Ketamine a potent anesthetic used in Veterinary Anaesthesia

Ketamine is a potent anesthetic administered in human and veterinary medicine, and rarely used illegally as a recreational drug. The drug is also a hopeful candidate for the fast treatment of depression in patients who do not respond to other medications. New research demonstrates using PET imaging studies on macaque monkeys that ketamine increases the activity of serotoninergic neurons in the brain areas regulating motivation. The researchers accomplish that ketamine's action on serotonin, often relishes the "feel-good neurotransmitter," may evaluate its antidepressant action in humans.

Ketamine has recently been recognised to have a stimulant activity with short onset and long-term duration in patients suffering from treatment-resistant major depressive disorder, who do not respond to standard medications and the examples are serotonin reuptake inhibitors, monoamine oxidase inhibitors and tricyclic antidepressants. However, the mechanisms depends upon ketamine's activity on the depressive brain have remained unclear. To understand the effects of ketamine on the serotonergic system in the brain, pioneered PET imaging on conscious non-human primates, together conducted a PET study on rhesus monkeys. The system was effortless for the monkeys, and PET outputs are performed frequently on people to analyze diagnostic conditions.

The researchers conducted PET imaging studies on four rhesus monkeys with two tracer molecules related to serotonin (5-HT) that bind highly selectively to the serotonin 1B receptor 5-HT1B and then to the  serotonin transporter SERT. From the diagnostic procedure of the 3 dimensional images generated by the PET scans, the researchers could infer that ketamine induces an increase in the binding of serotonin to its receptor 5-HT1B in the nucleus accumbens and the ventral pallidum, but they found there is a slight decrease in binding to its transporter SERT in these brain regions. The nucleus accumbens and the ventral pallidum are brain regions regionally associated associated with motivation and both have been shown to be involved in depression and these are so done to reduce pain during veterinary anesthesia.

 In addition, the researchers demonstrate that treatment with NBQX, a drug is basically known to block the anti-depressive effect of ketamine in rodents by actively selective  blocking the glutamate AMPA receptor, cancels the action of ketamine on 5-HT1B but not on binding with SERT . Taken together, these findings indicate that ketamine may act as an antidepressant by increasing the expression of postsynaptic 5-HT1B receptors, and that this process is mediated by the glutamate AMPA receptor. So the general anesthesia  are opted for several time in order to reduce pain.