JEROME F. FIEKERS

Associate Professor
Anatomy and Neurobiology

M.S., Pharmacology, Mass. College of Pharmacy
Ph.D., University of Connecticut Health Center
Postdoctoral training, University of Vermont

Jerome.Fiekers@uvm.edu

My laboratory is studying several projects related to neuroendocrine regulation of reproduction as well as hypothalamic control of pituitary cell function. Hypothalamic neurons synthesize and secrete releasing hormones which regulate the activity of target cells in the anterior pituitary. Gonadotropin-releasing hormone (GnRH) is released in a pulsatile fashion to direct the activity of the target gonadotrophs. . The origin and cellular mechanisms producing this release are undefined. My laboratory uses a combination of transgenic, electrophysiological, immunohistochemical and digital imaging approaches to study the cellular and subcellular mechanisms underlying GnRH release. We use immortalized cells lines, primary dissociated neurons as well as brain slices to study the secretion of GnRH by hypothalamic GnRH neurons. Electrophysiological techniques are used to determine the effects of releasing factors, neurotransmitters and drugs on this secretion. Since the release of GnRH is calcium-dependent, we also use real-time analysis of the changes in the concentration of intracellular ions (i.e., Ca²⁺) during physiological activation using ratiometric, fluorescent, photometric and digital imaging techniques. We are currently exploring subcellular Ca²⁺ dynamics using cell-specific expression of Ca²⁺ biosensors to detect physiological changes in cytosolic and organelle Ca²⁺ during physiological activation. The control of fertility and anterior pituitary cell function both under physiological conditions and during development and pathological conditions are of major interest.

Roe MW, Fiekers JF, Philipson LH and Bindokas VP Visualizing calcium signaling in cells by digitized widefield and confocal fluorescence microscopy. Humana Press. In press.

Heppner TJ and Fiekers JF (2003). Long-term potentiation of nicotinic synaptic transmission in rat superior cervical ganglia produced by phorbol ester and tetanic stimulation. Auton Neurosci.105:35-44.

Fiekers JF (2001). The contributions of plasma membrane Na⁺-Ca²⁺-exchange and the Ca²⁺-ATPase to the regulation of cytosolic calcium ([Ca²⁺]i) in a clonal pituitary cell line (AtT-20) of mouse corticotropes. Life Sci. 70: 681-98.

Fiekers JF, Gelbspan D, and Heppner TJ (2001). Calcium homeostasis in a clonal pituitary cell line of mouse corticotropes. Can J. Physiol. Pharmacol. 79: 502-11.

Bonnefont X, Fiekers J and Mollard P (2000). Rhythmic bursts of calcium transients in acute anterior pituitary slices. Endocrinology 141: 868-875.

Nietsch HH, Roe MW, Fiekers JF, Moore AL, and Lodofdky SD (2000). Activation of potassium and chloride channels by tumor necrosis factor alpha: role in liver cell death. J. Biol. Chem. 275: 20556-20561.