Ceramide modulates nicotinic receptor‐dependent Ca²⁺ signaling in rat chromaffin cells

Abstract

Ceramide, which is an integral component of the sphingomyelin signaling pathway, can attenuate voltage-gated Ca(2+) channel (VGCC) activity in a number of cell types. The aim of the present study was to determine whether ceramide can also modulate VGCC activity, and as a consequence nicotinic receptor-dependent Ca(2+) signaling and catecholamine secretion, in rat adrenal chromaffin cells. Short-term C(6)-ceramide (CER) treatment dose-dependently inhibited nicotine (NIC)-induced peak intracellular Ca(2+) transients. Sphingomyelinase elicited similar responses, whereas the inactive ceramide analog C(2)-dihydroceramide had no effect on NIC-induced Ca(2+) transients. CER suppressed KCl- and NIC-induced Ca(2+) transients to a similar extent, suggesting that the voltage-gated Ca(2+) channel was a primary site of inhibition. In direct support of this concept, whole-cell patch-clamp analysis demonstrated that CER and sphingomyelinase significantly reduced peak Ca(2+) currents. Pretreatment with staurosporine significantly attenuated CER-dependent inhibition of both NIC-induced Ca(2+) transients and peak Ca(2+) current, suggesting that the effects of CER are mediated at least in part by protein kinase C. Consistent with suppressed Ca(2+) signaling, CER also significantly inhibited NIC-induced catecholamine secretion measured at the single-cell level by carbon fiber amperometry. This effect of CER was also significantly attenuated by pretreatment with staurosporine These data demonstrate that the sphingomyelin signaling pathway can modulate nicotinic receptor-dependent Ca(2+) signaling and catecholamine secretion in rat chromaffin cells.

Application of a customized pathway-focused microarray for gene expression profiling of cellular homeostasis upon exposure to nicotine in PC12 cells

“…In particular, ceramide activation of PKC~was shown to inhibit AKT activity [3] via a possible physical interaction between PKC~and AKT [8]. In regards to the nicotinic acetylcholine receptors, ceramide also was shown to inhibit voltage-gated calcium activity, thus leading to a reduction in the nicotine-induced Ca + signaling and catecholamine secretion in adrenal chromaffin cells [22]. In our study, we found that PKC~expression along with that of PKCh was significantly reduced in PC-12 cells exposed to nicotine for 48 h, suggesting that nicotine may play a role in altering the negative feedback on AKT activity via modulations in PKC~( Table 2 and Fig.…”

C6‐ceramide inhibited Na+ currents by intracellular Ca2+ release in rat myoblasts

“…Mediation of the action of NGF and nicotinic receptors by ceramide via the release of intracellular calcium stores has been reported (Liu et al, 2001; Numakawa et al, 2003). Using a Ca 2+ ‐free bath solution, the fast Ca 2+ ‐chelating agent BAPTA, and Ca 2+ imaging, we found that intracellular Ca 2+ release was necessary for C 6 ‐ceramide‐induced reduction of I Na .…”

“…These biological effects of ceramides are associated with the regulation of intracellular enzymes such as protein kinase C (Bourbon et al, 2000), tyrosine kinases, diacylglycerol kinase, and phospholipases (Ruvolo, 2003). It has been reported that ceramides can also act on nerve growth factor (NGF) and nicotinic receptors by the release of intracellular calcium stores in cerebellar neurons and rat chromaffin cells (Liu et al, 2001; Numakawa et al, 2003).…”

PLC‐dependent intracellular Ca2+ release was associated with C6‐ceramide‐induced inhibition of Na+ current in rat granule cells

“…It has been reported that C 6 ‐ceramide could stimulate intracellular Ca 2+ release (Liu et al. 2001; Numakawa et al.…”

“…1999; Gulbins 2003). It has been reported that C 2 ‐ and C 6 ‐ceramides can also act on nerve growth factor and nicotinic receptors by the release of intracellular Ca 2+ stores in cerebellar neurons and rat chromaffin cells (Liu et al. 2001; Numakawa et al.…”