Intact rat brain cells were dissociated and used to study the regulation of muscarinic acetylcholine receptors upon exposure to muscarinic receptor agonists. Incubation of cells with carbamylcholine resulted in a time-dependent decrease in subsequent [3H]N-methylscopolamine specific binding, an effect which reached a steady state after 3 hr at 37°C. This effect of carbamylcholine was dependent on the concentration of the agonist in the incubation medium and was due to a reduction in the maximal binding capacity of the receptor with no decrease in the affinity of the remaining receptors. This preparation might be useful in future studies to elucidate the mechanisms underlying the regulation of muscarinic acetylcholine receptors in the central nervous system.
Bibliographical noteFunding Information:
This research was supported in part by a UMAB Graduate School Research Award, an NIH Biomedical Research Support Grant 2-507-440-$770-05 and a grant from the National Science Foundation (BNS-84-06357). The authors are grateful to Ms. Anita Saulsbury and Mrs. Pat Tretter for their excellent typing and to Mr. Michael Gentry for his continuous assistance.