Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand.
Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.
J Neuroendocrinol. 2023 Jul;35(7):e13232. doi: 10.1111/jne.13232. Epub 2023 Jan 24.
Maternal interactions with offspring are highly rewarding, which reinforces expression of essential caregiving behaviours that promote offspring survival. In rats, the rewarding effect of pups depends on reproductive state, with lactating females specifically developing strong preferences for pup-associated contexts. Whether this also occurs in mice is unknown, hence we aimed to characterise pup-related preference across reproductive states in female mice. In a conditioned place preference (CPP) test, pups were a rewarding stimulus to female mice prior to lactation, with virgin and pregnant females developing a preference for a pup-associated context. We have previously shown that lactogenic hormones, acting through the prolactin receptor (Prlr), play an important role in maternal motivation. Here, we aimed to investigate whether Prlr action is important for pup-related reward behaviour in mice. We showed that prolactin itself had a reinforcing effect in a CPP test, and that exposure to pups increased blood prolactin levels in virgin female mice. Prlr expression in CamKIIα-expressing neurons and GABAergic neurons has previously been shown to be important for different aspects of parental behaviour. However, we found that conditional Prlr deletion from either of these neuronal populations did not disrupt the development of a preference for pup-associated contexts in pregnant female mice, indicating that lactogenic action on these populations is not necessary for the rewarding effect of pups. Together, these data show that while lactogenic hormones likely contribute to a rewarding effect of pups, their action on two key neuronal populations is not necessary for this effect in female mice.
母体与后代的互动是非常有益的，这加强了表达基本的养育行为，促进了后代的生存。在大鼠中，幼崽的奖励效应取决于生殖状态，哺乳期雌性动物特别对与幼崽相关的环境表现出强烈的偏好。这种情况是否也发生在小鼠中尚不清楚，因此我们旨在描述雌性小鼠在不同生殖状态下与幼崽相关的偏好。在条件位置偏好（CPP）测试中，幼崽在哺乳期前对雌性小鼠具有奖励性刺激作用，未孕和怀孕的雌性小鼠对与幼崽相关的环境表现出偏好。我们之前已经表明，泌乳激素通过催乳素受体（Prlr）发挥作用，在母性行为的动机中起着重要作用。在这里，我们旨在研究 Prlr 作用是否对小鼠与幼崽相关的奖励行为很重要。我们表明，催乳素本身在 CPP 测试中具有强化作用，并且幼崽的暴露会增加未孕雌性小鼠血液中的催乳素水平。CamKIIα 表达神经元和 GABA 能神经元中的 Prlr 表达先前已被证明对不同方面的亲代行为很重要。然而，我们发现，这两种神经元群中条件性 Prlr 缺失均不会破坏怀孕雌性小鼠对与幼崽相关环境的偏好的发展，表明泌乳激素对这些神经元群的作用对于幼崽的奖励效应并非必需。总之，这些数据表明，尽管泌乳激素可能对幼崽的奖励效应有贡献，但它们对两个关键神经元群的作用对于雌性小鼠的这种效应并非必需。
