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The effects of transient dopamine antagonism on thyrotropin-releasing hormone-induced prolactin release in pseudopregnant rats.
Endocrinology. 1986 Nov; 119(5):1989-95.E

Abstract

The effectiveness of TRH in releasing PRL after transient dopamine (DA) blockade was investigated in female rats between days 3 and 11 of pseudopregnancy (PSP). At 0930 h on the morning of the experiment, each animal was injected with the DA antagonist domperidone (0.01 mg/rat, iv) or vehicle (acetic acid in saline); 5 min later, the DA agonist 2-bromo-alpha-ergocryptine maleate (CB-154; 0.5 mg/rat, iv) was administered. Sixty minutes later, TRH (1.0 micrograms/rat, iv) was administered. Blood samples were withdrawn via indwelling catheters before, 5, 20, 40, and 70 min after domperidone or vehicle administration, and 5 and 10 min after TRH administration. On day 3 of PSP, TRH-induced PRL release was significantly enhanced by the domperidone-CB154 treatment compared to that in vehicle-treated control rats. By day 9 of PSP, the effectiveness of TRH in stimulating PRL release after domperidone treatment was decreased by 50% compared to that on day 3 of PSP. This reduction in PRL response to TRH was not due to decreased progesterone levels, as no difference was observed in plasma progesterone between days 3 and 9. Rats that were given domperidone on day 11 of PSP did not exhibit a significant increase in sensitivity to TRH; however, the effectiveness of TRH was enhanced by domperidone on day 11 of PSP in animals that were hysterectomized on day 2 of PSP. Since DA receptor blockage increased the sensitivity to a putative PRL-releasing factor (TRH) and this mechanism was eliminated around the time that the PRL surges of PSP disappear, we suggest that this pituitary mechanism is a critical component of the PRL release mechanism during the surges of PSP. Further, the observed loss of the mechanism between days 9 and 11 of PSP may be due to the direct influence at the anterior pituitary of a uterine PRL inhibitory factor which has been recently described.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

3095097

Citation

Haisenleder, D J., et al. "The Effects of Transient Dopamine Antagonism On Thyrotropin-releasing Hormone-induced Prolactin Release in Pseudopregnant Rats." Endocrinology, vol. 119, no. 5, 1986, pp. 1989-95.
Haisenleder DJ, Moy JA, Gala RR, et al. The effects of transient dopamine antagonism on thyrotropin-releasing hormone-induced prolactin release in pseudopregnant rats. Endocrinology. 1986;119(5):1989-95.
Haisenleder, D. J., Moy, J. A., Gala, R. R., & Lawson, D. M. (1986). The effects of transient dopamine antagonism on thyrotropin-releasing hormone-induced prolactin release in pseudopregnant rats. Endocrinology, 119(5), 1989-95.
Haisenleder DJ, et al. The Effects of Transient Dopamine Antagonism On Thyrotropin-releasing Hormone-induced Prolactin Release in Pseudopregnant Rats. Endocrinology. 1986;119(5):1989-95. PubMed PMID: 3095097.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The effects of transient dopamine antagonism on thyrotropin-releasing hormone-induced prolactin release in pseudopregnant rats. AU - Haisenleder,D J, AU - Moy,J A, AU - Gala,R R, AU - Lawson,D M, PY - 1986/11/1/pubmed PY - 1986/11/1/medline PY - 1986/11/1/entrez SP - 1989 EP - 95 JF - Endocrinology JO - Endocrinology VL - 119 IS - 5 N2 - The effectiveness of TRH in releasing PRL after transient dopamine (DA) blockade was investigated in female rats between days 3 and 11 of pseudopregnancy (PSP). At 0930 h on the morning of the experiment, each animal was injected with the DA antagonist domperidone (0.01 mg/rat, iv) or vehicle (acetic acid in saline); 5 min later, the DA agonist 2-bromo-alpha-ergocryptine maleate (CB-154; 0.5 mg/rat, iv) was administered. Sixty minutes later, TRH (1.0 micrograms/rat, iv) was administered. Blood samples were withdrawn via indwelling catheters before, 5, 20, 40, and 70 min after domperidone or vehicle administration, and 5 and 10 min after TRH administration. On day 3 of PSP, TRH-induced PRL release was significantly enhanced by the domperidone-CB154 treatment compared to that in vehicle-treated control rats. By day 9 of PSP, the effectiveness of TRH in stimulating PRL release after domperidone treatment was decreased by 50% compared to that on day 3 of PSP. This reduction in PRL response to TRH was not due to decreased progesterone levels, as no difference was observed in plasma progesterone between days 3 and 9. Rats that were given domperidone on day 11 of PSP did not exhibit a significant increase in sensitivity to TRH; however, the effectiveness of TRH was enhanced by domperidone on day 11 of PSP in animals that were hysterectomized on day 2 of PSP. Since DA receptor blockage increased the sensitivity to a putative PRL-releasing factor (TRH) and this mechanism was eliminated around the time that the PRL surges of PSP disappear, we suggest that this pituitary mechanism is a critical component of the PRL release mechanism during the surges of PSP. Further, the observed loss of the mechanism between days 9 and 11 of PSP may be due to the direct influence at the anterior pituitary of a uterine PRL inhibitory factor which has been recently described. SN - 0013-7227 UR - https://www.unboundmedicine.com/medline/citation/3095097/The_effects_of_transient_dopamine_antagonism_on_thyrotropin_releasing_hormone_induced_prolactin_release_in_pseudopregnant_rats_ L2 - https://academic.oup.com/endo/article-lookup/doi/10.1210/endo-119-5-1989 DB - PRIME DP - Unbound Medicine ER -