الفهرس 
Chemistry of Polyunsaturated fatty acids (PUFAs)Only 14 pages are availabe for public view
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Abstract
The human brain is primarily composed of lipids (60–70% dry weight) comprised of a ratio of saturated fatty acids and unsaturated fatty acid (monounsaturated fatty acid and polyunsaturated fatty acids) (McNamara and Carlson, 2006).
Polyunsaturated fatty acids are important components of membrane cells and neurological tissue, Polyunsaturated fatty acids especially arachidonic acid and docosahexaenoic acid are particularly important for the central nervous system structure and function (Sethom et al., 2010).
Several biological mechanisms potentially explain the impact of omega- 3 Eiscosapentanoic acid in psychiatric disorders; these include (1) increased serotonergic neurotransmission, (2) alteration in dopaminergic function, (3) regulation of corticotrophin-releasing factor, (4) inhibition of protein kinase c, (5) suppression of phosphatidylinositol associated second messenger activity, (6) improved cerebral blood flow, (7) regulation of gene expression, (8) increased dendritic arborization and formation, (9) prevention of neuronal apoptosis, (10) competition of eiscosapentanoic acid with arachidonic acid for enzymatic action and resultant reduction of the inflammation response (Freeman et al., 2006).
There is evidence to suggest that abnormal phospholipid and related fatty acid metabolism may play a role in the aetiology of several psychiatric illnesses, including schizophrenia, bipolar mood disorder, major depression, dementia and attention deficit hyperactivity disorder (Parker et al., 2006).
There is evidence that altered composition of membrane levels of fatty acids is correlated with severity of psychotic symptoms and also with impairment of distinct cognitive parameters in subjects with schizophrenia (Sumiyoshi et al., 2010).
Deficiencies in w-3 polyunsaturated fatty acids have been reported in a wide range of psychiatric disorders that have included (but are not limited to) depression, suicidal tendencies and aggressive disorders (Young and Conquer, 2005).
The “arachidonic acid cascade hypothesis” asserts that these agents commonly alleviate bipolar disorders symptoms, particularly bipolar mania, by downregulating brain arachidonic acid metabolism (Rao et al., 2008).
Several natural compounds, including omega-3 fatty acids, have been suggested as potential augmenters of antidepressant drug effects especially in treatment-resistant depression (Liano et al., 2010).
Also, decreased levels of the docosahexaenoic essential fatty acid have also been reported in autism (Taylor and Benjamin, 2004).
In patients with social phobia, the abundance of eicosapentaenoic acid and docosahexaenoic acid in erythrocyte membranes is decreased in those with the illness and the extent of the reduction is correlated with the severity of the illness (Green et al., 2006).
Besides, it has been recently reported the first clinical trial demonstrating omega-3 to be effective monotherapy in childhood depression (Nemets et al., 2006).
However, randomized controlled clinical trials have been slow to accrue. Most but not all trials with omega-3 indicate that these fatty acids are effective as an adjunctive treatment for unipolar depression and may be beneficial in other mood disorders (Owen et al., 2008).
There is no doubt that further research is needed in this field to clarify the efficacy of omega-3 as monotherapy for the treatment of unipolar, bipolar, perinatal and childhood depression as well as the optimal dose and type of omega-3 supplement for each case ( Venna et al., 2009).