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001-es BibID:	BIBFORM073599
Első szerző:	Horváth Katalin M.
Cím:	Dual role of glucocorticoids in suckling-induced prolactin secretion / Katalin M. Horváth, Zsuzsanna Bánky, Béla E. Tóth, György M. Nagy, Béla Halász
Dátum:	2001
ISSN:	0969-711X
Megjegyzések:	The exact contribution of corticosteroids to the control of prolactin secretion in lactating rats is poorly understood. Therefore, the present studies were focused on the effect of adrenalectomy and dexamethasone treatment on the suckling-induced prolactin release. Animals were adrenalectomized on the 3rd day of lactation and tested on the 7th day of lactation. In adrenalectomized animals, the suckling stimulus failed to induce the characteristic increase in plasma prolactin levels. Dexamethasone pretreatment (400 microg/kg b.w. s.c. 24, 48, 72 h before testing) of adrenalectomized rats restored this prolactin response. The same treatment with dexamethasone given to control animals attenuated the suckling stimulus induced prolactin response. The present findings indicate that corticosteroids are essential for a basic prolactin response of lactating rats.
Tárgyszavak:	Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Endocrine. - 15 : 3 (2001), p. 287-290. -
További szerzők:	Bánky Zsuzsanna Tóth E. Béla (1960-) (orvos) Nagy György M. Halász Béla
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM073600
Első szerző:	Horváth Katalin M.
Cím:	Effect of adrenalectomy and dexamethasone treatment on prolactin secretion of lactating rats / Katalin M. Horváth, Zsuzsanna Bánky, Béla E. Tóth, Béla Halász, György M. Nagy
Dátum:	2001
ISSN:	0361-9230
Megjegyzések:	The contribution of corticosteroids to the control of prolactin secretion in lactating rats was investigated. The prolactin response to domperidone (20 ?g/kg b.w., i.v.), a dopamine receptor antagonist and to domperidone plus formalin stress was tested in adrenalectomized and/or dexamethasone-treated continuously nursing rats. Animals were adrenalectomized on the 3rd day of lactation and tested on the 7th day of lactation. Dexamethasone was injected s.c. 24 h before testing (400 ?g/kg b.w.) and on the day of testing (200 ?g/kg b.w.). Domperidone caused a significant rise in plasma prolactin levels. The prolactin response to domperidone was twice as high in solely adrenalectomized dams and in solely dexamethasone-treated rats compared to controls. In adrenalectomized animals treated with dexamethasone, the prolactin response to domperidone was like in controls. Formalin injection to either adrenalectomized plus domperidone-treated animals or to animals injected with dexamethasone plus domperidone, resulted in a statistically significant depletion of plasma prolactin. In controls and in adrenalectomized animals receiving dexamethasone and domperidone, the prolactin response to formalin was very similar, i.e., plasma prolactin levels did not change after the administration of formalin. The present findings suggest that in lactating rats, corticosteroids are involved in the prolactin response to domperidone and to formalin stress.
Tárgyszavak:	Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Brain Research Bulletin 56 : 6 (2001), p. 589-592. -
További szerzők:	Bánky Zsuzsanna Tóth E. Béla (1960-) (orvos) Halász Béla Nagy György M.
Internet cím:	DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM073602
Első szerző:	Horváth Katalin M.
Cím:	Inhibition of protein phosphatase 2A (PP2A) mimics suckling-induced sensitization of mammotropes : involvement of a pertussis toxin (PTX) sensitive G-protein and the adenylate cyclase (AC) / Katalin M. Horváth, Balázs Radnai, Tóth E. Béla, Márton I. K. Fekete, György M. Nagy
Dátum:	1999
ISSN:	0303-7207
Megjegyzések:	In lactating rats, suckling renders mammotropes more responsive to prolactin (PRL)-releasing stimuli and less responsive to PRL-inhibiting secretagogues. We have previously shown that a decrease in the activity of protein phosphatase 2A (PP2A) may be responsible for the decrease in responsiveness to the inhibitory secretagogue dopamine (DA). In our present experiments, we have studied the involvement of the adenylate cyclase (AC), stimulatory and inhibitory GTP-binding proteins and also the role of PP2A in the sensitization phenomenon. Pituitary cells obtained from mother rats separated from their pups for 4 h prior to dispersion (non-suckled), suckled for 10 or 30 min after the separation period (suckled) and without separation (continual suckling) were incubated in the presence of different doses of forskolin to activate AC and DA. In a further study, pituitary cells of non-suckled rats were pretreated with cholera toxin (CTX) or pertussis toxin (PTX) and tested for the stimulatory action of forskolin or TRH on PRL release. Ocadaic acid (OA) pretreatment has been used to investigate the involvement of PP2A. Hormone secretion was measured by the reverse hemolytic plaque assay (RHPA). Our results have shown that cells from non-suckled rats were unresponsive to forskolin. A 10-min suckling stimulus sensitizes pituitary mammotropes to respond with a PRL release to a dose-dependent activation of AC by forskolin. This sensitization of AC becomes a permanent feature of the cells when suckling continues for an additional 20 min. We have also found that pituitary mammotropes from non-suckled dams respond to forskolin or TRH with PRL release when they were preincubated with either PTX or the PP2A inhibitor OA. It clearly indicates that the non-responsive pituitary can be shifted to the responsive stage by uncoupling of inhibitory G-protein from its receptor as well as by inhibition of PP2A. This latter finding, consonant with our previous results, suggests that suckling may cause selective changes in the function of Gi of mammotropes due to a rapid phosphorylation which can remove tonic, GTP-dependent inhibitory function.
Tárgyszavak:	Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Molecular And Cellular Endocrinology 149 : 1-2 (1999), p. 1-7. -
További szerzők:	Radnai Balázs Tóth E. Béla (1960-) (orvos) Fekete I. K. Márton Nagy György M.
Internet cím:	DOI Intézményi repozitóriumban (DEA) tárolt változat
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