BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: neuron

Just Because My D1 Neurons Are Excited, Doesn’t Mean My Risk of Alcoholism Increases…Does it?!

Alcoholism can now not only be studied and analyzed at the psychological level, but also at the molecular level, thanks to researchers at the Texas A&M Health Science Center College of Medicine. They recently conducted a study that found how alcohol influences the dorsomedial striatum, the part of the brain that participates in decision-making and goal-driven behaviors.

The dorsomedial striatum is composed of medium spiny neurons, neurons that have many branches, or spines, protruding off their dendrites.

(Source: https://commons.wikimedia.org/wiki/File:Confocal_image_of_spiny_neuron_-_1.jpg)

Spiny neurons have receptors for dopamine, which is further categorized into dopamine D1 and D2 neurotransmitters. D1 neurons have receptors for D1 neurotransmitters. They send excitatory postsynaptic potentials and encourage the action potential/signal to continue. D2 neurons counteract D1 neurons; they send inhibitory postsynaptic potentials and discourage further actions. In this study, D1 neurons prove to be a major part of alcoholism and addiction.

High consumption of alcohol, scientists learned, excites D1 neurons. The more excited they become, the more compelled one feels to perform an action…in this case, the action is drinking another alcoholic beverage.

More drinking induces more D1 neuron excitement, which leads to even more drinking.

Not only does it affect a D1 neuron’s excitability, alcohol also makes physical changes to the neuron itself at the molecular level, and consequently affects the neuron’s function.

In their study, researchers divided their test subjects into two groups: one that’s exposed to alcohol and one that’s not. Analyzing their spiny neurons, scientists saw that though the number of spines in the neurons of the individuals of each group didn’t change, the ratio of the difference between mature and immature spines was dramatic. The subjects that drank alcohol had notably longer branches and a high number of mature mushroom-shaped spines. The abstainers’ neurons had shorter branches and more immature mushroom-shaped spines. Mature, mushroom-shaped spines are involved in long-term memory; activation of long-term memory through alcohol underlies addiction.

However, there’s promising news! The study also showed results that blocking, or at least partially blocking, D1 receptors via a drug can inhibit and reduce the desire for consumption of another drink.

This is a huge step towards finding a cure for alcoholism. Alcoholism is a disease that affects not only the individual, but also his or her family, relatives, friends, etc…With this study, the scientific community has more of an understanding of how to go about creating new drugs and combating alcoholism.

If we suppress this activity, we’re able to suppress alcohol consumption. This is the major finding. Perhaps in the future, researchers can use these findings to develop a specific treatment targeting these neurons.

-Jun Wang, M.D., Ph.D., the lead author on the paper and an assistant professor in the Department of Neuroscience and Experimental Therapeutics at the Texas A&M College of Medicine.

What do you think? Do you think this study promotes a viable option towards curing alcoholism and addiction, or is there another method out there that we should be pursuing? Leave a comment below!

 

Original Article

Out Like a Light: Sleep Switch in Brain Identified

Researchers from Oxford University’s Center of Neural Circuits and Behavior have identified the switch in the brain, which causes sleep, from a study of fruit flies. This switch regulates sleep promoting neurons in the brain. When one is tired and in need of sleep, these neurons will activate. Once you are fully rested, neuron activity will die down. Though this new insight was gained through studying fruit flies, or Drosophila, the researchers believe this information is also relevant to humans. In the human brain, there are similar neurons that are active during sleep and are the targets of general anesthetics that cause sleep. These facts support the idea that humans have a sleep mechanism like that found in fruit flies, according to Dr. Jeffrey Donlea, one of the lead authors of the study. The findings of this study were published in the journal, Neuron.The discovery of this sleep switch is important for a number of reasons like finding new treatments for sleep disorders, but it is just a small piece of the enigma that is sleep. The internal signal, which this sleep switch responds to, is still unknown, as is the activity of these sleep-promoting cells while we are awake. We do not even know why humans and all other animals need sleep.

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In spite of these mysterious, scientists do know how the body regulates sleep. Humans and animals have a body clock, which makes us accustomed to the 24 hour cycle of day and night, and a sleep switch, which logs the hours you are awake and causes you to sleep when you need rest. When this mechanism is off or not being used, sleep deficiency increases. The combination of these two is the most likely cause of us sleeping at night.

The significance of this switch in the process of sleep and its relationship to bodily function was found when studying the fruit flies. If they did not sleep, mutant flies cannot regain these lost sleep hours. Sleep-deprived flies are also more likely to nod off and be cognitively impaired. Like sleep-deprived humans, these flies were subject to severe learning and memory deficiencies. In the mutant flies, the researchers proved the insomnia of the flies was due to a broken part of the electrical activity switch, which caused the sleep-inducing neurons to always be off.

Why do you think sleep is important? How is this discovery significant and how do you think this information will be used in the future? Will the mystery of sleep be solved soon?

Photograph by Pedro Ribeiro Simões

Other helpful links:

  • http://www.sciencedaily.com/releases/2014/02/140219124730.htm
  • http://www.ninds.nih.gov/disorders/brain_basics/understanding_sleep.htm
  • http://www.sleepfoundation.org

Spinal Neurogenesis

An astrocyte cell grown in tissue culture as viewed by Gerry Shaw

Normally, when spinal neurons are lost during life due to disease or injury, they are lost for good, however, thanks to a recent study done by  Zhida Su and his colleagues at the University of Texas Southwestern Medical Center that may no longer be the case. The team took astrocytes—star-shaped support cells in the nervous system— from the spines of living mice and converted them into neurons. This research was based of the previous works of  Marius Wernig from the Stanford University School of Medicine, who first converted rat skin cells into stem cell like cells and then into neurons, Benedikt Berninger from Ludwig Maximillians University Munich, who took certain brain cells and turned them into neurons, and Olof Torper from Lund University, who transformed astroytes from the brains of mice into neurons. Su and his team were drawn to spinal astrocytes because they form scar tissue after spinal cord injuries.

Su and his team accomplished this transformation by injecting a series of viruses into the mice, one of which, SOX2, managed to convert the spinal astrocytes into neuroblasts, both in culture and in living mice who had suffered spinal injuries. Some of these neuroblasts then went on to form functioning neurons and with the addition of valproic acid the number of cells which matured doubled and actually interacted with existing motor neurons.  Although this process is slow and can take up to four weeks, it is incredibly promising and it is even suggested that, “For each reprogrammed [cell], perhaps more than one new neuron could be generated,” meaning that each neuroblast could divide and create multiple neurons. Although this research is extremely promising, only 3-6% of astrocytes effected become neuroblasts which has been in no way enough to study the effects on the health of the mice. However, this research is very young and could lead to major achievments in neurogenesis in the future and the “curing” of paralysis and other conditions that result from the destruction of neurons.

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