Acetylcholine and acetyl-CoA metabolism in differentiating SN56 septal cell line

Abstract

The rate of acetylcholine (ACh) synthesis was found to depend on the activity of choline acetyltransferase (ChAT) and on the concentrations of the two substrates of this enzyme, choline and acetyl-CoA. In SN56 cells treated for 3 days with 1 mM dbcAMP activities of ChAT and acetylcholinesterase (AChE) were elevated. It was accompanied by an increased activity of ATP-citrate lyase (ACL)-an enzyme responsible for provision of part of acetyl-CoA for ACh synthesis in cholinergic neurons. In contrast lactate dehydrogenase (LDH) and pyruvate dehydrogenase (PDH) activities were reduced by dbcAMP. Treatment with 0.001 mM all-trans retinoic acid (RA) elevated ChAT and LDH activities but reduced the activities of AChE and ACL. The combined treatment with db-cAMP and tRA increased ChAT activity in supra-additive fashion. The effects of these two compounds on the other enzymes were not additive. Neither compound altered the activities of carnitine acetyl-transferase, acetyl-CoA synthase, or acetyl-CoA hydrolase. On the other hand, they decreased acetyl-CoA content and rate of ACh release. Overall, the results indicate that tRA upregulates only ChAT expression, whereas dbcAMP upregulates several features of cholinergic neurons including ChAT, AChE, and ACL. Low levels of acetyl-CoA in differentiated cells may result in a low rate of ACh release and resynthesis during their depolarization.

Acute and chronic effects of aluminum on acetyl-CoA and acetylcholine metabolism in differentiated and nondifferentiated SN56 cholinergic cells

“…Hence, one may assume that various pathologic conditions may be more harmful to cholinergic neurons with low acetyl-CoAsynthesizing capacity and high rate of ACh metabolism, in which acetyl-CoA shortages would be more likely to appear. In accordance with this hypothesis are our recent observations that highly differentiated cholinergic SN56 cells (DC) maintained much lower steady-state level of acetyl-CoA than the nondifferentiated ones (NC; Szutowicz et al, 1999).…”

“…On the other hand, cells cultured in the retinoic acid/dibutyryl cyclic AMP-supplemented medium possessed high activities of ChAT and ACh content but low PDH activity, acetyl-CoA level, and ACh releasing ability (Figs. 1-4, Table II; Szutowicz et al, 1999).…”

ATP-Citrate Lyase Deficiency in the Mouse

“…Moreover, citrate and hydroxycitrate stimulate and inhibit, respectively, the in vitro synthesis of acetylcholine in rat caudate nuclei (30) and perfused rat phrenic nerve (31). Also, acetyl-CoA levels in cells have been reported to correlate directly with the rate of in vitro acetyl- choline synthesis in rat caudate nuclei (32) and SN56 hybrid cholinergic cells (33).…”

Targeting of multiple metabolites in neural cells monitored by using protein-based carbon nanotubes

“…The interest about cholinergic neurons is connected to Alzheimer's disease, where their early loss is associated with a metabolic impairment in brain, whose extent is proportional to the severity of the cognitive deficits [24,25]. Furthermore, RA treatment increases SN56 vulnerability to oxidative stress, as demonstrated by an increase of caspase-3 mediated cell death [26,27] and lactate dehydrogenase activity, which is responsible for lactate production and consumption [28]. From the detected responses we can infer that the amount of glucose is not enough for a correct cell feeding, as recorded just after 4 h. Coherently, in proliferating cells our biosensors measure a massive lactate production after 4 hours, followed by a dramatic decrease within 24 h, and a sharp increase between 24 and 48 h. Furthermore, our results show that in actively proliferating cells, the lack of glucose for 24 h results in the consumption of neuronal lactate, dynamically released into the medium.…”