Endocrine cells and blood vessels work in tandem to generate hormone pulses

Schaeffer, Marie; Hodson, David J.; Lafont, Chrystel; Mollard, Patrice

doi:10.1530/jme-11-0035

Cited by 40 publications

(27 citation statements)

References 88 publications

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“…When viewed at higher magnifications, the PRL network possesses a distinctive honeycomb appearance with recurrent rosette motifs, an arrangement that likely arises due to the close juxtaposition of lactotrophs with the capillary meshwork that pervades the gland parenchyma [87,89]. Of functional relevance, anatomical interactions between the PRL network and the vasculature may be essential to both dynamically compensate the energy requirements of highly-metabolising lactotrophs, as well as facilitate the extrusion of secreted hormone from the gland [90,91]. Perhaps as a consequence of sharing a common progenitor, the PRL and growth hormone (GH) networks are tightly intermingled, and as for the LH and proopiomelanocortin networks [92], this may have repercussions both for development (e.g.…”

Section: The Network Organisation Of Lactotrophsmentioning

confidence: 99%

Plasticity of the Prolactin (PRL) Axis: Mechanisms Underlying Regulation of Output in Female Mice

Tissier

Hodson

Martin

et al. 2014

Advances in Experimental Medicine and Biology

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The output of prolactin (PRL) is highly dynamic with dramatic changes in its secretion from the anterior pituitary gland depending on prevailing physiological status. In adult female mice, there are three distinct phases of output and each of these is related to the functions of PRL at specific stages of reproduction. Recent studies of the changes in the regulation of PRL during its period of maximum output, lactation, have shown alterations at both the level of the anterior pituitary and hypothalamus. The PRL-secreting cells of the anterior pituitary are organised into a homotypic network in virgin animals, facilitating coordinated bouts of activity between interconnected PRL cells. During lactation, coordinated activity increases due to the changes in structural connectivity, and this drives large elevations in PRL secretion. Surprisingly, these changes in connectivity are maintained after weaning, despite reversion of PRL output to that of virgin animals, and result in an augmented output of hormone during a second lactation. At the level of the hypothalamus, tuberoinfundibular dopamine (TIDA) neurons, the major inhibitors of PRL secretion, have unexpectedly been shown to remain responsive to PRL during lactation. However, there is an uncoupling between TIDA neuron firing and dopamine secretion, with a potential switch to enkephalin release. Such a process may reinforce hormone secretion through dual disinhibition and stimulation of PRL cell activity. Thus, integration of signalling along the hypothalamo-pituitary axis is responsible for increased secretory output of PRL cells during lactation, as well as allowing the system to anticipate future demands.

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Section: The Network Organisation Of Lactotrophsmentioning

confidence: 99%

Plasticity of the Prolactin (PRL) Axis: Mechanisms Underlying Regulation of Output in Female Mice

Tissier

Hodson

Martin

et al. 2014

Advances in Experimental Medicine and Biology

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“…The role of the vasculature in dynamic function of the pituitary, including regulation of blood flow, partial oxygen pressure, delivery of releasing factors and transport of secreted hormone from the gland have recently been reviewed (Schaeffer et al, , 2011a. Therefore, we will focus the description here on the relationship of the vasculature with hormone networks.…”

Section: Pituitary Vasculaturementioning

confidence: 99%

Anterior pituitary cell networks

Tissier

Hodson

Lafont

et al. 2012

Frontiers in Neuroendocrinology

128

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Both endocrine and non-endocrine cells of the pituitary gland are organized into structural and functional networks which are formed during embryonic development but which may be modified throughout life. Structural mapping of the various endocrine cell types has highlighted the existence of distinct network motifs and relationships with the vasculature which may relate to temporal differences in their output. Functional characterization of the network activity of growth hormone and prolactin cells has revealed a role for cell organization in gene regulation, the plasticity of pituitary hormone output and remarkably the ability to memorize altered demand. As such, the description of these endocrine cell networks alters the concept of the pituitary from a gland which simply responds to external regulation to that of an oscillator which may memorize information and constantly adapt its coordinated networks' responses to the flow of hypothalamic inputs.

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“…The pulse amplitude and frequency are responsible for specific downstream effects of GH, and changes can cause an uncoupling of the GH/IGF-1 system. [67][68][69] Alternatively, low IGF-1 in the presence of equivalent levels of GH compared with sham may be an age-dependent phenomenon. IGF-1 production begins to peak independently and prior to GH during adolescence.…”

Section: Incidence and Time Course Of Hormonal Changesmentioning

confidence: 99%

The Effects of Repeat Traumatic Brain Injury on the Pituitary in Adolescent Rats

Greco¹,

Hovda²,

Prins³

2013

Journal of Neurotrauma

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Adolescents are one of the highest groups at risk for sustaining both traumatic brain injury (TBI) and repeat TBI (RTBI). Consequences of endocrine dysfunction following TBI have been routinely explored in adults, but studies in adolescents are limited, and show an incidence rate of endocrine dysfunction in 16-61% in patients, 1-5 years after injury. Similar to in adults, the most commonly affected axis is growth hormone (GH) and insulin-like growth hormone 1 (IGF-1). Despite TBI being the primary cause of morbidity and mortality among the pediatric population, there are currently no experimental studies specifically addressing the occurrence of pituitary dysfunction in adolescents. The present study investigated whether a sham, single injury or four repeat injuries (24 h interval) delivered to adolescent rats resulted in disruption of the GH/IGF-1 axis. Circulating levels of basal GH and IGF-1 were measured at baseline, 24 h, 72 h, 1 week, and 1 month after injury, and vascular permeability of the pituitary gland was quantified via Evans Blue dye extravasation. Changes in weight and length of animals were measured as a potential consequence of GH and IGF-1 disruption. The results from the current study demonstrate that RTBI results in significant acute and chronic decreases in circulation of GH and IGF-1, reduction in weight gain and growth, and an increase in Evans Blue dye extravasation in the pituitary compared with sham and single injury animals. RTBI causes significant disruption of the GH/IGF-1 axis that may ultimately affect normal cognitive and physical development during adolescence.

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Endocrine cells and blood vessels work in tandem to generate hormone pulses

Cited by 40 publications

References 88 publications

Plasticity of the Prolactin (PRL) Axis: Mechanisms Underlying Regulation of Output in Female Mice

Plasticity of the Prolactin (PRL) Axis: Mechanisms Underlying Regulation of Output in Female Mice

Anterior pituitary cell networks

The Effects of Repeat Traumatic Brain Injury on the Pituitary in Adolescent Rats

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