Nom Nom Neurons

Ever felt like you can’t get rid of that insatiable hunger? You know you don’t need to eat but you definitely want to. How strong is your will power? Well imagine if someone could shine a light in your brain to make your hunger go away and get that diet back on track. Scientists at the University of North Carolina have found a specific pathway of neurons that, when activated or deactivated using a fancy technique called optogenetics (more on that later) can vastly alter the feeding habits of mice.

In a paper published in world leading journal Science, Jennings et al. (2013) showed that neurons connecting the lateral hypothalamus and the bed nucleus of the stria terminalis (BNST) are heavily involved in the feeling of hunger. When they activated these neurons they observed “voracious feeding behaviour” even in particularly well fed mice, these mice also showed a marked preference for high calorie foods over the healthy stuff (I reckon we all know about that one). If the links weren’t already in your mind they also found that the mice liked this effect and “actively nose-poked for photoactivation of the circuit”.

So what happens when you deactivate the pathway? Well the scientists tried that one too and surprise surprise the mice started to eat less. In fact feeding was even reduced in food-deprived mice.

But how on earth do you alter the activity on neurons on the spot in a live mouse? Well that’s where this clever technique call optogenetics comes in. The technique involves genetic modulation of a mouse to introduce ion channels or enzymes that are only activated when stimulated by light of a certain wavelength and means scientists can activate specific neurons (opening certain ion channels will activate the cell). This solves one of the major problems with classical genetic manipulation in that the effect is instantaneous. The implications of such a technique are huge and are beginning to make serious noises in the scientific community, watch this space!

So this all sounds pretty handy right? Shine a light and wave away all your heavy burdens (see what I did there). It could be a real weight off your mind (ok I’ll stop I promise). However as always there’s a fair few reasons Mr Weightwatchers needn’t worry just yet and I bet you’ve spotted the big one in the paragraph above. This technique relies on genetic manipulation, something I doubt anyone would be volunteering for just to drop the bingo wings. The activation system also required a source of light to be implanted and positioned in the correct area of the mouse brains, again not too sure I’d be putting my hand up for that one. Another interesting point was that they found that the mice with the deactivated neurons (and therefore with reduced food consumption) did not enjoy this feeling and avoided the deactivation, in other words it might make you skinny but you won’t be feeling too great!

Okay so I may have played up the whole implications of this research, however as I always say this is another really fascinating insight into the mechanisms of how our brains work, specifically how a bunch of electrical signals lead to that feeling of hunger we know so well. We’re learning more and more about the brain and with techniques such as optogenetics beginning to reveal their true potential the next few decades will certainly be some exciting ones for neuroscientists.

PS. Apologies for the slightly unrelated featured image. That cake was actually baked by me and another student upon leaving the neuroscience department at MedImmune. Shameless plug for one’s own baking.

 

Original Article

JENNINGS, J.H. et al. 2013. The Inhibitory Circuit Architecture of the Lateral Hypothalamus Orchestrates Feeding. Science [online]. 341(6153),pp.1517–1521. Available from: http://www.sciencemag.org/cgi/doi/10.1126/science.1241812 [Accessed September 26, 2013].

Written by Mike Daniels

Mike Daniels

I’m currently studying for a PhD in neuroinflammation at the the University of Manchester, UK. My work is based mainly on the role of a huge protein complex called the inflammasome in diseases such as Alzheimer’s, stroke and haemorrhagic fever.
When I’m not in the lab I’m usually found up a mountain or out in the countryside somewhere and am always on the lookout for any new science outreach ideas!

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