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001-es BibID:BIBFORM013978
Első szerző:Fehér Pálma (gyógyszerész)
Cím:Dephosphorylation/inactivation of tyrosine hydroxylase at the median eminence of the hypothalamus is required for suckling-induced prolactin and adrenocorticotrop hormone responses / Fehér Pálma, Oláh Márk, Bodnár Ibolya, Hechtl Dániel, Bácskay Ildikó, Juhász Béla, Nagy György M., Vecsernyés Miklós
Dátum:2010
ISSN:0361-9230
Megjegyzések:Wehave recently found that dopamine (DA) released from terminals of the hypothalamic neuroendocrine dopamine (NEDA) neurons plays a role not only in prolactin (PRL), but also in adrenocorticotrop hormone (ACTH) secretion, without having any influence on alfa-melanocyte-stimulating hormone (alfa-MSH) release in lactating dams. The aim of our present studies was to further investigate this DAerg regulation of ACTH using consecutively applied physiological stimulation (suckling) and pharmacological inhibition of the rate-limiting enzyme of DA synthesis (tyrosine hydroxylase, TH) by alfa-methyl-p-tyrosine (alfa-MpT) that acutely affect secretion of these pituitary hormones during lactation. Following 4 h separation period, two experimental groups were formed. In the first group, lactating rats were assembled with their litters for 60 min prior to alfa-MpT. In the second group, the alfa-MpT was injected first and 60 min later suckling stimulus was applied. Plasma samples were taken in every 15 min during the 90 min experimental period. Concentrations of plasma PRL, ACTH and alfa-MSH were measured by specific RIAs. Both stimuli applied in the first sequence, significantly elevated plasma PRL and ACTH levels in separated lactating dams, without having any effect on alfa-MSH secretion. Suckling applied in the first sequence was able to block the alfa-MpT-induced elevation of ACTH secretion, while PRL response was also significantly attenuated. alfa-MpT pretreatment prevented both PRL and ACTH responses to suckling stimulus. Investigating the dephosphorylation/inactivation of TH in the arcuate nucleus-ME (TIDA) regions, no pTH-immunoreactive perikarya or terminals can be found in continuously suckled dams. In contrast, after 4 h separation of the mothers from their litters, pTH-immunoreactivity can be clearly visualized in the external zone of ME. In alfa-MpT pretreated mothers following 4 h separation no pTH positive terminals are visible. No changes in the TH immunostaining can be observed in any of these experimental groups. In conclusion, dephosphorylation/inactivation of TH (the rate-limiting enzyme of the DA biosynthesis) in NEDA neurons is required for suckling-induced PRL and ACTH responses.
Tárgyszavak:Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
prolactin
Megjelenés:Brain Research Bulletin. - 82 : 1-2 (2010), p. 141-145. -
További szerzők:Oláh Márk Bodnár Ibolya Hechtl Dániel Bácskay Ildikó (1969-) (gyógyszerész, gyógyszertechnológus) Juhász Béla (1978-) (kísérletes farmakológus) Nagy György M. Vecsernyés Miklós (1959-) (gyógyszertechnológus, endokrinológus)
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001-es BibID:BIBFORM013981
Első szerző:Oláh Márk
Cím:Dopamine-Regulated Adrenocorticotropic Hormone Secretion in Lactating Rats : functional Plasticity of Melanotropes / Oláh Márk, Fehér Pálma, Ihm Zsófia, Bácskay Ildikó, Kiss Timea, Freeman Marc E., Nagy György M., Vecsernyés Miklós
Dátum:2009
ISSN:0028-3835
Megjegyzések:AbstractPro-opiomelanocortin (POMC) is processed to adrenocorticotropic hormone (ACTH) and beta-lipotropin in corticotropes of the anterior lobe, and to alpha-melanocyte-stimulating hormone (alpha-MSH) and beta-endorphin in melanotropes of the intermediate lobe (IL) of the pituitary gland. While ACTH secretion is predominantly under the stimulatory influence of the hypothalamic factors, hormone secretion of the IL is tonically inhibited by neuroendocrine dopamine (NEDA) neurons. Lobe-specific POMC processing is not absolute. For example, D(2) type DA receptor (D2R)-deficient mice have elevated plasma ACTH levels, although it is known that corticotropes do not express D2R(s). Moreover, observations that suckling does not influence alpha-MSH release, while it induces an increase in plasma ACTH is unexplained. The aim of the present study was to investigate the involvement of the NEDA system in the regulation of ACTH secretion and the participation of the IL in ACTH production in lactating rats. Untreated and estradiol (E(2))-substituted ovariectomized (OVX) females were also studied. The concentration of ACTH in the IL was higher in lactating rats than in OVX rats, while the opposite change in alpha-MSH level of the IL was observed. DA levels in the IL and the neural lobe were lower in lactating rats than in OVX rats. Suckling-induced ACTH response was eliminated by pretreatment with the DA receptor agonist, bromocriptine (BRC). Inhibition of DA biosynthesis by alpha-methyl-p-tyrosine (alphaMpT) and blockade of D2R by domperidone (DOM) elevated plasma ACTH levels, but did not influence plasma alpha-MSH levels in lactating rats. The same drugs had opposite effects in OVX and OVX + E(2) animals. In lactating mothers, BRC was able to block ACTH responses induced by both alphaMpT and DOM. Surgical denervation of the IL elevated basal plasma levels of ACTH. Taken together, these data indicate that melanotropes synthesize ACTH during lactation and its release from these cells i
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
dopamine
Megjelenés:Neuroendocrinology. - 90 : 4 (2009), p. 391-401. -
További szerzők:Fehér Pálma (1976-) (gyógyszerész) Ihm Zsófia Bácskay Ildikó (1969-) (gyógyszerész, gyógyszertechnológus) Kiss Tímea (1983-) (gyógyszerész) Freeman, Marc E. Nagy György M. Vecsernyés Miklós (1959-) (gyógyszertechnológus, endokrinológus)
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Intézményi repozitóriumban (DEA) tárolt változat
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