1. In Figure 2, the upper panel (physiological state) shows insulin activating PI3K/Akt signaling in endothelial cells, but the text (Section 4.2) clearly states that endothelial insulin receptor knockout does not impair baseline glucose homeostasis or vascular development. How do you reconcile this figure with the fact that endothelial insulin signaling appears largely dispensable for normal BBB function?
2. In Section 4.1, you cite Rhea et al. (2018) showing insulin crosses the BBB independently of insulin receptors, yet later state that endothelial insulin receptor knockout reduces ZO-1 expression and increases BBB permeability. If transport does not require the receptor, why would loss of the receptor affect BBB integrity? This mechanistic inconsistency is not addressed.
3. Figure 3 claims optogenetic control of LRP6. This is a transmembrane co-receptor, not an ion channel or opsin. What is the specific optogenetic tool used to precisely control LRP6? The cited reference (Wang et al., Brain 2022) does not describe optogenetics. This appears to be either a figure error or an unsupported statement.