US scientists are following peptide trails to look at how neurons communicate.

Jonathan Sweedler and colleagues at the University of Illinois at Urbana-Champaign have made microfluidic devices to monitor the peptides released by neurons as they communicate. By interfacing the devices with a mass spectrometry imaging technique, the team can both identify the peptides and map their release from the cells. 

The team's system includes a neuron reservoir to which reagents can be added. The team treated the cells with a solution of potassium chloride, stimulating the cells to release peptides. These peptides then flowed through microchannels attached to the reservoir where they were captured by an octadecyl-coated layer on the channel bed. The researchers were able to control solution flow through three different channels so that they gave separate results for before, during and after stimulation.

To analyse the captured peptides, the group separated the peptide layer from the device and examined it using matrix-assisted laser desorption/ionisation mass spectrometry (MALDI MS). This was combined with imaging software to show where the peptides were on the layer and their identities.

Robert Kennedy, an analytical chemist at the University of Michigan in Ann Arbor, US, welcomed the research. 'This adds substantially to the armamentarium of both microfluidics and single neuron studies as a simple approach to MALDI-MS imaging of chips,' he said. 'It should prove useful in answering long-standing questions about how neurons use peptides to communicate.'

Rachel Warfield