Yang J J, Larsen C M, Grattan D R, Erskine M S
Department of Biology, Boston University, Boston, MA, USA.
J Neuroendocrinol. 2009 Jan;21(1):30-9. doi: 10.1111/j.1365-2826.2008.01803.x.
Pseudopregnancy (PSP) is a neuroendocrine reflex triggered by vaginocervical stimulation similar to the neuroendocrine response of early pregnancy and is characterised by short-term neural activity, resulting in long-term neuroendocrine responses that cause repeated release of pituitary prolactin (PRL) over many days. PSP is a useful model to study how somatosensory input is transduced in the brain into neuroendocrine responses, and has been extensively characterised in rats. With increasing use of mice as an experimental model, however, and to allow use of transgenic mice to investigate mechanisms of this sensory response, it is important to characterise the principal neuroendocrine response of pseudopregnancy in this species. The present study aimed to examine the induction and neuroendocrine responses of PSP in mice using vasectomised stud males, to investigate mating-induced changes in vaginal cytology, uterine growth, and PRL secretion, and to map certain aspects of somatosensory transduction by assessing the neural activity marker FOS. Unlike the induction of pseudopregnancy in rats, which can be induced simply by multiple intromissions from a male or artificial mechanical stimulation of the cervix, PSP induction in mice required the receipt of an ejaculation from a male. In mice that received PSP-inducible mating stimuli, FOS expression was observed in a slightly different range of brain regions than has been observed in rats, with increases in the bed nucleus of the stria terminalis, medial preoptic area, and ventromedial hypothalamus, but not in limbic areas examined. Moreover, PSP mice expressed a single diurnal PRL surge on day 6 of PSP. Thus, the data demonstrate important species differences in the neuroendocrine mechanisms activated in response to a mating stimulus in mice compared with rats. A clear understanding of the species-specific response will be required in interpreting research into the reproductive biology of this species.
假孕（PSP）是一种由阴道 - 宫颈刺激引发的神经内分泌反射，类似于早期妊娠的神经内分泌反应，其特征是短期神经活动，导致长期神经内分泌反应，致使垂体催乳素（PRL）在许多天内反复释放。PSP是研究躯体感觉输入如何在大脑中转化为神经内分泌反应的有用模型，并且已在大鼠中得到广泛表征。然而，随着小鼠作为实验模型的使用日益增加，并且为了能够使用转基因小鼠来研究这种感觉反应的机制，表征该物种假孕的主要神经内分泌反应非常重要。本研究旨在使用输精管切除的种公鼠来检查小鼠假孕的诱导和神经内分泌反应，研究交配诱导的阴道细胞学、子宫生长和PRL分泌的变化，并通过评估神经活动标记物FOS来描绘躯体感觉转导的某些方面。与大鼠假孕的诱导不同，大鼠假孕可通过雄性的多次插入或人工机械刺激宫颈来简单诱导，而小鼠假孕的诱导需要接受来自雄性的射精。在接受可诱导PSP交配刺激的小鼠中，观察到FOS表达的脑区范围与在大鼠中观察到的略有不同，终纹床核、内侧视前区和腹内侧下丘脑有增加，但在所检查的边缘区域没有增加。此外，PSP小鼠在PSP第6天表现出单次昼夜PRL激增。因此，数据表明与大鼠相比，小鼠对交配刺激的神经内分泌机制存在重要的物种差异。在解释该物种生殖生物学的研究时，需要清楚了解物种特异性反应。
