Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: hypothalamic supraoptic

Sortuj według:

Ogranicz wyniki do:

The alpha2-adrenoceptors do not modify the activity of tyrosine hydroxylase, corticoliberine, and neuropeptide Y producing hypothalamic magnocellular neurons in the Long Evans and Brattleboro rats

100%

Bundzikova J., Pirnik Z., Zelena D., Mikkelsen J. D., Kiss A.

Journal of Physiology and Pharmacology

2010

tom 61

nr 4

391-398

The hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei are activated by body salt-fluid variations. Stimulation of 2-adrenoceptors by an agonist-xylazine (XYL) activates oxytocinergic but not vasopressinergic magnocellular neurons. In this study, tyrosine hydroxylase (TH), corticoliberine (CRH), and neuropeptide Y (NPY) magnocellular phenotypes, were analysed in response to 2-adrenoceptor manipulations and sustained hyperosmolality in vasopressin deficient homozygous Brattleboro (di/di) rats. Saline (0.9% NaCl, 0.1 ml/100g/bw), XYL (10 mg/kg/bw), atipamezole (ATIP, 2-adrenoceptors antagonist, 1 mg/kg/bw), and ATIP 5 min later followed by XYL, were applied intraperitoneally. Presence of immunolabeled Fos peptide signalized the neuronal activity. Ninety minutes after injections, the rats were anesthesized and sacrificed by transcardial perfusion with fixative. Coronal sections of 30 µm thickness double immunolabeled with Fos/neuropeptide were evaluated under light microscope. Under basal conditions, di/di in comparison with control Long Evans rats, displayed significantly higher number of TH, CRH, and NPY immunoreactive neurons in the SON and PVN (except NPY cells in PVN) and more than 90%, 75%, and 86% of TH, NPY, and CRH neurons, respectively, displayed also Fos signal in the SON. XYL did not further increase the number of Fos in the PVN and SON and ATIP failed to reduce the stimulatory effect of hypertonic saline in all neuronal phenotypes studied. Our data indicate that hyperosmotic conditions significantly influence the activity of TH, CRH, and NPY magnocellular neuronal phenotypes, but 2-adrenoceptors do not play substantial role in their regulation during osmotic challenge induced by AVP deficiency.

Effect of melatonin on the vasopressin secretion as influenced by tachykinin NK-1 receptor agonist and antagonist: in vivo and in vitro studies

80%

Juszczak M., Boczek-Leszczyk E., Stempniak B.

Journal of Physiology and Pharmacology

2007

tom 58

nr 4

The aim of the present study was to investigate the influence of melatonin on vasopressin (AVP) release from the rat hypothalamo-neurohypophysial (H-NH) system, both in vivo and in vitro, possibly modified by the peptide NK-1 and/or NK-2 receptor agonists and antagonists. Highly selective NK-1 receptor agonist, i.e., [Sar9,Met(O2)11]-Substance P, has been shown to enhance the AVP release from isolated rat H-NH system in vitro, while the NK-1 receptor antagonist - (Tyr6,D-Phe7,D-His9)-Substance P (6-11) as well as the NK-2 receptor selective agonist - (ß-Ala8)-Neurokinin A (4-10) and antagonist - (Tyr5,D-Trp6,8,9,Lys-NH210)-Neurokinin A (4-10) were essentially inactive in modifying AVP secretion. Melatonin inhibited basal release of AVP but was not able to reduce significantly the in vitro response of vasopressinergic neurones to NK-1 receptor agonist. After intracerebroventricular (icv) administration, substance P (SP), neurokinin A (NKA) and the NK-1 receptor agonist (all at the concentration of 10-7 M/L) significantly enhanced plasma AVP concentration. Such stimulatory effect of the latter peptide on AVP output from the neurohypophysis was reduced by an intravenous (iv) injection of melatonin, which itself (at a concentration of 5 ng/ml) caused a significant decrease in AVP release 10 min after injection. The inhibitory influence of melatonin on the AVP secretion was absent in rats injected icv with both tachykinin receptors antagonists, the NK-2 receptor agonist or NKA. The present data indicate a distinct role for NK-1 receptor in NKA/SP-mediated regulation of AVP release from the rat H-NH system. They have also shown that, under present experimental conditions, the stimulatory effect of NK-1 receptor activation on AVP secretion into the blood is sensitive to inhibitory influence of melatonin.

Ograniczanie wyników

2 Journal of Physiology and Pharmacology

1 Boczek-Leszczyk E.

1 Bundzikova J.

1 Juszczak M.

1 Kiss A.

1 Mikkelsen J. D.

1 Pirnik Z.

1 Stempniak B.

1 Zelena D.

1 2010

1 2007

Wyniki wyszukiwania

The alpha2-adrenoceptors do not modify the activity of tyrosine hydroxylase, corticoliberine, and neuropeptide Y producing hypothalamic magnocellular neurons in the Long Evans and Brattleboro rats

Effect of melatonin on the vasopressin secretion as influenced by tachykinin NK-1 receptor agonist and antagonist: in vivo and in vitro studies