The long range objectives of this project is to clarify cardioinhibition during cardioregulation in Limulus polyphemus. Gamma-aminobutyric acid (GABA) and 5-hydroxytryptamine (5-HT) both have been implicated as cardioinhibitory transmitters within Limulus polyphemus Central Nervous System (CNS). The precise physiological role played by GABA in cardioinhibition is not settled. In our effort to clarify neural control of inhibition in the CNS of Limulus polyphemus, we hypothesize that GABA co-exists with 5-HT in the CNS of Limulus as a neurotransmitter, and that GABA aids in a inhibitory response during cardioregulation in both the central and peripheral nervous system. We propose to identify GABAergic neurons within the CNS of Limulus by using immunocytochemistry. The identification of immunoreactive somata and fibers to immunoreactive somata. The antagonistic action of picrotoxin, and bicuculline will be assessed electrophysiologically, on GABA inhibitory response during analysis of burst frequency, burst content (spikes/burst), and burst duration. We propose to further characterize pharmacologically GABAergic receptors within Limulus CNS with the use of agonists and antagonists. Kinetics and pharmacological studies on the uptake and release of GABA is putative inhibitory neurotransmitter in Limulus and function in cardioregulation both in the central and peripheral nervous system.

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Tennessee State University
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Rana, Krupa; Whalen, Margaret (2015) Activation of protein kinase C and protein kinase D in human natural killer cells: effects of tributyltin, dibutyltin, and tetrabromobisphenol A. Toxicol Mech Methods 25:680-8
Hurd-Brown, Tasia; Udoji, Felicia; Martin, Tamara et al. (2013) Effects of DDT and triclosan on tumor-cell binding capacity and cell-surface protein expression of human natural killer cells. J Appl Toxicol 33:495-502
Sharow, Kyle A; Temkin, Boris; Asson-Batres, Mary Ann (2012) Retinoic acid stability in stem cell cultures. Int J Dev Biol 56:273-8
Hurd, Tasia; Walker, Jasmine; Whalen, Margaret M (2012) Pentachlorophenol decreases tumor-cell-binding capacity and cell-surface protein expression of human natural killer cells. J Appl Toxicol 32:627-34
Taylor, Thyneice R; Whalen, Margaret M (2011) Ziram activates mitogen-activated protein kinases and decreases cytolytic protein levels in human natural killer cells. Toxicol Mech Methods 21:577-84
Buchanan, FaMitah Q; Rochette-Egly, Cecile; Asson-Batres, Mary Ann (2011) Detection of variable levels of RAR? and RAR? proteins in pluripotent and differentiating mouse embryonal carcinoma and mouse embryonic stem cells. Cell Tissue Res 346:43-51
Hurd, Tasia; Whalen, Margaret M (2011) Tetrabromobisphenol A decreases cell-surface proteins involved in human natural killer (NK) cell-dependent target cell lysis. J Immunotoxicol 8:219-27
Udoji, Felicia; Martin, Tamara; Etherton, Rachel et al. (2010) Immunosuppressive effects of triclosan, nonylphenol, and DDT on human natural killer cells in vitro. J Immunotoxicol 7:205-12
Abraha, Abraham B; Rana, Krupa; Whalen, Margaret M (2010) Role of protein kinase C in TBT-induced inhibition of lytic function and MAPK activation in human natural killer cells. Arch Environ Contam Toxicol 59:661-9
Hinkson, Natasha C; Whalen, Margaret M (2010) Hexabromocyclododecane decreases tumor-cell-binding capacity and cell-surface protein expression of human natural killer cells. J Appl Toxicol 30:302-9

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