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ABSTRACT: The researchers discovered that female mice get access to aggression after giving birth through a generally inactive brain circuit in non -pregnant women. The same neurons drive aggression in men, but only light in mothers, activated by oxytocin and prolactin.
Silence these neurons prevented mothers from defending against the intruders of the cage. The findings highlight how the brain can unlock new behaviors for survival during specific life stages.
Key facts
Latent circuit: aggression neurons in female mice are inactive until they are triggered by motherhood. Hormone activation: oxytocin and prolactin switch in this system, allowing maternal defense. Brain flexibility: The results suggest a general principle of brain’s ability to access new behaviors when necessary.
Source: Stockholm University
Researchers at the University of Stockholm and the Karolinska Institute have found a system in the brain that can explain why females mice, which are not normally aggressive, suddenly and dramatically have access to this behavior after becoming pregnant and giving birth (the so -called maternal aggression).
The study shows that a group of neurons that control aggression in normally aggressive males are deactivated in non -pregnant women, but change active when it becomes a mother.
When the researchers silenced the neurons, the mother stopped attacking the intruders of the cage.
The study also shows that oxytocin and prolactin, hormones that control maternal body functions such as breastfeeding, can powerfully activate these neurons.
The study was conducted on animals and should be interpreted with caution in a human context. But the findings touch a bigger conceptual question: how can an individual access a behavior that is outside their normal repertoire, during a limited phase of his life?
The example studied here, with a brain circuit that can be turned on and off depending on whether an animal needs access to some behavior (regardless of sex) for survival (or its descendants), it can have a general meaning of how the plastic brain also works in humans.
“Surprisingly, it turned out that the same network of cells that drive aggression in male mice is latent in women, until motherhood turns the change of this system sensitive to hormones,” says the first author of the article Stefanos Stagkourakis, who now leads his own research group at the Scilifell and Karolinska Institute.
“This is a study on laboratory mice, and we currently do not know if the results can be transferred to humans. But the mechanism that we identify here how a behavior that is normally outside the repertoire of an individual can be available during a limited period of their life, it can reflect a principle of brain flexibility with relevance beyond maternal aggression,” says Professor Christian, professor of Neurochem at the University of Stockholm.
The study was conducted under the leadership of Christian Broberger, a professor of neurochemistry at the University of Stockholm. The experiments were carried out at the Institute Karolinska, where his laboratory was previously located.
Key questions answered:
A: They discovered that normally inactive aggression neurons in female mice are lit during motherhood, which allows protective aggression.
A: Oxytocin and prolactin, central hormones for maternal functions such as breastfeeding, strongly activated neurons related to aggression.
A: It suggests a broader principle of brain flexibility: behaviors outside the typical repertoire can be accessible when survival demands it.
On this news of maternal aggression and neuroscience research
Author: Per Larsson
Source: Stockholm University
Contact: Per Larsson – Stockholm University
Image: The image is accredited to Neuroscience News
Original research: open access.
“Maternal aggression driven by the transient mobilization of a circuit sensitive to latent hormones” by Stefanos Stagkourakis et al. Nature communications
Abstract
Maternal aggression driven by the transient mobilization of a latent hormone sensitive circuit
Aggression is sexually dimorphic behavior. In some species, including laboratory mouse, it is expressed in a robust way in males, while females are not aggressive in the non -perceptal state.
However, during nursing, women exhibit maternal aggression, a dramatic but transitory change in their repertoire of social behavior.
This phenotypic change that occurs in adulthood presents an opportunity to investigate whether behavioral programs biased by sex depend on mono or di-mortal neuronal circuits.
While it is known that maternal hormones cause nursing, their role in maternal aggression, particularly with respect to objective sites and cellular mechanisms, remains without being clear.
Here, we show that a molecularly defined subset of neurons ventral mouse (PMVDAT), with a role established in intermala aggression, transitions of quiescence to a hyperexcitable state during female breastfeeding.
It was discovered that maternal hormones, prolactin and oxytocin excite these cells through pre and post-synaptic electrophysiological actions.
Gain and loss of function related to the activity of PMVDAT neurons bidirectionally influence maternal aggression, while the activation of PMVDAT neurons suppressed the expression of competing social behavior.
This study identifies a sexually monomorphic neural substrate in mice capable of integrating hormonal signals, providing a probable mechanism that allows transitory access to a latent behavioral program.
