Characterization of a [3H]glutamate binding site in rat pineal gland: enhanced affinity following superior cervical ganglionectomy.
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.
Kus
L
L
Department of Cell Biology, Neurobiology and Anatomy, Loyola University Stritch School of Medicine, Maywood, IL 60153.
Handa
R J
RJ
McNulty
J A
JA
D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D002940:Circadian Rhythm / Q000502:physiology; D005728:Ganglia, Sympathetic / Q000502:physiology / Q000601:surgery; D015171:Ganglionectomy; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D006863:Hydrogen-Ion Concentration; D008297:Male; D010870:Pineal Gland / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017470:Receptors, Glutamate / Q000378:metabolism*; D013237:Stereoisomerism; D013696:Temperature; D013997:Time Factors
D005971:Glutamates; D017470:Receptors, Glutamate; D018698:Glutamic Acid