Identification of the neuropeptide content of individual rat neurohypophysial terminals

Custer, Edward E.; Ortiz‐Miranda, Sonia; Knott, Thomas; Rawson, Randi L.; Elvey, Christian; Lee, Ryan H.; Lemos, José R.

doi:10.1016/j.jneumeth.2007.03.006

Cited by 18 publications

(15 citation statements)

References 18 publications

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“…P2X7R antagonist AZ10606120 (10 μM) was applied 30 minutes prior to agonist application and maintained for the duration of the experiment. Eluted samples were frozen and stored at −20°C until AVP content could be determined with an AVP ELISA kit (Enzo Life Sciences, Plymouth Meeting, PA), as directed by manufacturer’s instructions (Custer et al, 2007). …”

Section: Methodsmentioning

confidence: 99%

P2X7 Receptors in Neurohypophysial Terminals: Evidence for their Role in Arginine‐Vasopressin Secretion

Cuadra

Custer

Bosworth

et al. 2013

Journal Cellular Physiology

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Arginine-vasopressin (AVP) plays a major role in maintaining cardiovascular function and related pathologies. The mechanism involved in its release into the circulation is complex and highly regulated. Recent work has implicated the purinergic receptor, P2X7R, in a role for catecholamine-enhanced AVP release in the rat hypothalamic-neurohypophysial (NH) system. However, the site of P2X7R action in this endocrine system and whether or not it directly mediates release in secretory neurons have not been determined. We hypothesized that the P2X7R is expressed and mediates AVP release in NH terminals. P2X7R function was first examined by patch-clamp recordings in isolated NH terminals. Results revealed that subpopulations of isolated terminals displayed either high ATP-sensitivity or low ATP-sensitivity, the latter of which was characteristic of the rat P2X7R. Additional recordings showed that terminals showing sensitivity to the P2X7R-selective agonist, BzATP, were further inhibited by P2X7R selective antagonists, AZ10606120 and brilliant blue-G. In confocal micrographs from isolated terminals of the NH showed that P2X7R-immunoreactivity was localized in the plasma membranes. Lastly, the role of P2X7R on AVP release was tested. Our results showed that BzATP evoked sustained AVP release in NH terminals, which was inhibited by AZ10606120. Taken together, our data lead us to conclude that the P2X7R is expressed in NH terminals and corroborates its role in AVP secretion.

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Section: Methodsmentioning

confidence: 99%

P2X7 Receptors in Neurohypophysial Terminals: Evidence for their Role in Arginine‐Vasopressin Secretion

Cuadra

Custer

Bosworth

et al. 2013

Journal Cellular Physiology

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“…It is certain that this preparation contains only nerve terminals with minimal contamination from the other components and numerous studies have confirmed that the physiological functioning of isolated terminals is the same as in the intact NH [29,41–44]. In addition, we can confirm by immunoblotting [42,45], or specific ELISAs [32] after patch-clamp recordings and Ca 2+ measurements, whether the individual terminal is vasopressinergic or oxcytocinergic. Recently, transgenic rats tagged by a visible fluorescent protein have been developed and successfully employed to study the physiology of AVP (enhanced green fluorescent protein), OT (enhanced cyan fluorescent protein) and OT (monomeric red fluorescent protein) in neurons and terminals [24,47–51]…”

Section: The Hypothalamic-neurohypophysial Systemmentioning

confidence: 98%

“…The differences in EC 50 , inactivation, and desensitization of the ATP responses in terminals vs. somata of the HNS indicate that different P2X receptors mediate the responses in the two compartments of these CNS neurons. The HNS somata receptor(s) appears to be a P2X2, P2X4, or P2X6 [100] while the HNS terminal receptor(s) appears to be a mixture of P2X2, P2X3, P2X4, and P2X7 receptors localized on AVP terminals [32,99] and probably only P2X7 is on OT terminals ([101]; see Fig. 3B).…”

