FRET based ratiometric Ca(2+) imaging to investigate immune-mediated neuronal and axonal damage processes in experimental autoimmune encephalomyelitis.
J Neurosci Methods 2015;
249:8-15. [PMID:
25864804 DOI:
10.1016/j.jneumeth.2015.04.005]
[Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 04/02/2015] [Accepted: 04/03/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND
Irreversible axonal and neuronal damage are the correlate of disability in patients suffering from multiple sclerosis (MS). A sustained increase of cytoplasmic free [Ca(2+)] is a common upstream event of many neuronal and axonal damage processes and could represent an early and potentially reversible step.
NEW METHOD
We propose a method to specifically analyze the neurodegenerative aspects of experimental autoimmune encephalomyelitis by Förster Resonance Energy Transfer (FRET) imaging of neuronal and axonal Ca(2+) dynamics by two-photon laser scanning microscopy (TPLSM).
RESULTS
Using the genetically encoded Ca(2+) sensor TN-XXL expressed in neurons and their corresponding axons, we confirm the increase of cytoplasmic free [Ca(2+)] in axons and neurons of autoimmune inflammatory lesions compared to those in non-inflamed brains. We show that these relative [Ca(2+)] increases were associated with immune-neuronal interactions.
COMPARISON WITH EXISTING METHODS
In contrast to Ca(2+)-sensitive dyes the use of a genetically encoded Ca(2+) sensor allows reliable intraaxonal free [Ca(2+)] measurements in living anesthetized mice in health and disease. This method detects early axonal damage processes in contrast to e.g. cell/axon morphology analysis, that rather detects late signs of neurodegeneration.
CONCLUSIONS
Thus, we describe a method to analyze and monitor early neuronal damage processes in the brain in vivo.
Collapse