Data for: Effects of reproductive status on behavioral and neural responses to isolated pup stimuli in female California mice

The transition to motherhood in mammals is marked by changes in females’ perception of and responsiveness to sensory stimuli from infants. Our understanding of maternally induced sensory plasticity relies most heavily on studies in uniparental, promiscuous house mice and rats, which may not be representative of rodent species with different life histories. We exposed biparental, monogamous California mouse (Peromyscus californicus) mothers and ovariectomized virgin females to one of four acoustic and olfactory stimulus combinations (Control: clean cotton and white noise; Call: clean cotton and pup vocalizations; Odor: pup-scented cotton and white noise; Call + Odor: pup-scented cotton and pup vocalizations) and quantified females’ behavior and Fos expression in select brain regions. Behavior did not differ between mothers and ovariectomized virgins. Among mothers, however, those exposed to the Control condition took the longest to sniff the odor stimulus, and mothers exposed to the Odor condition were quicker to sniff the odor ball compared to those in the Call condition. Behavior did not differ among ovariectomized virgins exposed to the different conditions. Fos expression differed across conditions only in the anterior hypothalamic nucleus (AHN), which response to aversive stimuli: among mothers, the Control condition elicited the highest AHN Fos and Call + Odor elicited the lowest. Among ovariectomized virgin females, Call elicited the lowest Fos in the AHN. Thus, reproductive status in California mice alters females’ behavioral responses to stimuli from pups, especially odors, and results in the inhibition of defense circuitry in response to pup stimuli.

哺乳动物向母性状态的转变，以雌性对幼崽感官刺激的感知与响应能力的变化为标志性特征。目前学界对母性诱导的感官可塑性的认知，大多基于单亲育幼、混交制的家鼠与大鼠研究，但这类模式生物或许无法代表具有不同生活史策略的啮齿类物种。
本研究将双亲抚育、单配制的加州鹿鼠（Peromyscus californicus）母鼠与卵巢切除的处女雌鼠，分别暴露于四种感官刺激组合之一：对照（干净棉垫与白噪音）、叫声组（干净棉垫与幼崽叫声）、气味组（带幼崽气味的棉垫与白噪音）、叫声+气味组（带幼崽气味的棉垫与幼崽叫声），并量化了雌鼠的行为表现与特定脑区的Fos表达水平。
母鼠与卵巢切除的处女雌鼠的整体行为并无显著差异。然而在母鼠群体中，暴露于对照条件的个体嗅探气味刺激的耗时最长；而暴露于气味组的母鼠，相较于叫声组母鼠，嗅探气味刺激的速度更快。不同刺激条件下的卵巢切除处女雌鼠，其行为表现无显著差异。
仅在下丘脑前核（anterior hypothalamic nucleus, AHN）这一响应厌恶刺激的脑区中，不同刺激条件下的Fos表达存在显著差异：在母鼠群体中，对照条件诱导的AHN区Fos表达水平最高，而叫声+气味组诱导的表达水平最低。在卵巢切除的处女雌鼠群体中，叫声组诱导的AHN区Fos表达水平最低。
综上，加州鹿鼠的生殖状态会改变雌性对幼崽感官刺激（尤其是气味刺激）的行为响应，并会抑制针对幼崽刺激的防御神经环路活动。