Anesthesiology

Anaesthetic drug ketamine has been recently studied in depressive illness that has not responded to standard medication. Researchers have now found the exact mechanism of how the drug works in the brains of individuals with depression and can keep the symptoms down for more than a week. The results of the study titled; “Sustained rescue of prefrontal circuit dysfunction by antidepressant-induced spine formation,” were published in the latest issue of the journal Science.

Ketamine in the brains

The team of researchers found that ketamine; in the brains of lab mice could improve the functions of certain circuits and this could help elevate mood. Within a few hours; they explain; the drug starts to restore the connections between the cells of these circuits. It is believe that these connections are damage in persons who suffer from depression.

Last month in March, the Food and Drug Administration approved Spravato a nasal spray that comprises of a isomer of ketamine and is indicate  for treatment of people with depression who do not respond to standard medication. Spravato has been use to treat depression in thousands of individuals. This study shows that exact method by which this drug works.

Treatment of people

Dr. Conor Liston; a neuroscientist and psychiatrist at Weill Cornell Medicine in New York and co-author of the study said that studying the effects of ketamine on mice brain with depression was a challenge because depression does not occur in mice. The team from US and Japan thus devised a way to create depression; like situation in the mice brain by giving the mice a stress hormone.

When given the hormone the mice failed to find interest in doing their favourite activities such as exploring a maze or eating sugar etc. thereafter the brains of the mice were studied using a special laser microscope. Liston explained; “Stress is associated with a loss of synapses in this region of the brain that we think is important in depression.”

Living brain cells

Thereafter when ketamine was administered to the mice; there was a restoration of these synapses. Liston said; “Ketamine was actually restoring many of the exact same synapses in their exact same configuration that existed before the animal was exposed to chronic stress.” The team backed up their findings by testing the drug on living brain cells in the lab as well. Liston explained; “You can kind of imagine Van Gogh’s Starry Night. 
The brain cells light up when they become active and become dimmer when they become inactive.” As the circuits are repair with ketamine; the brain cells lit up together; they noted.The team is surprise to see in the mice that they start to act normal and non-depress within a couple of hours of administering ketamine and this is even before their circuits are fully repair. “It wasn’t until 12 hours after ketamine treatment ; that we really saw a big increase in the formation of new connections between neurons;” Liston said.