Figure 3.

Differential DAGLα and DAGLβ expression and localization in aged human hippocampus and in Alzheimer’s disease. (A) Schematic overview of hippocampal subfields with open rectangles identifying the localization of dendritic fields shown in B and F. (B) MAP2⁺ dendritic shafts (arrows) are embedded in a fine meshwork of DAGLα⁺ and/or DAGLβ⁺ puncta, with the density of DAGLα immunoreactivity surpassing that of DAGLβ in the aged human hippocampus (control). (C) High-resolution imaging reveals coexistence of DAGLα and DAGLβ (arrowheads) in MAP2⁺ compartments. (D) 3D reconstruction of a MAP2⁺ pyramidal dendrite verifies the postsynaptic recruitment of DAGLs, and high-power rendering positions both DAGLα and DAGLβ in the dendritic spine neck (D₁). (E) Pearson’s correlation coefficient suggests moderate positive correlation between the fluorescence maxima of DAGLα and DAGLβ. (E₁ and E₂) Area occupancy and co-localization coefficients for DAGLα and DAGLβ immunoreactivities verify the greater abundance of DAGLα, and reveal differences in their probability of co-localization, respectively. Data were expressed as means ± SEM. (F) The distribution of DAGLα (arrowheads) does not change around amyloid-β_17-24⁺ senile plaques. However, DAGLβ immunoreactivity focally concentrates in periplaque regions (F₁) in small-diameter cell-like structures (arrowheads, F₁) but not CB₁ cannabinoid receptor⁺ (CB₁R) processes (open arrows). Such DAGLβ⁺ cells closely appose (arrowheads, F₂) CB₁ cannabinoid receptor⁺ axon terminals (arrows, F₂), and, based on their IBA-1 expression, were identified as activated microglia in Alzheimer’s brains (arrows, G–G₂). Asterisks in G–G₂ pinpoint the soma of the microglial cell. CA = Ammon’s horn; DF = dentate fascia; sub = subiculum. Scale bars = 40 μm (B₂), 10 μm (F and F₁), 4 μm (C₃, F₂ and G₃).