Enes-Marques Silvia, Giusti-Paiva Alexandre
Laboratório de Fisiologia Translacional, Departamento de Ciências Fisiológicas, Instituto de Ciências Biomédicas, Universidade Federal de Alfenas-MG, Campus Santa Clara, Av Jovino Fernandes Sales 2600, Prédio E Sala 300, Alfenas, MG, 37130-000, Brazil.
J Physiol Sci. 2018 Nov;68(6):789-798. doi: 10.1007/s12576-018-0594-8. Epub 2018 Jan 27.
Maternal behavior has a substantial impact on the behavioral, endocrine, and neural development of the pups. This study investigated the effect of altering the neonatal nutritional environment by modifying the litter size on maternal care and anxiety- and fear-like behaviors in rats during adulthood. On postnatal day (PND) 2, litters were adjusted to a small litter (SL) size of three pups per dam or normal litter (NL) size of 12 pups per dam. Maternal behaviors were scored daily during lactation (PND2-21). The weight gain, food intake, adiposity, and biochemical landmarks of offspring rats were evaluated. On PND60, performances in the open field, elevated plus-maze (EPM), and fear conditioning test were measured. The reduction of the litter size enhanced maternal care in lactating rats, increasing the arched-back posture and licking pups. SL offspring exhibited accelerated weight gain, hyperphagia, increased visceral fat mass, dyslipidemia, and hyperleptinemia in adulthood. The SL offspring of both sexes showed an increase in the anti-thigmotactic effect in the open field, an intact anxious-phenotype in the EPM, and a decrease in the time spent freezing during the fear-conditioning test, compared to NL. The neonatal environment as determined by litter size plays a crucial role in programming the adult metabolic phenotype as well as behavioral responses to stressful stimuli, with an impact on anxiety-like and fear behaviors. These behavioral changes in offspring may be, at least in part, a result of increased maternal care.
母性行为对幼崽的行为、内分泌和神经发育具有重大影响。本研究通过改变窝仔数来改变新生鼠的营养环境，调查其对成年大鼠母性关怀以及焦虑样和恐惧样行为的影响。在出生后第2天（PND2），将窝仔数调整为每只母鼠三只幼崽的小窝（SL）或每只母鼠12只幼崽的正常窝（NL）。在哺乳期（PND2 - 21）每天对母性行为进行评分。评估后代大鼠的体重增加、食物摄入量、肥胖程度和生化指标。在PND60时，测量旷场试验、高架十字迷宫（EPM）和恐惧条件反射试验中的表现。窝仔数减少增强了哺乳期大鼠的母性关怀，增加了弓背姿势和舔舐幼崽的行为。SL组后代成年后体重增加加速、食欲亢进、内脏脂肪量增加、血脂异常和高瘦素血症。与NL组相比，SL组两性后代在旷场试验中的避暗效应增加，在EPM中焦虑表型完整，在恐惧条件反射试验中冻结时间减少。由窝仔数决定的新生环境在塑造成年代谢表型以及对应激刺激的行为反应方面起着关键作用，对焦虑样和恐惧行为有影响。后代的这些行为变化可能至少部分是母性关怀增加的结果。
