Submitted to: Society for Neuroscience Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2005
Publication Date: 11/12/2005
Citation: Fisher, D.R., Bielinski, D.F., Joseph, J.A. 2005. Blueberry extract prevents c-2 ceramide disruption of ca2+ buffering in machr-transfected cos-7 cells. Society for Neuroscience Abstracts and Proceedings. Abstract No. 93.7 Interpretive Summary: NOT NEEDED
Technical Abstract: Muscarinic receptors (MAChRs) are intimately involved in various aspects of both neuronal and vascular functioning, show loss of sensitivity in aging and AD, and are selectively sensitive to oxidative stress (OSS) with MAChR subtypes with M1, M2, and M4 showing > OSS [the ability of the cell to extrude or sequester Ca2+ following depolarization by 750'M oxotremorine (oxo) and exposure to dopamine DA (1mM, 4 hrs) or A' 25-35 (100'M, 24hrs)] than M3 or M5 subtypes in transfected (tn) COS-7 cells. However, blueberry (BB) extract pretreatment prevented the DA or A'-induced deficits in Ca2+ buffering. A plethora of research suggests that the naturally occurring sphingolipid, ceramide, may have several negative cellular effects, including: oxidant formation, mitogenic stimuli, and cytokine formation. Moreover, it also appears that negative responses to ceramide increase as a function of age. Thus, the present study was carried out to determine whether: a) C2 ceramide would differentially affect M1 and M3 AchR-tn COS-7 cells and b) BB treatment would prevent any deleterious effects of C2 ceramide on oxo-induced calcium buffering. Results, thus far, have suggested that, unlike previous findings with H202 and DA, C2 ceramide disrupted oxo-induced responses in both M1 and M3 tn cells. However, BB-treatment of the cells offered protection against the effects of the C2 ceramide in M1 but not M3-tn cells. Although previous findings showed that the M3 i3 loop offered protection against DA induced deficits in Ca2+ buffering, this protection does not extend to ceramide. We are assessing possible differences in PKC isoforms (e.g., epsilon), CREB, and caspases that could account for these differences, but previous findings indicate that BB induction of protective ERK activity is higher in M1-tn COS-7 cells than those transfected with M3AChR, suggesting that magnitude of ERK signaling may be important in this protection.