Section: Purinergic Effectsmentioning

confidence: 99%

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Modulation/physiology of calcium channel sub-types in neurosecretory terminals

et al. 2012

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The hypothalamic-neurohypophysial system (HNS) controls diuresis and parturition through the release of arginine-vasopressin (AVP) and oxytocin (OT). These neuropeptides are chiefly synthesized in hypothalamic magnocellular somata in the supraoptic and paraventricular nuclei and are released into the blood stream from terminals in the neurohypophysis. These HNS neurons develop specific electrical activity (bursts) in response to various physiological stimuli. The release of AVP and OT at the level of neurohypophysis is directly linked not only to their different burst patterns, but is also regulated by the activity of a number of voltage-dependent channels present in the HNS nerve terminals and by feedback modulators. We found that there is a different complement of voltage-gated Ca2+ channels (VGCC) in the two types of HNS terminals: L, N, and Q in vasopressinergic terminals vs. L, N, and R in oxytocinergic terminals. These channels, however, do not have sufficiently distinct properties to explain the differences in release efficacy of the specific burst patterns. However, feedback by both opioids and ATP specifically modulate different types of VGCC and hence the amount of AVP and/or OT being released. Opioid receptors have been identified in both AVP and OT terminals. In OT terminals, μ-receptor agonists inhibit all VGCC (particularly R-type), whereas, they induce a limited block of L-, and P/Q-type channels, coupled to an unusual potentiation of the N-type Ca2+ current in the AVP terminals. In contrast, the N-type Ca2+ current can be inhibited by adenosine via A1 receptors leading to the decreased release of both AVP and OT. Furthermore, ATP evokes an inactivating Ca2+/Na+-current in HNS terminals able to potentiate AVP release through the activation of P2X2, P2X3, P2X4 and P2X7 receptors. In OT terminals, however, only the latter receptor type is probably present. We conclude by proposing a model that can explain how purinergic and/or opioid feedback modulation during bursts can mediate differences in the control of neurohypophysial AVP vs. OT release.

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“…Indirect ELISA testing was done with the immunogen neurophysin peptide (aa 78–128; manufacturer's information). This antibody was used for immunohistochemical detection of vassopressinergic neurons in the hypothalamus of mice (Russell et al,2003) and for labelling arginine‐vasopressin in isolated neurohypophyseal nerve terminals of the rat (Custer et al,2007).…”

Section: Methodsmentioning

confidence: 99%

Photografting of N‐isopropylacrylamide and glycidyl methacrylate binary monomers on polyethylene film: Effect of mixed solvent consisting of water and organic solvent

Irwan

Aoyama

Kuroda

et al. 2005

J of Applied Polymer Sci

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Photografting ( Ͼ 300 nm) of N-isopropylacrylamide (NIPAAm) and glycidyl methacrylate (GMA) binary monomers (NIPAAm/GMA) on low-density polyethylene film (thickness ϭ 30 m) was investigated at 60°C using mixed solvent consisting of water and an organic solvent such as acetone. Xanthone was used as a photoinitiator by coating it on the film surfaces. A maximum percentage of grafting was observed at a certain concentration of acetone in the mixed solvent, which was commonly observed for both ratios of NIPAAm/GMA, 8/2 and 7/3. Based on the photografting of NIPAAm/GMA on xanthonecoated film, monomer reactivity ratios of NIPAAm (r 1 ) and GMA (r 2 ) were calculated using the Fineman-Ross method. The values were 0.31 Ϯ 0.1 and 4.8 Ϯ 0.2 for the water solvent system, while they were 0.96 Ϯ 0.1 and 4.9 Ϯ 0.1 for the mixed solvent system. NIPAAm/GMA-grafted films with a homogeneous distribution of grafted chains were formed by photografting using water and mixed solvents. The NIPAAm/GMA-grafted films exhibited temperatureresponsive characters, whereas the grafted films showed a reversible change in the degree of swelling between 0 and 50°C, respectively. Epoxy groups in the grafted poly-(NIPAAm/GMA) chains could be aminated with ethylenediamine in N,NЈ-dimethylformamide at 70°C for 3 h. Complexes of the aminated NIPAAm/GMA-grafted chains with cupric ion exhibited catalytic activity for the decomposition of hydrogen peroxide at 20 to 50°C.

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Identification of the neuropeptide content of individual rat neurohypophysial terminals

Cited by 18 publications

References 18 publications

P2X7 Receptors in Neurohypophysial Terminals: Evidence for their Role in Arginine‐Vasopressin Secretion

P2X7 Receptors in Neurohypophysial Terminals: Evidence for their Role in Arginine‐Vasopressin Secretion

Modulation/physiology of calcium channel sub-types in neurosecretory terminals

Photografting of N‐isopropylacrylamide and glycidyl methacrylate binary monomers on polyethylene film: Effect of mixed solvent consisting of water and organic solvent

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