A comparison of viral strategies and model systems to target norepinephrine neurons in the locus coeruleus reveals high variability in transgene expression patterns
Fig 5
Behavioral screening of cre-expressing mice.
(A) Left: To assess anxiety-like behavior, mice were placed in one corner of the arena and left to explore the open field arena for 20 min. Right: The percentage of time spent in the center of the arena indicates no difference in anxiety-like behavior of cre-expressing mice (filled bars) as compared to wild-type littermates (empty bars) of different driver lines. (B) Left: To further test anxiety-like behavior, mice were placed on the central platform of the elevated plus maze and left to explore the maze for 5 min. Right: The percentage of time spent in open arms indicates no difference in anxiety-like behavior of cre-expressing mice as compared to wild-type littermates in any driver line. (C) Left: To assess working memory, mice were placed in the center of the Y-maze and left to explore the maze until 26 transitions were made, for a maximum of 15 min. Upon the first transition between arms (black arrow), the next transition is expected to occur towards the previously unexplored arm (green arrow), rather than to the arm that was just visited before (red arrow). Right: The percentage of alterations (i.e., consecutive visits of all three arms) over the total number of transitions is above chance level (dashed line) in all groups, while no genotype-dependent differences in working memory were detected between cre-expressing mice and wild-type littermates in any mouse line. (D) Left: To test spatial memory, mice are trained to find a hidden platform in a circular pool filled with opaque water on two consecutive days. On day three, the platform is removed, and the time spent in the area where the platform was previously located serves as a proxy for spatial memory. Right: the percentage of time spent in the platform quadrant was above chance level (dashed line) in all groups, while no genotype-dependent differences in spatial memory were detected between cre-expressing mice and wild-type littermates in any mouse line. All data is depicted as mean ± standard error of the mean. ns = not significant. **/*** for p < 0.01/0.001, respectively, tested against chance level. n = 8 females (circles) and 8 males (triangles). Numerical data underlying this figure can be found in S1 Data.