Observation of Acetylcholinesterase in Stress-Induced Depression Phenotypes by Two-Photon Fluorescence Imaging in the Mouse Brain

Abstract

Oxidative stress in depression is a prime cause of neurotransmitter metabolism dysfunction in the brain. Acetylcholinesterase (AChE), a key hydrolase in the cholinergic system, directly determines the degradation of neurotransmitters. However, due to the complexity of the brain and lack of appropriate in situ imaging tools, the mechanism underlying the changes in AChE activity in depression remains unclear. Hence, we generated a twophoton fluorescence probe (MCYN) for real-time visualization of AChE with excellent sensitivity and selectivity. AChE can specifically recognize and cleave the carbamic acid ester bond in MCYN, and MCYN emits bright fluorescence at 560 nm by two-photon excitation at 800 nm. By utilizing MCYN to monitor AChE, we discovered a significant increase in AChE activity in the brains of mice with depression phenotypes. Notably, with the assistance of a two-photon fluorescence imaging probe of the superoxide anion radical (O 2•− ), in vivo visualization for the first time revealed the positive correlation between AChE and O 2•− levels associated with depressive behaviors. This finding suggests that oxidative stress may induce AChE overactivation, leading to depression-related behaviors. This work provides a new and rewarding perspective to elucidate the role of oxidative stress regulating AChE in the pathology of depression.

A molecular approach to rationally constructing specific fluorogenic substrates for the detection of acetylcholinesterase activity in live cells, mice brains and tissues

“…[40][41][42] Recently, two groups proposed uorescent probes using the dimethyl-carbamate unit for the detection of AChE activity. 43,44 However, this carbamate moiety may react with CE. [45][46][47] Thus, developing a general uorogenic substrate for the specic detection of AChE remains a great challenge.…”

Facile Synthesis of Efficient Luminogens with AIE Features for Three‐Photon Fluorescence Imaging of the Brain through the Intact Skull

“…[ 4 ] Through optical access to the mouse brain by common craniotomy, researchers can obtain clear images through 2PF microscopy. [ 5 ] However, even with the help of a cranial window, 2PF imaging is generally limited to image the superficial depth due to light scattering of the excitation beam in biosubstrates. [ 6 ] Moreover, such invasive operation is far from satisfactory in practical application owing to the permanent loss of integral skull that results in a low survival rate of animal after operation.…”

Each phenyl group performs its own functions on luminescence: phenyl substituted effect in tetraphenylpyrazine

“…Organic p-conjugated fluorescent materials have been investigated in the past several decades owing to their promising applications in organic light-emitting diodes (OLEDs), [1][2][3][4][5][6] chemical sensors [7][8][9][10][11] and biological imaging. [12][13][14][15][16][17] However, the notorious problem of these classical luminescent materials is the familiar aggregation-caused quenching (ACQ), i.e., they weakly emit in their aggregated states such as powder and crystals compared to their dilute solutions. 18 To overcome this issue, Tang et al proposed the opposite phenomenon, namely, aggregation-induced emission (AIE).…”