Imaging the Hypothalamo-Neurohypophysial System

Bárez-López, Soledad; Scanlon, Liam; Murphy, David; Greenwood, Michael

doi:10.1159/000519233

Cited by 6 publications

(6 citation statements)

References 94 publications

(122 reference statements)

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“…AVP and OXT are transported down these axons and stored in terminals at the neurovascular interface of the posterior pituitary gland. In response to stimulation, AVP and OXT are secreted into the systemic circulation, acting as hormones on remote targets [1]. Regarding water balance, upon hyperosmotic stress, for example, chronic dehydration, AVP is released into the bloodstream to act at the kidney collecting duct to promote water reabsorption [2].…”

Section: Introductionmentioning

confidence: 99%

Transcriptional and Post-Transcriptional Regulation of Oxytocin and Vasopressin Gene Expression by CREB3L1 and CAPRIN2

Bárez-López¹,

Konopacka²,

Cross³

et al. 2022

Neuroendocrinology

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Introduction:Water homeostasis is achieved by secretion of peptide hormones arginine vasopressin (AVP) and oxytocin (OXT) that are synthesised by separate populations of magnocellular neurones (MCNs) in the hypothalamus. To further understand the molecular mechanisms that facilitate biosynthesis of AVP and OXT by MCNs, we have explored the spatiotemporal dynamic, of two genes identified by our group as being important components of the osmotic defence response: Caprin2 and Creb3l1. Methods:By RNA in situ hybridization and immunohistochemistry, we have characterised the expression of Caprin2 and Creb3l1 in MCNs in the basal state, in response to dehydration, and during rehydration in the rat. Results:We found that Caprin2 and Creb3l1 are expressed in AVP and OXT MCNs and in response to dehydration expression increases in both MCN populations. Protein levels mirror the increase in transcript levels for both CREB3L1 and CAPRIN2. In view of increased CREB3L1 and CAPRIN2 expression in OXT neurones by dehydration, we explored OXT specific functions for these genes. By luciferase assays, we demonstrate that CREB3L1 may be a transcription factor regulating Oxt gene expression. By RNA immunoprecipitation assays and northern blot analysis of Oxt mRNA poly(A) tails, we have found that CAPRIN2 binds Oxt mRNA and regulates its poly(A) tail length. Moreover, in response to dehydration, Caprin2 mRNA is subjected to nuclear retention, possibly to regulate Caprin2 availability to the cytoplasm. Conclusion:The exploration of the spatiotemporal dynamics of Creb3l1 and Caprin2 encoded mRNAs and proteins has provided novel insights beyond the AVP-ergic system revealing novel OXT-ergic system roles of these genes in the osmotic defence response.

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Section: Introductionmentioning

confidence: 99%

Transcriptional and Post-Transcriptional Regulation of Oxytocin and Vasopressin Gene Expression by CREB3L1 and CAPRIN2

Bárez-López¹,

Konopacka²,

Cross³

et al. 2022

Neuroendocrinology

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“…OT and AVP were derived from different prohormones (oxytocin‐neurophysin I (OT‐NPI) and vasopressin‐neurophysin II (AVP‐NPII), respectively), which were synthesized and cut in different neurons extending from the supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus into the posterior lobe. During secretion, the nerve bundles transporting OT‐NPI extend to the exterior region of the posterior lobe whereas the nerve bundles transporting AVP‐NPII extend to the interior of the posterior lobe 36 . CPP, a C‐terminal peptide fragment of vasopressin precursor, 37,38 was derived from the same prohormone (AVP‐NPII) and co‐localized with AVP in the central part of the posterior lobe (Figure 6F, red).…”

Section: Resultsmentioning

confidence: 99%

Imaging and quantification of neuropeptides in mouse pituitary tissue by atmospheric pressure matrix‐assisted laser desorption/ionization mass spectrometry

