Long Term Administration of Hypericum perforatum Improves Spatial Learning and Memory in the Water Maze.

Abstract

The aim of the present study is to investigate the effects of long-term Hypericum perforatum treatment on spatial learning and memory in rats. Hypericum preparation (HP) standardized to 0.3% hypericin content was administered orally for 9 weeks in doses of 4.3 and 13 m mg/kg corresponding to therapeutic dosages in humans of 0.3 and 0.9 mg of total hypericins daily. A Morris water maze paradigm was used. The mean escape latency over 4 d for the Control group (21.9 s) and HP 4.3 group (21.7 s) was significantly greater than the latency of the HP 13 group (15.8 s). In the probe trial on day 5, the HP 13 group crossed the correct annulus in the SE quadrant more often (4.5) than the other groups: Con (2.4) and HP 4.3 (3.1). After completion of the behavioral experiment, the regional brain concentrations of monoamines and metabolites were estimated in selected brain regions, i.e. prefrontal cortex, hippocampus and hypothalamus. Analysis of variance (ANOVA) demonstrated significant differences in the content of monoamines and metabolites between the treatment groups compared to the Control. The increased 5-hydroxytryptamine (5-HT) levels in the prefrontal cortex correlated positively with the retention of spatial memory. These findings show that the long-term administration of Hypericum perforatum can improve learning and spatial memory with significant changes in the content of monoamines in several brain regions.Key words Hypericum perforatum; water maze; spatial memory; monoamine; prefrontal cortex; 5-hydroxytryptamine west (SW) arbitrarily. Rats were trained to locate a transparent hidden plexiglas platform (10 cmϫ10 cm), 29 cm high and 1 cm below the water surface. The pool was surrounded by several prominent cues to spatial coordinates, including items such as a shelf, several posters, a video camera, illumination lights and the presence of the researcher and one assistant. All rats were given one session of four trials daily for four consecutive days. For each trial, the rat was placed in the water facing the wall of the pool at one of three equally spaced starting points, excluding the quadrant with the platform. The order in which these starting points were used was determined randomly for each trial and changed each day to prevent the use of a simple taxis strategy, but the location of the escape platform was always centered in the SE quadrant. A trial was terminated when the rat reached and entered the platform. If the animal did not find the platform within 60 s it was placed on the platform for 15 s before the next trial was initiated. Rats that failed to find the platform were given a latency score of 60 s. At the end of the day's session, the rat was wiped in a cloth to dry it, and returned to its home cage. The probe trial was conducted the day after the last training session. There was no platform in place during the probe trial, and none of the animals received any drug treatment prior to being placed in the maze. The rats were allowed to swim for 60 s before the end of the session. Data were recorded...

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“…Additionally, IHp showed antidepressant, anxiolytic, antiamnestic, antiinflammatory and analgesic and antistress activities in various animal models 2000a;2000b;2001a;2001b;Zhang, 2004). Some researchers recently found that HP had neuroprotective effects and diminished cognitive impairment and improved spatial learning and memory (Trofimiuk et al, 2005;Silva et al, 2004;Kumar et al, 2003;Widy-Tyszkiewicz et al, 2002;Kumar et al, 2002;Klusa et al, 2001;Kumar et al, 2000c). Other studies confirmed that hyperforin released hippocampal acetylcholine (Kiewert et al, 2004;Buchholzer et al, 2002) and HP reduced the degradation rate of acetylcholine (Re et al, 2003).…”

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“…in the volume of 1.5 mL/kg. This dose corresponds to the human recommended daily dose of 2.8 mg total hypericins (Widy-Tyszkiewicz et al, 2002;Kemper, 2003).…”

Effects of Hypericum perforatum extract on diabetes‐induced learning and memory impairment in rats

“…A number of studies have shown that Hypericum perforatum extract has memory enhancing properties in rodents (Khalifa, 2001; Klusa et al ., 2001, Kumar et al ., 2000). Long term administration of Hypericum perforatum also improves learning and spatial memory of the treated rats (Widy‐Tyszkiewicz et al ., 2002). Another study indicates anxiolytic and antipanic effects of H. perforatum extract on rats tested in the elevated T‐maze (Beijamini and Andreatini, 2003).…”