From Medicineworld.org: Antidepressants Boost Brain Growth
Cancer blog: I manage the cancer blog with lots of help and support form other bloggers. Through this cancer blog my friends and I try to bring stories of hope for patients with cancer. The cancer blog often republishes important blog posts from other cancer related blogs at Medicineworld.org. If you are searching for a blog that covers wide variety of cancer topics, this may be the one for you.
Breast cancer blog: Breast cancer blog is run by Emily and other bloggers and they bring you the latest stories, news and events that are related to breast cancer. Increasing awareness about breast cancer among women and in the general population is the main goal of this breast cancer blog.
Lung cancer blog: Lung cancer blog is managed by Scott with the help of other bloggers. Through this blog Scott and his friends constantly remind the readers about the dangers of smoking. It's a never-ending struggle against this miserable disease with which a social stigma of smoking is associated.
Colon cancer blog: Colon cancer blog is run by Sue and other bloggers. Sue brings a personal touch to the colon cancer blog since her mother died of colon cancer few years ago. She writes about stories, research news and advances in treatment related to colon cancer.
Prostate cancer blog: Prostate cancer is the most common cancer among American men. American Cancer Society estimates that over 230,000 new cases of prostate cancer occur in the United state every year. This important blog about prostate cancer is run by Mark and other bloggers. This blog brings news, stories, and other personal observations related to prostate cancer.
Medicineworld.org publishes a diabetes watch blog and this blog is run by JoAnn other bloggers. This diabetes watch blog brings you the latest in the field of diabetes. This includes personal stories, advances in diagnosis and treatment, and other observations about diabetes. Improving awareness about diabetes is an important mission of this group.
Antidepressants Boost Brain Growth
The study on rats, led by Vassilis E. Koliatsos, M.D., a neuropathologist at the Johns Hopkins University School of Medicine, found that selective serotonin reuptake inhibitors (SSRIs) increase the density of nerve-impulse-carrying axons in the frontal and parietal lobes of the neocortex and part of the limbic brain which control the sense of smell, emotions, motivation, and organs that work reflexively such as the heart, intestines and stomach. "It appears that SSRI antidepressants rewire areas of the brain that are important for thinking and feeling, as well as operating the autonomic nervous system," said Koliatsos.
Axons are long, filament-shaped extensions of neurons that, together with myelin, are the main constituents of nerves. Axons conduct chemically driven nerve impulses away from the cell body toward a narrow gap known as a synapse. Among the chemicals involved are such monoamines as norepinephrine and serotonin, which, at the synapse, are transferred to another neuron.
Antidepressants, such as Prozac, Zoloft and Paxil, have long been thought to exert their clinical effects by increasing synaptic concentrations of serotonin and norepinephrine, enhancing or stimulating their transference.
"But our findings -- that serotonin reuptake modulators increase the density of nerve synapses, particularly in the front part of the brain - may offer a better explanation of why antidepressants are effective and why they take time to work," according to Koliatsos.
For example, antidepressants increase synaptic monoamines within hours, and the regulatory effects on receptors are complete within a few days, yet clinically meaningful results from antidepressants commonly require a two- to four-week delay.
"This disparity between simple pharmacological effects and clinical experience might be due to the time it takes for serotonin axons to grow," Koliatsos said.
"For the patient, this hypothesis provides more tangible evidence of a real effect in the brain," he added.
In the Hopkins study, Koliatsos and his team gave either the selective serotonin reuptake inhibitor fluoxetine (Prozac), the selective serotonin reuptake enhancer tianeptine (a drug approved only for human use in France) or the selective norepineprine reuptake inhibitor desipramine, a so-called tricyclic antidepressant, to groups of rats for four weeks and studied anatomical patterns of serotonin stimulation on various parts of the brain. The results showed that fluoxetine and tianeptine, but not desipramine, increased the density of serotonin axons in the frontal and parietal neocortex and certain limbic cortical and subcortical areas.
One possible explanation for this action is the brain-derived growth factor (BDNF). BDNF is regulated by levels of serotonin and is known to be a prime candidate for causing serotonin axon growth, Koliatsos said.
In general, the relationships between brain serotonin concentrations and BDNF expression are very complex, but prior studies have suggested that both higher (such as caused by serotonin reuptake inhibitors) and lower (such as effected by tianeptine) concentrations of free serotonin might induce BDNF expression in such brain regions as the frontal and parietal cortex.
The scientists caution that since a prior study failed to show a correlation between tianeptine therapy and BDNF levels, further investigation of the complex regulations of BDNF by antidepressants is needed.
Funding for this study came from the National Institute of Mental Health.
The study is currently available at the Journal of Neurochemistry Web site: .
Source: Johns Hopkins Medicine
Did you know?
The beneficial effects of a widely used class of antidepressants might be the result of increased nerve-fiber growth in key parts of the brain, according to a Johns Hopkins study being published in the January 2006 issue of the Journal of Neurochemistry. The study on rats, led by Vassilis E. Koliatsos, M.D., a neuropathologist at the Johns Hopkins University School of Medicine, found that selective serotonin reuptake inhibitors (SSRIs) increase the density of nerve-impulse-carrying axons in the frontal and parietal lobes of the neocortex and part of the limbic brain which control the sense of smell, emotions, motivation, and organs that work reflexively such as the heart, intestines and stomach. "It appears that SSRI antidepressants rewire areas of the brain that are important for thinking and feeling, as well as operating the autonomic nervous system," said Koliatsos.
Medicineworld.org: Antidepressants Boost Brain Growth
The contents of this web page are protected. Legal action may follow for reproduction of materials without permission.