Obscure protein restores memory decline

In the not-too-distant-future, your grandma may give you a run for your money on your video games. Photo credit: http://www.funtoosh.com/pictures/
In the not-too-distant-future, your grandma may give you a run for your money on your video games. Photo credit: Funtoosh

Aging comes with all sorts of maladies, but one of the most frustrating is the feeling that you are not as sharp as you used to be. Cognitive decline has been previously linked, at least in part, to a dysregulation in the neuronal calcium homeostasis in the hippocampus, which is a brain region essential for learning and memory. One player that keeps in check the proper balance of calcium use is the protein FKBP1b, and, not surprisingly, its amounts are reduced in aging rats and Alzheimer’s suffering patients.

FKBP1b overexpression in hippocampal neurons reversed spatial memory deficits in aged rats. Fig. 3 (partial) from Gant, J. C., Chen, K. C., Kadish, I., Blalock, E. M., Thibault, O., Porter, N. M., Landfield, P. W. (29 July 2015). Reversal of Aging-Related Neuronal Ca2+ Dysregulation and Cognitive Impairment by Delivery of a Transgene Encoding FK506-Binding Protein 12.6/1b to the Hippocampus. The Journal of Neuroscience, 35(30):10878 –10887. doi: 10.1523/JNEUROSCI.1248-15.2015.
FKBP1b overexpression in hippocampal neurons reversed spatial memory deficits in aged rats. Fig. 3 (partial) from Gant et al. (2015): doi: 10.1523/JNEUROSCI.1248-15.2015.

Gant et al. (2015) sought to increase the expression of the FKBP1b protein in the hippocampus, in the hopes that its increase would result in better calcium homeostasis and, as a result, better memory performance in aging rats. They built a virus that carried the gene for making the FKBP1b protein and they injected this directly in the hippocampus. After they waited 5-6 weeks for the gene to be expressed, they tested the rats in the Morris water maze, a test for spatial memory. The old rats that received the injection performed as well as the young rats, and far better than the old rats who didn’t get the injection. Then the researchers made sure that the injection is the one responsible for the results, by checking the levels of the FKBP1b protein in the hippocampus (increased, as per specs), by recording from those neurons (they were awesome), and by imaging the calcium to make sure the balance was restored (ditto).

Reference: Gant, J. C., Chen, K. C., Kadish, I., Blalock, E. M., Thibault, O., Porter, N. M., Landfield, P. W. (29 July 2015). Reversal of Aging-Related Neuronal Ca2+ Dysregulation and Cognitive Impairment by Delivery of a Transgene Encoding FK506-Binding Protein 12.6/1b to the Hippocampus. The Journal of Neuroscience, 35(30):10878 –10887. doi: 10.1523/JNEUROSCI.1248-15.2015. Article + FREE PDF + Journal of Neuroscience cover

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The song of a fly… the courtship of another

Drosophila melanogaster image illustrating sexual dimorphism and mating behavior. Credit: TheAlphaWolf (Wikimedia Commons)
Drosophila melanogaster image illustrating sexual dimorphism and mating behavior. Credit: TheAlphaWolf (Wikimedia Commons)

Did you know that flies sing? True to the dictum that I just made up – ‘where is song, there is lust’ – it turns out not only that flies can sing, but they even have courtship songs! Granted, since they don’t have a larynx, the male flies sing by vibrating their wings in a certain way, which is unique to each fly species, and females listen with the feather-looking bit on top of their antennae, called arista. The behavior has generated enough research that a fairly hefty review about it has been published two years ago in Nature Reviews Neuroscience, pointing to a gene central to the male courtship circuitry and expressed only in the fly’s neurons, the fru gene (I bet it was called that way because when you make mutants you get fru/fru …).

Zhou et al. (2015) used a series of complicated experiments to successively activate or inhibit the neurons which express the fru gene, in order to identify the neural circuitry underlying hearing and processing the courtship songs. This circuitry is different in males and females, which makes sense since the serenading male expects different behaviors from his audience, depending on their sex; the listening males hurry to compete for the intended female and the females slow down and… listen carefully. Mind wondering: if I was the one serenading, wouldn’t I want to drive away the competitors, instead of drawing them in towards the object of my desire? Perhaps I want the competitors to also engage in courtship behavior so I can show off my wing vibrating prowess… Anyway, digression aside, in addition to figuring out which neuron does what, the authors managed to elicit courtship behavior in the listening males by optogenetically stimulating the 3rd and 4th order neurons in the newly identified circuit.

Besides being strangely interesting in itself, the research fills a gap in the understanding how courtship behavior is recognized, at least in fruit flies, which may be very useful information for other species as well, humans included.

Reference: Zhou, C., Franconville, R., Vaughan, A. G., Robinett, C. C., Jayaraman, V., & Baker, B. S. (21 September 2015). Central neural circuitry mediating courtship song perception in male Drosophila. Elife, 4:1-15. doi: 10.7554/eLife.08477. Article + FREE PDF

For the interested specialist, the MATLAB source code for analyzing calcium-imaging data can be found here.

By Neuronicus, 24 September 2015