The expression of nicotinic acetylcholine receptors by PC12 cells treated with NGF

Abstract

The expression of neuronal nicotinic ACh receptors (nAChRs) and the subunits that compose these receptors by PC12 cells exposed to NGF has been studied. The analysis of total RNA reveals that the neuronal nAChR subunits alpha 3, alpha S, beta 2, beta 3, and beta 4, but not alpha 2 and alpha 4, are expressed in our PC12 cells. Within 48 hr of adding NGF to cultures, the RNA corresponding to alpha 3, alpha 5, beta 3, and beta 4 is decreased, but the beta 2 RNA increases for up to 6 d after NGF treatment. To determine the influence of NGF treatment on subunit protein expression, subunit-specific antisera were prepared. Immunocytochemistry detected antigen for alpha 3, alpha 5, beta 2, beta 3, and beta 4 (but not alpha 2 and alpha 4) in both NGF-treated and nontreated PC12 cells. The expression of nAChR subunit proteins, as measured by direct binding of antibodies to PC12 cells, does not change subsequent to 6 d of treatment with NGF. Whole-cell recording of PC12 cells shows that both the individual cell current density and response to the agonist cytisine were not altered after 5-7 d in NGF. However, the number of cells exhibiting detectable ACh-induced currents doubled. These results indicate that NGF increases the number of PC12 cells expressing ACh-sensitive nAChR currents but the activation is not the result of altering the amounts of individual nAChR subunit proteins. These data, taken together with the decrease in most nAChR subunit RNAs (except beta 2), suggest that NGF regulation of nAChRs may be through a posttranscriptional mechanism.

Selective effects of carbamate pesticides on rat neuronal nicotinic acetylcholine receptors and rat brain acetylcholinesterase

“…The nAChRs in Torpedo electric organ are muscle-type nAChRs (for review see Karlin, 2002). PC12 cells express heteromeric neuronal nAChRs composed of ␣3, ␣5, ␤2, ␤3, and ␤4 subunits (Rogers et al, 1992) as well as homomeric ␣7 nAChRs (Drisdel and Green, 2000). The present results show that the carbamates cause inhibitory effects on four distinct subtypes of neuronal nAChRs investigated, i.e., ␣4␤2, ␣3␤2, and ␣3␤4.…”

Novel autocrine feedback control of catecholamine release. A discrete chromogranin a fragment is a noncompetitive nicotinic cholinergic antagonist.

“…4 A)? Perhaps reported differences or changes in nicotinic receptor subunit composition or stoichiometry in these models are important (56)(57)(58). Since nerve growth factor-treated PC12 cells may not be completely equivalent to noradrenergic neurons, we have not yet conclusively shown a catestatin effect upon such nerves.…”

Nicotinic Cholinergic Receptors in the Rat Cerebellum: Multiple Heteromeric Subtypes

“…Scott Rogers and Lorise Gahring (University of Utah, Salt Lake City, UT). These antisera have been described previously (Flores et al, 1992;Rogers et al, 1992). An antibody directed at a peptide sequence of the rat nAChR ␣3 subunit was affinity purified from rabbit serum.…”