#receptorinhibition

We all know those mornings. You stayed up too late studying, playing video games, or binging your favorite series. You wake up drowsy and distressed, then remember you have a test today. For a moment you panic, but you quickly realize you have the luxury of indulging in a hot cup of coffee. Your preconceived impression is that the coffee will cure your exhaustion– it’s almost too good to be true. Suddenly, you notice that you have become reliant on a beverage to take the place of quality sleep several days a week. But is this notion accurate? How well can caffeine mask a lack of sleep?

The reason people feel drowsy at any time of the day is due to a buildup of adenosine in the bloodstream. Adenosine is produced when the body consumes its central energy source (ATP). Adenosine in the bloodstream binds to adenosine receptors. Once bound, these receptors trigger a release of proteins that inhibit neuron activity, leading to drowsiness.

Caffeine’s solution to the abundance of adenosine acts as a temporary patch-up. Caffeine has the ability to block adenosine receptors, therefore preventing adenosine from causing drowsiness. The problem, however, is that caffeine does not stay bound to adenosine receptors for very long, so tiredness will likely kick in at some point later in the day. Since caffeine is just “patching up” the problem, it will never be nearly as effective as sleep which allows for the breakdown of adenosine.

I have noticed the effects of caffeine are much greater later in the day compared to consuming it in the morning. This is because caffeine tends to raise cortisol levels. Upon waking up, cortisol levels are already high. It is also the case that adenosine levels grow as the day progresses. These two factors explain why caffeine has stronger effects later in the day. There is a more drastic change caused by caffeine on cortisol levels and the “control” of free adenosine.

I found the process of caffeine binding to adenosine receptors to relate to our cell communication unit. When caffeine enters the bloodstream, it acts as a competitive inhibitor by preventing adenosine from binding. A competitive inhibitor takes the place of a substrate in an enzyme directly at the active site. This prevents a chemical reaction from occurring. In this case, caffeine is blocking a receptor that causes drowsiness when activated. If caffeine is blocking it, adenosine which would have caused drowsiness is unable to attach to the receptor. If the adenosine were to attach to this receptor, it would trigger a signal that is sent through neurons to cause the sensation.

Plants are very susceptible to injury in many forms. They can’t hide from a hungry bunny rabbit or invasive fungi. As humans, we have “fight or flight” instincts, but flight is a tall order for plants. Instead, they have “fight or fix” instincts. When damaged plants have two responses, to repair and regenerate or defend. New York University’s Center for Genomics and Systems Biology decided to perform a study on this known quality of plants.

The defense method is the production of specific compounds, but the scientists’ experiment focused on the regeneration response. “Breeding crops that more readily regenerate and can adapt to new environments is critical in the face of climate change and food insecurity” said NYU professor and leader of the study, Kenneth Birnbaum. The study was split into two parts a study, and an experiment.

The goal of the study was to understand the relationship between regeneration and defense responses. Does one happen or the other? Can they occur simultaneously? Does affecting one response have a subsequent affect on the opposing response?

The Scientists studied two plants; Arabidopsis and corn. Arabidopsis is common used as a model organism by plant biologists, while corn is the America’s largest crop. The answers they found to the previously posed questions are as follows. In most cases, both responses happen simultaneously and neither are at full strength. When the Scientists manually affected one of the responses, the other response did increase in frequency as a result. As Marcela Hernández Coronado of Cinvestav in Mexico put it, “The ‘fight or fix’ responses seem to be connected, like a seesaw or scales — if one goes up, the other goes down. Plants are essentially hedging their bets after an attack,”

The scientists were able to narrow down the cause of varying level of each response to plant glutamate receptor-like (GLRs) proteins. These receptors are related to glutamate receptors found in the human brain; hence the title of “Plant Therapists”. They learned that these receptors are responsible for regulating regeneration response and in turn, increasing defense response.

Considering the relationship with neural receptors, the scientists used preexisting drugs meant for these relative receptors. They used neural antagonists to inhibit GLRs. The antagonists are competitive inhibitors, that bind to the active site of the receptor blocking reception of signal molecules. The limited activity of the GLRs made the plants decide to heavily favor regeneration as the signals telling it otherwise were blocked.

The scientists also studied “quadruple mutants” in comparison to normal plants. The plants with mutated GLR had an increased rate of regeneration, further proving the effects of GLR on regulating the ratio between the two responses. Overall however, the plants that were given the neural antagonists were more successful in increased regeneration than the quadruple mutants.

BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: #receptorinhibition

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Plant Therapists: Scientists help plants make the decision to regenerate rather than defend themselves after injury

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