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Study authors Aaron Sathyanesan, Ph.D., Joseph Abbah, B.Pharm., Ph.D., Srikanya Kundu, Ph.D. and Vittorio Gallo, Ph.D.

Children’s perinatal hypoxia research lauded

Study authors Aaron Sathyanesan, Ph.D., Joseph Abbah, B.Pharm., Ph.D., Srikanya Kundu, Ph.D. and Vittorio Gallo, Ph.D.

Study authors Aaron Sathyanesan, Ph.D., Joseph Abbah, B.Pharm., Ph.D., Srikanya Kundu, Ph.D. and Vittorio Gallo, Ph.D.

Chronic sublethal hypoxia is associated with locomotor miscoordination and long-term cerebellar learning deficits in a clinically relevant model of neonatal brain injury, according to a study led by Children’s National Health System researchers published by Nature Communications. Using high-tech optical and physiological methods that allow researchers to turn neurons on and off and an advanced behavioral tool, the research team found that Purkinje cells fire significantly less often after injury due to perinatal hypoxia.

The research team leveraged a fully automated, computerized apparatus – an Erasmus Ladder – to test experimental models’ adaptive cerebellar locomotor learning skills, tracking their missteps as well as how long it took the models to learn the course.

The research project, led by Aaron Sathyanesan, Ph.D., a Children’s postdoctoral research fellow, was honored with a F1000 primevery good rating.” The Children’s research team used both quantitative behavior tests and electrophysiological assays, “a valuable and objective platform for functional assessment of targeted therapeutics in neurological disorders,” according to the recommendation on a digital forum in which the world’s leading scientists and clinicians highlight the best articles published in the field.

Calling the Erasmus Ladder an “elegant” behavioral system, Richard Lu, Ph.D., and Kalen Berry write that the Children’s National Health System research team “revealed locomotor behavior and cerebellar learning deficits, and further utilized multielectrode recording/optogenetics approaches to define critical pathophysiological features, such as defects in Purkinje cell firing after neonatal brain injury.”

Lu, Beatrice C. Lampkin Endowed Chair in Cancer Epigenetics, and Berry, an associate faculty member in the Cancer and Blood Diseases Institute, both at Cincinnati Children’s, note that the Children’s results “suggest that GABA signaling may represent a potential therapeutic target for hypoxia-related neonatal brain injury that, if provided at the correct time during development post-injury, could offer lifelong improvements.”

In addition to Sathyanesan, Children’s co-authors include Co-Lead Author, Srikanya Kundu, Ph.D., and Joseph Abbah, both of Children’s Center for Neuroscience Research, and Vittorio Gallo, Ph.D., Children’s Chief Research Officer and the study’s senior author.

Research covered in this story was supported by the Intellectual and Developmental Disability Research Center under award number U54HD090257.

Vittorio Gallo

Vittorio Gallo, Ph.D., honored with Senator Jacob Javits Award in the Neurosciences

Vittorio Gallo

Vittorio Gallo, Ph.D., Children’s Chief Research Officer, has been awarded a prestigious Senator Jacob Javits Award in the Neurosciences, which extends federal funding for Gallo’s lab for at least seven years. The long-term support is offered to “investigators with a history of exceptional talent, imagination and preeminent scientific achievement.”

Only National Institute of Neurological Disorders and Stroke (NINDS) staff members or NINDS Council members may nominate researchers for the coveted awards, named in honor of Sen. Jacob Javits, (R-New York). Before his death, Sen. Javits advocated for additional research in a wide variety of disorders of the brain and nervous system.

“It’s a great recognition from the neuroscience community and from NINDS for contributions to neuroscience and outstanding service to the neuroscience community,” Gallo says. “It’s also very exciting because it gives additional national visibility to our Center for Neuroscience Research and to Children’s National Health System, as one of the nation’s leading research institutions.”

Through the award, Gallo’s successful five-year Research Project Grant from the National Institutes of Health will be converted to a seven-year award. In the fourth year of federal funding, he can apply for a budgetary increase.

“Thanks to this funding, I predict we will be able to identify cellular and molecular mechanisms that underlie developmental delays in children who experienced neonatal brain injury,” Gallo says.

“We are really starting to understand this very complex problem: How does neonatal brain injury lead to developmental delays later in a child’s life? What are the mechanisms? We know there are cognitive and behavioral abnormalities that are common to children who have experienced hypoxia as newborns. But we don’t really know how these behavioral abnormalities arise at the physiological, cellular and molecular levels.”

Gallo says identifying these cellular targets will make it possible to tailor interventions that target distinct cell types at different times in the child’s life.

Recent work by Gallo’s lab includes a research paper published online Aug. 13, 2018, by Nature Communications that found chronic sublethal hypoxia is associated with locomotor miscoordination and long-term cerebellar learning deficits in a clinically relevant model of neonatal brain injury.

toddler on a playground

Perinatal hypoxia associated with long-term cerebellar learning deficits and Purkinje cell misfiring

toddler on a playground

The type of hypoxia that occurs with preterm birth is associated with locomotor miscoordination and long-term cerebellar learning deficits but can be partially alleviated with an off-the-shelf medicine, according to a study using a preclinical model.

