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

父性关怀在哺乳动物中很少见，但在发生父性关怀的物种中，包括人类，可能会对后代的生存和发育产生关键影响。虽然神经内分泌和经验对父亲行为的影响已经在许多物种中进行了研究，但对父亲护理开始的最接近的调节仍然知之甚少。在雌性哺乳动物中，与孕期(即怀孕、分娩和哺乳期)相关的荷尔蒙变化在一定程度上通过减少新妈妈对新生儿的焦虑或新生恐惧症反应来激活母体行为。目前尚不清楚减少焦虑在男性父母照顾的开始中是否起到了类似的作用，但焦虑的几个生理和行为指标与父亲照顾的各个方面呈负相关。这项研究的目的是研究减少焦虑在“允许”男性表达父性行为方面的作用。这项研究与人类和人类的行为有很大的相关性，父亲的参与和照顾不足与家庭互动中的许多困难和孩子作为父母的随后的行为有关。为了测试这一点，研究人员将研究加利福尼亚州的老鼠，它们表现出许多与人类相同的社会行为和家庭结构。分娩中的雌性哺乳动物摄入胎盘是非常常见的，这会引起母亲的行为和生理变化，从而加强对后代的照顾。在几种双亲哺乳动物中，父亲在幼崽出生时也会摄取胎盘；然而，雄性吞噬胎盘的功能尚不清楚。PI和PI共同进行的最新研究发现，当没有性经验的加州雄性小鼠(Permyscus CalforNicus)通过口服灌胃胎盘时，它们随后显示出接近新对象或无关幼崽的潜伏期缩短，以及终纹背侧床核的神经活动(Fos免疫反应)减少，终纹是大脑中与焦虑相关的区域。因此，这些行为和神经结果表明，摄入胎盘可能会减少男性的焦虑。几项研究发现，在这一物种和其他物种中，焦虑和父亲照顾之间存在反向关系的间接证据。这项拟议的工作将检验这一假设，即加州雄性老鼠的胎盘吞噬减少了它们的焦虑，这样做可能会增加它们作为父亲的反应性。第一次怀孕的父亲和处女男性将通过口服胎盘或仅在油中灌胃进行治疗，或者不治疗，随后测试焦虑样行为和父亲行为。将对血浆中别孕酮(一种从胎盘中产生的抗焦虑类固醇)进行检测，并将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)，以确定吞噬胎盘是否可以通过别孕酮的抗焦虑作用来减少新生儿父亲的焦虑。这一结果将为男性吞噬胎盘的功能意义以及对男性父母照顾的激活可能产生的影响提供新的见解。

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.