an increased resistance to epileptic discharge.

Administration, Oral↗
PubMed1971

Acetylcholine liberation from cerebral cortex during paradoxical (REM) sleep.

The rate of liberation of free acetylcholine from the surface of prostigmin-treated cerebral cortex in the freely moving cat has been determined in states of slow wave sleep, paradoxical or activated sleep, and waking. The average rate during slow wave sleep (1.2 nanograms per minute per square centimeter of cortical surface) increased during paradoxical sleep (2.2 nanograms per minute) and during waking (2.1 nanograms per minute). The rate of acetylcholine release is thus related to the electroencephalogram pattern of desynchronized activatin of the cortex rahter than to the behavioral responsiveness of the animals.

Acetylcholine↗