Oxygen deprivation associated with preterm birth leaves telltale signs on the brains of newborns in the form of alterations to cerebellar white matter at the cellular and the physiological levels. Now, an experimental model of this chronic hypoxia reveals that those cellular alterations have behavioral consequences.

Chronic sublethal hypoxia is associated with locomotor miscoordination and long-term cerebellar learning deficits in a clinically relevant model of neonatal brain injury, according to a study led by Children’s National Health System researchers published online Aug. 13, 2018, by Nature Communications. Using high-tech optical and physiological methods that allow researchers to turn neurons on and off and an advanced behavioral tool, the research team finds that Purkinje cells fire significantly less often after injury due to perinatal hypoxia. However, an off-the-shelf medicine now used to treat epilepsy enables those specialized brain cells to regain their ability to fire, improving locomotor performance.

Step out of the car onto the pavement, hop up to the level of the curb, stride to the entrance, and climb a flight of stairs. Or, play a round of tennis. The cerebellum coordinates such locomotor performance and muscle memory, guiding people of all ages as they adapt to a changing environment.

“Most of us successfully coordinate our movements to navigate the three-dimensional spaces we encounter daily,” says Vittorio Gallo, Ph.D., Children’s Chief Research Officer and the study’s senior author. “After children start walking, they also have to learn how to navigate the environment and the spaces around them.”

These essential tasks, Gallo says, are coordinated by Purkinje cells, large neurons located in the cerebellum that are elaborately branched like interlocking tree limbs and represent the only source of output for the entire cerebellar cortex. The rate of development of the fetal cerebellum dramatically increases at a time during pregnancy that often coincides with preterm birth, which can delay or disrupt normal brain development.

“It’s almost like a short circuit. Purkinje cells play a very crucial role, and when the frequency of their firing is diminished by injury the whole output of this brain region is impaired,” Gallo says. “For a family of a child who has this type of impaired neural development, if we understand the nature of this disrupted circuitry and can better quantify it, in terms of locomotor performance, then we can develop new therapeutic approaches.”

Study authors Aaron Sathyanesan, Ph.D., Joseph Abbah, B.Pharm., Ph.D., Srikanya Kundu, Ph.D. and Vittorio Gallo, Ph.D.

The research team leveraged a fully automated, computerized apparatus that looks like a ladder placed on a flat surface, encased in glass, with a darkened box at either end. Both the hypoxic and control groups had training sessions during which they learned how to traverse the horizontal ladder, coaxed out of the darkened room by a gentle puff of air and a light cue. Challenge sessions tested their adaptive cerebellar locomotor learning skills. The pads they strode across were pressure-sensitive and analyzed individual stepping patterns to predict how long it should take each to complete the course.

During challenge sessions, obstacles were presented in the course, announced by an audible tone. If learning was normal, then the response to the tone paired with the obstacle would be a quick adjustment of movement, without breaking stride, says Aaron Sathyanesan, Ph.D., co-lead author. Experimental models exposed to perinatal hypoxia showed significant deficits in associating that tone with the obstacle.

“With the control group, we saw fewer missteps during any given trial,” Sathyanesan says. “And, when they got really comfortable, they took longer steps. With the hypoxic group, it took them longer to learn the course. They made a significantly higher number of missteps from day one. By the end of the training period, they could walk along all of the default rungs, but it took them longer to learn how to do so.”

Purkinje cells fire two different kinds of spikes. Simple spikes are a form of constant activity as rhythmic and automatic as a heartbeat. Complex spikes, by contrast, occur less frequently. Sathyanesan and co-authors say that some of the deficits that they observed were due to a reduction in the frequency of simple spiking.

Two weeks after experiencing hypoxia, the hypoxic group’s locomotor performance remained significantly worse than the control group, and delays in learning could still be seen five weeks after hypoxia.

Gamma-aminobutyric acid (GABA), a neurotransmitter, excites immature neurons before and shortly after birth but soon afterward switches to having an inhibitory effect within in the cerebellum, Sathyanesan says. The research team hypothesizes that reduced levels of excitatory GABA during early development leads to long-term motor problems. Using an off-the-shelf drug to increase GABA levels immediately after hypoxia dramatically improved locomotor performance.

“Treating experimental models with tiagabine after hypoxic injury elevates GABA levels, partially restoring Purkinje cells’ ability to fire,” Gallo says. “We now know that restoring GABA levels during this specific window of time has a beneficial effect. However, our approach was not specifically targeted to Purkinje cells. We elevated GABA everywhere in the brain. With more targeted and selective administration to Purkinje cells, we want to gauge whether tiagabine has a more powerful effect on normalizing firing frequency.”

In addition to Gallo and Sathyanesan, Children’s co-authors include Co-Lead Author, Srikanya Kundu, Ph.D., and Joseph Abbah, B.Pharm., Ph.D., both of Children’s Center for Neuroscience Research.

Research covered in this story was supported by the Intellectual and Developmental Disability Research Center under award number U54HD090257.