Erfurth A, Wurtman RJ. Sensitive measurement of agonist-stimulated [3H]inositol monophosphate accumulation in rat cortical miniprisms.
BRAIN RESEARCH. BRAIN RESEARCH PROTOCOLS 1997;
1:139-44. [PMID:
9385077 DOI:
10.1016/s1385-299x(96)00022-0]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Phosphoinositide (PI) breakdown is an important transmembrane signaling mechanism in rat brain and numerous transmitter receptors are linked to this mechanism. Since agonist-stimulated PI breakdown is often changed after drug pretreatment, assessment of changes in PI breakdown represents an important tool in drug development. PI breakdown is commonly monitored by assaying [3H]inositol monophosphate ([3H]IP1) accumulation in the presence of lithium as an inhibitor of inositol monophosphatase. The present protocol presents a lithium-inhibited [3H]IP1 accumulation assay that enhances relatively weak agonist-stimulated [3H]IP1 accumulation signals by thorough oxygenation during agonist stimulation. The protocol is particularly useful in the measurement of [3H]IP1 accumulation after in vitro exposure to relatively weak stimulants, such as serotonin (5-HT), and/or after animal pretreatments that decrease the response to the agonist. In the case of 5-HT stimulation the monoamine oxidase (MAO) inhibitor, tranylcypromine, was added to the incubation medium to inhibit breakdown of exogenous serotonin. We used this protocol to measure 5-HT- and carbachol-stimulated [3H]IP1 accumulation in cortical miniprisms obtained from rats pretreated with D-fenfluramine. D-Fenfluramine is a drug that acutely releases 5-HT into the synaptic cleft and blocks its reuptake.
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