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Serotonin-induced decrease in hypothalamic tyrosine hydroxylase activity and corresponding increase in prolactin release are abolished at midpregnancy and by transplants of rat choriocarcinoma cells.
Endocrinology. 1992 Dec; 131(6):2527-32.E

Abstract

We investigated the effect of central serotonin (5-hydroxytryptamine, 5-HT) administration on hypothalamic tuberoinfundibular dopamine neurons and related changes in neuronal activity to circulating PRL levels in two physiological models: 1) pregnant rats expressing (day 8) or not expressing (days 11 and 16) PRL surges, and 2) ovariectomized rats transplanted with rat choriocarcinoma cells, which secrete functional placental lactogen-I. Over a 4-min period between 0900 and 1400 h, rats were administered either vehicle or 5-HT (20 micrograms/6 microliters) through lateral ventricular cannulae. Plasma PRL levels were determined by RIA. NSD 1015 (25 mg/kg intraarterial), a dihydroxyphenylalanine (DOPA) decarboxylase inhibitor, was injected 20 min after initiation of ventricular infusion. Ten min later, the stalk-median eminence (SME) was dissected. The rate of DOPA accumulation, determined by measuring DOPA levels in the SME by HPLC, was used as an index of tyrosine hydroxylase catalytic activity, indicating tubero infundibular dopamine neuronal activity. In day-8 pregnant rats 5-HT reduced DOPA accumulation to 57% of vehicle-injected controls and increased circulating PRL levels 13-fold. In contrast, on days 11 and 16 of pregnancy 5-HT did not alter DOPA accumulation in the SME or plasma PRL levels. In nonpregnant rats ovariectomized for 24 h, 5-HT decreased DOPA accumulation in the SME to 43% of vehicle-infused controls and increased PRL levels approximately 26-fold. However, in nonpregnant rats with rat choriocarcinoma cells, 5-HT produced no changes in either DOPA accumulation in the SME or in circulating PRL levels. The inability of 5-HT to reduce tyrosine hydroxylase activity after mid-pregnancy may account for the lack of a PRL response. Placental lactogens secreted at midpregnancy, particularly placental lactogen-1, may induce this loss of 5-HT effect.

Authors+Show Affiliations

Department of Physiology, University of Kansas Medical Center, Kansas City 66160-7401.No affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

1359960

Citation

Mathiasen, J R., et al. "Serotonin-induced Decrease in Hypothalamic Tyrosine Hydroxylase Activity and Corresponding Increase in Prolactin Release Are Abolished at Midpregnancy and By Transplants of Rat Choriocarcinoma Cells." Endocrinology, vol. 131, no. 6, 1992, pp. 2527-32.
Mathiasen JR, Tomogane H, Voogt JL. Serotonin-induced decrease in hypothalamic tyrosine hydroxylase activity and corresponding increase in prolactin release are abolished at midpregnancy and by transplants of rat choriocarcinoma cells. Endocrinology. 1992;131(6):2527-32.
Mathiasen, J. R., Tomogane, H., & Voogt, J. L. (1992). Serotonin-induced decrease in hypothalamic tyrosine hydroxylase activity and corresponding increase in prolactin release are abolished at midpregnancy and by transplants of rat choriocarcinoma cells. Endocrinology, 131(6), 2527-32.
Mathiasen JR, Tomogane H, Voogt JL. Serotonin-induced Decrease in Hypothalamic Tyrosine Hydroxylase Activity and Corresponding Increase in Prolactin Release Are Abolished at Midpregnancy and By Transplants of Rat Choriocarcinoma Cells. Endocrinology. 1992;131(6):2527-32. PubMed PMID: 1359960.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Serotonin-induced decrease in hypothalamic tyrosine hydroxylase activity and corresponding increase in prolactin release are abolished at midpregnancy and by transplants of rat choriocarcinoma cells. AU - Mathiasen,J R, AU - Tomogane,H, AU - Voogt,J L, PY - 1992/12/1/pubmed PY - 1992/12/1/medline PY - 1992/12/1/entrez SP - 2527 EP - 32 JF - Endocrinology JO - Endocrinology VL - 131 IS - 6 N2 - We investigated the effect of central serotonin (5-hydroxytryptamine, 5-HT) administration on hypothalamic tuberoinfundibular dopamine neurons and related changes in neuronal activity to circulating PRL levels in two physiological models: 1) pregnant rats expressing (day 8) or not expressing (days 11 and 16) PRL surges, and 2) ovariectomized rats transplanted with rat choriocarcinoma cells, which secrete functional placental lactogen-I. Over a 4-min period between 0900 and 1400 h, rats were administered either vehicle or 5-HT (20 micrograms/6 microliters) through lateral ventricular cannulae. Plasma PRL levels were determined by RIA. NSD 1015 (25 mg/kg intraarterial), a dihydroxyphenylalanine (DOPA) decarboxylase inhibitor, was injected 20 min after initiation of ventricular infusion. Ten min later, the stalk-median eminence (SME) was dissected. The rate of DOPA accumulation, determined by measuring DOPA levels in the SME by HPLC, was used as an index of tyrosine hydroxylase catalytic activity, indicating tubero infundibular dopamine neuronal activity. In day-8 pregnant rats 5-HT reduced DOPA accumulation to 57% of vehicle-injected controls and increased circulating PRL levels 13-fold. In contrast, on days 11 and 16 of pregnancy 5-HT did not alter DOPA accumulation in the SME or plasma PRL levels. In nonpregnant rats ovariectomized for 24 h, 5-HT decreased DOPA accumulation in the SME to 43% of vehicle-infused controls and increased PRL levels approximately 26-fold. However, in nonpregnant rats with rat choriocarcinoma cells, 5-HT produced no changes in either DOPA accumulation in the SME or in circulating PRL levels. The inability of 5-HT to reduce tyrosine hydroxylase activity after mid-pregnancy may account for the lack of a PRL response. Placental lactogens secreted at midpregnancy, particularly placental lactogen-1, may induce this loss of 5-HT effect. SN - 0013-7227 UR - https://www.unboundmedicine.com/medline/citation/1359960/Serotonin_induced_decrease_in_hypothalamic_tyrosine_hydroxylase_activity_and_corresponding_increase_in_prolactin_release_are_abolished_at_midpregnancy_and_by_transplants_of_rat_choriocarcinoma_cells_ L2 - https://academic.oup.com/endo/article-lookup/doi/10.1210/endo.131.6.1359960 DB - PRIME DP - Unbound Medicine ER -