The naked mole rat holds together not only the strength of social ties, but also intolerance of fresh air. To such conclusion the American scientists, studied the behavior of animals in different conditions. Apparently, the diggers so spent a lot of time in close quarters that used to live at high concentrations of carbon dioxide. And since it works as an external anticonvulsant, their internal mechanisms of inhibition of nerve cells work less well than other rodents. That is why, the diggers rarely leave their colony to start a new one — in the fresh air and warm they have cramps. A study published in the journal Current Biology.
Naked mole rats — one of the few known eusocial mammals. Inside their colonies, there is a strict hierarchy, and reproduction assigned to several individuals from “elite”. However, the other animals in the colony, deprived of privileges, as a rule, do not aspire to leave her and start her. Moreover, most of the time the diggers hold together in a heap. Apparently, this behavior is necessary for heating: comfortable temperature for life digger — 31-34 degrees, and underground passages where they live, it is often much colder: 19-28 degrees. Together, the animals change the conditions in one part of their homes so that they become optimal for their metabolism.
However, inside a pile of warm and humid: decreases oxygen concentration and increases carbon dioxide content (hypercapnia). Long been known that naked mole rats are able to go without oxygen for some time, and in General, their needs are reduced. It is also known that they are weaker than other mammals, works pain sensitivity, so in response to the heat of their lungs begin to work harder. Thus, they do not seek to lower the carbon dioxide content in the inhaled air, and thus must have special adaptations to such conditions.
A group of researchers from new York University under the direction of Dan mcclosky (Dan McCloskey) suggested that naked mole rats may differ from other rodents by the peculiarities of their nervous system. The fact that carbon dioxide inhibits the activity of mammalian neurons and reduces their excitability. And if the diggers live in the permanent presence of external anticonwulsanta, we can assume that their internal braking mechanisms start to work worse.
One of such mechanisms is the transport protein KCC2 in the membrane of neurons. It uses energy cells in order to get chloride ions out of the neuron. When the neuron receives inhibitory signal (for example, under the action of the neurotransmitter GABA), chlorine comes back inside the cell and lowers her anxiety. Accordingly, the more work the KCC2, the better the cell responds to GABA and the more effective it turns out to slow down. If KCC2 is causing the problems, it can lead to hyperactivity of neurons, as happens in some people with epilepsy or schizophrenia.
To find out how does the life of naked mole rats, depending on the concentration of carbon dioxide, the researchers equipped each animal in a colony of a radio transmitter and followed their movement. It turned out that the diggers spend an average of more than 70 percent of the time nest in the room, lying in a single heap. Much less often they visit other rooms are reserved for food and toilet. The location of the breeding room during the time of observation was changed several times, but it invariably was above all the concentration of carbon dioxide — up to 2.33 per cent (the content in other rooms — about 0.05 percent, nearly as in atmospheric air).
However, from this observation it does not follow that animals feel comfortable in such conditions. To test this, the authors filled with carbon dioxide other, breeding room, and measured the amount of time that they held the diggers. It turned out that 2.5 percent carbon dioxide (as in first room) increase the frequency of room visits the animals in half, and 11 percent of five times. Thus, it turned out that naked mole rats do tend to stuffy rooms.