Endocrinology, Vol 128, 997-1005, Copyright © 1991 by Endocrine Society

ARTICLES

Hyperprolactinemia increases and hypoprolactinemia decreases tyrosine hydroxylase messenger ribonucleic acid levels in the arcuate nuclei, but not the substantia nigra or zona incerta

LA Arbogast and JL Voogt
Department of Physiology, University of Kansas Medical School, Kansas City 66103.

The effects of experimentally produced hypoprolactinemia and hyperprolactinemia on tyrosine hydroxylase (TH) mRNA signal levels were examined in dopaminergic neurons ovariectomized rats. TH mRNA signal levels and relative TH quantity in the arcuate nuclei, zona incerta, and substantia nigra were evaluated by in situ hybridization and immunocytochemistry, respectively. The catalytic activity of TH in the stalk-median eminence (SME) was determined from the in vitro rate of 3,4-dihydroxyphenylalanine (DOPA) accumulation after inhibiting DOPA decarboxylase with brocresine. Chronic administration of bromocriptine (BROMO), a dopamine (DA) agonist, for 3 days reduced circulating rat PRL (rPRL) levels compared to those in the vehicle-treated controls. BROMO treatment decreased TH mRNA signal levels in the arcuate nuclei, the intensity of TH immunostaining in the arcuate-median eminence area, and the rate of DOPA accumulation in the SME. Concomitant administration of ovine PRL (oPRL) reversed the effects of BROMO on TH, resulting in markedly increased TH mRNA signal levels, intensity of TH immunostaining, and rate of DOPA accumulation. Treatment with oPRL by itself for 3 days increased TH mRNA signal levels in the arcuate nuclei and TH activity in the SME, compared to vehicle. Chronic treatment with haloperidol, a DA antagonist, increased circulating levels of endogenous rPRL and increased TH activity in the SME to values similar to those after oPRL treatment. However, in contrast to oPRL, mRNA levels in the arcuate nuclei of haloperidol-treated rats were similar to levels in vehicle-treated animals. To evaluate whether the effect of PRL on TH was species specific, oPRL or rPRL was continuously infused into the jugular vein using an osmotic minipump. TH mRNA levels in the arcuate nuclei were elevated above control levels by either oPRL or rPRL administration. TH mRNA levels in the DA perikarya located in the zona incerta and substantia nigra were not altered by treatment with a DA agonist, a DA antagonist, or PRL. These results indicate that hypoprolactinemia or hyperprolactinemia can selectively reduce or augment, respectively, TH mRNA levels in the tuberoinfundibular dopaminergic neurons. The alterations in TH mRNA content probably contribute to the decrease or increase in TH activity associated with hypoprolactinemia or hyperprolactinemia, respectively.

This article has been cited by other articles:

				B. Liu and L. A. Arbogast Phosphorylation State of Tyrosine Hydroxylase in the Stalk-Median Eminence Is Decreased by Progesterone in Cycling Female Rats Endocrinology, April 1, 2008; 149(4): 1462 - 1469. [Abstract] [Full Text] [PDF]

				C. E. Khodr, S. M. Clark, D. L. Hurley, and C. J. Phelps Long-Term, Homologous Prolactin, Administered through Ectopic Pituitary Grafts, Induces Hypothalamic Dopamine Neuron Differentiation in Adult Snell Dwarf Mice Endocrinology, April 1, 2008; 149(4): 2010 - 2018. [Abstract] [Full Text] [PDF]

				P. Fitzgerald and T. G Dinan Prolactin and dopamine: What is the connection? A Review Article J Psychopharmacol, March 1, 2008; 22(2_suppl): 12 - 19. [Abstract] [PDF]

				N.-A. Liu, Q. Liu, K. Wawrowsky, Z. Yang, S. Lin, and S. Melmed Prolactin Receptor Signaling Mediates the Osmotic Response of Embryonic Zebrafish Lactotrophs Mol. Endocrinol., April 1, 2006; 20(4): 871 - 880. [Abstract] [Full Text] [PDF]

