Skip to main content

Week 1: Santarelli and Bessa

By
These two papers, Santarelli et al. (2003) and Bessa et al. (2009) both investigate the method by which antidepressants cause their associated behavior effects – more specifically in regards to neurogenesis and neuroplasticity. 

Santarelli argues that neuroplasticity is necessary for antidepressants to induce desired behavioral effects. He tested this by measuring the feeding latency on the Novelty-Suppressed Feeding Test (NSFT) of rats by directing radiation to the hippocampal region to groups of rats both receiving and not receiving antidepressants. 

Bessa’s article is a response to Santarelli’s, as he also investigates the method behind antidepressants but argues that neurogenesis is not required to achieve the desired behavioral and molecular benefits of antidepressants. Bessa argues that neuronal remodeling and synaptic plasticity are the factors required for the behavioral efficacy of antidepressants, and explains that although hippocampal neurogenesis is promoted by antidepressants, it is not necessary for them to work. 

Although these papers have differing conclusions, I do not see them as contradictory. They both agree that neurogenesis is involved with antidepressant function, but Bessa argues that it is not the required event that makes antidepressants effective. Bessa’s experiment was more robust and rigorous because he 1) tested depressive behavior through several paradigms and 2) acknowledges the problems with X-ray methods and instead uses methylazoxymethanol (MAM) to block neurogenesis. 

Something that stood out to me when reading Santarelli’s paper was how he simplified depression. Santarelli only measured the behavioral efficacy of antidepressants in one way – through the Novelty-Suppressed Feeding Test (NSFT). Even in animal models, it is important to recognize the complexity of depression and the variety of symptoms and behaviors that antidepressants can affect. Bessa’s investigation was more thorough in its methods as it tested the behavioral efficacy of antidepressants through a variety of methods, specifically the Sucrose Preference Test (SPT), the Forced Swimming Test (FST), and the NSFT. Overall, Bessa’s article painted depression and the functionality of antidepressants in a more complicated and intricate way which I believe speaks to the multidimensional nature of the illness and its effects.

As far as future research goes, I would be interested in seeing the comparative hippocampal neurogenesis and neuronal remodeling of several more different kinds of antidepressants. I am not aware specifically of the molecular differences in varying types of antidepressants (as well as the differences in their behavioral effects) but would be interested in seeing if the neuronal remodeling changes across types.

Comments

Post a Comment

Popular posts from this blog

Gut-Brain Interactions: Buffington et al, Reber et al 2016

By
April 13 Papers (Buffington et. al, Reber et. al) I found this week’s papers to be quite novel in that they both proposed potential treatments for neurodevelopmental or psychiatric disorders that target bacterial or microbial abnormalities and how these give rise to certain behavioral and physical symptoms associated with the disorders. I thought this was a very unusual yet interesting approach, and as I have not previously studied the gut-brain axis, these papers offered me a fresh perspective on researching psychiatric and neurodevelopmental disorders. They were also unconventional in their focus of the physical symptoms that often accompany mental disorders, as this is not something that I have seen many other papers touch upon very much. Particularly, I was surprised by the Reber et al paper’s focus on the link between psychiatric disorders and inflammation in organs other than the brain, such as the colon, and the Buffington et al paper’s description of a relationship between ...
Post a Comment
Read more

Gut-brain axis

By
This weeks papers Reber et al. 2016 and Buffington et al. 2016 present a super interesting look into the gut-brain axis. Regarding both of these papers, it was amazing to see how potent favorable or unfavorable gut microbiome compositions are in affecting neuronal signaling and overall behavior. Reber et al. shows how immunoregulatory immunization with specifically heat killed M.vaccae can serve as a protective factor against chronic subordinate stress induce colotis as well as behavioral symptoms due to chronic stress as such. Interestringly, this paper depleted regulatory T cell activity via the anti CD25 antibody in order to show that the antiinflammatory mechanism induced by m vaccae immunization is depented on the secondary regulatory mechanisms offered by Treg proliferation and signaling. But, when T reg signaling was removed, this did not seem to cause a significant change in behavior . Therefore, this begs the consideration of what othe rmechanisms may be at play in order ...
Post a Comment
Read more

Ramirez et al.: 2013 and 2015 Papers

By
In these papers, Ramirez et al. strive to understand how memory encoding via optogenetic manipulation of engram-bearing cells in the hippocampus, specifically the dentate gyrus, can affect an animal’s response to a stressful context.  The first paper, published in 2013, was crucial to the field as it introduced this very exciting technique; in this paper, Ramirez et al. use tet-tag to manipulate brain circuity and establish associations between two contexts. Throughout the paper, this is referred to as “false memories.” Using these artificial memories, the investigators are able to manipulate the animal’s fear response in a specific context. Specifically, after the animals are conditioned to a repeated fearful stimulus (a foot shock, in context B), activation of the involved DG cells in a different context (context A’) will also initiate a fear response (in absence of any foot shock). In this experiment, the false memory is used to create an unnatural fear association in a given...
Post a Comment
Read more