He upper layer of V1. CB1-positive varicosities presumably contact MAP2-positive dendrites (white arrowheads) and soma (asterisk, yellow arrowheads). Scale, 3 mm. (B) Double immunofluorescent staining of CB1 (magenta) and synaptophysin (green) in the upper layer of V1. Rectangles indicate the ROIs for the correlation coefficient (CC) analysis set on varicosities (orange) and shafts (blue) of CB1-positive structures. Scale, 1 mm. (C) Box and whisker plots showing the CC values of CB1 and synaptophysin in varicosities (var, n = 154 ROIs) and shafts (shaft, n = 140 ROIs). The horizontal lines show the 25th, 50th, and 75th percentiles, and the whiskers show the max and minimum values. Mann-Whitney U test, **: p,0.01. (D) Double immunofluorescent staining of CB1 (magenta) and VGAT, VGluT1, 298690-60-5 price VGluT2 (green). Representative photographs of the upper layer (top row), middle layer (middle row), and deep layer (bottom row) of V1. Scale, 3 mm. (E) Box and whisker plots showing the CC values of CB1 and VGAT, VGluT1, or VGluT2 in each layer of V1 (n = 6 CAL 120 animals each; in the upper layer, n = 1226 ROIs (CB1/VGAT), 1203 ROIs (CB1/VGluT1), 1212 ROIs (CB1/VGluT2); in the middle layer, n = 492 ROIs (CB1/VGAT), 435 ROIs (CB1/VGluT1), 498 ROIs (CB1/VGluT2); in the deep layer, n = 1556 ROIs (CB1/VGAT), 1712 ROIs (CB1/VGluT1), 1492 ROIs (CB1/VGluT2)). The small circles indicate the outliers of the distribution of the CC values. In the box and whisker plots containing the outliers, the bottom of the whisker shows the value of the 25th percentile-1.5IQR. Statistical comparison among layers was performed by Bonferronicorrected Mann-Whitney U test (***: p,0.00033). doi:10.1371/journal.pone.0053082.gEach image was smoothed over 363 pixels to remove high frequency noise on the image. We manually set the ROIs (969 pixels, approximately 1 mm2) at varicosity-like structures and shaft structures in CB1 images. The shaft structure of CB1 was defined as the structure that contains thin fibers with low signal intensity and the varicosity-like structure was defined as the structure that has a large immunopositive area with high signal intensity connected by thin fibers. CC value was calculated as follows: ? ?i 1 Xi{X Yi{Y CC Pn ?? ?? Yi{Y i 1 Xi{X Pn where Xi and Yi indicate the individual pixel intensities of CB1 and each of synaptophysin, VGAT, VGluT1, VGluT2 in a ROI,respectively. X and Y indicate the mean intensity of these components in the ROI. n is total number of pixels in the ROI. CC value ranges -1 to 1, and 1 signifies the perfect overlap of two images.Results Distribution of CB1 in the Visual CortexWe first determined the distribution of CB1 in the visual cortex of P30 mice. Thalami containing the LGN exhibited few immunopositive CB1 signals (Fig. 1A, insert). In V1, the immunopositive CB1 signal 1527786 was mainly observed as fibrous structures in layers II/III and VI (Fig. 1B). In the visual cortex, an intense CB1 signal, localized in the medial area 11967625 of theRegulation of CB1 Expression in Mouse VFigure 3. Developmental change of CB1 expression in V1. (A) Representative western blots of CB1 and GAPDH in V1 at different postnatal ages. (B) Mean and SEM of CB1 blot densities of each age group (n = 8 hemispheres each from 4 animals, one-way factorial ANOVA, p,0.05, post hoc Tukey’s test, *: p,0.05). The blot densities were normalized to the mean density of P10. (C) CB1 immunostaining of the binocular region of V1 at postnatal ages indicated on top. Scale, 100 mm. (D) Layer.He upper layer of V1. CB1-positive varicosities presumably contact MAP2-positive dendrites (white arrowheads) and soma (asterisk, yellow arrowheads). Scale, 3 mm. (B) Double immunofluorescent staining of CB1 (magenta) and synaptophysin (green) in the upper layer of V1. Rectangles indicate the ROIs for the correlation coefficient (CC) analysis set on varicosities (orange) and shafts (blue) of CB1-positive structures. Scale, 1 mm. (C) Box and whisker plots showing the CC values of CB1 and synaptophysin in varicosities (var, n = 154 ROIs) and shafts (shaft, n = 140 ROIs). The horizontal lines show the 25th, 50th, and 75th percentiles, and the whiskers show the max and minimum values. Mann-Whitney U test, **: p,0.01. (D) Double immunofluorescent staining of CB1 (magenta) and VGAT, VGluT1, VGluT2 (green). Representative photographs of the upper layer (top row), middle layer (middle row), and deep layer (bottom row) of V1. Scale, 3 mm. (E) Box and whisker plots showing the CC values of CB1 and VGAT, VGluT1, or VGluT2 in each layer of V1 (n = 6 animals each; in the upper layer, n = 1226 ROIs (CB1/VGAT), 1203 ROIs (CB1/VGluT1), 1212 ROIs (CB1/VGluT2); in the middle layer, n = 492 ROIs (CB1/VGAT), 435 ROIs (CB1/VGluT1), 498 ROIs (CB1/VGluT2); in the deep layer, n = 1556 ROIs (CB1/VGAT), 1712 ROIs (CB1/VGluT1), 1492 ROIs (CB1/VGluT2)). The small circles indicate the outliers of the distribution of the CC values. In the box and whisker plots containing the outliers, the bottom of the whisker shows the value of the 25th percentile-1.5IQR. Statistical comparison among layers was performed by Bonferronicorrected Mann-Whitney U test (***: p,0.00033). doi:10.1371/journal.pone.0053082.gEach image was smoothed over 363 pixels to remove high frequency noise on the image. We manually set the ROIs (969 pixels, approximately 1 mm2) at varicosity-like structures and shaft structures in CB1 images. The shaft structure of CB1 was defined as the structure that contains thin fibers with low signal intensity and the varicosity-like structure was defined as the structure that has a large immunopositive area with high signal intensity connected by thin fibers. CC value was calculated as follows: ? ?i 1 Xi{X Yi{Y CC Pn ?? ?? Yi{Y i 1 Xi{X Pn where Xi and Yi indicate the individual pixel intensities of CB1 and each of synaptophysin, VGAT, VGluT1, VGluT2 in a ROI,respectively. X and Y indicate the mean intensity of these components in the ROI. n is total number of pixels in the ROI. CC value ranges -1 to 1, and 1 signifies the perfect overlap of two images.Results Distribution of CB1 in the Visual CortexWe first determined the distribution of CB1 in the visual cortex of P30 mice. Thalami containing the LGN exhibited few immunopositive CB1 signals (Fig. 1A, insert). In V1, the immunopositive CB1 signal 1527786 was mainly observed as fibrous structures in layers II/III and VI (Fig. 1B). In the visual cortex, an intense CB1 signal, localized in the medial area 11967625 of theRegulation of CB1 Expression in Mouse VFigure 3. Developmental change of CB1 expression in V1. (A) Representative western blots of CB1 and GAPDH in V1 at different postnatal ages. (B) Mean and SEM of CB1 blot densities of each age group (n = 8 hemispheres each from 4 animals, one-way factorial ANOVA, p,0.05, post hoc Tukey’s test, *: p,0.05). The blot densities were normalized to the mean density of P10. (C) CB1 immunostaining of the binocular region of V1 at postnatal ages indicated on top. Scale, 100 mm. (D) Layer.