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Role of serotonin in nocturnal and diurnal surges of prolactin in the pregnant rat.
Endocrinology. 1989 Dec; 125(6):2875-80.E

Abstract

Two surges of PRL designated as nocturnal (N) and diurnal (D) are observed during early pregnancy. The present study was undertaken to determine the involvement of serotonin (5-HT) in regulating these PRL surges. On day 7 of pregnancy intracarotid catheters were implanted, and blood samples were obtained at 0200 and 0400 h on day 8 and between midnight and 0600 h on day 9 to monitor the N surge. Rats were killed by decapitation, brains were quickly removed, frozen on dry ice, and stored at -70 C until later determination of indole and catecholamines. Pretreatment 24 h earlier with para-chlorophenylalanine (PCPA; 250 mg/kg BW), an inhibitor of 5-HT biosynthesis, did not affect the N PRL surge, although the hypothalamic concentrations of 5-HT and its metabolite 5-hydroxyindole acetic acid were greatly reduced. On the other hand, administration at 2400 h of ketanserin (KET; 10 mg/kg BW, ip) or LY-53857 (5 mg/kg BW, ip), two selective 5-HT2 antagonists, significantly (P less than 0.025 for KET and P less than 0.01 for LY-53857) reduced the N PRL surge. Neither KET nor LY-53857 altered the hypothalamic content of biogenic amines compared to that in saline-treated controls. Intravenous treatment with LY-53857 (1 mg/kg) at 0200 h after the onset of the N surge induced no change in plasma PRL levels compared to those in controls. To test whether 5-HT plays a role in the D surge, rats were decapitated at 1800 h after drug injection. Pretreatment with the same dose of PCPA (24 h), KET (2 h), or LY-53857 (2 h) that was given to rats in the N surge study significantly (P less than 0.01) reduced plasma PRL levels. As observed in the N study, PCPA greatly diminished the hypothalamic content of 5-HT and 5-hydroxyindole acetic acid, and also reduced dopamine, but to a much lesser extent than 5-HT. It is concluded that 5-HT contributes significantly to the generation of the D surge. Its role during the N surge remains uncertain due to the contradictory effects of the synthesis inhibitor PCPA and the receptor antagonists KET and LY-53857.

Authors+Show Affiliations

Mistry A
Department of Physiology, University of Kansas Medical Center, Kansas City 66103.
Voogt JL
No affiliation info available

MeSH

3,4-Dihydroxyphenylacetic AcidAnimalsCircadian RhythmDopamineErgolinesFemaleFenclonineHydroxyindoleacetic AcidHypothalamusKetanserinPregnancyPregnancy, AnimalProlactinRatsRats, Inbred StrainsSerotonin

Pub Type(s)

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

Language

eng

PubMed ID

2479530

Citation

Mistry, A, and J L. Voogt. "Role of Serotonin in Nocturnal and Diurnal Surges of Prolactin in the Pregnant Rat." Endocrinology, vol. 125, no. 6, 1989, pp. 2875-80.
Mistry A, Voogt JL. Role of serotonin in nocturnal and diurnal surges of prolactin in the pregnant rat. Endocrinology. 1989;125(6):2875-80.
Mistry, A., & Voogt, J. L. (1989). Role of serotonin in nocturnal and diurnal surges of prolactin in the pregnant rat. Endocrinology, 125(6), 2875-80.
Mistry A, Voogt JL. Role of Serotonin in Nocturnal and Diurnal Surges of Prolactin in the Pregnant Rat. Endocrinology. 1989;125(6):2875-80. PubMed PMID: 2479530.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Role of serotonin in nocturnal and diurnal surges of prolactin in the pregnant rat. AU - Mistry,A, AU - Voogt,J L, PY - 1989/12/1/pubmed PY - 1989/12/1/medline PY - 1989/12/1/entrez SP - 2875 EP - 80 JF - Endocrinology JO - Endocrinology VL - 125 IS - 6 N2 - Two surges of PRL designated as nocturnal (N) and diurnal (D) are observed during early pregnancy. The present study was undertaken to determine the involvement of serotonin (5-HT) in regulating these PRL surges. On day 7 of pregnancy intracarotid catheters were implanted, and blood samples were obtained at 0200 and 0400 h on day 8 and between midnight and 0600 h on day 9 to monitor the N surge. Rats were killed by decapitation, brains were quickly removed, frozen on dry ice, and stored at -70 C until later determination of indole and catecholamines. Pretreatment 24 h earlier with para-chlorophenylalanine (PCPA; 250 mg/kg BW), an inhibitor of 5-HT biosynthesis, did not affect the N PRL surge, although the hypothalamic concentrations of 5-HT and its metabolite 5-hydroxyindole acetic acid were greatly reduced. On the other hand, administration at 2400 h of ketanserin (KET; 10 mg/kg BW, ip) or LY-53857 (5 mg/kg BW, ip), two selective 5-HT2 antagonists, significantly (P less than 0.025 for KET and P less than 0.01 for LY-53857) reduced the N PRL surge. Neither KET nor LY-53857 altered the hypothalamic content of biogenic amines compared to that in saline-treated controls. Intravenous treatment with LY-53857 (1 mg/kg) at 0200 h after the onset of the N surge induced no change in plasma PRL levels compared to those in controls. To test whether 5-HT plays a role in the D surge, rats were decapitated at 1800 h after drug injection. Pretreatment with the same dose of PCPA (24 h), KET (2 h), or LY-53857 (2 h) that was given to rats in the N surge study significantly (P less than 0.01) reduced plasma PRL levels. As observed in the N study, PCPA greatly diminished the hypothalamic content of 5-HT and 5-hydroxyindole acetic acid, and also reduced dopamine, but to a much lesser extent than 5-HT. It is concluded that 5-HT contributes significantly to the generation of the D surge. Its role during the N surge remains uncertain due to the contradictory effects of the synthesis inhibitor PCPA and the receptor antagonists KET and LY-53857. SN - 0013-7227 UR - https://www.unboundmedicine.com/medline/citation/2479530/Role_of_serotonin_in_nocturnal_and_diurnal_surges_of_prolactin_in_the_pregnant_rat_ DB - PRIME DP - Unbound Medicine ER -