Molecular linkage studies of bipolar disorder

Understanding the pathophysiology of depression: From monoamines to the neurogenesis hypothesis model - are we there yet?

A number of factors (biogenic amine deficiency, genetic, environmental, immunologic, endocrine factors and neurogenesis) have been identified as mechanisms which provide unitary explanations for the pathophysiology of depression. Rather than a unitary construct, the combination and linkage of these factors have been implicated in the pathogenesis of depression. That is, environmental stressors and heritable genetic factors acting through immunologic and endocrine responses initiate structural and functional changes in many brain regions, resulting in dysfunctional neurogenesis and neurotransmission which then manifest as a constellation of symptoms which present as depression.

Current concept in neural regeneration research: NSCs isolation, characterization and transplantation in various neurodegenerative diseases and stroke: A review

Since last few years, an impressive amount of data has been generated regarding the basic in vitro and in vivo biology of neural stem cells (NSCs) and there is much far hope for the success in cell replacement therapies for several human neurodegenerative diseases and stroke. The discovery of adult neurogenesis (the endogenous production of new neurons) in the mammalian brain more than 40 years ago has resulted in a wealth of knowledge about stem cells biology in neuroscience research. Various studies have done in search of a suitable source for NSCs which could be used in animal models to understand the basic and transplantation biology before treating to human. The difficulties in isolating pure population of NSCs limit the study of neural stem behavior and factors that regulate them. Several studies on human fetal brain and spinal cord derived NSCs in animal models have shown some interesting results for cell replacement therapies in many neurodegenerative diseases and stroke models. Also the methods and conditions used for in vitro culture of these cells provide an important base for their applicability and specificity in a definite target of the disease. Various important developments and modifications have been made in stem cells research which is needed to be more specified and enrolment in clinical studies using advanced approaches. This review explains about the current perspectives and suitable sources for NSCs isolation, characterization, in vitro proliferation and their use in cell replacement therapies for the treatment of various neurodegenerative diseases and strokes.

Pathophysiology of depression and mechanisms of treatment

Major depression is a serious disorder of enormous sociological and clinical relevance. The discovery of antidepressant drugs in the 1950s led to the first biochemical hypothesis of depression, which suggested that an impairment in central monoaminergic function was the major lesion underlying the disorder. Basic research in all fields of neuroscience (including genetics) and the discovery of new antidepressant drugs have revolutionized our understanding of the mechanisms underlying depression and drug action. There is no doubt that the monoaminergic system is one of the cornerstones of these mechanisms, but multiple interactions with other brain systems and the regulation of central nervous system function must also be taken into account In spite of all the progress achieved so far, we must be aware that many open questions remain to be resolved in the future.

Overview of the field

Clinical descriptions of depression date back to antiquity. Scientific investigations of mood disorders started only 150 years ago. An historical overview of depression leads into today's knowledge that depressive disorders are common, serious, and sometimes life-threatening and that their effects are persistent and costly. Depressive disorders have a high prevalence, around 5% in the general population, with at least 20% of patients suffering with chronic conditions, such as cardiovascular disease and diabetes. Neuroimaging technology provides unprecedented opportunities for elucidating the neurobiological correlates of mood disorders. Neuroimaging studies of primary mood disorders have identified neurophysiologic abnormalities in the orbital and medial prefrontal cortex (PFC), the amygdala, and the related parts of the striatum and thalamus. There has been a revolution in our understanding of the pathogenesis of depression, with recent work demonstrating, among others, the critical impact of stress. There is an abundant evidence from family, twin, and adoption studies that genetic factors play an important role in the etiology of affective disorders. A variety of hormonal abnormalities, such as altered levels of cortisol, growth hormone, or thyroid hormones, indicate the existence of endoctrine disturbances. Despite the initial findings of immunosuppresion in depression, some studies have indicated that immune activation could also be present and might even play a role in the onset of depressive symptoms. Neurotrophic factors are among the growth factors that have been studied for their role in the adult nervous system. Despite advances in the pharmacotherapy of depression, only one third of patients respond favorably to antidepressant drugs. One third do not respond at all, and in clinical trials, at least one third respond to placebo. There is clearly an urgent need for novel antidepressants.