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Effect of transient dopamine antagonism on thyrotropin-releasing hormone-induced prolactin secretion in the serotonin-blocked, estrogen-treated ovariectomized rats.
Neuroendocrinology. 1989 Mar; 49(3):281-5.N

Abstract

Recent studies showed that a brief interruption of dopamine (DA) action markedly increased the thyrotropin-releasing hormone (TRH)-stimulated prolactin (PRL) release. It is thus of interest to delineate whether the estrogen-induced afternoon PRL surge involves the same mechanism. Long-term ovariectomized rats pretreated with polyestradiol phosphate (PEP, 0.1 mg/rat s.c.) for 6 days were used in this study. They also received either p-chlorophenylalanine (PCPA, 250 mg/kg i.p.) or ketanserin (Ket, 10 mg/kg i.p.), two serotonergic drugs known to inhibit the estrogen-induced afternoon PRL surge. Then the animals were either treated with a DA antagonist, domperidone (Domp, 0.01 mg/rat i.v.), or vehicle at 16.00 h on the sampling day. Ten minutes later, the ones receiving Domp were injected with a DA agonist, 2-bromo-alpha-ergocryptine (CB154, 0.5 mg/rat i.v.), followed 50 min later by the administration of TRH (1 microgram/rat i.v.). Plasma samples taken through indwelling intraatrial catheters were assayed for PRL by radioimmunoassay. The estrogen-induced afternoon PRL surges were completely blocked in both PCPA- and Ket-treated animals. A significant PRL surge with similar amplitude, however, was induced by either Domp or TRH, although pretreatment with Domp did not cause any potentiating effect on the action of TRH. On the other hand, Domp induced only a small rise of PRL secretion and TRH was totally ineffective in rats untreated with PEP. It is concluded that both DA antagonism and TRH stimulation can induce significant PRL release in the afternoon of estrogen-treated, serotonin-blocked rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Authors+Show Affiliations

Pan JT
Institute of Physiology, National Yang-Ming Medical College, Taiwan, Republic of China.
Wang PS
No affiliation info available

MeSH

AnimalsBromocriptineDomperidoneDopamine AntagonistsEstradiolEstradiol CongenersFemaleFenclonineKetanserinOvariectomyProlactinRatsRats, Inbred StrainsSerotoninThyrotropin-Releasing Hormone

Pub Type(s)

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

Language

eng

PubMed ID

2524012

Citation

Pan, J T., and P S. Wang. "Effect of Transient Dopamine Antagonism On Thyrotropin-releasing Hormone-induced Prolactin Secretion in the Serotonin-blocked, Estrogen-treated Ovariectomized Rats." Neuroendocrinology, vol. 49, no. 3, 1989, pp. 281-5.
Pan JT, Wang PS. Effect of transient dopamine antagonism on thyrotropin-releasing hormone-induced prolactin secretion in the serotonin-blocked, estrogen-treated ovariectomized rats. Neuroendocrinology. 1989;49(3):281-5.
Pan, J. T., & Wang, P. S. (1989). Effect of transient dopamine antagonism on thyrotropin-releasing hormone-induced prolactin secretion in the serotonin-blocked, estrogen-treated ovariectomized rats. Neuroendocrinology, 49(3), 281-5.
Pan JT, Wang PS. Effect of Transient Dopamine Antagonism On Thyrotropin-releasing Hormone-induced Prolactin Secretion in the Serotonin-blocked, Estrogen-treated Ovariectomized Rats. Neuroendocrinology. 1989;49(3):281-5. PubMed PMID: 2524012.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of transient dopamine antagonism on thyrotropin-releasing hormone-induced prolactin secretion in the serotonin-blocked, estrogen-treated ovariectomized rats. AU - Pan,J T, AU - Wang,P S, PY - 1989/3/1/pubmed PY - 1989/3/1/medline PY - 1989/3/1/entrez SP - 281 EP - 5 JF - Neuroendocrinology JO - Neuroendocrinology VL - 49 IS - 3 N2 - Recent studies showed that a brief interruption of dopamine (DA) action markedly increased the thyrotropin-releasing hormone (TRH)-stimulated prolactin (PRL) release. It is thus of interest to delineate whether the estrogen-induced afternoon PRL surge involves the same mechanism. Long-term ovariectomized rats pretreated with polyestradiol phosphate (PEP, 0.1 mg/rat s.c.) for 6 days were used in this study. They also received either p-chlorophenylalanine (PCPA, 250 mg/kg i.p.) or ketanserin (Ket, 10 mg/kg i.p.), two serotonergic drugs known to inhibit the estrogen-induced afternoon PRL surge. Then the animals were either treated with a DA antagonist, domperidone (Domp, 0.01 mg/rat i.v.), or vehicle at 16.00 h on the sampling day. Ten minutes later, the ones receiving Domp were injected with a DA agonist, 2-bromo-alpha-ergocryptine (CB154, 0.5 mg/rat i.v.), followed 50 min later by the administration of TRH (1 microgram/rat i.v.). Plasma samples taken through indwelling intraatrial catheters were assayed for PRL by radioimmunoassay. The estrogen-induced afternoon PRL surges were completely blocked in both PCPA- and Ket-treated animals. A significant PRL surge with similar amplitude, however, was induced by either Domp or TRH, although pretreatment with Domp did not cause any potentiating effect on the action of TRH. On the other hand, Domp induced only a small rise of PRL secretion and TRH was totally ineffective in rats untreated with PEP. It is concluded that both DA antagonism and TRH stimulation can induce significant PRL release in the afternoon of estrogen-treated, serotonin-blocked rats.(ABSTRACT TRUNCATED AT 250 WORDS) SN - 0028-3835 UR - https://www.unboundmedicine.com/medline/citation/2524012/Effect_of_transient_dopamine_antagonism_on_thyrotropin_releasing_hormone_induced_prolactin_secretion_in_the_serotonin_blocked_estrogen_treated_ovariectomized_rats_ DB - PRIME DP - Unbound Medicine ER -