lilial and hydroxyisohexyl-3-cyclohexene-carboxaldehyde

We investigate in this study the biochemical effects on cells in culture of two commonly used fragrance chemicals: lyral and lilial. Whereas both chemicals exerted a significant effect on primary keratinocyte(s), HaCat cells, no effect was obtained with any of HepG2, Hek293, Caco2, NIH3T3, and MCF7 cells. Lyral and lilial: (a) decreased the viability of HaCat cells with a 50% cell death at 100 and 60 nM respectively; (b) decreased significantly in a dose dependant manner the intracellular ATP level following 12-h of treatment; (c) inhibited complexes I and II of electron transport chain in liver sub-mitochondrial particles; and (d) increased reactive oxygen species generation that was reversed by N-acetyl cysteine and trolox and the natural antioxidant lipoic acid, without influencing the level of free and/or oxidized glutathione. Lipoic acid protected HaCat cells against the decrease in viability induced by either compound. Dehydrogenation of lyral and lilial produce α,β-unsaturated aldehydes, that reacts with lipoic acid requiring proteins resulting in their inhibition. We propose lyral and lilial as toxic to mitochondria that have a direct effect on electron transport chain, increase ROS production, derange mitochondrial membrane potential, and decrease cellular ATP level, leading thus to cell death.

Topics: Acetylcysteine; Adenosine Triphosphate; Aldehydes; Animals; Antioxidants; Cell Line, Tumor; Cell Survival; Chromans; Cyclohexenes; Electron Transport Chain Complex Proteins; Glutathione; Humans; L-Lactate Dehydrogenase; Mice; Mitochondrial Membranes; NIH 3T3 Cells; Perfume; Reactive Oxygen Species; Thioctic Acid

Topics: Aldehydes; Calcium Channels; Cell Line; Cyclohexenes; Humans; Mitochondria; Nerve Tissue Proteins; Perfume; Transient Receptor Potential Channels; TRPA1 Cation Channel; TRPV Cation Channels

Vertebrate olfactory receptor neurons (ORNs) transduce odor stimuli into electrical signals by means of an adenylyl cyclase/cAMP second messenger cascade, but it remains widely debated whether this cAMP cascade mediates transduction for all odorants or only certain odor classes. To address this problem, we have analyzed the generator currents induced by odors that failed to produce cAMP in previous biochemical assays but instead produced IP(3) ("IP(3)-odors"). We show that in single salamander ORNs, sensory responses to "cAMP-odors" and IP(3)-odors are not mutually exclusive but coexist in the same cells. The currents induced by IP(3)-odors exhibit identical biophysical properties as those induced by cAMP odors or direct activation of the cAMP cascade. By disrupting adenylyl cyclase to block cAMP formation using two potent antagonists of adenylyl cyclase, SQ22536 and MDL12330A, we show that this molecular step is necessary for the transduction of both odor classes. To assess whether these results are also applicable to mammals, we examine the electrophysiological responses to IP(3)-odors in intact mouse main olfactory epithelium (MOE) by recording field potentials. The results show that inhibition of adenylyl cyclase prevents EOG responses to both odor classes in mouse MOE, even when "hot spots" with heightened sensitivity to IP(3)-odors are examined.

Topics: 1-Methyl-3-isobutylxanthine; Adenine; Adenylyl Cyclase Inhibitors; Adenylyl Cyclases; Aldehydes; Ambystoma; Animals; Cyclic AMP; Cyclohexenes; Electrophysiology; Enzyme Inhibitors; Imines; Inositol 1,4,5-Trisphosphate; Mice; Odorants; Olfactory Receptor Neurons; Phosphodiesterase Inhibitors; Signal Transduction; Smell; Stimulation, Chemical

Chemoelectrical signal transduction in olfactory neurons appears to involve intracellular reaction cascades mediated by heterotrimeric GTP-binding proteins. In this study attempts were made to identify the G protein subtype(s) in olfactory cilia that are activated by the primary (odorant) signal. Antibodies directed against the alpha subunits of distinct G protein subtypes interfered specifically with second messenger reponses elicited by defined subsets of odorants; odor-induced cAMP-formation was attenuated by Galphas antibodies, whereas Galphao antibodies blocked odor-induced inositol 1,4, 5-trisphosphate (IP3) formation. Activation-dependent photolabeling of Galpha subunits with [alpha-32P]GTP azidoanilide followed by immunoprecipitation using subtype-specific antibodies enabled identification of particular individual G protein subtypes that were activated upon stimulation of isolated olfactory cilia by chemically distinct odorants. For example odorants that elicited a cAMP response resulted in labeling of a Galphas-like protein, whereas odorants that elicited an IP3 response led to the labeling of a Galphao-like protein. Since odorant-induced IP3 formation was also blocked by Gbeta antibodies, activation of olfactory phospholipase C might be mediated by betagamma subunits of a Go-like G protein. These results indicate that different subsets of odorants selectively trigger distinct reaction cascades and provide evidence for dual transduction pathways in olfactory signaling.

Topics: Acetates; Aldehydes; Amino Acid Sequence; Animals; Benzaldehydes; Cilia; Cyclic AMP; Cyclohexenes; Cyclopentanes; Eugenol; GTP-Binding Proteins; Inositol 1,4,5-Trisphosphate; Molecular Sequence Data; Nitriles; Odorants; Olfactory Mucosa; Oxylipins; Photoaffinity Labels; Rats; Rats, Sprague-Dawley; Signal Transduction