Bruckmaier R M, Wellnitz O, Blum J W
Institut für Tierzucht, Universität Bern, Schweiz.
J Dairy Res. 1997 Aug;64(3):315-25. doi: 10.1017/s002202999700232x.
Inhibition of milk ejection in cows by oxytocin receptor blockade (Atosiban) and alpha-adrenergic receptor stimulation (phenylephrine) prior to prestimulation was compared with inhibition of milk ejection in unfamiliar surroundings. In addition, Atosiban and phenylephrine were administered after a 1 min prestimulation or 1 min after the start of milking. Oxytocin concentrations increased during milking in all treatments. The spontaneously removed milk fraction (before oxytocin was injected) was similar for Atosiban and phenylephrine treatments and in unfamiliar surroundings, but lower than in controls. Peak flow rates were similar in all treatments, but reduced as compared with controls when phenylephrine and Atosiban were administered before prestimulation. Peripheral (Atosiban, phenylephrine) and central (unfamiliar surroundings) inhibition of milk ejection reduced the amount of available milk similarity. Drug treatments resulted in similar peak flow rates; however, teats were contracted after phenylephrine administration but not after Atosiban. The inhibition induced by Atosiban could be abolished by oxytocin injection, but not induced by phenylephrine, which was antagonized by alpha-adrenergic receptor blockade. These results indicate that inhibition of milk ejection through activation of alpha-adrenergic receptors is based on blockade of milk flow into the cistern, but not through the teats.
将催产素受体拮抗剂（阿托西班）和α-肾上腺素能受体激动剂（去氧肾上腺素）在预刺激前对奶牛排乳的抑制作用与在陌生环境中排乳的抑制作用进行了比较。此外，在1分钟预刺激后或挤奶开始1分钟后给予阿托西班和去氧肾上腺素。所有处理中，挤奶期间催产素浓度均升高。阿托西班和去氧肾上腺素处理组以及在陌生环境中，自发排出的乳汁部分（注射催产素前）相似，但低于对照组。所有处理中的峰值流速相似，但在预刺激前给予去氧肾上腺素和阿托西班时，与对照组相比有所降低。外周（阿托西班、去氧肾上腺素）和中枢（陌生环境）对排乳的抑制作用使可获得的乳汁量相似性降低。药物处理导致相似的峰值流速；然而，给予去氧肾上腺素后乳头收缩，而给予阿托西班后乳头未收缩。阿托西班诱导的抑制作用可通过注射催产素消除，但去氧肾上腺素不能诱导这种抑制作用，α-肾上腺素能受体拮抗剂可拮抗去氧肾上腺素的作用。这些结果表明，通过激活α-肾上腺素能受体抑制排乳是基于阻断乳汁流入乳池，而不是通过乳头。
