Keverne E B, Kendrick K M
University of Cambridge, Sub-Department of Animal Behaviour, Madingley, UK.
Acta Paediatr Suppl. 1994 Jun;397:47-56. doi: 10.1111/j.1651-2227.1994.tb13265.x.
Non-parturient sheep, hormonally primed and presented with newborn lambs are, at best, indifferent to them and if approached by the lamb may show violent rejection. However, non-gestant ewes primed with oestrogen and progesterone, but given vaginocervical stimulation, do show a rapid onset in maternal behaviour. This stimulation is ineffective in promoting maternal behaviour with epidural anaesthesia. Vaginocervical stimulation increases the release of oxytocin into cerebrospinal fluid and in-vivo microdialysis has revealed high levels of oxytocin release in limbic brain areas known to be important for maternal behaviour. Oxytocin, when given intraventricularly, produces the full complement of acceptance and suckling behaviour in non-gestant ewes. Although ineffective when given alone, opioids potentiate the release of oxytocin in the limbic brain and increase the intensity of maternal responding, while the opioid receptor blocker, naltrexone, prevents both maternal induction and oxytocin release. This neural basis for maternally motivated behaviour may be equally relevant to human behaviour, although the mechanisms available for addressing these peptidergic systems have clear differences.
未分娩的母羊，即使经过激素预处理并接触新生羔羊，最多也只是对它们漠不关心，如果羔羊靠近，母羊可能会表现出强烈的排斥反应。然而，用雌激素和孕酮预处理但给予阴道宫颈刺激的未孕母羊，确实会迅速出现母性行为。在硬膜外麻醉的情况下，这种刺激对促进母性行为无效。阴道宫颈刺激会增加催产素释放到脑脊液中，体内微透析显示，在已知对母性行为重要的边缘脑区有高水平的催产素释放。给未孕母羊脑室内注射催产素，会产生全套的接纳和哺乳行为。阿片类药物虽然单独使用时无效，但能增强边缘脑区催产素的释放，并增加母性反应的强度，而阿片受体阻滞剂纳曲酮则会阻止母性诱导和催产素释放。这种母性行为的神经基础可能同样适用于人类行为，尽管调节这些肽能系统的机制存在明显差异。