				F. Y. Ma, G. M. Anderson, T. D. Gunn, V. Goffin, D. R. Grattan, and S. J. Bunn Prolactin Specifically Activates Signal Transducer and Activator of Transcription 5b in Neuroendocrine Dopaminergic Neurons Endocrinology, December 1, 2005; 146(12): 5112 - 5119. [Abstract] [Full Text] [PDF]

				C. J. Phelps Postnatal Regression of Hypothalamic Dopaminergic Neurons in Prolactin-Deficient Snell Dwarf Mice Endocrinology, December 1, 2004; 145(12): 5656 - 5664. [Abstract] [Full Text] [PDF]

				M. E. Cruz-Soto, M. D. Scheiber, K. A. Gregerson, G. P. Boivin, and N. D. Horseman Pituitary Tumorigenesis in Prolactin Gene-Disrupted Mice Endocrinology, November 1, 2002; 143(11): 4429 - 4436. [Abstract] [Full Text] [PDF]

				N. Ben-Jonathan and R. Hnasko Dopamine as a Prolactin (PRL) Inhibitor Endocr. Rev., December 1, 2001; 22(6): 724 - 763. [Abstract] [Full Text] [PDF]

				D. R. Grattan, J. Xu, M. J. McLachlan, I. C. Kokay, S. J. Bunn, R. C. Hovey, and H. W. Davey Feedback Regulation of PRL Secretion Is Mediated by the Transcription Factor, Signal Transducer, and Activator of Transcription 5b Endocrinology, September 1, 2001; 142(9): 3935 - 3940. [Abstract] [Full Text] [PDF]

				E. Terasawa and D. L. Fernandez Neurobiological Mechanisms of the Onset of Puberty in Primates Endocr. Rev., February 1, 2001; 22(1): 111 - 151. [Abstract] [Full Text]

				M. E. Freeman, B. Kanyicska, A. Lerant, and G. Nagy Prolactin: Structure, Function, and Regulation of Secretion Physiol Rev, October 1, 2000; 80(4): 1523 - 1631. [Abstract] [Full Text] [PDF]

				J. P. Moore Jr., A. Cai, M. E. Hostettler, L. A. Arbogast, J. L. Voogt, and J. F. Hyde Pituitary Hormone Gene Expression and Secretion in Human Growth Hormone-Releasing Hormone Transgenic Mice: Focus on Lactotroph Function Endocrinology, January 1, 2000; 141(1): 81 - 90. [Abstract] [Full Text] [PDF]

				C. J. Phelps and D. L. Hurley Pituitary Hormones as Neurotrophic Signals: Update on Hypothalamic Differentiation in Genetic Models of Altered Feedback Experimental Biology and Medicine, October 2, 1999; 222(1): 39 - 58. [Abstract] [Full Text]

				L. A. Arbogast, G. V. Shah, and J. L. Voogt 3',5' Cyclic Adenosine Monophosphate Mediates the Salmon Calcitonin-Induced Increase in Hypothalamic Tyrosine Hydroxylase Activity Endocrinology, July 1, 1999; 140(7): 3273 - 3281. [Abstract] [Full Text]

				Y. Lee 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, May 1, 1999; 140(5): 2159 - 2166. [Abstract] [Full Text]

				L. A. Arbogast and J. L. Voogt Endogenous Opioid Peptides Contribute to Suckling-Induced Prolactin Release by Suppressing Tyrosine Hydroxylase Activity and Messenger Ribonucleic Acid Levels in Tuberoinfundibular Dopaminergic Neurons Endocrinology, June 1, 1998; 139(6): 2857 - 2862. [Abstract] [Full Text] [PDF]

				L. A. Arbogast and J. L. Voogt Prolactin (PRL) Receptors Are Colocalized in Dopaminergic Neurons in Fetal Hypothalamic Cell Cultures: Effect of PRL on Tyrosine Hydroxylase Activity Endocrinology, July 1, 1997; 138(7): 3016 - 3023. [Abstract] [Full Text] [PDF]

				J. A. Maurer and S. Wray Neuronal Dopamine Subpopulations Maintained in Hypothalamic Slice Explant Cultures Exhibit Distinct Tyrosine Hydroxylase mRNA Turnover Rates J. Neurosci., June 15, 1997; 17(12): 4552 - 4561. [Abstract] [Full Text] [PDF]