Extract preparation from Sideritis scardica enhances memorizing skills of mice in Morris water maze
The Greek mountain tea is well known in Europe, occurring mainly in Turkey, Bulgaria and Greece. The botanical species hereof is Sideritis scardica Griseb. Over centuries it was used as relaxing tea (so called Shepard's tea or Mursalski tea). Actual in vitro investigations showed influence on reuptake-inhibition of neurological transmitters by Sideritis scardica extracts. Due to this, investigations were performed about in-vivo effects of Sideritis extracts relating to mental CNS disorders (Alzheimer's disease) and cognition.
As an established test model for cognition and spatial memory, we used the Morris water maze (MWM). Beginning with this model 30 years ago, healthy mice were tested treatment group vs. non-treatment group. Newest investigations demonstrate that a within-subject comparison approach is both valid and effective in reducing variability. Today, transgenic AD mice are available which allow testing of active substances against AD. Therefore, we introduced a Ginkgo biloba extract as positive control which is used as off-label cognition enhancer in elderly and AD patients. Following four groups (n = 6) were tested:
transgenic AD mice (Alzheimer's disease model in C57BL/6 background, untreated as control 1);
healthy background control mice (C57BL/6, untreated as control 2);
transgenic AD mice treated with Sideritis scardica extract;
transgenic AD mice treated with Ginkgo biloba extract (acc. Ph.Eur.)
Healthy control group (2) showed reduced latencies (-20%) as compared to the transgenic group (1, AD control), which confirms the suitability of (1) for our approach. The group (3) of Sideritis scardica treated AD mice showed significant lower latencies (-60% vs. control 1, and -40% vs. control 2, resp.), whereas the group of Ginkgo treated mice did not differ from any control 1 or 2. The behavioral testing results for the Sideritis group (3) correlate with the histopathological finding – reduction of total ß-Amyloid amount by 55% vs. control (1).