Where are the most mitochondria in the body found and relate this to a) Migraines, b) Cardiomyopathies, c) Strokes, d) Fibromyalgia

Where are the most mitochondria in the body found and relate this to a) Migraines, b) Cardiomyopathies, c) Strokes, d) Fibromyalgia.

The mitochondria are a very interesting organelle seen only in eukaryotic cells (or multicellular organisms) (1). A single celled organism only has a single membrane to absorb nutrients from the environment, whereas a multicellular organism has cells with no environmental contact and relies on its neighbors for energy/nutrition (2). With evolution, multicellular organisms became more complex and soon organisms had organs deep within its tissues that relied on the tissues (like the skin, the GI tract, the lungs, etc.) interfacing with the environment to obtain nutrition (2). The mitochondria have been an integral part of large organisms in providing energy which is provided in the currency of acetyl-coA (1). A system or systems have developed to coordinate which organs or tissues would receive more “currency” than other depending on the demands from the environment (e.g., huge meal would shunt more energy going to GI system; heavy exercise would shunt energy away from GI system towards muscles and heart; stressful situation requiring quick thinking will shunt energy towards brain) (2). The density of mitochondria in an organ system depends on kinds of metabolic demands the organism experiences – typically, we see mitochondria in nervous system, heart and skeletal muscle, and , the liver and GI tract (2). One system that has no mitochondria in the red blood cell (1).

Abnormal conditions of the mitochondria can lead to pathological states. For instance, migraine may be considered a mitochondrial condition – there is biochemical evidence that the energy failure in neurons and supporting cells can trigger migraine mechanism (typically focusing on the aura of migraine (2). Due to cardiac muscle high demand for energy, mitochondrial dysfunction will often appear as cardiomyopathy often in childhood (4). As the mitochondria is the center for many energetic reactions, breaking apart molecules and releasing free radicals, it is also the location of oxidative damage which can lead to disease (5). In the brain, evidence is significant for reactive oxygen species (ROS) overproduction as a cause of neuronal death in a variety of neurological disorders including ALS, Parkinson’s disease, trauma, and stroke (5). Ongoing studies are looking at “anti-oxidants” or other treatments to prevent oxidative damage (5). Whether fibromyalgia is a “mitochondrial disorder” or not remains under investigation, however evidence does show that oxidative stress may indeed play a role in this condition (6). In this article, defective skeletal muscle Co-enzyme Q10 (an essential electrion carrier in the respiratory chain and a strong anti-oxidant) is linked to oxidative stress which may be associated with fibromyalgia (6).

Sources:
1/ Gropper et al. Advanced Nutrition in Human Metabolism. 7th Ed. Cengage. 2018.
2/ Andrews, P.W., Bharwani, A., Lee, K.R., Fox, M., Thomson, J.A., 2015. Is serotonin an upper or a downer? The evolution of the serotonergic system and its role in depression and the antidepressant response. Neuroscience & Biobehavioral Reviews 51, 164–188. https://doi.org/10.1016/j.neubiorev.2015.01.018
3/ Yorns, W.R., Hardison, H.H., 2013. Mitochondrial Dysfunction in Migraine. Seminars in Pediatric Neurology 20, 188–193. https://doi.org/10.1016/j.spen.2013.09.002
4/ El-Hattab, A.W., Scaglia, F., 2016. Mitochondrial Cardiomyopathies. Front Cardiovasc Med 3, 25. https://doi.org/10.3389/fcvm.2016.00025
5/ Yang, J.-L., Mukda, S., Chen, S.-D., 2018. Diverse roles of mitochondria in ischemic stroke. Redox Biol 16, 263–275. https://doi.org/10.1016/j.redox.2018.03.002
6/ Cordero, M.D., de Miguel, M., Carmona-López, I., Bonal, P., Campa, F., Moreno-Fernández, A.M., 2010. Oxidative stress and mitochondrial dysfunction in fibromyalgia. Neuro Endocrinol. Lett. 31, 169–173.