Erowid References Database
Snyder SH, Bennet JP.
“Neurotransmitter Receptors In The Brain: A Biochemical Identification”.
Annual Review of Physiol.. 1976;38:153-175.
INTRODUCTION Until very recently, studies of neurotransmitter receptors in the brain have relied almost exclusively on neurophysiologic techniques. Indeed, the major criterion for the identity of a compound as a neurotransmitter, that it mimic the actions of the natural transmitter, implies neurophysiologic approaches (117). However, neurophysiologic studies have some inherent limitations. For instance, when a substance is injected iontophor¸tically, the investigator does not know the exact concentration utilized and it is difficult to compare the concentrations of two administered compounds because the amount released from the micropipette depends on the electrical charge of the compound, its concentration within the pipette, and a constant unique to each micropipette, the transport number. Examining large numbers of drugs and multiple concentrations is much more readily accomplished with typical biochemical protocols permitting 1 or more assays in a day. In iontophoretic investigations, it is difficult to work with drugs that are uncharged or only weakly ionic. GENERAL PRINCIPLES IN BIOCHEMICAL LABELING OF NEUROTRANSMITTER RECEPTORS Recent successes in biochemical identification of neurotransmitter receptors in the brain derive from satisfactory solutions to certain technical issues. Labeling usually involves binding radioactive forms of the neurotransmitter itself, the agonist, or of a suitable antagonist to brain membrane preparations. However, most radioactive chemicals bind to biological membranes in a relatively nonspecific fashion, presumably due to ionic attractions, hydrophobic interactions, and van der Waal's forces. Because the density of neurotransmitter receptors in the brain appears to be in the
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