Mendes-Lima Tiberiade, Kirsten Thiago Berti, Felicio Luciano Freitas, Teodorov Elizabeth, Queiroz-Hazarbassanov Nicolle, Bernardi Maria Martha
Environmental and Experimental Pathology, Paulista University (UNIP), University of São Paulo, São Paulo, SP, Brazil.
Neuroimmunomodulation. 2017;24(1):1-10. doi: 10.1159/000469711. Epub 2017 May 6.
A common problem during the postpartum period and during lactation is being affected by infection due to Gram-negative bacteria. In this situation, a sick mother needs to choose between caring for her pups or the need for survival. This study analyzed the effects of lipopolysaccharide (LPS)-induced sickness behavior on selection between maternal behavior (MB) and predatory behavior (PB) in lactating rats. To assess the LPS-induced sickness behavior, the plasma tumor necrosis factor-α (TNF-α) levels were measured.
Lactating rats received 100 µg/kg LPS or saline solution on day 5 or 6 of lactation, 2 h before testing. Five pups and 5 cockroaches were introduced to the experimental cage at the same time and maternal and PB were observed for 30 min. The MB was measured by the pup contact, grouping, grooming, and kyphosis and the PB by contacting, eating, and foraging insects. General maternal activity was also observed, including exploration, self-grooming, and immobility. Immediately after the observations, blood was collected to measure the plasma TNF-α levels.
LPS administration reduced the time and frequency of pup contact, grouping, grooming, and kyphosis, with an increase in the latency to first pup contact and grouping. With regard to PB, the time of foraging and eating insects increased, and the latencies to first insect contact, eating insects, and foraging decreased. With regard to general maternal activity, immobility time and TNF-α levels increased in the LPS-treated group.
LPS exposure switched MB to PB, prioritizing maternal survival. Thus, in more favorable situations, these rats may have new offspring and therefore her species would survive for long.
产后及哺乳期常见的一个问题是受到革兰氏阴性菌感染的影响。在这种情况下，患病的母亲需要在照顾幼崽和自身生存需求之间做出选择。本研究分析了脂多糖（LPS）诱导的疾病行为对哺乳期大鼠母性行为（MB）和捕食行为（PB）选择的影响。为评估LPS诱导的疾病行为，检测了血浆肿瘤坏死因子-α（TNF-α）水平。
在哺乳期第5天或第6天测试前2小时，给哺乳期大鼠注射100μg/kg LPS或生理盐水溶液。同时将5只幼崽和5只蟑螂放入实验笼中，观察母性行为和捕食行为30分钟。通过幼崽接触、聚集、梳理毛发和脊柱后凸来测量母性行为，通过接触、进食和捕食昆虫来测量捕食行为。还观察了一般的母性活动，包括探索、自我梳理毛发和静止不动。观察结束后立即采血检测血浆TNF-α水平。
给予LPS减少了幼崽接触、聚集、梳理毛发和脊柱后凸的时间和频率，首次幼崽接触和聚集的潜伏期增加。关于捕食行为，捕食和进食昆虫的时间增加，首次接触昆虫、进食昆虫和捕食的潜伏期缩短。关于一般的母性活动，LPS处理组的静止不动时间和TNF-α水平增加。
接触LPS将母性行为转变为捕食行为，优先考虑母体生存。因此，在更有利的情况下，这些大鼠可能会有新的后代，从而其物种得以长期存活。
