melatonin in dogs?
April 21, 2006 3:35 PM   Subscribe

Is melatonin present in the brains of other mammals, specifically dogs? Does it serve the same function? How unique or not unique is the brain chemistry of humans?
posted by geekhorde to Science & Nature (7 answers total)
Wikipedia article.
posted by fvw at 3:50 PM on April 21, 2006

Cool. Should have thought of that.
posted by geekhorde at 4:05 PM on April 21, 2006

How unique or not unique is the brain chemistry of humans?

The reason that we use animals to study questions that are ultimately about human neurobiology is that we think we're not really all that unique after all. There are certain to be differences in structure, connections, and issues of scale, but of all of the differences the function of particular chemicals is likely to be very, very similar.

At least, similar in the mechanistic sense, which makes it a good model. Perhaps somewhat less simple in the "what role does it play" sense; we really don't know yet, I think.
posted by metaculpa at 5:46 PM on April 21, 2006

It'd kinda... difficult to cut up human brains and experiment on those cells. Well, not difficult, just - well, what would you say to letting us abort human fetuses, mash up (dissociate) their brains and grow them to experiment on? Cadaveric brains don't work very well (although they do have their uses) for a lot of experiments trying to figure out how brains work.

One of the fundamental difficulties with interpreting data from non-human animals is exactly your question - just how similar is the biochemistry between different species? Some things are remarkably equivalent, others - vastly different. Many mouse and rat models of human diseases are absolutely useless when it comes to applying what we learn from them to developing a clinical treatment for humans.

WRT brains, on a gross level, it's not too dissimilar. Once you get into the particulars, well, it's hit and miss. It depends on what you're looking at.

posted by PurplePorpoise at 6:19 PM on April 21, 2006

Are you asking with the purpose of giving your dog a Melatonin supplement in mind?

Because... I've always wondered about that myself...
posted by disillusioned at 11:50 PM on April 21, 2006

Protein sequence identity between human and canine Melatonin Receptor 1A

hmm, can't seem to get it to paste correctly. The alignment is here as an rich text document.

There are significant parts that seem to be well preserved, but there are also very divergent runs as well. I don't have the map of where the binding sites are.

I'd imagine it giving dogs human melatonin and dog melatonin to humans may have some activity but likely far less than native melatonin.

My guess would be that it would be less effective than, say, bovine or porcine insulin in humans (which worked reasonably well before the advent of recombinant human insulin produced in bacteria).
posted by PurplePorpoise at 3:36 PM on April 24, 2006

Hmm, got me thinking - it appears that melatonin you buy over the counter is mostly from animals (extracted directly from brain [pineal gland] tissue) or "analogues" found in plants (ie., garbage not really melatonin.

There appears to be "pharmaceutical grade" melatonin but I can't find out whether it's synthesized by organic chemistry or recombinant that's made to be produced by bacteria.
posted by PurplePorpoise at 3:47 PM on April 24, 2006

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