Activity of putative oxytocin neurones during reflex milk ejection in conscious rabbits.

Paisley, A.C.; Summerlee, A. J. S.

doi:10.1113/jphysiol.1984.sp015076

Cited by 31 publications

(24 citation statements)

References 22 publications

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“…OT might therefore inhibit pituitary ACTH secre tion by reducing hypothalamic CRH release. This site of action might be of particular importance during lacta tion, because various in vitro [23] and in vivo [23][24][25] studies demonstrate OT release inside hypothalamic nu clei during milk ejection. On the other hand, exoge nously administered OT does not cross the blood-brain barrier (BBB) [26][27][28] and thus an inhibitory action of OT on ACTH may be supposed at the level of structures located outside the BBB, such as the median eminence, where OT and CRH are both present [29] or the anterior pituitary gland itself.…”

Section: Discussionmentioning

confidence: 99%

Relationship between Plasma Profiles of Oxytocin and Adrenocorticotropic Hormone during Suckling or Breast Stimulation in Women

Chiodera¹,

et al. 1991

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Oxytocin (OT) administration has been shown to inhibit adrenocorticotropic hormone (ACTH)/cortisol secretion in several experimental conditions. In the present study, the plasma OT responses to suckling in 7 lactating women or to mechanical breast stimulation in 6 normally menstruating women (experimental tests) or to sham stimuli in the same subjects (control tests) were measured and correlated with the simultaneous changes in plasma ACTH/cortisol levels. All women showed similar basal levels of OT, ACTH and cortisol, which remained unmodified after sham stimulation. In contrast, both suckling and breast stimulation produced a significant increase in plasma OT levels and a significant decrease in plasma ACTH concentrations. When OT and ACTH data were considered together, a significant negative correlation was found between the OT increase and the simultaneous ACTH decline. Plasma cortisol levels were lower during suckling or breast stimulation than in control conditions. These data show an inverse relationship between plasma OT and ACTH levels during suckling and breast stimulation in humans, suggesting an inhibitory influence of OT on ACTH/cortisol secretion in a physiological condition.

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Section: Discussionmentioning

confidence: 99%

Relationship between Plasma Profiles of Oxytocin and Adrenocorticotropic Hormone during Suckling or Breast Stimulation in Women

Chiodera¹,

et al. 1991

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“…Then, in the 1980s, Summerlee and colleagues, working in Cross's former department at Bristol, published a series of papers that reported the activity of oxytocin neurons recorded over prolonged periods in conscious rats and rabbits through parturition and lactation (Summerlee 1981, Summerlee & Lincoln 1981, Paisley & Summerlee 1984). These studies achieved two things of particular importance: first, the milk-ejection reflex as described in anesthetised rats was essentially identical to the reflex in conscious rats; and second, similar bursting activity was generated during parturition, linked to the delivery of young.…”

Section: Parturitionmentioning

confidence: 99%

60 YEARS OF NEUROENDOCRINOLOGY: The posterior pituitary, from Geoffrey Harris to our present understanding

Leng¹,

Pineda²,

Sabatier³

et al. 2015

Journal of Endocrinology

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Geoffrey Harris pioneered our understanding of the posterior pituitary, mainly with experiments that involved the electrical stimulation of the supraoptico-hypophysial tract. In the present essay, we explain how his observations included clues to the pulsatile nature of the oxytocin signal -clues that were followed up by subsequent workers, including his students and their students. These studies ultimately led to our present understanding of the milk-ejection reflex and of the role of oxytocin in parturition. Discoveries of wide significance followed, including: the recognition of the importance of pulsatile hormone secretion; the recognition of the importance of stimulus-secretion coupling mechanisms in interpreting the patterned electrical activity of neurons; the physiological importance of peptide release in the brain; the recognition that peptide release comes substantially from dendrites and can be regulated independently of nerve terminal secretion; and the importance of dynamic morphological changes to neuronal function in the hypothalamus. All of these discoveries followed from the drive to understand the milk-ejection reflex. We also reflect on Harris's observations on vasopressin secretion, on the effects of stress, and on oxytocin secretion during sexual activity.

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“…The relationship between activation of the oxytocin neurones and the release of assayable quantities of hormone in the circulation has not been investigated however. We have recently shown that oxytocin neurones in the rabbit display characteristic patterns of activity during reflex milk ejection and these patterns can be related to the sucking behaviour of the young (Paisley & Summerlee, 1984). We here report experiments carried out to relate the discharge of oxytocin neurones to the plasma oxytocin concen¬ trations detected in the same animals during nursing, and have examined the temporal changes in oxytocin neurone activity and related these changes to plasma oxytocin concentrations measured during the develop¬ ment and maintenance of lactation and during wean¬ ing.…”

mentioning

confidence: 99%

Aspects of the neuronal and endocrine components of reflex milk ejection in conscious rabbits

Summerlee¹,

Paisley²,

O’Byrne

et al. 1986

Journal of Endocrinology

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Nursing behaviour and reflex milk ejection were studied over 257 suckling periods in 26 Californian rabbits. Detailed plasma profiles of oxytocin were obtained for 161 suckling periods in 16 animals. Plasma oxytocin was detected by radioimmunoassay in serial samples of 0.2 ml blood collected during nursing. Oxytocin titres were below the lower limit of the assay (5 pmol/l) before suckling, and started to rise at a rate of 2.8 +/- 0.8 (S.D.) pmol/l per s 10-30 s after the onset of suckling. Peak levels of hormone were 345 +/- 113 pmol/l and were attained towards the end of nursing. In 33 of these experiments simultaneous records of activity from oxytocin neurones were taken whilst chronically sampling the blood. Each neurone gave an average of seven bursts of neurosecretory activity in suckling. Onset of this bursting pattern of discharge began 5-24 s before the rise in plasma oxytocin was detected. Oxytocin neurone activity alone was monitored in a further 55 suckling periods in eight rabbits. A marked relationship between the duration of suckling period, milk yield, peak oxytocin levels and the length of neurosecretory bursts was demonstrated over the course of lactation. All four parameters increased in parallel from day 1 to reach maximal values on days 15-20 of lactation then started to wane until the doe ceased nursing her litter on days 25-27 of lactation.

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Activity of putative oxytocin neurones during reflex milk ejection in conscious rabbits.

Cited by 31 publications

References 22 publications

Relationship between Plasma Profiles of Oxytocin and Adrenocorticotropic Hormone during Suckling or Breast Stimulation in Women

Relationship between Plasma Profiles of Oxytocin and Adrenocorticotropic Hormone during Suckling or Breast Stimulation in Women

60 YEARS OF NEUROENDOCRINOLOGY: The posterior pituitary, from Geoffrey Harris to our present understanding

Aspects of the neuronal and endocrine components of reflex milk ejection in conscious rabbits

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