Project description:As an attempt to assess physio-psychological effects elicited in odorant-inhaled rats, gene expression profiling in the central nervous system was carried out with rats housed under stressful conditions. (R)-(-)-linalool inhalation to rats during 2 h restraint significantly up-regulated the expression of genes in hypothalamus, which were found to be related to neuron differentiation and regulation of transcription as well as immediate early genes. The expressions of 104 among focused stress-regulated genes were significantly altered by the inhalation. The (R)-(-)-linalool inhalation significantly repressed the restraint-induced changes in the expression levels of 77 of the 104. It also promoted the expression of the remaining 27 genes including those related to anti-apoptotic heat shock proteins. The differences in their hypothalamic gene expressions revealed that the inhaled odorants actually influenced stress responses, based on the restraint-induced hypothalamic gene expressions related to apoptosis. These results indicate that the analysis of gene expression profiles in rats subjected to a stressful condition is useful to evaluate odorant-induced effects as shown by the particular results that (R)-(-)-linalool inhalation under only 2 h restraint- stressed condition induces neuron differentiation against apoptosis.
Project description:To uncover molecular mechanisms underlying reduction of responses to restraint stress by racemic (R,S)-linalool inhalation, gene expression profiling at the hypothalamus of restraint stressed rats exposed to racemic (R,S)-linalool was carried out. Inhaled (R,S)-linalool returned the expression of 560 stress-induced probe sets to a normal status. These genes were associated with synaptic transmission via neurotransmitters including anxiolytic neuropeptides such as oxytocin and neuropeptide Y, and also included a number of major histocompatibility complex (MHC) class I necessary for neural development and plasticity. These results reveal some of the molecular mechanisms for odor inhalation under stress condition at the hypothalamus.
Project description:Formaldehyde, an important industrial chemical, is used for multiple commercial purposes throughout the industrialized world. This simple, one carbon aldehyde is a natural metabolite formed in cells throughput the body. However, it is also a rodent nasal carcinogen, when inhaled by rats every day for two-years at irritant concentrations. High tumor incidences occur at concentration of 10 ppm and above; no tumors are observed at concentrations below 6.0 ppm. The US Environmental Protection Agency (US EPA) is now (2007) conducting a risk assessment to try to evaluate possible cancer risks for much lower levels of human exposure. Sensitive methods are needed to evaluate tissue responses below those concentrations that are clearly irritant or carcinogenic. This microarray study was undertaken to evaluate the mode of action for nasal responses to inhaled formaldehyde in Fisher 344 rats over a range of exposure concentrations. The range of concentrations used spanned those at which virtually no tissue responses were observed (0.7 ppm) to those that represent the highest concentration in the cancer studies (15 ppm) that produced nasal tumors in half the exposed group of rats. The study identified doses at which there were no statistically significant changes in gene expression; intermediate doses with changes in a small number of genes not easily grouped by function; and then concentrations where changes were consistent with irritation and cell stress responses. Experiment Overall Design: Eight week old male F344/NCrl rats were exposed to formaldehyde through either instillation or inhalation. For animals exposed via instillation, 40 ul per nostril of 400 mM formaldehyde was instilled intranasally. Vehicle control animals were instilled with 40 ul per nostril of distilled water. All animals exposed via instillation were sacrificed 6 hours post-exposure. For animals exposed via inhalation, whole-body exposures were performed at doses of 0, 0.7, 2, 6, and 15 ppm (6 hours per day, 5 days per week). Inhalation animals were sacrified at 6 hours, 24 hours, 5 days, and 19 days following initiation of exposure except for the 15 ppm concentration which was sacrificed at only the 6 hour time point. Following sacrifice, tissue from the Level II region of the nose was dissected and digested with a mixture of proteases to remove the epithelial cells. The epithelial cells scquired from this section of the nose consisted primarily of transitional epithelium with some respiratory epithelium. Microarray analysis was performed on the epithelial cells.