Structural Biochemistry/Neuroscience

Definition

Neuroscience is a science that describes the study of the nervous system. It involves studying its anatomy, chemistry, physiology, development, and functioning. It is an interdisciplinary science that involves psychology, mathematics, physics, chemistry, engineering, computer science, philosophy and medicine. It should be noted that there is a difference between neuroscience and neurobiology. Neurobiology specifically refers to the biology of the nervous system whereas neuroscience refers to the entire science (chemistry, physics, etc.) of the nervous system. Neuroscience has become a enormously popular field in the last few years; for example, the Society for Neuroscience currently has about 30,000-40,000 members, maybe more.

Alzheimer's Disease

Alzheimer’s disease is a form of dementia. It is a degenerative, terminal disease that is currently incurable. Death of neurons in the hippocampus of the brain causes memory impairment in those with Alzheimer’s disease. As the neurons degenerate, neurofibrillary tangles develop. Neurofibrillary tangles are intracellular accumulations of hyperphosphorylataed tau. There is now evidence that a truncated p73 isoform, ΔNp73, protect the neurons against tau hyperphosphorylation and tangle formation. It prevents tangle formation by inhibiting c-Jun N-terminal kinase (JNK). Furthermore, ΔNp73 protects neurons against cell death by antagonizing p53. P53 mediates programmed cell-death in a process called apoptosis. It kills neurons by inducing the expression of pro-apoptotic proteins. P53 over expression results in tau hyperphosphorylation in cells. The new discovery that ΔNP73 protects neurons from tau hyperphosphorylation as well as tangle formation provides insight for potential therapeutic roles of ΔNp73 inducers. Drugs can be developed to enhance the neuroprotective actions of ΔNp73.

Alzheimer's Disease (AD) seems to be initiated by the dysfunctional activities of two proteinases (γ- and β-secretase) which generate a series of aggregation-prone peptides called Aβ from their substrate, amyloid precursor protein (APP). The amount of Aβ peptides that accumulates is believed to be the main factor that induces neuronal dysfunction and death.

Parkinson's Disease

Parkinson's disease is a motor disorder caused by the death of neurons in the midbrain area. These neurons are typically capable of releasing dopamine, a biogenic amide neurotransmitter, at synapses located in the basal nuclei. When the neurons are destroyed, nerve cells are no longer able to send signals that allow for communication between the substantia nigra and corpus striatum in the brain. Lack of these signals affect the control of muscle movement. The symptoms that result include tremors in the limb or muscle, slowed movement and poor balance. Currently, little is known about the cause for the destruction of neurons and why Parkinson's disease occurs. However, molecular studies have been able to link genetics to rare cases that occur in young adults. Consequently, this has led to the belief that this disease may be inherited although there is still much controversy surrounding this discussion. Scientists are also determining whether or not defects in genes required for mitochondrial function has also been linked to and early onset of this disease.

Similar to Alzheimer's, Parkinson's disease is more common as people get older. For adults at age 65, around 1% are at risk for Parkinson's while at age 85, this rises to 5%. There are nearly 1 million people in the US today that suffer from Parkinson's disease. There is currently no cure for Parkinson's disease. However, there are methods used to maintain the symptoms that include brain surgery, drugs that have the ability to be converted into dopamine and cross the blood brain barrieras well as deep brain stimulation. In laboratories, scientists have also experimented using rats with a similar induced condition. They place dopamine secreting neurons in the midbrain or basal nuclei that help control motor functions. Whether or not this technique would work on humans is still being researched.

Sources

[1] Carlson, Neil R. Physiology of Behavior. Boston: Pearson Education, Inc., 2007.

[2] Glass, Jon. "What Causes Parkinson's? Age, Genetics, Environment, and Other Factors." WebMD. WebMD, n.d. Web. 27 Oct. 2012. <http://www.webmd.com/parkinsons-disease/parkinsons-causes>.

[3] Reece, Jane B. Campbell Biology, 2011

Reference

1. Molony A, et al. “Alzheimer’s disease: insights from Drosophila melanogaster models.” Trends Biochem Sci. 2010 Apr;35(4):228-35. Epub 2009 Dec 25.