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Catecholamines and pituitary function. 2. Prolactin response to different dopamine doses in normal cycling women and patients with prolactin-secreting pituitary tumors, both before and after endogenous catecholamine synthesis inhibition.
Horm Metab Res. 1984 Dec; 16(12):658-62.HM

Abstract

The inhibitory effect of various doses of dopamine on serum PRL levels was assessed in both normal cycling women and patients with tumoral hyperprolactinemia before and after endogenous catecholamine synthesis inhibition by alpha-methyl-p-tyrosine, a strong and specific tyrosine-hydroxylase inhibitor. Dopamine infusion induced a significant decrease in the serum PRL levels in both normal cycling and hyperprolactinemic subjects. The mean percent inhibition of baseline PRL induced by the various dopamine infusion rates (0.1, 0.5, 1.0 and 2.0 micrograms/kg/min) was similar in regularly cycling women and in patients with tumoral hyperprolactinemia both before and after endogenous catecholamine synthesis inhibition by alpha-methyl-p-tyrosine. Alpha-methyl-p-tyrosine pretreatment significantly increased serum PRL concentrations in normal women and enhanced their responsiveness to the exogenously administered dopamine. Hyperprolactinemic patients, on the contrary, did not show any significant variation in either basal PRL release or the PRL sensitivity to dopamine infusion after endogenous catecholamine synthesis inhibition. These data indicate that reduced dopamine delivery to the adenomatous lactotroph, either due to a primary hypothalamic abnormality or to a deranged vascular pituitary arrangement, rather than a reduced PRL sensitivity to dopamine inhibition, is the main event accounting for PRL hypersecretion in women with PRL-secreting pituitary tumors.

Authors

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Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

6441763

Citation

Nicoletti, I, et al. "Catecholamines and Pituitary Function. 2. Prolactin Response to Different Dopamine Doses in Normal Cycling Women and Patients With Prolactin-secreting Pituitary Tumors, Both Before and After Endogenous Catecholamine Synthesis Inhibition." Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme, vol. 16, no. 12, 1984, pp. 658-62.
Nicoletti I, Filipponi P, Fedeli L, et al. Catecholamines and pituitary function. 2. Prolactin response to different dopamine doses in normal cycling women and patients with prolactin-secreting pituitary tumors, both before and after endogenous catecholamine synthesis inhibition. Horm Metab Res. 1984;16(12):658-62.
Nicoletti, I., Filipponi, P., Fedeli, L., Gregorini, G., Ambrosi, F., Sfrappini, M., Santeusanio, F., & Brunetti, P. (1984). Catecholamines and pituitary function. 2. Prolactin response to different dopamine doses in normal cycling women and patients with prolactin-secreting pituitary tumors, both before and after endogenous catecholamine synthesis inhibition. Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme, 16(12), 658-62.
Nicoletti I, et al. Catecholamines and Pituitary Function. 2. Prolactin Response to Different Dopamine Doses in Normal Cycling Women and Patients With Prolactin-secreting Pituitary Tumors, Both Before and After Endogenous Catecholamine Synthesis Inhibition. Horm Metab Res. 1984;16(12):658-62. PubMed PMID: 6441763.
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TY - JOUR T1 - Catecholamines and pituitary function. 2. Prolactin response to different dopamine doses in normal cycling women and patients with prolactin-secreting pituitary tumors, both before and after endogenous catecholamine synthesis inhibition. AU - Nicoletti,I, AU - Filipponi,P, AU - Fedeli,L, AU - Gregorini,G, AU - Ambrosi,F, AU - Sfrappini,M, AU - Santeusanio,F, AU - Brunetti,P, PY - 1984/12/1/pubmed PY - 1984/12/1/medline PY - 1984/12/1/entrez SP - 658 EP - 62 JF - Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme JO - Horm Metab Res VL - 16 IS - 12 N2 - The inhibitory effect of various doses of dopamine on serum PRL levels was assessed in both normal cycling women and patients with tumoral hyperprolactinemia before and after endogenous catecholamine synthesis inhibition by alpha-methyl-p-tyrosine, a strong and specific tyrosine-hydroxylase inhibitor. Dopamine infusion induced a significant decrease in the serum PRL levels in both normal cycling and hyperprolactinemic subjects. The mean percent inhibition of baseline PRL induced by the various dopamine infusion rates (0.1, 0.5, 1.0 and 2.0 micrograms/kg/min) was similar in regularly cycling women and in patients with tumoral hyperprolactinemia both before and after endogenous catecholamine synthesis inhibition by alpha-methyl-p-tyrosine. Alpha-methyl-p-tyrosine pretreatment significantly increased serum PRL concentrations in normal women and enhanced their responsiveness to the exogenously administered dopamine. Hyperprolactinemic patients, on the contrary, did not show any significant variation in either basal PRL release or the PRL sensitivity to dopamine infusion after endogenous catecholamine synthesis inhibition. These data indicate that reduced dopamine delivery to the adenomatous lactotroph, either due to a primary hypothalamic abnormality or to a deranged vascular pituitary arrangement, rather than a reduced PRL sensitivity to dopamine inhibition, is the main event accounting for PRL hypersecretion in women with PRL-secreting pituitary tumors. SN - 0018-5043 UR - https://www.unboundmedicine.com/medline/citation/6441763/Catecholamines_and_pituitary_function__2__Prolactin_response_to_different_dopamine_doses_in_normal_cycling_women_and_patients_with_prolactin_secreting_pituitary_tumors_both_before_and_after_endogenous_catecholamine_synthesis_inhibition_ L2 - http://www.thieme-connect.com/DOI/DOI?10.1055/s-2007-1014876 DB - PRIME DP - Unbound Medicine ER -