Dopaminergic neurons feel the heat

Rapid and reversible activation of distinct neural populations using capsaicin - an active component of chilli peppers which leads to a burning sensation - is reported this week in Nature Communications. The model described in this work demonstrates a robust and remotely controlled genetic tool that modulates a specific cell population in mice, without the need for invasive and labour intensive approaches. The ability to control the electrical activity of a neuronal subtype is a valuable tool in deciphering the role of discreet cell populations in complex neural circuits. Many recent techniques that allow remote control of neurons are labour intensive, invasive, and may also cause tissue damage. Richard Palmiter and colleagues show that capsaicin, administered via systemic injection or by voluntary consumption, can be used to increase neural activity in transgenic mice and directly induce dopamine release. They report that capsaicin-induced activation of dopaminergic neurons reversibly alters both physiological and behavioural responses in the knockout mice within minutes and that these effects last around 10mins. They also observe apparent behavioural sensitisation which is similar to the increased locomotor activity elicited by repeated administration of psychostimulants that release dopamine. The team go on to show that this technique is translatable to different neural circuits by applying a similar strategy to serotonergic neurons. The authors suggest that that the selective activation of neurons using this capsaicin based method may be instrumental in the decoding of the neural connectome and how it relates to physiology and behaviour in health and disease.

doi: 10.1038/ncomms1749

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