Study may help explain 'awakenings' that occur with popular sleep-aid Ambien

June 29, 2009

Some people who take the fast-acting sleep-aid zolpidem (Ambien) have been observed walking, eating, talking on the phone and even driving while not fully awake. Many often don't remember doing any of these activities the next morning. Similarly, this drug has been shown to awaken the minimally conscious into a conscious state. A new study by Georgetown University Medical Center (GUMC) researchers may help explain why these "awakenings" occur.

The study, published online in the Monday, suggests that while some powerful are shut down with zolpidem, the powerful activates other circuits when deprived of activity.

" or neurons are highly reactive to incoming activity throughout life," explains Molly M. Huntsman, an assistant professor in the department of pharmacology at Georgetown University Medical Center and corresponding author for the study. "When is silenced, many neurons automatically react to this change. We see this in our study which suggests that inhibitory neurons responsible for stopping neural activity are themselves shut down by zolpidem. The excitatory neurons, responsible for transmitting activity, are then allowed to re-awaken and become active again, without monitoring because the inhibitory neurons are 'asleep'."

Rodents are especially dependent upon their whiskers to explore their environment; for the study, researchers trimmed the whiskers of mice (while under anesthesia). They then studied the region of the brain responsive to whisker movements to examine activity-dependent brain circuits. After removing the whiskers and depriving neural activity, the inhibitory neurons that normally don't respond to sedation by zolpidem underwent a change, becoming more sensitive. The researchers posited that these neurons are shut down and, in turn, not able to monitor other brain circuits.

"This was really unexpected. It appears the receptors on some inhibitory neurons were changed and were able to be inhibited by zolpidem, preventing them from performing their normal functions. We merely wanted to use zolpidem as a tool to examine which type of functional inhibitory receptor is expressed in certain neurons. Yet it turns out that sensory deprivation in the form of whisker trimming is enough to alter the receptor composition expressed in these cells." Huntsman says.

Researchers say that while the study suggests that zolpidem shuts down active neural pathways and perhaps then triggers others, the activation of this trigger is unknown.

"Nevertheless, the paradoxical activation of brain circuits by a powerful sedative definitely needs more attention in additional studies both human and in animal models," Huntsman concludes.

Source: Georgetown University Medical Center (news : web)

Related Stories

Recommended for you

'Human chronobiome' study informs timing of drug delivery, precision medicine approaches

December 13, 2017
Symptoms and efficacy of medications—and indeed, many aspects of the human body itself—vary by time of day. Physicians tell patients to take their statins at bedtime because the related liver enzymes are more active during ...

Study confirms link between the number of older brothers and increased odds of being homosexual

December 12, 2017
Groundbreaking research led by a team from Brock University has further confirmed that sexual orientation for men is likely determined in the womb.

Potassium is critical to circadian rhythms in human red blood cells

December 12, 2017
An innovative new study from the University of Surrey and Cambridge's MRC Laboratory of Molecular Biology, published in the prestigious journal Nature Communications, has uncovered the secrets of the circadian rhythms in ...

Estrogen discovery could shed new light on fertility problems

December 12, 2017
Estrogen produced in the brain is necessary for ovulation in monkeys, according to researchers at the University of Wisconsin-Madison who have upended the traditional understanding of the hormonal cascade that leads to release ...

Time of day affects severity of autoimmune disease

December 12, 2017
Insights into how the body clock and time of day influence immune responses are revealed today in a study published in leading international journal Nature Communications. Understanding the effect of the interplay between ...

3-D printed microfibers could provide structure for artificially grown body parts

December 12, 2017
Much as a frame provides structural support for a house and the chassis provides strength and shape for a car, a team of Penn State engineers believe they have a way to create the structural framework for growing living tissue ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.