其他摘要 | In this competitive and conflict-ridden modern society, prosocial behavior contributes to social harmony, survival, reproduction, and cultural transmission in social groups. Among the multifaceted spectrum of prosocial behaviors, acts of rescue and assistance represent an advanced form of prosociality. For instance, human heroism often involves self-sacrifice to aid others. Beyond the human realm, instances of spontaneous rescue-like behaviors have been documented in various species, including primates, whales, and dolphins. Within the controlled confines of laboratory settings, researchers have successfully demonstrated that rats can acquire the ability to rescue trapped peers through training. However, the fundamental question of whether mice can spontaneously engage in rescue-like behaviors devoid of explicit incentives remains a subject of ongoing debate.
The present study, through the observation of mouse behavior, reveals that mice engage in behaviors such as grooming, licking, and gentle prodding towards conspecifics in a state of anesthesia. By quantifying and controlling experimental factors, a new binary social behavior paradigmthe mouse rescue-like behavior paradigmis established. This study marks the first evidence that mice can spontaneously perform rescue-like behavior to expedite the recovery of an anesthetized conspecific, and this rescue paradigm occurs naturally among mice without prior training.
Upon further investigation of this rescue-like behavior, the study reveals that the essential process involves the demonstrator mouse in distress releasing pheromones that induce stress in the observer mouse. In response to the stress, the observer mouse, in order to reduce their own stress levels, exhibits typical prosocial behaviors towards the stressor (i.e., the demonstrator mouse), such as grooming and licking. Interestingly, throughout the entire rescue process, both the observer and demonstrator mice, solely through their stereotypical behaviors and physiological responses, coordinate with each other to perform what appears to be a "sophisticated" rescue-like behavior, aiding their companions/self in escaping danger. This reflects the preadaptive characteristics and cryptic genetic variation in the process of biological evolution, where certain phenotypes and traits that are not typically expressed can play a crucial role in ensuring the survival of a species under special circumstances.
Utilizing this rescue-like behavior paradigm, the present study employed techniques such as transgenic mice, chemogenetics, optogenetics, fiber photometry, and computational neuroscience to further explore the neural mechanisms underlying mouse rescue-like behavior. The experiments reveal that, during rescue-like behavior, oxytocin (OXT) neurons in the paraventricular nucleus of hypothalamus (PVN) release OXT to the central amygdala (CeA) and dorsal bed nucleus of the stria terminalis (dBNST), subsequently activating OXT receptors (OXTR) in CeA and dBNST neurons. Furthermore, the present study finds that the OXT''vN-OXTRCea and OXT''vN-OXTR}NST pathways mediate the emotional and motor functions of rescue-like behavior, respectively.
Lastly, through a meticulous analysis and quantification of calcium signals and dynamics of oxytocin within these two neural pathways, the present study delineated strikingly disparate temporal and response patterns of these two pathways. The OXTPVN-OXTRCea pathway exhibits transient responses at the initiation of rescue-like behavior, acting as an emotional trigger facilitating the rescue process. In stark contrast, the OXTPVN-OXTRdBNST pathway manifests a highly synchronized response pattern with licking behavior, governing the motor function of rescue-like behavior.
In summary, the present study establishes the groundbreaking experimental paradigm of spontaneous rescue-like behavior in mice, shedding light on the mechanisms through which two parallel OXT signaling pathways, PVN-CeA and PVN-dBNST, mediate rescue-like behavior with varying response patterns, encompassing emotional and motor functions. |
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