Keverne E B, Lévy F, Guevara-Guzman R, Kendrick K M
Sub-Department of Animal Behaviour, University of Cambridge, Madingley, U.K.
Neuroscience. 1993 Oct;56(3):557-65. doi: 10.1016/0306-4522(93)90356-k.
The ewe's ability to selectively recognize her lamb depends upon vaginocervical feedback to the brain stimulating an interest in lamb odours. This process is facilitated by previous maternal experience. We have used in vivo microdialysis to measure changes in the release of intrinsic transmitters in the olfactory bulb (glutamate, dopamine and GABA) at parturition to determine if their release profiles differ depending upon the ewe's past maternal olfactory experience. Glutamate and GABA release increased significantly at parturition in multiparous but not primiparous ewes. Dopamine release increased in both groups but mean basal levels of this transmitter were significantly higher in primiparous ewes during the pre-partum period and the first few hours postpartum. The changes in the underlying neural circuitry which determine these differences are established within 6 h of parturition, as revealed by artificial stimulation of the reproductive tract. This procedure renders the system plastic enabling adoption of strange lambs and, contingent, on this, the release of intrinsic transmitters no longer differs between the two groups of ewes. Pharmacological challenges to the olfactory bulb using retrodialysis in nulliparous and multiparous (maternally inexperienced and experienced) ewes produced significant differences between the groups for induction of glutamate and GABA release, but not that of dopamine. K+ challenges produced greater increases in glutamate and GABA release in multiparous than in nulliparous ewes, while dopamine release did not differ with experience. Glutamate receptor blockade produced increases in glutamate ase without changing GABA release.(ABSTRACT TRUNCATED AT 250 WORDS)
母羊选择性识别自己羔羊的能力取决于阴道宫颈向大脑的反馈，这种反馈会激发对羔羊气味的兴趣。先前的母性经历会促进这一过程。我们利用体内微透析技术来测量分娩时嗅球内内在递质（谷氨酸、多巴胺和γ-氨基丁酸）释放的变化，以确定其释放模式是否因母羊过去的母性嗅觉经历而有所不同。多胎母羊在分娩时谷氨酸和γ-氨基丁酸的释放显著增加，而初产母羊则没有。两组母羊的多巴胺释放均增加，但在产前和产后最初几个小时，初产母羊中这种递质的平均基础水平显著更高。人工刺激生殖道显示，决定这些差异的潜在神经回路变化在分娩后6小时内就已形成。这个过程使系统具有可塑性，能够接受陌生的羔羊，在此基础上，两组母羊内在递质的释放不再有差异。在未生育和多胎（无母性经验和有母性经验）母羊中，通过逆向透析对嗅球进行药理学刺激，两组在诱导谷氨酸和γ-氨基丁酸释放方面存在显著差异，但多巴胺释放没有差异。钾离子刺激使多胎母羊谷氨酸和γ-氨基丁酸的释放比未生育母羊增加得更多，而多巴胺释放不受经验影响。谷氨酸受体阻断导致谷氨酸酶增加，而γ-氨基丁酸释放没有变化。（摘要截短为250字）
