Feeding Research

4 posts / 0 new
Last post
mfudge
mfudge's picture
Feeding Research

Just wanted to open a forum to discuss current research in feeding. Am a PhD student at The University of Western Ontario. I'm very interested in discussing taste reactivity and the behaviours that are measured to further understand the range of combinations of behaviours measured across different labs. Does anyone think a standard approach could ever be developed?

Donald Sweet
Donald Sweet's picture
I did my doctoral research on

I did my doctoral research on the neural basis of appetite regulation. I'm not sure what you mean by "taste reactivity," though we did a lot of work on flavor discrimination and diet pallatability in our lab.

All of my work involved neuropeptides, mostly orexin-A/hypocretin-1, also NPY, leptin, and opioids. If you can be more specific in your question, I might be the guy you want to talk to...

Don

mfudge
mfudge's picture
Hi Don,

Hi Don,

Sorry for not being clear in my question. Taste reactivity is a behavioural test created by Grill and Norgren in 1978 that looks at the orofacial responses of rats to a direct infusion of a solution (like sucrose, etc). The great thing about this test is that the facial responses are reflexes and are common across species. We can learn more about how taste mediates food intake by looking at how a rat's reaction to the palatability (how good it takes) of the solution is altered. There are two categories of behaviours: ingestive "yum" responses and active rejection "yuck" responses. There is at the moment no standard on which behaviours should be included in these categories. So depending on the lab that the paper came from, each category measures a different set of behaviours. For example: yum responses can include mouth movements, pawlicking and tongue protrusions. Yuck responses can include gapes, chin rubs, paw treading, forelimb flails and head shakes. Not all of these behaviours have been correlated to signalling either yum or yuck. Head shakes happen even if just plain water is infused so it's not necessarily a yuck response.

I'm interested in discussing what behaviours should be paid attention to.

I am also interested in talking about feeding and appetite regulation in general though. In my work, I use a behavioural approach and focus on the hormonal regulation of food intake. My master's looked at the effects of the progesterone metabolite allopregnanolone on food intake. I am currently looking into different aspects of estrogen and estrogen based drugs on feeding.

Mel

Donald Sweet
Donald Sweet's picture
Mel,

Mel,

I sure did misunderstand where you were coming from! I remember learning about that type of study at some point, but I'm afraid I have no experience with it.

I think the only intelligent thing I can add is that I agree it's not only a good idea but also necessary to agree on standards. A lack of standards in any outcome variable makes it way too easy to see what we want to see in our data. But I KNOW you already knew that! ;o)

I've recently moved on to doing Morris water maze studies, and I've found a similar lack of standards on what I believe is a much more common test. There are no standards for water opacity or for which of the MANY variables measured by tracking software are actually meaningful measurements of spatial learning.

That being said, a few ideas come to mind. I assume the rats are restrained, with prior adaptation to the restraint. Having a liquid infused into their mouths could, regardless of flavor, be an inherently stressful situation. Therefore the opioid responses to palatable flavors might be slightly attenuated. The reflexes you refer to shouldn't be affected though.

After reading your post I went online to learn more, and I found a review article that seems to address some of the questions you're asking. Maybe you've already read it, but in case you haven't, here's the citation:

Berridge KC. Measuring hedonic impact in animals and infants: microstructure of affective taste reactivity patterns.
Neurosci Biobehav Rev. 2000 Mar;24(2):173-98.

I downloaded the pdf and read a little bit (and learned a lot!). Thanks for bringing this issue up--I've learned quite a bit already, even if I wasn't much help to you.

Best of luck!

Don