Characterization of a [3H]glutamate binding site in rat pineal gland: Enhanced affinity following superior cervical ganglionectomy |
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Authors: | Laura Kus Robert J Handa John A McNulty |
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Institution: | Department of Cell Biology, Neurobiology and Anatomy, Loyola University Stritch School of Medicine, Maywood, IL, U.S.A. |
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Abstract: | Abstract: Glutamate, an excitatory neurotransmitter/neuromodulator involved in cell-to-cell communication within the central nervous system, is now believed to play a role in neuroendocrine function. In this study we describe a single, saturable, stereospecific, and temperature-, time-, and pH-dependent binding site for glutamate in the pineal gland of the rat (Kd= 612 ± 23 nM, Bmax= 3.17 ± 0.33 pmol/mg protein). After removal of the sympathetic innervation to the pineal gland, 3H]glutamate binding displayed a higher apparent affinity (Kd= 412 ± 28 nM) (P < 0.05) without a change in binding site number (Bmax= 3.60 ± 0.24 pmol/mg protein). No difference in 3H]glutamate binding site number was observed in pineal glands obtained from animals sacrificed during the middle of the light and dark periods. These data suggest a possible modulatory role for a glutamate binding site in pineal gland function. |
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Keywords: | autoradiography— excitatory amino acid— glutamate— pineal gland— superior cervical sympathectomy |
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