Disease relevance of Milk Ejection

• Also, PRL-R AS treatment impaired maternal behaviour (P < 0.05), whereas physiological parameters of lactation (weight gain of the litter, number of milk ejection reflexes during a 20-min suckling period) were not affected [1].
• IMP was also measured in eleven cows after injection of 0, 10 or 50 micrograms Atosiban/kg body weight: in seven during oxytocin infusions, in four after oxytocin injections in successively increasing dosages (0.05, 0.1, 0.2, 0.5, 1 and 10 i.u.). The occurrence of milk ejection was indicated by a rise in IMP [2].

Psychiatry related information on Milk Ejection

• Although the neuroendocrine response to suckling was attenuated in rats receiving the OXT antagonist, maternal behavior, assessed as the time at which six to eight pups began suckling and the time from the onset until the occurrence of the third milk ejection reflex, was unaffected [3].
• Sleep deprivation blocked milk ejection and enhanced suckling-induced PRL levels in dams that had been previously separated from their pups [4].

High impact information on Milk Ejection

• Intravenous injection of porcine relaxin in anaesthetized lactating rats inhibits milk ejection and injection of relaxin into the cerebral ventricles disturbs the pattern of the milk ejection reflex [5].
• During lactation, oxytocin neurones evolve a synchronized electrical activation which permits pulsatile hormone release at milk ejection [6].
• In addition to uterine contractions during labor and milk ejection during nursing, oxytocin has been implicated in anterior pituitary function, paracrine effects in the testis and ovary and the neural control of maternal and sexual behaviors [7].
• Postpartum injections of oxytocin to the oxytocin deficient mothers restore milk ejection and rescue the offspring [7].
• The winged helix gene, Mf3, is required for normal development of the diencephalon and midbrain, postnatal growth and the milk-ejection reflex [8].

Chemical compound and disease context of Milk Ejection

• In the Oxt antisense group, there was a significant reduction in the number of milk ejection reflexes (to 34.6 +/- 4.88%, P < 0.001), as well as in the weight gain of the litter (to 18.8 +/- 6.98%, P < 0.03) compared with vehicle (100%)-, mixed base-, or vasopressin antisense-treated animals, which did not differ from each other [9].
• None of the treated rats were able to lactate because of defects in maternal behavior and milk ejection; the litters died usually within 48 h postpartum [10].

Biological context of Milk Ejection

• Treatment of LOBEX rats with 1-desamino-8-D-arginine vasopressin and oxytocin reduced water consumption and allowed for milk ejection and milk intake by the pups but did not restore the suckling-induced rise in PRL [11].
• During suckling, oxytocin (OT) neurons display a bursting electrical activity, consisting of a brief burst of action potentials which is synchronized throughout the OT neuron population and which periodically occurs just before each milk ejection in the lactating rat [12].
• Deficiency in mouse oxytocin prevents milk ejection, but not fertility or parturition [13].
• It is now well established that oxytocin, as well as stimulating uterine contractions and milk ejection, promotes the development of maternal behaviour and also bonding between mother and offspring [14].
• Cows with totally inhibited milk ejection in response to vaginal stimulation during milking after first relocation had numerically, but not significantly lower cortisol levels (8.8+/-3.4 ng/ml; AUC/min) in response to ACTH than did cows with at least partial milk ejection (38.7+/-12.9 ng/ml) [15].

Anatomical context of Milk Ejection

• Furthermore, relaxin (1 microgram per rat) injected into the cerebral ventricles profoundly disturbed the pattern of reflex milk ejection without affecting the response of the mammary gland to oxytocin [16].
• Application of GABA into one supraoptic nucleus counteracted this inhibitory effect on milk ejection [17].
• The incidence and pattern of milk ejections, and mammary gland sensitivity to oxytocin were similar in the two groups.(ABSTRACT TRUNCATED AT 400 WORDS)[18]
• Changes in spike activity were compared with the amount of oxytocin released from the neurohypophysis, as measured by the rise in intramammary pressure at milk ejection [19].
• The design of effective in vivo antagonists of rat uterus and milk ejection responses to oxytocin [20].

Associations of Milk Ejection with chemical compounds

• The correlation of the firing pattern of these neurones with milk ejection enabled distinction between oxytocin and vasopressin neurones [21].
• Central inhibitory effects of muscimol and bicuculline on the milk ejection reflex in the anaesthetized rat [22].
• However, in marked and unexpected contrast, application of GABA and isoguvacine facilitated or triggered milk-ejection reflex bursting activity whereas GABAA antagonists interrupted this reflex activity [17].
• The concentration of lactose in plasma did not vary significantly during periods of suckling, or after stimulation of milk ejection by oxytocin [23].
• No significant effect on the milk ejection reflex was seen with i.c.v. isotonic saline (n = 5) [22].

Gene context of Milk Ejection

• A train of APWs modelled after the bursting pattern recorded from an OT-containing neurone during the milk ejection reflex was effective in supporting an exocytotic DeltaC(m) in isolated MNCs, indicating that the somata of SON neurones respond to physiological patterns of neuronal activity with Ca(2+)-dependent exocytotic activity [24].
• Because PTHrP can cause smooth muscle relaxation, we hypothesized that the peptide might affect the contractility of the breast myoepithelial cell and thereby affect milk ejection [25].
• The winged helix gene, Foxb1, controls development of mammary glands and regions of the CNS that regulate the milk-ejection reflex [26].
• The extracted AVP and oxytocin had identical retention times to those of the synthetic peptides on high-performance liquid chromatography (HPLC) and were biologically active in assays for antidiuretic and milk-ejection activity (with potencies of 310 units/mg and 340 units/mg respectively) [27].
• In conscious rats, VIP levels rose significantly from 18 +/- 5 to 102 +/- 30 pM after 5 min of suckling and to 123 +/- 25 pM after 20 min of suckling when milk ejection occurred [28].

Analytical, diagnostic and therapeutic context of Milk Ejection

• Using double in situ hybridization, we demonstrate here an increase in the expression of nitric oxide synthase messenger RNA by oxytocin neurons, but not vasopressin neurons, of the supraoptic nucleus at the time of lactation, when oxytocin is in demand due to another neuroendocrine stimulus, the milk-ejection reflex [29].
• In addition, the role of adrenal hormones and the peripheral sympathetic nervous system in the regulation of milk ejection under these experimental conditions was assessed following bilateral adrenalectomy and treatment with pentolinium, a ganglionic blocker which does not cross the blood-brain barrier [30].
• Intraventricular injection of oxytocin (6, 60 and 600 microU) significantly increased both milk ejection frequency and the number of spikes in the oxytocinergic neurones characteristic bursts [31].
• On the other hand, intraperitoneal injection of 0.15 M NaCl affected neither these parameters of oxytocin neurones nor the amplitude of milk ejection [32].
• Electrical stimulation of the XIII thoracic nerve (the 'mammary nerve') causes milk ejection and the release of prolactin and other hormones [33].

References