A Follow up: Depression, p21, CREB, and more

Everyone once in a while, someone sends Sci email. Often it’s silly. This one, however, was very good in that it asked for some clarification on a series of posts that I’ve been working on looking at clinical depression and possible causes and treatments, including neurogenesis in the hippocampus, cell cycle controls, and CREB.
And luckily, the guy who sent it gave Sci permission to repost, which is good, because it allows me to clarify some stuff. Here goes:

Hi Sci: I read your blog about how antidepressants stimulate neurogenesis in the hippocampus. Since the CREB deficient mice had robust neurogenesis and normal serotonin I wasn’t sure why they were anxious. Apparently they did benefit from antidepressants right away on the tail suspension and forced swim tests so the neurogenesis hypothesis took a bit of a whack. To add to the complexities I just read about MIF (macrophage migration inhibitory factor). Apparently reducing the amount of MIF in the rat hippocampus dramatically reduces neurogenesis and increases anxiety. Do you understand how CREB and MIF are related? I’m trying to get a handle on this whole complex area. Thanks.

All right, I’m going to try this before my first cup of coffee and we’ll see how it goes:

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Cell Cycle p21, Depression, and Neurogenesis and in the Hippocampus

This is somewhat of a followup post. What’s really cool about this paper (to Sci, anyway), is that it brings two different areas that she’s been interested in into one cool glob of SCIENCE. And it helps to explain many of the questions that Sci got in response to two of the papers she has blogged about recently.
They are these:
1) The Incredible Healing Mouse: Bedelbeava et al. “Lack of p21 expression links cell cycle control and appendage regeneration in mice” Proceeding of the National Academy of Sciences, 2010.
2) The neurogenesis theory of depression and a little guy called CREB: Gur et al. “cAMP Response Element-Binding Protein Deficiency Allows for Increased Neurogenesis and a Rapid Onset of Antidepressant Response” The Journal of Neuroscience, 2007.
And NOW, behold their MUTANT OFFSPRING:
xmen60s.jpg
ResearchBlogging.org Pechnick et al. “p21 restricts neuronal proliferation in the subgranular zone of the dentate gyrus of the hippocampus” PNAS, 2008.
Well ok, technically it isn’t a mutant offspring, because this paper was BEFORE the first paper and after the second. So I guess it’s a stepchild. Or a sibling. Or just the results of how Sci was searching PubMed that day.
Anyway.
Let’s start with some background.

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The Neurogenesis theory of depression and a little guy called CREB

Sci wishes she could begin this post with something clever. But she has a cold. Suffice it to say that this paper is cool and interesting. And also, as Sci has a cold, I expect all of you to read this post out loud to yourselves in suitably stuffy, gluey Sci-voices.
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(*sniff*)
ResearchBlogging.org Gur et al. “cAMP Response Element-Binding Protein Deficiency Allows for Increased Neurogenesis and a Rapid Onset of Antidepressant Response” The Journal of Neuroscience, 2007.
(Yeah, yeah, the title is long and scary. Worry not, Sci will ‘splain.)
And this paper is especially good because it allows Sci to write a post on a topic she’s been meaning to get to even since she did a depression series way back when: the neurogenesis theory of antidepressant responses.
So here we go. And a new neuron is born.
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(From Bumpy Brains. Sci thinks the rendition of diapers as glia is hilarious.)

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SSRIs: Talkin’ ’bout Prozac

I’m sure many of you have seen some of my posts on depression pharmacotherapies, the serotonin theory, and the serotonin system. But I’m still getting a lot of questions, and a lot of misconceptions about how the various drugs work. So I’m going to provide a little more information on the types of pharmacotherapies. And this time, you’re also getting PICTURES!
SSRI diagram1.png
Yup. We’ve been here before.

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