Artigo

Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat

We investigated the effects of adenosine on prolactin (PRL) secretion from rat anterior pituitaries incubated in vitro. The administration of 5-N- methylcarboxamidoadenosine (MECA), an analog agonist that preferentially activates A2 receptors, induced a dose-dependent (1 nM to 1 µM) increase in the...

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Autor principal: DINIZ, Domingos Luiz Wanderley Picanço
Outros Autores: VALENÇA, Marcelo Moraes, FAVARETTO, Ana Lucia Vianna, RODRIGUES, José Antunes
Grau: Artigo
Idioma: eng
Publicado em: 2013
Assuntos:
Adenosina
Hipófise
Prolactina
Acesso em linha: http://repositorio.ufpa.br/jspui/handle/2011/3318
id ir-2011-3318
recordtype dspace
spelling ir-2011-33182017-10-16T15:57:28Z Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat DINIZ, Domingos Luiz Wanderley Picanço VALENÇA, Marcelo Moraes FAVARETTO, Ana Lucia Vianna RODRIGUES, José Antunes Adenosina Hipófise Prolactina We investigated the effects of adenosine on prolactin (PRL) secretion from rat anterior pituitaries incubated in vitro. The administration of 5-N- methylcarboxamidoadenosine (MECA), an analog agonist that preferentially activates A2 receptors, induced a dose-dependent (1 nM to 1 µM) increase in the levels of PRL released, an effect abolished by 1,3-dipropyl-7-methylxanthine, an antagonist of A2 adenosine receptors. In addition, the basal levels of PRL secretion were decreased by the blockade of cyclooxygenase or lipoxygenase pathways, with indomethacin and nordihydroguaiaretic acid (NDGA), respectively. The stimulatory effects of MECA on PRL secretion persisted even after the addition of indomethacin, but not of NDGA, to the medium. MECA was unable to stimulate PRL secretion in the presence of dopamine, the strongest inhibitor of PRL release that works by inducing a decrease in adenylyl cyclase activity. Furthermore, the addition of adenosine (10 nM) mimicked the effects of MECA on PRL secretion, an effect that persisted regardless of the presence of LiCl (5 mM). The basal secretion of PRL was significatively reduced by LiCl, and restored by the concomitant addition of both LiCl and myo-inositol. These results indicate that PRL secretion is under a multifactorial regulatory mechanism, with the participation of different enzymes, including adenylyl cyclase, inositol-1-phosphatase, cyclooxygenase, and lipoxygenase. However, the increase in PRL secretion observed in the lactotroph in response to A2 adenosine receptor activation probably was mediated by mechanisms involving regulation of adenylyl cyclase, independent of membrane phosphoinositide synthesis or cyclooxygenase activity and partially dependent on lipoxygenase arachidonic acid-derived substances. 2013-01-15T13:21:47Z 2013-01-15T13:21:47Z 2002-07 Artigo de Periódico PICANÇO-DINIZ, D.L.W. et al. Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat. Brazilian Journal of Medical and Biological Research, Ribeirão Preto, v. 35, n. 7, p. 855-860, jul. 2002. Disponível em: <http://www.scielo.br/pdf/bjmbr/v35n7/4379.pdf>. Acesso em: 11 dez. 2012. http://dx.doi.org/10.1590/S0100-879X2002000700015. 1414-431X http://repositorio.ufpa.br/jspui/handle/2011/3318 eng Acesso Aberto application/pdf
institution Repositório Institucional - Universidade Federal do Pará
collection RI-UFPA
language eng
topic Adenosina
Hipófise
Prolactina
spellingShingle Adenosina
Hipófise
Prolactina
DINIZ, Domingos Luiz Wanderley Picanço
Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat
topic_facet Adenosina
Hipófise
Prolactina
description We investigated the effects of adenosine on prolactin (PRL) secretion from rat anterior pituitaries incubated in vitro. The administration of 5-N- methylcarboxamidoadenosine (MECA), an analog agonist that preferentially activates A2 receptors, induced a dose-dependent (1 nM to 1 µM) increase in the levels of PRL released, an effect abolished by 1,3-dipropyl-7-methylxanthine, an antagonist of A2 adenosine receptors. In addition, the basal levels of PRL secretion were decreased by the blockade of cyclooxygenase or lipoxygenase pathways, with indomethacin and nordihydroguaiaretic acid (NDGA), respectively. The stimulatory effects of MECA on PRL secretion persisted even after the addition of indomethacin, but not of NDGA, to the medium. MECA was unable to stimulate PRL secretion in the presence of dopamine, the strongest inhibitor of PRL release that works by inducing a decrease in adenylyl cyclase activity. Furthermore, the addition of adenosine (10 nM) mimicked the effects of MECA on PRL secretion, an effect that persisted regardless of the presence of LiCl (5 mM). The basal secretion of PRL was significatively reduced by LiCl, and restored by the concomitant addition of both LiCl and myo-inositol. These results indicate that PRL secretion is under a multifactorial regulatory mechanism, with the participation of different enzymes, including adenylyl cyclase, inositol-1-phosphatase, cyclooxygenase, and lipoxygenase. However, the increase in PRL secretion observed in the lactotroph in response to A2 adenosine receptor activation probably was mediated by mechanisms involving regulation of adenylyl cyclase, independent of membrane phosphoinositide synthesis or cyclooxygenase activity and partially dependent on lipoxygenase arachidonic acid-derived substances.
format Artigo
author DINIZ, Domingos Luiz Wanderley Picanço
author2 VALENÇA, Marcelo Moraes
FAVARETTO, Ana Lucia Vianna
RODRIGUES, José Antunes
author2Str VALENÇA, Marcelo Moraes
FAVARETTO, Ana Lucia Vianna
RODRIGUES, José Antunes
title Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat
title_short Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat
title_full Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat
title_fullStr Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat
title_full_unstemmed Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat
title_sort stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat
publishDate 2013
url http://repositorio.ufpa.br/jspui/handle/2011/3318
_version_ 1832604786502926336
score 11.755432

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