Teruhisa Komori

Potential antidepressant effects of lemon odor in rats

Antidepressant effects brought about by olfactory stimulation with various odorants were investigated with the forced swimming test, a reliable means for screening antidepressant effects. Lemon odor significantly reduced total immobility time and potentiated the imipramine-induced reduction of total immobility time in the test. This synergistic effect of lemon odor and imipramine was not due to lemon odor decreasing the metabolism of imipramine. Lemon odor decreased locomotor activity in the open field, suggesting its effects to differ from those of psychostimulants but to be similar to those of antidepressants. The effects of citral, which is one of the main components of lemon odor, were as strong as those of lemon odor. The remaining odorants tested in this study failed to have any effects on total immobility time in the forced swimming test or on locomotor activity in the open field.

Effects of repeated stress on expression of interleukin-6 (IL-6) and IL-6 receptor mRNAS in rat hypothalamus and midbrain

We examined the effects of single and repeated stress on the expression of interleukin-6 (IL-6) and IL-6 receptor (IL-6R) mRNAs in the rat midbrain and hypothalamus using reverse transcriptase-polymerase chain reaction (RT-PCR). Following a single episode of restraint stress for 4 hours (1R) or 4 hours per day on two (2R) or three (3R) consecutive days, the hypothalamus and midbrain were removed immediately and the levels of IL-6 and IL-6R mRNAs in both regions were determined. Regional differences in stress-related changes in mRNA levels were noted. The expression of IL-6 mRNA in the hypothalamus did not change in 1R group but decreased in 2R and 3R groups. The expression of IL-6R mRNA in the same region significantly diminished in all groups. In the midbrain, the expression of IL-6 mRNA increased in 1R group and decreased in 2R and 3R, while the expression of IL-6R mRNA significantly diminished in 1R and 3R groups but was not different from control in 2R group. Our findings indicate that repeated stress in rats produce changes in IL-6 and IL-6R mRNAs in the midbrain and hypothalamus that are different than those of a single stress episode.

The influence of restraint stress on the expression of mRNAs for IL-6 and the IL-6 receptor in the hypothalamus and midbrain of the rat

Using the reverse transcriptase-polymerase chain reaction (RT-PCR), we investigated the influence of restraint stress on the expression of the mRNA for interleukin-6 (IL-6) and the mRNA for the IL-6 receptor (IL-6R) in the rat brain. After rats had been restrained for 4 hours, the hypothalamus and midbrain were removed at fixed intervals up to 24 hours, and levels of IL-6 mRNA and of IL-6R mRNA in these regions were determined by RT-PCR. Restraint stress significantly enhanced the expression of IL-6 mRNA and reduced that of IL-6R mRNA in the midbrain, whereas the stress caused the reduced expression of IL-6R mRNA without any change in the level of IL-6 mRNA in the hypothalamus. After the stress, the expression of mRNAs for IL-6 and IL-6R continued to diminish in both regions. These findings indicate that the levels of mRNAs for both of IL-6 and IL-6R in the rat brain can be influenced by restraint stress.

The expressions of mRNAs for interleukin-6 (IL-6) and the IL-6 receptor (IL-6R) in the rat hypothalamus and midbrain during restraint stress.

Over the past few years, it has been reported that physical and psychological stress elevate plasma interleukin-6 (IL-6), and that neural cells can produce IL-6 and have receptors for IL-6 (IL-6R). However, it is unknown whether IL-6 plays a role in regulating the functions of neural cells in response to stress. We demonstrated recently, using the reverse transcriptase-polymerase chain reaction (RT-PCR), that the levels of mRNAs for IL-6 and IL-6R in the rat brain are changed by restraint stress for four hours. In the present study, we investigated the expression of mRNAs for IL-6 and the IL-6R in the rat hypothalamus and midbrain during restraint stress. After rats had been restrained for 10, 30, 60, 120 or 240 min, the hypothalamus and midbrain were removed immediately and levels of IL-6 mRNA and of IL-6R mRNA in these regions were determined by RT-PCR. The expression of mRNAs for IL-6 and IL-6R in both regions was reduced after short-term (30-60 min) restraint stress and tended to return toward the control level after 120 min restraint stress. After long-term (240 min) restraint stress, the level of IL-6 mRNA was significantly increased in the midbrain, while the level of IL-6R mRNA was significantly reduced in both regions. These findings suggest that the need for IL-6 might decline after short-term restraint stress and, moreover, that the synthesis and secretion of IL-6 might be enhanced and IL-6 might be needed as a neurotrophic factor in the midbrain after long-term stress.

