Neuron: Oxytocin-mediated neural circuit plasticity in parent-child behavior

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Before becoming parents, unmated male mice would attack other young pups, but after becoming parents, they showed paternal love towards their own pups
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The hormone oxytocin produced by the central nervous system is involved in functions such as sensory information processing, social behavior, and fear memory
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Oxytocin secreted by neurons in the paraventricular nucleus of the hypothalamus (PVH) plays an important role in male parent-child social activities such as baby care: light activation of oxytocinergic neurons in the PVH brain region or intraventricular injection of oxytocin can promote baby care behavior
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On April 20, 2022, Kazunari Miyamichi's research team at RIKEN published an article in the journal Neuron, revealing the neural circuit plasticity mechanism of oxytocin in regulating parent-child behavior in male mice
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Figure 1: Knockout of oxytocin in the PVH brain area inhibits parent-child behavior.
Male mice with "father" status after mating with female mice exhibit pup-care behavior, but oxytocin is specifically knocked out in the PVH brain region.
These paternal males showed marked abandonment of their young after oxytocin or induced oxytocinergic neuron death, and no longer cared for them
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Activation of oxytocinergic neurons in the PVH brain region of unmated male mice promotes pup-care behavior
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Virus tracing experiments found that in the analysis of the proportion of oxytocinergic neurons in the PVH brain region receiving excitatory and inhibitory inputs, compared with unmated male mice, oxytocinergic neurons in the PVH brain region of parental male mice received Excitatory inputs to the lateral hypothalamus (LHA) and the medial part of the preoptic medial nucleus (MPNm) were significantly increased
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Figure 2: Oxytocinergic neurons in PVH brain regions receive inputs from different brain regions This increase in excitatory input started after 5 days, but disappeared after 5 weeks of solitary confinement
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Photoactivation of the LHA→PVH loop can significantly enhance the excitatory postsynaptic current of neurons in the LHA region of parental male mice, while light-activated MPNm→PVH does not have this enhanced effect.
These structural and functional results indicate that the male parent is smaller Oxytocin neurons in the murine PVH region receive more excitatory input from the LHA region
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To further explore how excitatory input in the LHA brain region regulates parent-child behavior, the researchers housed male parent male mice alone or with their pups, and found that living with the pups significantly activated excitatory neurons in the LHA brain region of male mice
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Chemical activation of the LHA→PVH circuit significantly reduced pup aggression in unmated male mice, but this effect was attenuated by knockout of oxytocin
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In general, unmated male mice attacked the pups, but after transitioning to 'parents', oxytocinergic neurons in the PVH region of male mice received more excitatory structural input from the LHA region, excitatory Synaptic transmission was also enhanced, reducing behavior in aggressive pups, suggesting that plasticity in the structure of synaptic connections in neural circuits may serve as a structural basis for plasticity in parent-child behavior
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[Reference] 1.
Plasticity of neural connections underlying oxytocin-mediated parental behaviors of male mice, Neuron, https://doi.
org/10.
1016/j.
neuron.
2022.
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033 The pictures in the text are from the reference