As a part of the current society, you may figure how the carbon dioxide gas is such a menace as it melts glaciers across the globe, wipes out the wildlife due to global warming, and causes sustainability issues. However, not all species are adversely affected by higher concentrations of the carbon dioxide. The naked mole-rats are one of such species as CO2 happens to be their tool for survival.
Researchers have been conducting studies to observe other animal behaviors for years to try and develop a better understanding of the human body anatomy and the way it works. There were similar reasons behind conducting the study “Nest Carbon Dioxide Masks GABA-Dependent Seizure Susceptibility in the Naked Mole-Rat”, on the 30th of April 2020. Dan McCloskey happens to be one of the authors of the research, and he plans to find a relation between this bizarre naked mole-rat behavior and epileptic attacks that happen in humans.
Cold-blooded mammals lack the defensive mechanism to survive in an environment with ever-changing temperatures. There are not any cold-blooded mammals present on earth, except the naked mole-rat. This means that if a naked mole-rat is placed in a warm environment, its body temperature would keep rising, and it will rise until it proves fatal. Similarly, the body temperature would keep dropping in a cooler environment until the rat drops dead. Naked mole-rats rely on their self-built environment to keep changes in the temperature to a minimum and increase their survival rate.
It was observed that as the temperature in the surrounding atmosphere increases, naked mole-rats move further down into their burrows, and when the burrows were tested for the concentration of carbon dioxide, they showed an astonishing abundance of 2.33%.
Some naked mole-rats were placed under extremely hot conditions that they started hyperventilating, and after a while, they experienced a seizure. When the rats were hyperventilating, they were losing huge amounts of carbon dioxide from their bodies. Since there was less carbon dioxide present in their blood, it became less acidic and more basic.
In another environment, naked mole-rats were placed under high temperatures, but this time they were provided an atmosphere with a high concentration of carbon dioxide gas. Under these conditions, the results were not fatal, and the rats survived. Even the rats who went under a seizure because of high temperatures were brought back to sanity by exposing them to high concentrations of carbon dioxide.
So far, it was established that carbon dioxide is crucial for the survival of naked mole-rats, but the underlying mystery as to why it was happening still had to be uncovered.
To further the research, McCloskey teamed up with a few other researchers and started studying febrile seizures. Febrile seizures are usually experienced by young children who’re under the age of 5, while they happen when the child is under a high fever. With the seizures happening under high temperatures in both of the species, the dots started to connect.
Before comparing the genetic similarities between a human baby and naked mole-rat, it is important to know that the blood contains certain concentrations of charges, that are there because of different ions. One of the ions present in the blood is the chloride ion that is negatively charged. There are two charge regulatory systems in a human body, a protein known as KCC2, and a neurotransmitter that goes by the biological name of GABA. They both regulate the amount of chloride ions found in the cells. However, if both of the charges present in a brain cell reach a certain balance, the brain sends an electrical pulse. GABA is activated to counter this electrical pulse.
Inside a human baby’s body, the amount of KCC2 is lesser that the concentration of chloride ions in the cells. Similar KCC2 producing genes are found in naked mole-rats. However, as a child grows up, they develop more KCC2 producing genes, but nothing of such sort happens during the life span of naked mole-rats.
An experiment was carried out where naked mole-rats were fed diazepam to counter their seizures. Again, there were two controlled environments, one where there was less concentration of carbon dioxide and another where there was more concentration of carbon dioxide. The experiment was carried out at room temperature. Better results were produced in the environment where there was more concentration of carbon dioxide.
With the less amount of KCC2 present in their bodies, naked mole-rats used carbon dioxide to support their GABA, and reduce the electrical activity happening inside the brain. This is more of a survival tactic used by these rats, since KCC2 utilizes a lot of energy to work. Naked mole-rats tend to minimize the energy usage within their bodies with the help of carbon dioxide, while staying deep inside their burrows.
The research helped the scientists to have a better understanding regarding GABA, and it gave them the idea of curing epilepsy amongst humans by exposing them to higher concentrations of carbon dioxide.
The study also helped in finding the true nature of naked mole-rats, and why they love spending so much time in their deep dark burrows.
- Michael Zions, Edward F. Meehan, Michael E. Kress, Donald Thevalingam, Edmund C. Jenkins, Kai Kaila, Martin Puskarjov, Dan P. McCloskey. Nest Carbon Dioxide Masks GABA-Dependent Seizure Susceptibility in the Naked Mole-Rat. Current Biology, 2020; DOI: 10.1016/j.cub.2020.03.071
- Martin Puskarjov, Patricia Seja, Sarah E Heron, Tristiana C Williams, Faraz Ahmad, Xenia Iona, Karen L Oliver, Bronwyn E Grinton, Laszlo Vutskits, Ingrid E Scheffer, Steven Petrou, Peter Blaesse, Leanne M Dibbens, Samuel F Berkovic, Kai Kaila. A variant of KCC2 from patients with febrile seizures impairs neuronal Cl− extrusion and dendritic spine formation. DOI 10.1002/embr.201438749
- Kai Kaila, Theodore J. Price, John A. Payne, Martin Puskarjov, Juha Voipio. Cation-chloride cotransporters in neuronal development, plasticity and disease. Doi:10.1038/nrn3819.