Importance of Serotonin

Serotonins are clutches of neurons that lie in the central nervous system (CNS). These extend throughout the CNS. The serotonin presence is very extensive and they exert biological influences in a person. They are assumed to have a role in sleep, memory, appetite, cognition, body temperature, heart function, sexual performance, muscle control, endocrine secretion control etc. These neurons also inhibit certain activities of nervous system and they induce CNS that soothes, maintains tranquility and generates feeling of happiness and contentment.

It is a known fact that serotonin is involved in disorders like schizophrenia, Parkinson’s disease, depression etc. Serotonin insufficiencies are one of the causative factors in bulimia, migraine headaches, phobias, obsessive-compulsive disorders, besides schizophrenia.

The involvement of serotonin (also called 5-hydroxytryptamine, 5-HT) in depressive conditions does not indicate that it is one of the causes of depression. But depression and low serotonin levels are common place in many people who complain of depressive symptoms. Research does not confirm whether depression causes low serotonin levels or drop in serotonin levels cause depression.

But there is a common agreement on one thing. When a person is in a depressed state, elevating of serotonin levels in the system will help alleviate the symptoms of depression. One thing they do know is that depression can often be lifted by raising serotonin levels. Serotonin is the quintessential ‘feel good’ chemical of the brain. It has vast influence in matters connected with the brain.

Serotonin is also associated with mood changes that occur in the brain. Mood drops to gloominess when serotonin level falls. The antidepressants medications work precisely on elevating this 5-HT level to counter depression. Medications either boost serotonin levels or inhibit and retard re-absorption by the secreting nerves.

Depression is associated with symptoms of impairment of motor function, difficulties in cognition, memory problems, and apathy. As previously mentioned, serotonin is assumed to be associated with motor activity. Abnormality in serotonin functioning explains the effect of reduced motor activity on depressed patients where the patients become lethargic and exert themselves to the maximum even to accomplish small tasks, like getting up, walking or climbing. This abnormality is also associated with temporary memory lapses and incoherence.

Serotonin Reuptake Inhibitors

There are a category of antidepressant medications called selective serotonin reuptake inhibitors (SSRIs) that are used to prevent re-absorption of serotonin. Communication and transfer of information between nerve cells are conducted through nerve impulses. Brain’s neurochemicals, called neurotransmitters, act as medium to facilitate communication. Serotonin is one such neurotransmitter.

There are other important neurotransmitters such as norepinephrine and dopamine. These chemicals reside in the synaptic space between the nerve ends. The nerve communication is between sending nerve and receiving nerve with receptors. The sending nerve end secretes these chemicals which act as medium. As long as these chemicals stay in the supply, there will be feeling of buoyancy and contentment in a person. But, the sending nerve also acts like a pump and re-absorbs these chemicals back. They are presumed to do so to keep up chemical balance in the brain. When this re-absorption effort severely depletes serotonin level, a person will feel the symptoms of depression. The SSRI medications selectively block this re-absorption process, thereby ensuring enough supply of serotonin in the system.

The following are some other aspects of serotonin reuptake inhibitors:

Indications: These medications are used for treatment of panic disorder, post-traumatic stress disorder, generalized anxiety disorder, social phobia, obsessive-compulsive disorder and bulimia nervosa.

Efficacy: It is estimated that about 70 percent of people who suffer from depression respond positively to these inhibitor medications. A newer drug, venlafaxine, is found to be more effective. Of the newer antidepressants, venlafaxine may be slightly more effective. No additional advantage is found with increased dosages than normal.

Tolerance: People are likely to stick with treatment for a long time as these inhibitors are well tolerated. Among the medications, fluvoxamine is proved to be less favorable because of adverse effects on GI track.

Toxicity: These reuptake inhibitor drugs affect GI track severely. These drugs induce sexual deficiencies, restlessness, nightmares and weight alterations. The tendency of these medications to aggravate upper gastro-intestinal bleed is confirmed. Caution to be observed while prescribing these drugs to the elderly patients.