The endogenous lipid agent N-arachidonoylethanolamine (anandamide), among other effects, has been shown to be involved in nociceptive processing both in the central and peripheral nervous systems. Anandamide is thought to be synthesised by several enzymatic pathways both in a Ca 2+ -sensitive and Ca 2+ -insensitive manner, and rat primary sensory neurons produce anandamide. Here, we show for the first time, that cultured rat primary sensory neurons express at least four of the five known Ca 2+ -insensitive enzymes implicated in the synthesis of anandamide, and that application of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-arachidonoyl, the common substrate of the anandamide-synthesising pathways, results in anandamide production which is not changed by the removal of extracellular Ca 2+ . We also show that anandamide, which has been synthesised in primary sensory neurons following the application of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-arachidonoyl induces transient receptor potential vanilloid type 1 ion channel-mediated excitatory effect that is not inhibited by concomitant activation of the cannabinoid type 1receptor. Finally, we show that sub-populations of transient receptor potential vanilloid type 1 ion channel-expressing primary sensory neurons also express some of the putative Ca 2+ -insensitive anandamide-synthesising enzymes. Together, these findings indicate that anandamide synthesised by primary sensory neuron via a Ca 2+ -insensitive manner has an excitatory rather than an inhibitory role in primary sensory neurons and that excitation is mediated predominantly through autocrine signalling.
The interaction of vacancies with 111 In atoms is studied in Hg 1Ϫx Cd x Te compounds via perturbed-angular correlation ͑PAC͒ experiments, for xϭ0.065, 0.21, 0.44, and 0.95. In the low-x ͑Hg-rich͒ compounds, Hg vacancies are created by heating in vacuum. For the xϭ0.21 alloy, we have previously shown that In C -vac C pairs ͑A centers consisting of an In atom on a cation site and a vacancy at a neighboring cation site͒ are abundant after quenching from elevated temperatures. These defects are characterized by two PAC signals with quadrupole interaction frequencies Q 1 ϭ83 MHz and Q 2 ϭ92 MHz, and asymmetry parameters 1 ϭ 2 ϭ0.08. For the xϭ0.065-0.44 alloys, the data presented in this article show that the fractions f 1 and f 2 of In atoms associated with these two frequencies vary with x according to whether one or two Hg atoms are nearest neighbors to the Te atom that is bound to the In atom and the vacancy. The data are explained by the polarizable point-ion model. For the xϭ0.95 compound, PAC signals are observed only when stable In is added to the compound, indicating that the presence of In creates vacancies, and that self-compensation via A centers is dominant. In this case, the well-known frequencies Q 4 ϭ100 MHz and Q 5 ϭ112 MHz are seen for samples quenched from several different temperatures between 325 and 525°C, or slow cooled from 475°C or below. In contrast, for a sample slowly cooled from 525°C, the frequency Q 6 ϭ60 MHz was dominant. This signal could be due to In C Ϫvac C pairs in which the vacancy is singly charged, or to In-group I pairs. We attribute the frequencies Q 4 ϭ100 MHz and Q 5 ϭ112 MHz, like Q 1 and Q 2 , to In C -vac C pairs having doubly charged vacancies.
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