Acute ether stress induced a decrease in hypothalamic serotonin content. The lowest level was observed 20 to 30 min after ether exposure. This was followed by an increase reaching the maximum exceeding the basal level at 60 to 90 min. 120 minutes after stress the hypothalamic serotonin level returned to normal. The maximum plasma corticosterone concentration was observed at 30 min; it returned to normal 90 min after ether stress. Different stressors such as surgical, formalin, electric shock, histamine, cold and restraint caused a similar depletion in the hypothalamic serotonin content and a rise of the plasma corticosterone level at 30 min. At 90 min the plasma corticosterone level returned to normal and the hypothalamic serotonin content approached the normal values in restrained and cold stressed animals. After other stressors the plasma corticosterone level was still higher than the basal level at 90 min and it was associated with a different level of serotonin content. Adrenalectomy decreased the serotonin content in the hypothalamus and after ether stress a small but significant decrease could be observed which was normalized at 60 min. A single dose of corticosterone increased the plasma corticosterone level and the hypothalamic serotonin content. It was also able to restore the serotonin level in adrenalectomized animals. Prolonged treatment with 1 mg/kg b.w./day for 7 days had no effect 24 hours after the last injection. A single dose of ACTH increased corticosterone secretion and hypothalamic serotonin content. After adrenalectomy, this treatment was ineffective. Chronic ACTH treatment had no effect. The data indicate that acute stress induces a biphasic change in the hypothalamic serotonin content. The first phase consists of a decrease of the hypothalamic serotonin content, which precedes the increase in plasma corticosterone level and seems to be independent of the pituitary adrenal system, and a second phase characterized by an increase of the hypothalamic serotonin level and its return to normal. In these changes, the increase of adrenal corticosterone secretion may play an important role.
|Number of pages||10|
|Journal||Acta physiologica Academiae Scientiarum Hungaricae|
|Publication status||Published - Dec 1 1973|
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