wimsey1
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I'm posting this article for those who are interested in the biological causes of depression. While we don't clearly understand the connections, we do recognize the role of the hypothalmus in the regulation of 3 neurotransmitters (serotonin, norepinephrine and dopamine) involved with clinical depression, as well as the regulatory function of the hypothalmus in monitoring the hormone cortisol. We often feel shame when admitting we are depressed, and Lord knows, we have reasons to be depressed. This creates a powerful feedback loop of behavior, thought and neurological reinforcements that can only deepen our depression if not addressed properly. Bottom line: we get depressed, our body already has trouble with the flow of powerful neurotransmitters and hormones, and our reactions to that can make matters worse. Knowledge is the beginning of recovery, and acknowledging we have a problem, is the key! Hope this helps. lance
Biological Causes of Depression
Those who research clinical depression have been interested in a particular part of the brain called the limbic system. This is the area of the brain that regulates activities such as emotions, physical and sexual drives, and the stress response. There are various structures of the limbic system that are of particular importance. The hypothalamus is a small structure located at the base of the brain. It is responsible for many basic functions such as body temperature, sleep, appetite, sexual drive, stress reaction, and the regulation of other activities. The hypothalamus also controls the function of the pituitary gland which in turn regulates key hormones. Other structures within the limbic system that are associated with emotional reaction are the amygdala and hippocampus. The activities of the limbic are so important and complex that disturbances in any part of it, including how neurotransmitters function, could affect your mood and behavior.
Within the brain, there are special chemicals called neurotransmitters that carry out many very important functions. Essentially, they help transfer messages throughout structures of the brain's nerve cells. These nerve cells, called neurons, are organized to control specialized activities. We each have somewhere between 10-100 billion neurons within our brains. Whenever we do anything, react, feel emotions, think, our neurons transmit messages in the form of electrical impulses from one cell to another.
Neurotransmitters travel from neuron to neuron in an orderly fashion. They are specifically shaped so that after they pass from a neuron into the synapse, they can be received onto certain sites, called receptors, on a neighboring neuron. Neurotransmitters can fit a number of different receptors, but receptor sites can only receive specific types of neurotransmitters. Of the 30 or so neurotransmitters that have been identified, researchers have discovered associations between clinical depression and the function of three primary ones: serotonin, norepinephrine, and dopamine. These three neurotransmitters function within structures of the brain that regulate emotions, reactions to stress, and the physical drives of sleep, appetite, and sexuality. Structures that have received a great deal of attention from depression researchers include the limbic system and hypothalamus. It is unknown whether changes in levels of neurotransmitters cause the development of depression or depression causes changes in neurotransmitters. It may happen both ways. Researchers believe that our behavior can affect our brain chemistry, and that brain chemistry can affect behavior. For instance, if a person experiences numerous stressors or traumas this may cause his or her brain chemistry to be affected, leading to clinical depression. On the other hand, that same person may learn how to change depressed thoughts and behavior and cope with stressful events. Doing this may also change brain chemistry and relieve depression. Another area of research in determining the causes of clinical depression is focused on the endocrine system. This system works with the brain to control numerous activities within the body. The endocrine system is made up of small glands within the body, which create hormones and release them into the blood. The hormones that are released into the body by the glands regulate processes such as reaction to stress and sexual development. It has been found that a great number of people who are depressed have abnormal levels of some hormones in their blood despite having healthy glands, especially the hormone cortisol. Problems with hormone levels may be intertwined with the changes in brain chemistry that are seen in clinical depression. The endocrine system is connected with the brain at the hypothalamus which controls many bodily activities such as sleep, appetite, and sexual drive. The hypothalamus also regulates the pituitary gland that, in turn, controls the hormonal secretion of other glands. The hypothalamus uses some of the neurotransmitters that have been associated with depression as it manages the endocrine system. These neurotransmitters, serotonin, norepinephrine, and dopamine all have a role in the management of hormone function. The hypothalamus may be the culprit when it comes to excessive levels of cortisol in the blood. It is responsible for starting the process that leads to the secretion of cortisol by the adrenal glands. The hypothalamus first manufactures corticotrophic-releasing hormone (CRH). The pituitary gland is then stimulated into releasing adrenocorticotrophic hormone (ACTH). This hormone then makes the adrenal glands secret cortisol in the blood. When the endocrine system is functioning properly, the hypothalamus monitors the level of cortisol that is in the blood. When the level rises, the hypothalamus slows down its influence on the pituitary gland in production of CRH. When cortisol levels become reduced, the hypothalamus causes the pituitary gland to produce more CRH. In a person who is depressed, the hypothalamus may continuously influence the pituitary to produce CRH without regard to the amount of cortisol that is in the blood.
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