Navigation Links
Brain Networks Strengthened by Closing Ion Channels

Yale School of Medicine and University of Crete School of Medicine researchers report in Cell April 20 the first evidence of a molecular mechanism// that dynamically alters the strength of higher brain network connections.

This discovery may help the development of drug therapies for the cognitive deficits of normal aging, and for cognitive changes in schizophrenia, bipolar disorder, or attention deficit hyperactivity disorder (ADHD).

“Our data reveal how the brain’s arousal systems influence the cognitive networks that subserve working memory—which plays a key role in abstract thinking, planning, and organizing, as well as suppressing attention to distracting stimuli,” said Amy Arnsten, lead author and neurobiology professor at Yale.

The brain’s prefrontal cortex (PFC) normally is responsible for so-called executive functions. The ability of the PFC to maintain such memory-based functions declines with normal aging, is weakened in people with ADHD, and is severely disrupted in disorders such as schizophrenia and bipolar disorder.

The current study found that brain cells in PFC contain ion channels called hyperpolarization-activated cyclic nucleotide-gated channels (HCN) that reside on dendritic spines, the tiny protrusions on neurons that are specialized for receiving information. These channels can open when they are exposed to cAMP (cyclic adenosine monophosphate). When open, the information can no longer flow into the cell, and thus the network is effectively disconnected. Arnsten said inhibiting cAMP closes the channels and allows the network to reconnect.

The study also found alpha-2A adrenergic receptors near the channels that inhibit the production of cAMP and allow the information to pass through into the cell, connecting the network. These receptors are stimulated by a natural brain chemical norepinephrine or by medications like guanfacine.

“Guanfacine can strengthen the connectivity of these networks by keeping these channels closed, thus improving working memory and reducing distractibility,” she said. “This is the first time we have observed the mechanism of action of a psychotropic medication in such depth, at the level of ion channels.”

Arnsten said the excessive opening of HCN channels might underlie many lapses in higher cognitive function. Stress, for example, appears to flood PFC neurons with cAMP, which opens HCN channels, temporarily disconnects networks, and impairs higher cognitive abilities.

There is also evidence that this pathway may not be properly regulated with advancing age, resulting in destruction of cAMP. The dysregulation of the pathway may contribute to increased forgetfulness and susceptibility to distraction as we grow older.

The research is also relevant to common disorders such as ADHD, which is associated with weaker regulation of attention and behavior. ADHD is highly heritable, and some patients with ADHD may have genetic changes in molecules that weaken the production of norepinephrine. Treatments for ADHD all enhance stimulation of the norepinephrine receptors.

These new data also have important implications for the researchers’ studies of more severe mental illnesses like schizophrenia and bipolar disorder, which can involve mutations of a molecule called DISC1 (Disrupted in Schizophrenia) that normally regulates cAMP. Loss of function of DISC1 in patients with schizophrenia or bipolar disorder would increase vulnerability to cortical network disconnection and profound PFC deficits. This may be especially problematic during exposure to even mild stress, which may explain the frequent worsening of symptoms following exposure to stress. “We find it remarkable to relate a genetic mutation in patients to the regulation by an ion channel of PFC neuronal networks,” said Arnsten.

Co-authors include Min Wang, Brian Ramos, Yousheng Shu, Arthur Simen, Alvaro Duqye, Avis Bren nan, Susheel Vijayraghavan, Anne Dudley, Eric Nou, David McCormick, James Mazer and Constantinos Paspalas, who also has an appointment at the University of Crete School of Medicine in Heraklion, Greece.

The work was supported by research grants from the National Institute on Aging and the National Institute of Mental Health, as well as from Shire Pharmaceuticals Group plc and an award from the Kavli Institute of Neuroscience at Yale.

Arnsten and Yale have a license agreement with Shire Pharmaceuticals for the development of guanfacine for the treatment of patients with ADHD. Yale has submitted a patent application on the use of HCN blockers for the treatment of PFC cognitive deficits based on the data reported in the Cell paper.

Source-YALE Universiy
MED/B
'"/>




Related medicine news :

1. Use of Cellular Phones associated with Increased risk of Brain Tumors
2. Brain death – How to cope with it
3. “Brain fingerprinting”- The new lie detectr
4. Nasal Spray Could Take Drugs Direct to Brain.
5. Virus Combats Brain Tumour
6. Nasal Spray Could Take Drugs Directly to Brain
7. Control of anger disorder connected to Brain Dysfunction
8. High Levels of Protein Linked to Brain Shrinkage
9. Brain damage affects artistic skill
10. Brain cells protected by new compounds
11. Brain changes observed in people with sleep apnoea
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:6/27/2016)... Aliso Viejo, California (PRWEB) , ... June 27, 2016 , ... ... that are fully customizable inside of Final Cut Pro X," said Christina Austin - ... with another unique style. Final Cut Pro X users can now reveal ...
(Date:6/27/2016)... , ... June 27, 2016 , ... TopConsumerReviews.com recently awarded ... Eyeglasses . , Millions of individuals in the United States and Canada wear ... a way to both correct vision and make a fashion statement. Even celebrities use ...
(Date:6/26/2016)... Cary, North Carolina (PRWEB) , ... June 26, 2016 , ... ... the release of a new product that was developed to enhance the health of ... harvested for centuries. , The two main herbs in the PawPaws Cat Kidney ...
(Date:6/25/2016)... ... , ... Austin residents seeking Mohs surgery services, can now turn to Dr. ... Russell Peckham for medical and surgical dermatology. , Dr. Dorsey brings specialization to include ... in Mohs Micrographic Surgery completed by Dr. Dorsey was under the direction of Glenn ...
(Date:6/25/2016)... ... ... As a lifelong Southern Californian, Dr. Omkar Marathe earned his Bachelors in ... School of Medicine at UCLA. He trained in Internal Medicine at Scripps Green Hospital ... at the UCLA-Olive View-Cedars Sinai program where he had the opportunity to train in ...
Breaking Medicine News(10 mins):
(Date:6/23/2016)... , June 23, 2016 Research and ... Devices Medical Market Analysis 2016 - Forecast to 2022" ... The report contains up to date financial data derived ... Assessment of major trends with potential impact on the market ... of market segmentation which comprises of sub markets, regional and ...
(Date:6/23/2016)... 2016 Research and Markets has announced ... report to their offering. ... a favourable commercial environment for MedImmune to enter. The US ... will serve to drive considerable growth for effective anti-influenza medications. ... cap sales considerably, but development is still in its infancy. ...
(Date:6/23/2016)... , June 23, 2016 , ... on Thursday, July 7, 2016 , , , , LOCATION: ... , , , , EXPERT PANELISTS:  , , , ... Senior Industry Analyst, Christi Bird; Senior Industry Analyst, Divyaa Ravishankar and ... The global pharmaceutical industry is witnessing an exceptional era. ...
Breaking Medicine Technology: