Pedersen C A, Prange A J
Proc Natl Acad Sci U S A. 1979 Dec;76(12):6661-5. doi: 10.1073/pnas.76.12.6661.
Oxytocin produces uterine contractions and milk ejection, functions related to parturition and nuturing. Studies were conducted to determine if this peptide, native to the brain and the posterior pituitary gland, plays a role in the induction of maternal behavior. Intact virgin female rats were given 0.4 mug of oxytocin, 0.4 mug of [Arg(8)]vasopressin, or saline through lateral ventricular cannulae. Forty-two percent of intact rats receiving oxytocin displayed full maternal behavior towards foster pups. None of the saline- or vasopressin-treated animals displayed full maternal behavior. Criteria in five behavioral categories had to be fulfilled by an animal within 2 hr of injection for its behavior to be considered fully maternal. When partial maternal responses were considered, oxytocin was significantly more effective than saline and marginally more effective than vasopressin. Five animals responding fully maternally after oxytocin injection were allowed to stay with pups for 10 days. All five continued to display full maternal behavior during this time. Nearly all animals that responded fully maternally to oxytocin injection were in the last day of diestrus or in proestrus or estrus. This suggested that elevated or recently elevated levels of estrogen may be necessary for the induction of full maternal behavior by oxytocin. Twenty-seven virgin female rats were ovariectomized and given either 100 mug of estradiol benzoate per kg in oil subcutaneously or oil alone immediately after operation. Forty-eight hours later, all animals received 0.4 mug of oxytocin intracerebroventricularly. Eleven of 13 estrogen-primed animals became fully maternal; none of 14 nonprimed animals became fully maternal.
催产素可引起子宫收缩和射乳，这两种功能与分娩和哺育相关。人们开展了多项研究以确定这种源于大脑和垂体后叶的肽是否在母性行为的诱发过程中发挥作用。通过侧脑室插管，给未交配的成年雌性大鼠注射0.4微克催产素、0.4微克[精氨酸(8)]加压素或生理盐水。接受催产素注射的未交配大鼠中，42%对寄养幼崽表现出完全的母性行为。接受生理盐水或加压素处理的动物均未表现出完全的母性行为。注射后2小时内，动物必须满足五个行为类别的标准，其行为才能被视为完全母性的。若考虑部分母性反应，催产素比生理盐水显著更有效，比加压素略有效。五只注射催产素后表现出完全母性行为的动物被允许与幼崽待在一起10天。在此期间，所有五只动物都继续表现出完全的母性行为。几乎所有对催产素注射表现出完全母性行为的动物都处于动情后期的最后一天或处于发情前期或发情期。这表明，雌激素水平升高或近期升高可能是催产素诱发完全母性行为所必需的。27只未交配的成年雌性大鼠接受卵巢切除手术，术后立即皮下注射每千克100微克的油剂苯甲酸雌二醇或仅注射油剂。48小时后，所有动物经脑室内注射0.4微克催产素。13只接受雌激素预处理的动物中有11只表现出完全的母性行为；14只未预处理的动物均未表现出完全的母性行为。
