The Regenerative Capacity of the Progenitors - Essay Example

Neuroscience The brain of an adult has been the of many discussions and thorough research. Scientists are also devising new modes of simulation and this has led to new and better approaches of understanding human brain. We find that studies such as bioinformatics where by simulators are being used to carry out this research. In the experiments that will be discussed, we find that there are many experiments that are being carried out on the study of progenitors. Recent discoveries on neurological progenitors have led to wide interest on how neurons can be regenerated. Endogenous progenitors have made them a subject of interest by many scientists. They are usually found in the hippocampus of the brain and they are involved in the regeneration of neurons (Gould 236). They usually regenerate after an ischemic attack to an individual. Studies are also being carried out to understand how the neurons that are newly formed integrate with old circuitry in the brain. Therefore, the following experiments will try to highlight how studies are being carried out in this area. Introduction The human brain is one of the most important features in human anatomy. The brain plays a key role in ensuring that the body plays or performs its key functions. Among the functions that the brain plays include; coordination of body functions, reasoning understanding various elements that happen within the external environment. GABA has long been recognized as receptor that plays a key role in the brain. They are ligand-gated channels and they are also known as inotropic receptors. There are also metabotropic receptors that play a key role as a receptor (Brodal 89). Sodium and potassium play a key role in the circuitry process. They help in transmission of nerve impulses. There are experimental evidence that have been carried out to mainly demonstrate how new nerves are generated and how the experimental designs were carried out. The brain is mainly composed of brain tissues and cells. These tissues are necessary in ensuring that the brain performs its functions. When these cells are destroyed, one may end up losing his or her life through brain death. An experiment was carried out by Nakatomi et al.., was trying to find out how the hippocampal pyramidal neurons were regenerated after an Ischemic brain injury (Sciverse 428). The regeneration was through the recruitment of the neural progenitors that were endogenous in nature. From their abstract, they describe how the adult brain is one of the most vulnerable parts of the body when it is compromised or insulted. Recently, neural progenitors were discovered in adult mammals. This discovery helped in building the foundation of how regeneration can take place. The regeneration is possible when the endogenous progenitors are regenerated. The progenitors usually regenerate or proliferate when ischemia occurs. When this happens migration of the ischemia occurs and this happens in the hippocampus and it is at this place that regeneration occurs. The reason why this is possible is because there are growth factors that play key role in the regeneration process. They therefore increase the number of new born neurons. Studies have suggested that the newly regenerated neurons usually integrate with brain circuitry (Brodal 90). These novel revelations have indicated that it is possible to regenerate new cells in the brain and this could have therapeutic uses against neurological diseases and strokes (Sciverse 435). Introduction to the experiment The scientists postulated that the adult brain has got the capacity to always regenerate. This capacity is also replicated by the liver, skin and other resident cells. This usually happens through the proliferation of nearby stem cells. It has always been a long standing myth that the adult central nervous system has always been unable to self- generate or even self-repair. This is far from the truth. There are cell lines that are known as the gila that are usually present in the adult central nervous system. They are believed to be responsible for the regeneration process. There are also progenitors that are also involved in the same process. The scientists then concluded that with these features available in the human central nervous system, and then it would be very possible to ensure that neurons would be regenerated very easily. Consistent with new studies it has also been postulated that when neurogenesis occurs, then novel neurons can be found in the central nervous system. There are studies that are being carried out so that there can be cures for certain neurological diseases. When these studies are usually being carried out, they usually have the sole objective of ensuring that there are therapies for the degenerative disorders (Sciverse 456). Objective of the experiment The main objective of the experiment was to seek the regenerative capacity of the progenitors that were endogenous in nature. The scientists when carrying out the experiments had the sole objective of finding out the regenerative capacity of the progenitors. They were mainly focusing on the hippocampus. The main function of the adult hippocampus is that, it is a vital centre for memory and learning. This area of the brain is mainly sensitive to insults and a very good example is ischemia. Although it is believed that the can actively generate neurogenic sites, there is only one neuronal subtype. The neuronal subtype that is on focus is the denate gyrus. This is site is believed to be the reason as to why there are new neurons that generated. From the study, it was somewhat evident that regeneration of new neurons in adults is somewhat limited. The scientists used this as the benchmark for their studies and they did this by stimulating the adult neural progenitors. They can be stimulated in situ or by introduction