Major dopamine system helps restore consciousness after general anesthesia, study finds

July 22, 2014, American Society of Anesthesiologists

Researchers may be one step closer to better understanding how anesthesia works. A study in the August issue of Anesthesiology, the official medical journal of the American Society of Anesthesiologists (ASA), found stimulating a major dopamine-producing region in the brain, the ventral tegmental area (VTA), caused rats to wake from general anesthesia, suggesting that this region plays a key role in restoring consciousness after general anesthesia. Activating this region at the end of surgery could provide a novel approach to proactively induce consciousness from anesthesia in surgical patients, researchers say.

"While generally safe, it is well known that patients should not be under general anesthesia longer than necessary," said Ken Solt, M.D., lead author, Massachusetts General Hospital Department of Anesthesia, Critical Care and Pain Medicine and assistant professor of anesthesia, Harvard Medical School, Boston. "Currently, there are no treatments to reverse the effects of general anesthesia. We must wait for the anesthetics to wear off. Having the ability to control the process of arousal from general anesthesia would be advantageous as it might speed recovery to normal cognition after surgery and enhance operating room (O.R.) efficiencies."

Although the brain circuits that drive the process of emerging from general anesthesia are not well understood, recent studies suggest that certain arousal pathways in the brain may be activated by certain drugs to promote consciousness. The authors previously reported that methylphenidate (Ritalin), a drug used to treat attention deficit hyperactivity disorder, awakened rats from by activating dopamine-releasing pathways.

In the current study, rats were given the general anesthetics isoflurane or propofol. Once unconscious, researchers performed targeted , through implanted steel electrodes, on the two major regions of the rats' brains that contain dopamine-releasing cells – the VTA (the area of the brain that controls cognition, motivation and reward in humans) and the substantia nigra, which controls movement.

Researchers found that electrical stimulation of the VTA caused the rats to regain consciousness, suggesting that dopamine released from cells in this area of the brain is likely involved in arousal. Interestingly, electrical stimulation of the VTA had an effect similar to that of the drug methylphenidate in restoring consciousness after anesthesia.

"We now have evidence that dopamine released by cells in the VTA is mainly responsible for the awakening effect seen with methylphenidate," said Dr. Solt. "Because dopamine-releasing cells in the VTA are important for cognition, we may be able to use drugs that act on this region not only to induce in anesthetized patients, but to potentially treat common postoperative emergence-related problems such as delirium and restore cognitive function."

Explore further: Common stimulant may speed recovery from general anesthesia

Related Stories

Common stimulant may speed recovery from general anesthesia

September 21, 2011
Administration of the commonly used stimulant drug methylphenidate (Ritalin) was able to speed recovery from general anesthesia in an animal study conducted at Massachusetts General Hospital (MGH). The report, appearing in ...

Recovery from propofol anesthesia may be sped by use of common stimulant

April 5, 2012
The ability of the commonly used stimulant methylphenidate (Ritalin) to speed recovery from general anesthesia appears to apply both to the inhaled gas isoflurane, as previously reported, and to the intravenous drug propofol. ...

Study examines how brain 'reboots' itself to consciousness after anesthesia

June 18, 2014
One of the great mysteries of anesthesia is how patients can be temporarily rendered completely unresponsive during surgery and then wake up again, with all their memories and skills intact.

Rats' brains may 'remember' odor experienced while under general anesthesia

March 18, 2014
Rats' brains may remember odors they were exposed to while deeply anesthetized, suggests research in rats published in the April issue of Anesthesiology.

To recover consciousness, brain activity passes through newly detected states

June 9, 2014
Anesthesia makes otherwise painful procedures possible by derailing a conscious brain, rendering it incapable of sensing or responding to a surgeon's knife. But little research exists on what happens when the drugs wear off.

Common brain processes of anesthetic-induced unconsciousness identified

May 23, 2013
A study from the June issue of Anesthesiology found feedback from the front region of the brain is a crucial building block for consciousness and that its disruption is associated with unconsciousness when the anesthetics ...

Recommended for you

Study points to possible new therapy for hearing loss

October 15, 2018
Researchers have taken an important step toward what may become a new approach to restore hearing loss. In a new study, out today in the European Journal of Neuroscience, scientists have been able to regrow the sensory hair ...

Sugar, a 'sweet' tool to understand brain injuries

October 15, 2018
Australian researchers have developed ground-breaking new technology which could prove crucial in treating brain injuries and have multiple other applications, including testing the success of cancer therapies.

Scientists examine how neuropathic pain responds to Metformin

October 15, 2018
Scientists seeking an effective treatment for one type of chronic pain believe a ubiquitous, generic diabetes medication might solve both the discomfort and the mental deficits that go with the pain.

Abnormal vision in childhood can affect brain functions

October 13, 2018
A research team has discovered that abnormal vision in childhood can affect the development of higher-level brain areas responsible for things such as attention.

Study: Ketogenic diet appears to prevent cognitive decline in mice

October 12, 2018
We've all experienced a "gut feeling"—when we know deep down inside that something is true. That phenomenon and others (like "butterflies in the stomach") aptly describe what scientists have now demonstrated: that the gut ...

Two seemingly opposing forces in the brain actually cooperate to enhance memory formation

October 12, 2018
The brain allows organisms to learn and adapt to their surroundings. It does this by literally changing the connections, or synapses, between neurons, strengthening meaningful patterns of neural activity in order to store ...

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.