J Neurophysiol 108: 1473-1483, 2012. First published June 6, 2012; doi:10.1152/jn.00825.2011.-Previously we demonstrated that sphingosine 1-phosphate receptor 1 (S1PR(1)) played a prominent, but not exclusive, role in enhancing the excitability of small-diameter sensory neurons, suggesting that other S1PRs can modulate neuronal excitability. GS-7977 cell line To examine the potential role of S1PR(2) in regulating neuronal excitability we used the established selective antagonist of S1PR(2), JTE-013. Here we report that exposure
to JTE-013 alone produced a significant increase in excitability in a time- and concentration-dependent manner in 70-80% of recorded neurons. Internal perfusion of sensory neurons with guanosine 5′-O-(2-thiodiphosphate) (GDP-beta-S) via the recording pipette inhibited the sensitization produced by JTE-013 as well as prostaglandin E-2. Pretreatment with pertussis toxin or the selective S1PR(1) antagonist W146 blocked the sensitization produced by JTE-013. These results indicate that JTE-013 might act as an agonist at other G protein-coupled receptors. In neurons that were sensitized by JTE-013, single-cell RT-PCR studies demonstrated that these neurons did not express the mRNA for S1PR(2). In behavioral studies, injection of JTE-013 into the rat’s hindpaw produced a significant increase in the mechanical sensitivity in the
ipsilateral, but not contralateral, paw. Injection of JTE-013 did not affect buy ARS-1620 the withdrawal latency to thermal stimulation.
Thus JTE-013 augments neuronal excitability independently of S1PR(2) PF-562271 nmr by unknown mechanisms that may involve activation of other G protein-coupled receptors such as S1PR(1). Clearly, further studies are warranted to establish the causal nature of this increased sensitivity, and future studies of neuronal function using JTE-013 should be interpreted with caution.”
“Venoms of brown spiders in the genus Loxosceles contain phospholipase D enzyme toxins that can cause severe dermonecrosis and even death in humans. These toxins cleave the substrates sphingomyelin and lysophosphatidylcholine in mammalian tissues, releasing the choline head group. The other products of substrate cleavage have previously been reported to be monoester phospholipids, which would result from substrate hydrolysis. Using P-31 NMR and mass spectrometry we demonstrate that recombinant toxins, as well as whole venoms from diverse Loxosceles species, exclusively catalyze transphosphatidylation rather than hydrolysis, forming cyclic phosphate products from both major substrates. Cyclic phosphates have vastly different biological properties from their monoester counterparts, and they may be relevant to the pathology of brown spider envenomation.”
“Hyperosmotic stress has been widely explored as a means of improving specific antibody productivity in mammalian cell cultures.