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Feedback effects of placental lactogens on prolactin levels and Fos-related antigen immunoreactivity of tuberoinfundibular dopaminergic neurons in the arcuate nucleus during pregnancy in the rat.
Endocrinology. 1999 May; 140(5):2159-66.E

Abstract

PRL in the rat exerts its luteotropic action during the first half of pregnancy. After midpregnancy, placental lactogens (PLs) take the place of PRL to stimulate progesterone secretion from the corpus luteum. Simultaneously, PLs trigger a negative feedback on PRL secretion. However, the brain mechanisms for the negative feedback induced by PLs are not fully understood. Here, we report changes in plasma PRL levels, tuberoinfundibular dopaminergic (TIDA) neuronal activity as measured by Fos-related antigen (FRA)/tyrosine hydroxylase (TH) immunoreactivity, and TH catalytic activity as measured by dihydroxyphenylalanine (DOPA) accumulation in the stalk-median eminence (SME) after experimental manipulation of PL levels. On day 4 of pregnancy, animals received Rcho-1 cells intracerebroventricularly (i.c.v.) to increase the level of PLs in the brain or HRP-1 cells as controls. On day 12 of pregnancy, hysterectomy alone or i.c.v. HRP-1 injection plus hysterectomy were performed to remove the source of PLs. Rcho-1 i.c.v. injection plus hysterectomy were performed to examine the effect of replacement of the PL source. Sham-hysterectomized animals were used as a control group. Animals were killed 2 days after each treatment at 0200 and 1800 h, which represent the peak times of PRL surges, and at 1400 h, which represents the intersurge time, by either transcardial perfusion for FRA/TH immunocytochemistry or decapitation 30 min after NSD 1015 injection to assess DOPA accumulation with HPLC-electrochemical detection. Rcho-1 cells completely abolished PRL surges on day 6 of pregnancy and increased the percentage of FRA/TH immunoreactivity in the dorsomedial, ventrolateral, and caudal subdivisions of the arcuate nucleus. This change in neuronal activity reflected the amount of DOPA accumulation in the SME, which was high at all time points. On day 14 of pregnancy, removal of the PL source by hysterectomy resulted in increased PRL levels and decreased neuronal activity of TIDA neurons at all three time points. Similar profiles were observed in animals that received i.c.v. HRP-1 injection plus hysterectomy. Replacement of the source of PL with Rcho-1 cells in hysterectomized rats resulted in low PRL secretion, high neuronal activity of TIDA neurons, and high TH catalytic activity. These patterns were the same as those in sham-operated animals. Our results demonstrate that PLs induce an increase in the neuronal activity of dopaminergic neurons, as measured by FRA/TH immunoreactivity and TH catalytic activity in the SME. Removal of the PL source elevates plasma PRL levels at all times during the second half of pregnancy and does not restore PRL surges.

Authors+Show Affiliations

Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City 66160-7401, USA.No affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

10218967

Citation

Lee, Y, and J L. Voogt. "Feedback Effects of Placental Lactogens On Prolactin Levels and Fos-related Antigen Immunoreactivity of Tuberoinfundibular Dopaminergic Neurons in the Arcuate Nucleus During Pregnancy in the Rat." Endocrinology, vol. 140, no. 5, 1999, pp. 2159-66.
Lee Y, Voogt JL. Feedback effects of placental lactogens on prolactin levels and Fos-related antigen immunoreactivity of tuberoinfundibular dopaminergic neurons in the arcuate nucleus during pregnancy in the rat. Endocrinology. 1999;140(5):2159-66.
Lee, Y., & Voogt, J. L. (1999). Feedback effects of placental lactogens on prolactin levels and Fos-related antigen immunoreactivity of tuberoinfundibular dopaminergic neurons in the arcuate nucleus during pregnancy in the rat. Endocrinology, 140(5), 2159-66.
Lee Y, Voogt JL. Feedback Effects of Placental Lactogens On Prolactin Levels and Fos-related Antigen Immunoreactivity of Tuberoinfundibular Dopaminergic Neurons in the Arcuate Nucleus During Pregnancy in the Rat. Endocrinology. 1999;140(5):2159-66. PubMed PMID: 10218967.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Feedback effects of placental lactogens on prolactin levels and Fos-related antigen immunoreactivity of tuberoinfundibular dopaminergic neurons in the arcuate nucleus during pregnancy in the rat. AU - Lee,Y, AU - Voogt,J L, PY - 1999/4/28/pubmed PY - 1999/4/28/medline PY - 1999/4/28/entrez SP - 2159 EP - 66 JF - Endocrinology JO - Endocrinology VL - 140 IS - 5 N2 - PRL in the rat exerts its luteotropic action during the first half of pregnancy. After midpregnancy, placental lactogens (PLs) take the place of PRL to stimulate progesterone secretion from the corpus luteum. Simultaneously, PLs trigger a negative feedback on PRL secretion. However, the brain mechanisms for the negative feedback induced by PLs are not fully understood. Here, we report changes in plasma PRL levels, tuberoinfundibular dopaminergic (TIDA) neuronal activity as measured by Fos-related antigen (FRA)/tyrosine hydroxylase (TH) immunoreactivity, and TH catalytic activity as measured by dihydroxyphenylalanine (DOPA) accumulation in the stalk-median eminence (SME) after experimental manipulation of PL levels. On day 4 of pregnancy, animals received Rcho-1 cells intracerebroventricularly (i.c.v.) to increase the level of PLs in the brain or HRP-1 cells as controls. On day 12 of pregnancy, hysterectomy alone or i.c.v. HRP-1 injection plus hysterectomy were performed to remove the source of PLs. Rcho-1 i.c.v. injection plus hysterectomy were performed to examine the effect of replacement of the PL source. Sham-hysterectomized animals were used as a control group. Animals were killed 2 days after each treatment at 0200 and 1800 h, which represent the peak times of PRL surges, and at 1400 h, which represents the intersurge time, by either transcardial perfusion for FRA/TH immunocytochemistry or decapitation 30 min after NSD 1015 injection to assess DOPA accumulation with HPLC-electrochemical detection. Rcho-1 cells completely abolished PRL surges on day 6 of pregnancy and increased the percentage of FRA/TH immunoreactivity in the dorsomedial, ventrolateral, and caudal subdivisions of the arcuate nucleus. This change in neuronal activity reflected the amount of DOPA accumulation in the SME, which was high at all time points. On day 14 of pregnancy, removal of the PL source by hysterectomy resulted in increased PRL levels and decreased neuronal activity of TIDA neurons at all three time points. Similar profiles were observed in animals that received i.c.v. HRP-1 injection plus hysterectomy. Replacement of the source of PL with Rcho-1 cells in hysterectomized rats resulted in low PRL secretion, high neuronal activity of TIDA neurons, and high TH catalytic activity. These patterns were the same as those in sham-operated animals. Our results demonstrate that PLs induce an increase in the neuronal activity of dopaminergic neurons, as measured by FRA/TH immunoreactivity and TH catalytic activity in the SME. Removal of the PL source elevates plasma PRL levels at all times during the second half of pregnancy and does not restore PRL surges. SN - 0013-7227 UR - https://www.unboundmedicine.com/medline/citation/10218967/Feedback_effects_of_placental_lactogens_on_prolactin_levels_and_Fos_related_antigen_immunoreactivity_of_tuberoinfundibular_dopaminergic_neurons_in_the_arcuate_nucleus_during_pregnancy_in_the_rat_ L2 - https://academic.oup.com/endo/article-lookup/doi/10.1210/endo.140.5.6730 DB - PRIME DP - Unbound Medicine ER -