Scientists conducted one experiment in which they made few mice as their subject but those who were identified as serotonin deficient. As discussed earlier it is a crucial chemical that causes severe depression. In reality there are several categories of depression but we have yet generalized a term depression to signify psychological illness. These mice found to be more vulnerable than their normal littermates who are acquainted to social stressors. The Duke Experiment result, that is going to appear this week in the Proceedings of the National Academy of Sciences has claimed that, the serotonin-deficient mice did not reciprocate to a standard anti-depression pill Prozac; which acts by thrusting serotonin transmission between adjacent neurons.

Intention behind conducting such experiment is to know the root cause behind a question, why few patients do not respond in expected manner while they undergo a treatment with antidepressant drugs that belongs to selective serotonin reuptake group and are commonly available in the market to serve the purpose. Results suggest several possible therapeutic strategies to strengthen the treatment in order to destroy resistance against anti-depression pills. "To our surprise conclusion seems to be very exciting because it explains in a simply elucidated animal model of serotonin deficiency. Low level of serotonin is also a supplementary factor to the occurrence of depression. Psycho-social stress may lead to the poor functioning of selective serotonin reuptake group to reduce the symptoms of depression," said Marc Caron, the James B. Duke professor of cell biology in the Duke University School of Medicine.

Although root causes of depression are not yet understood properly. Scientists have thought about an experiment in conventional dimension that low brain serotonin could be a one aspect behind depression, this concept is not an easy task to examine directly, and there is persistent controversy about it. Researchers have received commendable appreciation for the many natural factors; largely stress that can be a sign of convalescence or aggravated signs of depression.
Team of researchers in one experiment decided to use a transgenic mouse that had only 20% to 40% of normal levels of serotonin in brain. These mice were a product of an extremely rare mutation that was primarily diagnosed in a small group of people with acute depression.

After a period of three week treatment with the help of Prozac, scientists noticed the stress based diminished symptoms of depression in absolutely normal mice, but not mutant mice.
Thus to summarize in nutshell Prozac and antidepressant drugs that belong to other SSRIs work effectively by impeding an ability of cells to recapture this neurotransmitter serum , so it supports to the conclusion that the drugs would be less effective in animals with abnormally low levels of serotonin, added Caron. A few case studies helped to bring a fact on the surface that if we target lateral habenula which is a part of human brain then it could possibly help to suppress resistance against the treatment. Researches address this particular area of the brain as punishment' region because its neurons remain active if not treated with reward.