of growth factors onto the neurons. These growth factors act by replacing the CA1 neurons that are pyramidal. The newly formed neurons act as synapses that are functional and are well integrated into the circuitry of the brain. In addition to all these, there are other receptors that are found in the brain and play a key role in regeneration of new tissues. A good example is the GABA, which is a receptor and it plays certain inhibitory roles. Results of the experiment From studies that were carried out on rodents, it was found that there was selective degeneration of the CA1 of the hippocampus. What remained a mystery was whether regeneration of neurons would occur after ischemia had occurred. A rat model that had its CA1 neurons eliminated in a manner that was highly reproducible. This feature still left the animals to survive in an environment where there was severe ischemia damage. From the experiment it was noted that the animal model had its CA1 removed. Form the study, they were able to conclude that the neurons were able to be regenerated one way or another and this could be key to solving many and novel degenerative diseases (Brodal 80). There are other key elements that play crucial roles in studying degenerative illnesses such as stroke. Overview of the second experiment In the second experiment, there principal investigators were Elizabeth Gould and et al… The topic of the experiment was how learning can enhance neurogenesis in an adult’s hippocampus. From the introduction of the experiment, we get to understand that the hippocampus is usually generated when an individual becomes an adult. This is suggestive that the new cells are very important in the functioning process of the hippocampus. The main objective of the study was to find out adult -generated neurons are dependent on the learning process of the hippocampus. In this study, newly formed cells were labeled with the analogue of thymidine that is known as bromodeoxyuridine. This was incorporated after study of various behaviors (Nevoigt 456). From the experiment, the adult neurons are generated in the rat. This happened after the associative tasks had learnt through various processes. Introduction to the experiment For decades, the learning process of the hippocampus has been greatly studied in detail. What remains to be mystery are the cellular mechanisms for this kind of association. Throughout adulthood, the hippocampus usually produces new neurons that and this happens in many vertebrates. These vertebrates may range from primates to birds. The experiment mainly had a basis of finding out the associative learning process was taking place. The fates of new cells were being studied. The new cells were labeled with an analogue of thymidine. Experimental design and results What were used were two different tasks that were hippocampus-dependent and independent ones. In the maze tasks, there was no difference in latency that was recorded in the animals that was trained. Over the period, the rats showed a decrease in latency over a period of time. There were studies that were carried out in the previous thymidine-auto radiographic. From the studies, it was evident that the new cells kept on generating after every two hours and a week after the synthesis of DNA had occurred. They would then decline later after labeling had taken place. It is likely that the reason for the decrease would be due to apoptosis or cell death. This is opposed to the view that there might have been dilution to dilution of the label. The data below was reported for the experiment The following graph was also obtained from the experiment Rats Brdu Labeled cells control 2000 Trace paired 6000 Trace unpaired 2000 From the above experiment animals received Brdu labeled cells that were radio labeled. They rats received the injections before they were perfused The experiment also endeavored to determine whether there were any chances of the learning process altering the survival of newly generated cells. What the scientists did was to engage the animals in a task that would take place when the number of the cells that are in question would low in terms of numbers. The animals that received the radiolabeled cells within their dentate gyrus were compared to controls that were naïve in nature. The brains of the test animals were examined days later to study if there were any effects that were reported. The difference was that there seemed to be a specific reaction to the dentate gyrus. Hippocampal cells were found to be located in the granule cell layer. This happened after dependent learning of the hippocampus was expressed by the marker of neurons that were immature. When an examination was carried out one week later after the training, it was found out that the number of radiolabeled cells had still remained as hippocampus-dependent learning groups. When the cells were examined a week later, there were no differences that were observed. There was no difference in the volume of granule of the cell layers. When the cells are exposed to similar environmental conditions, it was found that the responses had no responses at all. Rats that were exposed to a water maze for a similar period of time, had a trained group that was similar to the rest had no difference at all to the ones that had radio labeled cells. The task of training on the associative learning tasks does not entirely require the hippocampus. Discussion of the experiment The results from the experiment do help the scientists in getting a clear direction or association between the new neurons that were generated and hippocampus dependent learning. There are different types of learning that that usually depend on a part of the brain that is known as the hippocampus. These include; trace eye blink conditioning and the water-maze training. On the other hand, learning does not actually require the part