Neumann I D, Toschi N, Ohl F, Torner L, Krömer S A
Max Planck Institute of Psychiatry, Kraepelinstr. 2, D80804 Munich, Germany.
Eur J Neurosci. 2001 Mar;13(5):1016-24. doi: 10.1046/j.0953-816x.2001.01460.x.
In order to study neuroendocrine and behavioural stress responses in female rats post partum we aimed to establish a relevant emotional stressor -- the maternal defence test based on maternal aggression of a lactating resident towards a virgin or lactating intruder approaching the cage. Exposure to maternal defence significantly elevated corticotropin (ACTH) and corticosterone responses of the residents and of virgin or lactating intruders, with an attenuated response in lactating residents and lactating intruders. Exposure to maternal defence increased plasma oxytocin in virgin intruders only. The aggressive behaviour displayed by the residents was directly correlated with the amount of defensive behaviour of the intruder and independent of the intruder's reproductive state. However, the amount of maternal and explorative behaviours displayed by the lactating residents was significantly higher when exposed to a lactating, compared to a virgin, intruder. ACTH responses in lactating residents exposed to virgin intruders were significantly correlated to the amount of offensive (direct correlation) and maternal (inverse correlation) behaviours they displayed. Plasma prolactin concentrations, elevated in lactating compared to virgin rats under basal conditions, were found to be reduced in the lactating residents and intruders in response to exposure to the maternal defence test, whereas it was unchanged in virgin intruders. To test for the involvement of brain oxytocin in neuroendocrine and behavioural responses of the lactating residents an oxytocin receptor antagonist (0.1 microg/5 microL) was infused icv 10 min prior to testing. This treatment increased basal, but not stress-induced, ACTH, corticosterone and oxytocin secretion. Whereas parameters of aggressive behaviour were unchanged, the antagonist reduced signs of maternal behaviour during maternal defence. In summary, the maternal defence test has been characterized as a relevant emotional stressor for female rats which is useful for studying neuroendocrine and emotional responses in females, in particular in the context of reproductive adaptations.
为了研究产后雌性大鼠的神经内分泌和行为应激反应，我们旨在建立一种相关的情绪应激源——基于哺乳期笼中母鼠对接近笼子的未生育或哺乳期入侵者的母性攻击行为的母性防御试验。暴露于母性防御试验显著提高了笼中母鼠以及未生育或哺乳期入侵者的促肾上腺皮质激素（ACTH）和皮质酮反应，哺乳期母鼠和哺乳期入侵者的反应有所减弱。暴露于母性防御试验仅使未生育入侵者的血浆催产素增加。笼中母鼠表现出的攻击行为与入侵者的防御行为量直接相关，且与入侵者的生殖状态无关。然而，与未生育入侵者相比，哺乳期母鼠暴露于哺乳期入侵者时，其表现出的母性行为和探索行为量显著更高。暴露于未生育入侵者的哺乳期母鼠的ACTH反应与它们表现出的攻击行为量（正相关）和母性行为量（负相关）显著相关。与基础条件下未生育大鼠相比，哺乳期大鼠的血浆催乳素浓度升高，但发现哺乳期母鼠和入侵者在暴露于母性防御试验后血浆催乳素浓度降低，而未生育入侵者的血浆催乳素浓度未变。为了测试脑内催产素是否参与哺乳期母鼠的神经内分泌和行为反应，在测试前10分钟向脑室内注射催产素受体拮抗剂（0.1微克/5微升）。这种处理增加了基础状态下的ACTH、皮质酮和催产素分泌，但未增加应激诱导的分泌。虽然攻击行为参数未变，但拮抗剂减少了母性防御期间的母性行为迹象。总之，母性防御试验已被确定为雌性大鼠相关的情绪应激源，有助于研究雌性动物的神经内分泌和情绪反应，特别是在生殖适应方面。
