Triple play in science communication

We are highlighting Emory BCDB graduate student Emma D’Agostino, who is a rare triple play in the realm of science communication. Emma has her own blog, where she talks about what it’s like to have cystic fibrosis. Recent posts have discussed the science of the disease and how she makes complicated treatment decisions together with her doctors. She’s an advisor to the Cystic Fibrosis Foundation on patient safety, communicating research and including the CF community Read more

Deep brain stimulation for narcolepsy: proof of concept in mouse model

Emory neurosurgeon Jon Willie and colleagues recently published a paper on deep brain stimulation in a mouse model of narcolepsy with cataplexy. Nobody has ever tried treating narcolepsy in humans with deep brain stimulation (DBS), and the approach is still at the “proof of concept” stage, Willie says. People with the “classic” type 1 form of narcolepsy have persistent daytime sleepiness and disrupted nighttime sleep, along with cataplexy (a loss of muscle tone in response Read more

In current vaccine research, adjuvants are no secret

Visionary immunologist Charlie Janeway was known for calling adjuvants – vaccine additives that enhance the immune response – a “dirty little secret.” Janeway’s point was that foreign antigens, by themselves, were unable to stimulate the components of the adaptive immune system (T and B cells) without signals from the innate immune system. Adjuvants facilitate that help. By now, adjuvants are hardly a secret, looking at some of the research that has been coming out of Emory Read more

hypothalamus

Deep brain stimulation for narcolepsy: proof of concept in mouse model

Emory neurosurgeon Jon Willie and colleagues recently published a paper on deep brain stimulation in a mouse model of narcolepsy with cataplexy. Nobody has ever tried treating narcolepsy in humans with deep brain stimulation (DBS), and the approach is still at the “proof of concept” stage, Willie says.

People with the “classic” type 1 form of narcolepsy have persistent daytime sleepiness and disrupted nighttime sleep, along with cataplexy (a loss of muscle tone in response to emotions), sleep paralysis and vivid dream-hallucinations that bleed into waking time. If untreated, narcolepsy can profoundly interfere with someone’s life. However, the symptoms can often be effectively, if incompletely, managed with medications. That’s why one question has to be: would DBS, implemented through brain surgery, be appropriate?

The room where it happens. Sandwiched between the thalamus and the pituitary, the hypothalamus is home to several distinct bundles of neurons that regulate appetite, heart rate, blood pressure and sweating, as well as sleep and wake. It’s as if in your house or apartment, the thermostat, alarm clock and fuse box were next to each other.

Emory audiences may be familiar with DBS as a treatment for conditions such as depression or Parkinson’s disease, because of the pioneering roles played by investigators such as Helen Mayberg and Mahlon DeLong. Depression and Parkinson’s can also often be treated with medication – but the effectiveness can wane, and DBS is reserved for the most severe cases. For difficult cases of narcolepsy, investigators have been willing to consider brain tissue transplants or immunotherapies in an effort to mitigate or interrupt neurological damage, and similar cost-benefit-risk analyses would have to take place for DBS.

Willie’s paper is also remarkable because it reflects how much is now known about how narcolepsy develops. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Neurosurgery via genetics to modulate anxiety

If you hear someone talking about a stress hormone, they’re probably talking about cortisol. It’s released by the adrenal glands in stressful situations, whether you have to escape a bear or just give a speech. Cortisol is supposed to prepare the body for “fight or flight.”

Kerry Ressler, MD, PhD

Let’s step back a bit, and look at how the brain triggers cortisol production: through a peptide produced in the brain called CRF (corticotropin-releasing factor). CRF is elevated in several disorders such as depression and PTSD, and is also thought to be involved in drug and alcohol dependency.

Neurons that make CRF are found in locations all over the brain, so studying them can be tricky. Kerry Ressler and his colleagues have developed an intriguing tool for studying CRF. In the places where CRF is produced in a mouse’s brain, they can take out the gene of their choice.

Green spots (above) and blue staining (below) indicate where CRF is produced in the mouse brain.
PVN = hypothalamus, paraventricular nucleus
CeA = central amygdala

In a new paper in PNAS, postdoc Georgette Gafford and Ressler use this tool in a subtle way. They have mice where a gene for a GABA receptor, one of the main inhibitory receptors (brakes) in the nervous system, is deleted, but only in the CRF neurons. This basically has the effect of turning up the volume on CRF production in several parts of the brain. It appears that modulating GABA receptors is something that normally happens to regulate CRF production, but in this case, a restraint on these stress-sensitive cells has been taken off.

“These mice are normal in many ways – normal locomotor and pain responses and no difference in depressive-like behavior or Pavlovian fear conditioning. However, these mutants have increased anxiety-like behavior,” Gafford and Ressler write.

They also have “impaired extinction of conditioned fear,” meaning that they have trouble becoming NOT afraid of something, like a buzzing sound, to which they have been sensitized by shocks. This is analogous to PTSD in which patients remain afraid and aren’t able to successfully inhibit their prior fear learning, even after the context is now safe.  [A 2011 paper goes into more detail on this biological aspect of PTSD in a civilian population.]

“These data indicate that disturbance of this specific population of neurons causes increased anxiety and impaired fear extinction, and helps us to further understand mechanisms of fear- and anxiety-related disorders such as PTSD,” Ressler and Gafford write.

In the mutant mice, a drug that blocks CRF rescued their behavioral impairments. Some other recent investigations of mice with CRF overproduction in the brain revealed “surprising paradoxical effects.”

Drugs that block CRF have been in clinical trials, some with mixed results.  A trial now proceeding at Emory is evaluating a CRF antagonist in women with PTSD.

Ressler, associate professor of psychiatry and behavioral sciences, is a Howard Hughes Medical Investigator, with a laboratory at the Yerkes National Primate Research Center. He is also co-director of the Grady Trauma Project.

 

 

Posted on by Quinn Eastman in Neuro Leave a comment