of the brain that is known as the hippocampus. There are theories that have been postulated about the hippocampal function. These theories assert that hippocampus plays many roles in the brain function. It could either play a temporal role or a spatial role. Experimental overview The third experiment was mainly carried out by James B. Aimone et al. the title of the experiment was “Computational influence of Adult Neurogenesis on Memory Encoding”. A brief summary of the experiment shows that the adult neurogenesis of hippocampus usually leads to incorporation of many cell granules (Brodal 99). In this experiment, there is evidence that is computed and presented. The adult neurogenesis presents three contributions that distinct but separate as a whole (James 456). The neurons have got an extended maturation rate and this makes them quite excitable. The real model will suggest that the experience in gyrus dentate is well suited for the function of encoding. Introduction The dentate gyrus or the DG is one of the most important regions that are found in the brain. It plays a key role in the generation of new neurons within the brain. Thousands of new cells are usually formed and they form part of the brain circuitry. When the newly cells are formed, they usually undergo the maturation process and this is very important in the development of ells. When they mature, they develop properties that are electrical in nature. For the neurons to survive there are conditions that must be available so that their survival can be enabled. There should be ample physical activity for the cells to mature and an environment that is well enriched with the necessary nutrients. These conditions are extremely necessary for the growth of the tissues. Despite an increase in the understanding of how neurons integrate into a network that is fully functional, their core functions are unclear. Objective and results of the experiment The researchers wanted to address the question of neurogenesis functions and they wanted to do this with a computational model. This model had a system that was well incorporated. The model principally focused on pattern separation. When the adult model was designed by a complex neural network, which had many details in it, there was an understanding that was made for the neural. There are very many approaches that have been devised to understand how the network fully functions. There are two input regions that are involved in the computational model. One of them is the neurogenic layer and the entorhinal cortex. There are also three interneuron layers that are involved. Experimental Design In the experiment that was conducted Hironobu Iguchi and et al, they trying to investigate how CREB is required for the growth of the growth of the epidermal growth factor (EGF). They were trying to understand the serum response element on activation of the neural stem cells. From their brief introduction, it is quite evident that neurogenesis is quite a common phenomenon. It is a phenomenon that is characterized by the generation of new cells. It also restricted too many regions in the brain of an adult. This in effect means that it does not occur in every part of the brain. The main objective of the experiment was to investigate whether cAMP, which is a transcription factor and a response element is involved in cell proliferation. The stem progenitor exists not only in the brain but also in regions that are restricted. From the results that were obtained from the experiment, it is quite evident that cAMP-PKA-CREB is required for stimulation of the EGF-stimulated proliferation of the NSC. When the experiment was concluded, it was evident that the cells that were cultured were immune-reactive. The experiment was able to determine that the cAMP-PKA pathway are involved in the proliferation and regulation of adult NSCs From above experiments, there are clear things that are a common feature. Neurogenesis is a phenomenon that occurs in adults and it is not restricted to any particular area of the brain. Nerves play a central role in the transmission of nerve impulses. GABA, sodium and phosphorus are also part and parcel in the transmission process. Sodium and phosphorus play key role in the transmission process in that they act as electrolytes in the entire process. Sodium is also required in hydrochloric acid formation (Brodal 67). Hydrochloric acid in turn acts as a disinfectant or repellent against pathogens that may affect the body. The two electrolytes are also involved in action potential and that they help in the general transmission of nerve impulses. Regeneration of nerve cells is a common phenomenon. The regeneration is possible when the endogenous progenitors are regenerated (Iguchi 748). The progenitors usually regenerate or proliferate when ischemia occurs. When this happens migration of the ischemia occurs and this happens in the hippocampus and it is at this place that regeneration occurs. Works Cited Brodal, P. The Central Nervous System: Structure and Function. London: Oxford University Press, 2010. Gould, E. "Learning enhances adult nuerogenesis in the hippocampal formation." Nature America (1999): 260-265.Print Iguchi, H. ". cAMP response element-binding protein (CREB) is required for epidermal growth factor (EGF)-induced cell proliferation and serum response element activation in neural stem cells isolated from the forebrain subventricular zone of adult mice." Endocrine Journal (2011): 747-759.Print James, B. "Computation Influence of Adult Neurogenesis on Memory Encoding." Neurogenesis journal (2011): 656-678.Print Nevoigt, Elke. Microbiology and Molecular Biology Reviews. Wednesday September 2008. Tuesday November 2011 .Print Sciverse. "Regeneration of Hippocampal Pyramidal Neurons after Ischemic Brain Injury by Recruitment of Endogenous Neural Progenitors." Cell (2002): 429-441.Print Read More