Effects of a Long-Term Inhalation of Fragrances on the Stress- Induced Immunosuppression in Mice

The aim of this study was to determine the effects of the long-term application of various fragrances on the suppression of immune response induced by high-pressure stress in mice. The immune response was analyzed based on plaque-forming cell (PFC) count, using mice sensitized with sheep red blood cells. The decreased PFC involving thymic involution induced by high-pressure stress in mice was restored by exposing the stressed mice to tuberose, lemon, oakmoss and labdanum for 24 h following exposure to stress. The decreased PFC and thymic involution from stress were restored by exposure to lemon and oakmoss, but not to tuberose and labdanum when the mice were exposed to those fragrances continuously for 3 weeks before the stress was given, followed by exposure to the same fragrances for 24 h after the stress. The decreased PFC and thymic involution from stress were restored by exposure to lemon and labdanum for 24 h after the stress, but not to tuberose over 3 weeks before the stress was given. These data suggest that the neuroimmunomodulatory effects of fragrances may be affected by tolerance depending on the kinds of fragrances in the case of a long-term application.

Effects of single and repeated prolonged stress on mu-opioid receptor mRNA expression in rat gross hypothalamic and midbrain homogenates

This study tested the hypothesis that stress-induced opioid peptides may have stimulative and inhibitive influence on mu opioid receptor (MOR) mRNA expression and hypothalamus. Several studies have investigated the effects of stress on MOR mRNA expression in rat brain, but almost none compared the response to single versus repeated stresses. Here, we examined the effects of single and repeated stress on MOR mRNA expression in different rat brain regions using reverse transcriptase-polymerase chain reaction (RT-PCR). Following a single episode of restraint stress for 4 h (1R) or 4 h per day on 2 (2R) or 3 (3R) consecutive days, the hypothalamus and midbrain were removed immediately and MOR mRNA levels in both regions were determined by RT-PCR. Blood samples were also collected for simultaneous measurement of serum adrenocorticotropic hormone (ACTH) and corticosterone (CS). MOR mRNA expression was significantly higher in both regions in the 2R group, whereas expression levels in the 3R group did not differ from controls. In the 1R group, hypothalamic MOR expression was equivalent to that in controls, but expression was significantly higher in the midbrain. Serum ACTH levels were significantly higher only in the 1R group, whereas serum CS was significantly higher in both the 1R and 3R groups. Our findings indicate that the influence of restraint stress on MOR mRNA expression in the hypothalamus is different than in the midbrain region in rats. Endogenous opioid peptides released in response to stress may paradoxically have an effect on the HPA axis.

Effects of single and repeated stresses on the expression of mRNA for α1-adrenoceptors in the rat hypothalamus and midbrain

We examined the effects of single or repeated stress on the expression of mRNA for alpha1-adrenoceptors in the rat hypothalamus and midbrain using the reverse transcriptase-polymerase chain reaction (RT-PCR). Single stress significantly increased the mRNA level for alpha1-adrenoceptors in the midbrain, but had no effect on mRNA levels in the hypothalamus. Repeated stress significantly decreased mRNA levels for alpha1-adrenoceptors in both regions.

Psychoneuroimmunological benefits of aromatherapy

Abstract This review examines the in vivo effect of fragrances on stress-induced changes to physiological and psychological functions in both animals and humans.

The influence of physical restraint or fasting on plaque-forming cell response in mice

Abstract This study was designed to investigate the effects of 1‐ and 3‐day (16 h/day) physically restrained or fasting on immunological and endocrine responses in CBF1 mice. The influence of stressors on these responses was evaluated using anti‐sheep red blood cell plaque‐forming assay, and by examining T cell subsets, thymus weight and endocrine hormone levels. The results revealed that a significant elevation of the plaque‐forming cells (PFC) was found in spleen cells in 1‐day restrained mice, that the PFC were conversely suppressed following 3‐day physically restrained stress, and that the PFC were not affected by 1‐ or 3‐day fasting stress. Serum levels of norepinephrine were found to be significantly increased only in 1‐day physically restrained mice. No change of T cell subsets and thymus weight was found in 1‐day physically restrained mice. A significant increase in serum corticosterone levels was elicited in both 1‐ and 3‐day physically restrained mice, and 3‐day fasting mice, while increased Lyt2‐positive T cells and thymic atrophy were found only in 3‐day physically restrained mice. These findings suggest that immune function was differentially affected by the duration and types of stressors.

TYROSINE HYDROXYLASE ACTIVITY IN DISCRETE BRAIN REGIONS OF DEPRESSION MODEL RATS

Abstract: Tyrosine hydroxylase (TH) activity was measured in discrete brain regions of rats during short‐term forced running stress (FRS). TH activity was also determined in a depression‐like state and in a recovered state after a long‐term FRS. Under the short‐term FRS, the TH activity showed a significant increase in the locus ceruleus, certain limbic regions and tuberoinfundibular system. In the depression‐like state, however, there was a significant decrease in the locus ceruleus and certain limbic regions, but a significant increase was seen in the median eminence. The TH activity in recovered rats showed no difference from the level in the controls. These findings demonstrate an adaptive increase in the TH activity in relation to stress, and may also indicate a failure of adaptation in the depression‐like state.