Neural Changes Associated with Obesity

 

Around the globe, obesity has become a growing issue over the past two decades. It has been linked to the development and worsening of health conditions in individuals who suffer from obesity. As obesity is on the rise in countries throughout the world, researchers turn to our brains to better understand how obesity changes our bodies in order to help develop treatments.

Some of the researchers studying obesity and its effects, it has on our brains are Dr. Jennifer Beshel, Dr. Josh Dubnae, and Dr. Yi Zhong. Dr. Beshel and her team have spent the better part of a decade researching the Drosophila’s central neural circuits in eating behaviors. Within their study, “A Leptin Analog Locally Produced in the Brain Acts via a Conserved Neural Circuit to Modulate Obesity-Linked Behaviors in Drosophila”, this team found that the Drosophila neuropeptide F’s regulatory effects on feeding behavior are similar to the neuropeptide Y regulator found in humans. Additionally, Beshel’s team found that the unpaired 1 (upd1) ligand within Drosophila is the analog to the human leptin hormone. Pointing to the notion that Drosophila is a wonderful organism to study obesity in as this fly’s neural circuits are analogous to those found in humans. During this study, Beshel either removed functional domeless receptors or the functional npd1gene, both inhibit the ability for the Drosophila brain to produce satisfaction signaling which leads to weight gain. There is a similar response occurs with leptin and leptin receptors within the human brain; as leptin is unable to bind to leptin receptors, the brain is unable to signal satisfaction and unable to inhibit eating behaviors. It should be noted that within humans, it has been studied that the majority of cases involving obesity do not have nonfunctional leptin or leptin receptors. Instead, it is theorized that leptin resistance has developed within the brain leading to improper signaling.

Another group of researchers studying the effects of obesity within the central nervous system is Dr. Sophia Sui, Dr. Michael Ridding, and Dr. Brenton Hordacre. In the article, “Obesity is Associated with Reduced Plasticity of the Human Motor Cortex”, Dr. Sui and her team discussed their findings on the effects obesity has on neural plasticity within the motor cortex. Through continuous theta burst transcranial magnetic stimulation (TMS), Dr. Sui was able to reduce the activity on neurons within the motor cortex, specifically the neurons associated with hand muscles. Within the group of individuals within a height range, there was a significant reduction of neural activity within the hand indicating that there is a high level of plasticity within the motor cortex. Within the group of obese individuals, there was a minimal amount of reduction of neural activity within the hand indicating that there is a low level of plasticity within the motor cortex. Lower plasticity can be correlated to worsening cognition, memory, and issues in learning, so this study can link structural changes to behavioral ones. It is crucial to note that this research study long-term depression only, so more studies are needed to fully understand the long-term changes in neurons. This research helps to gain insight into how obesity impacts our neurons and neural connections that influence overall health.

Obesity has begun to plague our nation and globe. As obesity rises, so does the known and unknown health consequences associated with it. Dr. Beshel’s research on Drosophila gives insight into the neural circuit and its inhibition that contributes to the development and preservation of obesity. Dr. Sui’s research with TRM on the motor cortex gives insight into one of the neurological consequences, reduced plasticity, linked to obesity. In order to reduce obesity worldwide, we must gain more knowledge through this research to better understand how obesity changes our bodies.  

 Citations:

Beshel J, Dubnau J, Zhong Y. A Leptin Analog Locally Produced in the Brain Acts via a Conserved Neural Circuit to Modulate Obesity-Linked Behaviors in Drosophila. Cell Metab. 2017;25(1):208-217. doi:10.1016/j.cmet.2016.12.013

Sui SX, Ridding MC, Hordacre B. Obesity is Associated with Reduced Plasticity of the Human Motor Cortex. Brain Sci. 2020;10(9):E579. Published 2020 Aug 21. doi:10.3390/brainsci10090579