Dr. Marc E. Freeman BIOLOGICAL SCIENCE
FACULTY MEMBER

Dr. Marc E. Freeman

Office: (850) 644-3896
Lab: (850) 644-9807
Fax: (850) 644-0989
Mail code: 4370
E-mail freeman@neuro.fsu.edu

Personal Home Page

Lloyd M. Beidler Professor of Biological Science;
Ph.D., West Virginia University, 1970

Research and Professional Interests:

We study the way an important area of the brain, the hypothalamus, regulates the secretion of hormones from the pituitary gland that are involved in reproductive processes.

We are particularly interested in the control of secretion of prolactin, the hormone that controls milk synthesis in the mammary gland. The hypothalamus controls prolactin secretion from the anterior pituitary gland in an inhibitory manner. The inhibitory chemical made by nerve cells in the hypothalamus is dopamine. When released into the small blood supply connecting the hypothalamus with the pituitary gland, dopamine inhibits prolactin secretion. Prolactin-releasing stimuli, such as nursing by the hungry infant, inhibit dopamine release from the hypothalamus.

Using approaches such as culture of pituitary cells, radioimmunoassay for measuring prolactin, immunocytochemistry for visualizing dopamine nerve cells and their gene activity and high performance liquid chromatography along with electrochemical detection for measuring changes in dopamine in the brain we are pursuing the following problems:

  • It was previously believed that only one population of dopamine nerve cells in the hypothalamus affect prolactin secretion. We have identified two others that directly affect prolactin secretion and are in the process of characterizing the relative contribution of each

  • Prolactin inhibits its own secretion by activating dopamine nerve cells in the hypothalamus. We have identified prolactin receptors on dopamine nerve cells and are in the process of determining how prolactin regulates the activity of these cells.

  • We have found that dopamine is not only inhibitory to prolactin secretion, but under certain circumstances it can be stimulatory. We are in the process of determining how dopamine can both stimulate and inhibit the same pituitary cell that secretes prolactin.

  • We have discovered that a chemical found in the cells lining the blood vessels of all mammals, endothelin, affects the secretion of most of the anterior pituitary hormones. We are now determining the role endothelin plays in the secretion of each.

Pursuit of these problems has invariably led to many new, unanticipated, exciting questions that assume a place on our laboratory menu.

Selected Publications:

Freeman, M.E., B. Kanyicska, A. Lerant and G. Nagy. Prolactin: structure, function and regulation of secretion. Physiological Reviews 80: 1523-1631, 2000.

Kanyicska, B., A. Lerant and M. E. Freeman. Endothelin-like immunoreactivity in lactotrophs, gonadotrophs, and somatotrophs of the rat anterior pituitary gland are affected differentially by ovarian steroid hormones. Endocrine 14: 263-268, 2001.

Lerant, A., B. Kanyicska and M.E. Freeman. Nuclear translocation of STAT5 and increased expression of Fos-related antigens (FRAs) in hypothalamic dopaminergic neurons after prolactin administration. Brain Research 904: 259-269, 2001.

Gerhold, L. M., T. L. Horvath, M. E. Freeman. Vasoactive intestinal peptide fibers from the suprachiasmatic nucleus innervate neuroendocrine dopaminergic neurons. Brain Research 919: 48-56, 2001. 

Tóth, B.E., K. Homicskó, B. Radnai, W. Maruyama, J. E. DeMaria , M. Vecsernyés, M. I.K. Fekete, F. Fülöp, M. Naoi , M. E. Freeman, and G. M. Nagy. Salsolinol is a putative endogenous neuro-intermediate lobe prolactin releasing factor. Journal of Neuroendocrinology 13: 1042-1050, 2001.

Kanyicska,B., M.T.Sellix and M.E.Freeman. Autocrine regulation of prolactin secretion by endothelins: a permissive role for estradiol. Endocrine 16: 133-138, 2001.

Lerant, A. A, J.E. DeMaria and M. E. Freeman. Decreased expression of Fos-related antigens (FRAS) in the hypothalamic dopaminergic neurons after immunoneutralization of endogenous prolactin. Endocrine16: 181-187, 2001.

Gerhold, L. M, M.T. Sellix and M. E. Freeman. Antagonism of vasoactive intestinal peptide mRNAin the suprachiasmatic nucleus disrupts neuroendocrine dopaminergic neuronal activity. Journal of Comparative Neurology 450: 135-143, 2002.

Sellix, M.T. and M. E. Freeman. Circadian rhythms of neuroendocrine dopaminergic neurons neuronal activity in ovariectomized rats. Neuroendocrinology 77: 59-70, 2003.

Kanyicska, B., M.T. Sellix and M. E. Freeman. Autocrine regulation of prolactin secretion by endothelins throughout the estrous cycle. Endocrine 20: 53-58, 2003.

Sellix, M.T., .M. Egli, R. P. Henderson and M. E. Freeman. Ovarian steroid hormones modulate circadian rhythms of neuroendocrine dopaminergic neuronal activity. Brain Research 1005:168-185, 2004

Egli, M., R. Bertram, M.T. Sellix, and M. E. Freeman. Rhythmic secretion of prolactin in rats: Action of oxytocin coordinated by vasoactive intestinal polypeptide of suprachiasmatic nucleus origin. Endocrinology 145:3386-3394, 2004.

Egli , M., Bertram, R., Toporikova, N., Sellix , M. T., Blanco, W. and M. E. Freeman. Prolactin secretory rhythm of mated rats induced by a single injection of oxytocin. American Journal of Physiology: Endocrinology and Metabolism.. 290: E566-E572, 2006.

Bertram, R., Egli, M. ,Toporikova, N. and M. E. Freeman. A mathematical model for the mating-induced prolactin rhythm of female rats. American Journal of Physiology: Endocrinology and Metabolism. 290: E573-E582, 2006.

Sellix, M. T., Egli, M.,. Poletini, M. O., . McKee, D. T., Bosworth, M.D., Fitch, C. A.and M.E. Freeman. Anatomical and functional characterization of circadian clock gene expression in neuroendocrine dopaminergic neurons. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology 290: R1309-R1323, 2006.

Bertram, R., Tabak, J., Toporikova, N. and M. E. Freeman. Endothelin action on pituitary lactotrophs: one receptor, many GTP-binding proteins. Science STKE, 2006, Issue 319, pp. pe4, 24 January 2006, [DOI: 10.1126/stke.3192006pe4].

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