Facilitatory effect of oxytocin on oxytocin cell background activity in the rat is suckling-dependent.
The injection of oxytocin into the third ventricle during suckling in lactating rats not only enhances neurosecretory bursts but also the background activity of oxytocin cells. However, removing the young rats 10 min after the oxytocin injection is immediately followed by a decrease in background activity, while injecting oxytocin alone (i.e. without suckling) or suckling alone (i.e. without oxytocin injection) has no effect. These results, which show that the facilitatory effect of oxytocin on oxytocin cell background activity is suckling-dependent, suggest that oxytocin could act either on the afferent pathways for milk ejection or on oxytocin cells themselves, but only if they received inputs from mammary glands. Various hypotheses on the site and mode of action of oxytocin are discussed.
D000344:Afferent Pathways / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000833:Animals, Suckling; D004594:Electrophysiology; D005260:Female; D007774:Lactation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000294:innervation / Q000502:physiology; D008893:Milk Ejection; D010121:Oxytocin / Q000494:pharmacology / Q000502:physiology*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains
D010121:Oxytocin