Study 20
Pharmaceutic investigations of the antidepressant effect of Hypericum perforatum L
AU: Winterhof-H, Butterweck-V, Nahrstedt-A, Gumbinger-HG, Schulz-V, Erping-S, Bosshamer-F, Wieligmann-A
SO: "Phytopharmaka in Forschung und klinischer Anwendung" Loew D :1995 Steinkopff Verlag GmbH & Co. KG. Darmstadt S39-52
Basal Temperature
Hypericum extract did raise the basal temperature in mice a statistically significant amount. The effect lasted for more than 4 hours.
The ketamin sleeping time
Hypericum and Buproprion (a dopamine reuptake inhibitor) did shorten ketamin-induced sleeping time in rats; the opposite effect of Imipramine, which lengthened the sleeping time. Hypericin alone was not as effective.
The open field test
Hypericum did not show any unspecific activating effects on male rats in the so-called "open field test" (a test where you measure the spontaneous activity of rats by the amount of lines crossed in a field).
Forced swimming "Porsolt test"
In the so-called "forced swimming" or "Porsolt test" hypericum showed an effect similar to Imipramine on the behavior of mice.
The Porsolt test measures how long mice remain immobile in a stress situation. It can be seen as a way to measure the "fighting spirit" of mice and has previously been proven to be an effective indicator of the antidepressant effect of different pharmaceutical compounds.
In this study it was found that 125 mg of 0.24-0.32% hypericum extract had an effect similar to 10 mg Imipramine on the forced swimming behavior of mice. This indicates that 10 mg of Imipramine could be seen as equivalent to 0.35 mg of total hypericin (0.28 % x 125 mg = 0.35 mg).
Porsolt test together with dopamine blockage
When exposed to the dopamineantagonists Haloperodol (Haldol) and Sulpirid, the effect of hypericum in the Porsolt test was blocked. Rats only given Haloperidol and Sulpirid also performed better. This indicates that dopamine might be of great importance in the effect of hypericum extract.
Effect on dopamine metabolism
Hypericum extract did increase the ratio of homovanillin acid to dopamine in rat brains. This indicates an increased turnover of dopamine as a result of hypericum medication.
Effect on prolactin and cortisol levels
Both serum-cortisol and serum-prolactin were lowered significantly after three weeks of treatment with hypericum extract in male rats. The lowering of prolactin is an indirect indicator of a dopamine effect of hypericum extract, as an increase of dopamine generally leads to a decrease of prolactin and vice versa.
Copyright © 1996 by Harold H. Bloomfield, M.D. and Peter McWilliams
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