Yang,

Liu,

et al. 2024

Rapid Comm Mass Spectrometry

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RationaleAtmospheric pressure matrix‐assisted laser desorption/ionization (AP‐MALDI) mass spectrometry has enabled the untargeted analysis and imaging of neuropeptides and proteins in biological tissues under ambient conditions. Sensitivity in AP‐MALDI can be improved by using sample‐specific preparation methods.MethodsA comprehensive and detailed optimization strategy including instrument parameters, matrix spraying and sample tissue washing pretreatment was implemented to enhance the sensitivity and coverage of neuropeptides in mouse pituitary tissues by commercial AP‐MALDI mass spectrometry imaging (MSI).ResultsThe sensitivity of a commercial AP‐MALDI system for endogenous neuropeptides in mouse pituitary was enhanced by up to 15.2‐fold by shortening the transmission gap from the sample plate to the inlet, attaching copper adhesive tape to an indium tin oxide‐coated glass slide, optimizing the matrix spray solvent and using sample tissue washing pretreatment. Following careful optimization, the distributions of nine endogenous neuropeptides were successfully visualized in the pituitary. Furthermore, the quantitative capability of AP‐MALDI for neuropeptides was evaluated and the concentrations of neuropeptides oxytocin and vasopressin in the pituitary posterior lobe were increased approximately twofold under hypertonic saline stress.ConclusionMouse pituitary neuropeptides have emerged as important signaling molecules due to their role in stress response. This work indicates the potential of modified AP‐MALDI as a promising AP MSI method for in situ visualization and quantification of neuropeptides in complex biological tissues.

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“…Fresh‐frozen brains were sliced into 16 μm coronal sections and directly mounted on Superfrost Plus slides (Thermo Fisher Scientific, Waltham, MA, USA) and stored −80°C. RNAscope in situ hybridization was performed as described 21,22 using the probes Rn‐AVP‐C2 (Advanced Cell Diagnostics, 401421‐C2) targeting 20–525 of rat Avp gene, Rn‐OPN3 (Advanced Cell Diagnostics, 578411) targeting 418–1702 of rat Opn3 gene and Rn‐OXT‐C3 (Advanced Cell Diagnostics, 479631‐C3) targeting 3–493 of rat Oxt gene.…”

Section: Methodsmentioning

confidence: 99%

“…The HNS consists of two distinct populations of magnocellular neurones (MCNs) in the SON and PVN that separately synthesise either AVP or OXT. MCN axons project to blood capillaries of the posterior pituitary gland neuro‐vascular interface 15 . To counteract hyperosmotic imbalance, such as that evoked by chronic dehydration or salt‐loading, 12 the HNS releases AVP and OXT into the bloodstream 16 to regulate water balance.…”

Section: Introductionmentioning

confidence: 99%

“…MCN axons project to blood capillaries of the posterior pituitary gland neuro-vascular interface. 15 To counteract hyperosmotic imbalance, such as that evoked by chronic dehydration or salt-loading, 12 the HNS releases AVP and OXT into the bloodstream 16 to regulate water balance. Moreover, MCNs also send extra-neurohypophysial collateral projections to other brain areas that can potentially regulate behavioural responses to physiological challenges 17 including social behaviour, 18 stress response and energy balance.…”

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confidence: 99%

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Male rat hypothalamic extraretinal photoreceptor Opsin3 is sensitive to osmotic stimuli and light

Bárez‐López,

Bishop,

Searby

et al. 2024

J Neuroendocrinology

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The light‐sensitive protein Opsin 3 (Opn3) is present throughout the mammalian brain; however, the role of Opn3 in this organ remains unknown. Since Opn3 encoded mRNA is modulated in the supraoptic and paraventricular nucleus of the hypothalamus in response to osmotic stimuli, we have explored by in situ hybridization the expression of Opn3 in these nuclei. We have demonstrated that Opn3 is present in the male rat magnocellular neurones expressing either the arginine vasopressin or oxytocin neuropeptides and that Opn3 increases in both neuronal types in response to osmotic stimuli, suggesting that Opn3 functions in both cell types and that it might be involved in regulating water balance. Using rat hypothalamic organotypic cultures, we have demonstrated that the hypothalamus is sensitive to light and that the observed light sensitivity is mediated, at least in part, by Opn3. The data suggests that hypothalamic Opn3 can mediate a light‐sensitive role to regulate circadian homeostatic processes.

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Imaging the Hypothalamo-Neurohypophysial System

Cited by 6 publications

References 94 publications

Transcriptional and Post-Transcriptional Regulation of Oxytocin and Vasopressin Gene Expression by CREB3L1 and CAPRIN2

Transcriptional and Post-Transcriptional Regulation of Oxytocin and Vasopressin Gene Expression by CREB3L1 and CAPRIN2

Imaging and quantification of neuropeptides in mouse pituitary tissue by atmospheric pressure matrix‐assisted laser desorption/ionization mass spectrometry

Male rat hypothalamic extraretinal photoreceptor Opsin3 is sensitive to osmotic stimuli and light

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