DISSERTATION RESEARCH: Effects of placentophagia on anxiety and paternal behavior in male California mice (Peromyscus californicus)

父系抚育在哺乳动物中很少见，但在发生这种情况的物种中，对后代的生存和发育有关键影响，包括人类。尽管在许多物种中已经研究了神经内分泌和经验对父系行为的影响，但对父系照顾开始的直接调节仍然知之甚少。在雌性哺乳动物中，与母性开始相关的激素变化（即怀孕、分娩和哺乳）通过减少新妈妈对新生儿的焦虑样或新生儿恐惧症反应来激活母性行为。目前尚不清楚焦虑的减少是否在男性亲本照顾的开始中起着类似的作用，但焦虑的一些生理和行为测量与父亲照顾的各个方面呈负相关。本研究的目的是研究焦虑的减少“允许”男性父亲行为的表达的作用。这项研究与人类和人类行为有很大的相关性，父亲的参与和照顾不足与家庭互动和儿童作为父母的后续行为中观察到的许多困难有关。为了验证这一点，研究人员将研究加利福尼亚老鼠，它们表现出许多与人类相同的社会行为和家庭结构。哺乳期雌性哺乳动物吞食胎盘是很常见的，可以引起母亲的行为和生理变化，从而增强对后代的照顾。在一些双亲哺乳动物中，父亲也会在幼崽出生时摄入胎盘；然而，雄性食胎盘的功能尚不清楚。最近由联合PI和PI进行的研究发现，当性经验不足的雄性加利福尼亚小鼠（加利福尼亚细肌鼠）通过口服给药胎盘时，它们随后表现出接近新物体或不相关幼鼠的潜伏期减少，以及与焦虑相关的脑区终纹背床核的神经活动（fos -免疫反应性）减少。因此，这些行为学和神经学结果表明，摄入胎盘可能会减少男性的焦虑。几项研究发现了间接证据，证明在这种动物和其他物种中，焦虑和父权照顾之间存在反比关系。这项提议的工作将检验这样一种假设，即雄性加利福尼亚鼠的噬胎盘行为可以减少它们的焦虑，并由此增加它们对父亲的反应。首次怀孕的父亲和处女男性将通过口服胎盘油或单独用油进行治疗，或不进行治疗，随后测试焦虑样行为和父亲行为。将检测血浆中的异孕酮（胎盘中产生的一种抗焦虑类固醇），并测定大脑中已知调节焦虑和父亲护理的区域的神经活动（fos -免疫反应性），以确定食胎盘是否可以通过异孕酮的抗焦虑作用来减轻新父亲的焦虑。研究结果将为雄性食胎盘行为的功能意义以及对雄性亲本抚育激活的可能影响提供新的见解。

Paternal care is rare in mammals, but can have a critical influence on offspring survival and development in the species in which it occurs, including humans. Although neuroendocrine and experiential influences on paternal behavior have been studied in numerous species, the proximate regulation of the onset of paternal care remains poorly understood. In female mammals, hormonal changes associated with the onset of motherhood (i.e., with pregnancy, parturition and lactation) activate maternal behavior in part by decreasing new mothers' anxiety-like or neophobic responses towards their newborns. It is unknown whether anxiety reduction plays a similar role in the onset of male parental care, but several physiological and behavioral measures of anxiety have been negatively correlated with aspects of paternal care. The aim of this research is to study the role of reduction in anxiety "permitting" the expression of paternal behavior by males. This research has great relevance to human and human behavior and inadequate paternal involvement and care is associated with many difficulties observed in family interactions and subsequent behavior of children as parents. To test this researcher will study the California mice, which displays many of the same social behavior and family structures as humans. Ingestion of placenta by parturient female mammals is very common, and can elicit behavioral and physiological changes in mothers that enhance their care of offspring. In several biparental mammals, fathers also ingest placenta during the birth of their young; however, the function of placentophagia by males is unknown. Recent research conducted by the co-PI and PI has found that when sexually inexperienced male California mice (Peromyscus californicus) are administered placenta via oral gavage, they subsequently show reduced latencies to approach a novel object or an unrelated pup, as well as reduced neural activity (Fos-immunoreactivity) in the dorsal bed nucleus of the stria terminalis, a brain region associated with anxiety. Thus, these behavioral and neural results suggest that placenta ingestion may reduce anxiety in males. Several studies have found indirect evidence for an inverse relationship between anxiety and paternal care in this and other species. The proposed work will test the hypothesis that placentophagia by male California mice reduces their anxiety, and by doing so may increase their paternal responsiveness. First-time expectant fathers and virgin males will be treated via oral gavage with placenta in oil or oil alone, or left untreated, and subsequently tested for anxiety-like behavior and paternal behavior. Plasma will be assayed for allopregnanolone (an anxiolytic steroid produced in placenta), and neural activity (Fos-immunoreactivity) will be determined in brain areas known to regulate anxiety and paternal care, to determine if placentophagia may reduce anxiety in new fathers through anxiolytic effects of alloprenanolone. Results will provide novel insights into the functional significance of placentophagia by males as well as possible influences on the activation of male parental care.