title: An inhibitor of leukotriene synthesis affects vasopressin secretion following osmotic stimulus in rats.
abstract: Previous studies revealed the presence of LTC(4) synthase in paraventricular vasopressinergic neurons, suggesting a role for leukotrienes (LTs) in certain neuroendocrine system functions. Our aim was to study the effect of an inhibitor of LT synthesis in the release of arginine vasopressin (AVP) following an osmotic stimulus in rats. Male Wistar rats received an intra-cerebroventricular injection of 2 μl of the LT synthesis inhibitor MK-886 (1, 2, or 4 μg/kg), or vehicle (DMSO 5%), 1h before an intraperitoneal injection of hypertonic saline (NaCl 2M) or isotonic saline (NaCl 0.01 M) in a volume corresponding to 1% of body weight. Thirty minutes after the osmotic stimulus, the animals were decapitated and blood was collected for determining hematocrit, plasma osmolality and plasma AVP levels. As expected, the injection of hypertonic saline significantly increased (P<0.05) the hematocrit, plasma osmolality and plasma AVP levels. While inhibiting LT synthesis by central administration of MK-886 did not cause any additional increase in hematocrit or osmolality, plasma AVP levels were augmented (P<0.05). We conclude that central leukotrienes may have a modulatory role in AVP secretion following an osmotic stimulus, this deserving future studies.
authors.affiliation: Departamento de Morfologia, Estomatologia e Fisiologia da Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Josilene Fioravanti
authors.initials: JF
authors.lastname: dos Santos
authors.forename: Gabriela Ravanelli
authors.initials: GR
authors.lastname: de Oliveira-Pelegrin
authors.forename: Letícia Antunes
authors.initials: LA
authors.lastname: Athayde
authors.forename: Maria José Alves
authors.initials: MJ
authors.lastname: da Rocha
mesh_terms: D058946:5-Lipoxygenase-Activating Protein Inhibitors / Q000494:pharmacology; D058927:5-Lipoxygenase-Activating Proteins / Q000378:metabolism; D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood / Q000378:metabolism*; D001835:Body Weight; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006400:Hematocrit; D007211:Indoles / Q000008:administration & dosage / Q000494:pharmacology*; D020024:Leukotriene Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D015289:Leukotrienes / Q000096:biosynthesis* / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D009994:Osmolar Concentration; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage / Q000494:pharmacology; D012965:Sodium Chloride / Q000008:administration & dosage; D002722:Chlorobenzenes
chemical_list: D058946:5-Lipoxygenase-Activating Protein Inhibitors; D058927:5-Lipoxygenase-Activating Proteins; D001127:Arginine Vasopressin; D005982:Glutathione Transferase; D007211:Indoles; D020024:Leukotriene Antagonists; D015289:Leukotrienes; D012462:Saline Solution, Hypertonic; D012965:Sodium Chloride; C548594:Alox5ap protein, rat; C060893:MK-886; D002722:Chlorobenzenes; C041116:leukotriene-C4 synthase