Marijuana and Cocaine Substitutes

       I swear this blog is not being turned into part of a drug ring! This week my biology class had to blog about the nervous system, and two substances that affect the nervous system are marijuana and cocaine. Marijuana was recently extremely controversial in the United States with debates over whether it should be legalized or not. To add fuel to the fire, marijuana may actually help with diseases related to the nervous system! Cocaine is also a drug which stimulates the production of a substance known as dopamine in the brain. Like your parents would say, drugs are awful and will ruin your life, so I will talk about two things which have the same effect of stimulating pleasure and dopamine production, food and music!
       But first we need an actual biology lesson. The basic structural unit of the nervous system is the neuron, or nerve cell, which is seen in the diagram below.

Neurons consist of a cell body called the soma. The extensions of the soma which receive neurotransmitters are the dendrites. Then the long extension of the cell body is the axon which sends nerve impulses to other neurons. The axon is also covered in a myelin sheath which speeds the movement of chemical messengers. So the nervous system consists of chains of neurons which send chemical messengers known as neurotransmitters like a single file line of people doing the wave. We will get in to the specifics of this nerve messaging later, but I have to say neurons look like that guy, Agent Pleakley, from Lilo and Stitch. 

      One disease which damages these nerve cells is multiple sclerosis. Damage occurs when the nerve cells lose the myelin sheaths on their axons which makes it difficult to send messages to other neurons and causing scar tissue to form where the myelin sheath is missing. This is why it is named multiple sclerosis which means "many scars." Multiple sclerosis reminds me of the character Doodlebob from Spongebob Squarepants. 

 Doodlebob tried taking away Spongebob's life with his eraser like certain molecules involved in multiple sclerosis try to take away the myelin sheaths from axons of nerve cells with inflammatory molecules. Okay back to biology. Side effects of this disease are impairment of muscle control, speech, and vision, but recently scientists have conducted studies that show marijuana could ameliorate (SAT vocabulary for the win) these conditions. Marijuana contains substances known as cannabinoids. The presence of these substances prevents the production of inflammatory molecules from cells that remove the myelin sheaths from nerve cells. This is why when cannabinoids were given to mice that had partially paralyzed limbs, they were soon able to walk without a limp. Scientists now look to expand this treatment to humans. This would have been a very compelling argument in the legalization of marijuana. "It can allow the paralyzed to walk and do other miracles." On a serious note, I've always been one of those people who was completely against drugs under any circumstances, but if it could be used for medicinal purposes like helping multiple sclerosis patients regain movement, then maybe its use in certain instances should be reevaluated. 

       So how do neurons communicate? Neurons communicate using a form of local signaling called synaptic signaling. Synaptic signaling is the process by which nerve cells "fire" neurotransmitters into the synapse (the gap between adjacent neurons) to communicate with another neuron. The neurotransmitter signal molecules can leave the axon of one nerve cell in a vesicle in a process similar exocytosis entering the synapse. They will then be received by neuroreceptor proteins on a neighboring neuron's dendrite. To "fire" neurotransmitters, nerve cells have to achieve the action potential. Typically a nerve cell has a greater concentration of K+ ions inside of it and a greater concentration of Na+ ions outside of it. The inside of a cell is also negative due to proteins resting at a charge of -70mV. In order to fire a chemical message, the cell must raise its charge to -55mV, so it takes in Na+ ions and makes K+ions leave the cell causing the rising curve seen below. 

 

Once it passes the -55mV and becomes very positive, the prior concentration gradients of Na+ and K+ ions outside and inside of the cell are restored using the sodium potassium pump. One molecule that the brain can make to act as a neurotransmitter is dopamine whose passage between nerve cells ultimately stimulates pleasure. 

        Drugs like cocaine and amphetamine try to achieve this feeling of pleasure by producing dopamine in the brain. But drugs do not deserve any place in anyone's life, so they can be substituted with food and music! Ironically food and music also produce dopamine like cocaine. This makes a lot of sense to me because I receive instant pleasure just when I see Chipotle! Then when people play songs over and over because they love it, it's almost like they have a drug addiction (yeah, I know that's a ridiculous comparison). Maybe this is why people say listening to music helps them when they're running because the dopamine levels in your brain would counteract the pain your muscles would feel. From experience in spring track, I think even eating food before a race helps with pain resistance. Now I'm not saying to eat a Thanksgiving meal before you run the two mile race because otherwise that will be an even longer, more miserable experience. No pleasure at all. With music, dopamine is typically released when you feel a "chill" or "at a peak emotional moment." Imagine people's dopamine levels when Adele used to constantly play on the radio. They must have been drowning in dopamine! In the same article that described this effect of food and music on the brain, the writer also described this part of the brain called the auditory cortex. When this structure of the brain was stimulated electrically, people supposedly heard music. So scientists think that this part of the brain allows you to hear music in your head even when it's not being played.