Blood levels of oxytocin and vasopressin during suckling in the rabbit and the problem of their independent release
Article first published online: 1 MAR 1970
© 1970 The Physiological Society
The Journal of Physiology
Volume 206, Issue 3, pages 711–722, March 1, 1970
How to Cite
1970), Blood levels of oxytocin and vasopressin during suckling in the rabbit and the problem of their independent release. The Journal of Physiology, 206 doi: 10.1113/jphysiol.1970.sp009039., , , (
- Issue published online: 1 MAR 1970
- Article first published online: 1 MAR 1970
- Cited By
1. Oxytocin and vasopressin were assayed in samples of blood collected from conscious rabbits during suckling. The milk yields were determined from the weight gain of the litters.
2. With normal milk yields (35–155 g), relatively high concentrations (31–375 μu./ml.) of oxytocin were present in the blood but vasopressin was detected in only one out of eight samples. It is concluded that the release of oxytocin by the milk-ejection reflex is essential for normal milk removal in the rabbit and that this hormone is released independently of vasopressin.
3. When the milk yield did not exceed 15 g, an amount which could be removed by passive withdrawal from the mammary gland, vasopressin was detected in four out of five blood samples but none contained a detectable concentration of oxytocin. This result can be explained by the intervention of emotional stress which is known to block the milk-ejection reflex but which acts as a stimulus for the release of vasopressin.
4. Emotional stress could inhibit the milk-ejection reflex either centrally by blocking the release of oxytocin, or peripherally by blocking the response of the mammary gland to circulating oxytocin. The absence of the hormone in blood during ineffectual suckling suggests that the block is central.