2023-10-31 12:00:06
A research team has just demonstrated that molecular changes that occur in the brain following postnatal stress have lasting effects on the propensity for anxiety and sensitivity to pain in mice that have experienced this stress. Surprisingly, these changes are also observed in the descendants of these mice, even if they were not exposed to this stress. The details of this studyco-directed by two researchers from the Research Center (Scientific research refers primarily to all the actions undertaken with a view to…) CERVO, Marco Battaglia, of the University of Toronto (University of Toronto , U of T) is a public university…), and Yves De Koninckof the Faculty of Medicine (Medicine (from the Latin medicus, “which heals”) is the science and…) of Laval University (Laval University is one of the largest universities in Canada. It a like…), have just been published in the journal Science Advances.
To carry out this demonstration, the researchers used two groups of mice. The first, the control group, consisted of mouse pups who, at birth, had been left in the care of their mother. In the second group, the mice from the same litter spent their first day of life with their mother. Over the next three days, they were successively entrusted to three different “adoptive mothers”. From their fifth day of life, they were reunited with their biological mother.
“We observed no difference between the two groups in terms of stress indicators or the care given to the young mice by the biological or adoptive mothers,” reports Professor De Koninck. “As far as we can judge, the stress experienced by “The mice were light. Nevertheless, they retained lasting repercussions.”
Indeed, once the mice became adults, the researchers subjected them to an anxiety test – we measured their breathing rate in an environment (The environment is everything that surrounds us. It is all the natural elements and…) where the CO2 concentration is higher than normal – and pain perception tests. “The mice in the adoption group responded more strongly (hyperventilation) to the CO2 test than the mice in the control group. They were also more sensitive to heat and pressure stimuli (Pressure is a fundamental physical concept. It can be seen as a reported force…) mechanics (In everyday language, mechanics is the domain of machines, engines, vehicles, organs…)”, reports Yves De Koninck.
Baby mice temporarily separated from their mothers at an early age show higher levels of anxiety propensity and pain sensitivity as adults. They can pass these traits on to their descendants through a route other than genetics.— Getty
Images/Ale Ks
The same series of tests was carried out in the first and second generation descendants of these mice. “Even though these mice had not been separated from their mothers at birth, their responses to anxiety and pain tests were comparable to those of mice exposed to postnatal stress,” he points out. The research team managed to identify the cause of the phenomenon. “In neurons in certain regions of the brain, there are acidity receptors, ASICs, which are associated with the propensity for anxiety and sensitivity to pain,” explains Professor De Koninck. “We discovered that three ASIC receptors were overexpressed in mice exposed to postnatal stress as well as in their offspring. This is probably due to an epigenetic mechanism that promotes the expression of genes encoding these receptors. This mechanism constitutes the molecular memory of postnatal stress experienced by mouse pups . It persists until adulthood and can be transmitted non-genetically to offspring.”
A reversible phenomenon
The role of ASIC receptors might be confirmed thanks to amiloride, a drug prescribed to treat hypertension, heart failure (Heart failure ( IC) or heart failure corresponds to a condition…) and cirrhosis (Cirrhosis is a chronic liver disease in which the hepatic architecture is…) of the liver. “Amiloride blocks ASIC receptors, preventing them from performing their functions,” explains Professor De Koninck. A single dose administered by nasal spray before the tests is enough for the mice in the adoption group to regain levels of propensity for anxiety. and sensitivity to pain comparable to those of mice in the control group.”
When we talk regarding propensity for anxiety or sensitivity to pain in humans, we often think of complex interactions between numerous genetic and environmental factors, continues the researcher. “Without denying the complexity (Complexity is a notion used in philosophy, epistemology (by…) of these problems, they are ultimately expressed by molecular changes in the brain. In our study, a separation (In a way general, the word separation designates an action consisting of separating something…) temporary maternal at birth has repercussions on acidity receptors in the brain which are involved in the propensity for anxiety and in sensitivity to pain . These molecular changes are transmissible to offspring, but they are also reversible.”
It should be noted that ASIC receptors are also present in the brains of other mammals, notably in humans, underlines Professor De Koninck. “We now hope to continue our work by studying the effectiveness of amiloride to treat panic disorder and certain forms of pain sensitivity in humans.”
The signatories of the study published in Science Advances are Marco Battaglia, from the University of Toronto, Orlane Rossignol, Louis-Etienne Lorenzo, Jasmin Deguire, Antoine G. Godin, and Yves De Koninck, of the CERVO Research Center, and Francesca R. D’Amato, of the National Research Council of Italy.
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