*2.2. Rotenone-Induced Parkinsonian Models in C. elegans Profit from HT and HD*

Exposure to the pesticide rotenone induces the parkinsonian syndrome in wild type *C. elegans*, which manifests in impaired fitness and movement [50]. A swim assay (illustrated in Figure 4D,E) was performed to determine whether HD and HT are able to reduce the rotenone induced symptoms. 10 μM rotenone strongly impaired the movement capacities at the 3rd and 7th day of adulthood in all tested parameters (Figure 4A–C) when compared to untreated nematodes at the same age (Figure 2A–C). Interestingly, both polyphenol treatments showed similar beneficial effects on nematodes suffering from rotenone at both tested ages. The body wave number (illustrated in Figure 4F) was decreased by up to 30% and 24% after HD- and HT-treatment, respectively (Figure 4B). The thrashing speed was increased after HT-treatment by 68% and 56% at the 3rd and 7th day of adulthood, respectively and by 119% and 55% at the 3rd and 7th day of adulthood, respectively, after HD- treatment (Figure 4A). But the strongest effects were observed in the activity index with an increase of 142% (A3) and 116% (A7) after HT-treatment and 209% (A3) and 58% (A7) after HD-treatment (Figure 4C).

**Figure 4.** Effect of HD and HT on rotenone induced locomotion impairment. 10 μM rotenone administration with and without simultaneous HD or HT treatment started at the fourth larval stage. The wave initiation rate (**A**), the body wave number (**B**) and the activity index (**C**) are shown at the third (A3) and seventh (A7) day of adulthood. Data are pooled from two biological repeats with ≥44 worms per treatment and age. The bars represent the mean ± SEM and differences compared to control were considered significant at *p* < 0.05 (\*) and *p* < 0.001 (\*\*). The appearance of single frames in swim analysis are shown before (**D**) and after (**E**) image processing. In addition, single nematodes recognized by CeleST (as indicated by the green outline) are shown with increasing number of body waves (**F**). The blue scale bars represent 2.5 mm (**D**,**E**) and 200 μm (**F**), respectively.
