Satiety factor oleoylethanolamide recruits the brain histaminergic system to inhibit food intake

Key factors driving eating behavior are hunger and satiety, which are controlled by a complex interplay of central neurotransmitter systems and peripheral stimuli. The lipid-derived messenger oleoylethanolamide (OEA) is released by enterocytes in response to fat intake and indirectly signals satiety to hypothalamic nuclei. Brain histamine is released during the appetitive phase to provide a high level of arousal in anticipation of feeding, and mediates satiety. However, despite the possible functional overlap of satiety signals, it is not known whether histamine participates in OEA-induced hypophagia. Using different experimental settings and diets, we report that the anorexiant effect of OEA is significantly attenuated in mice deficient in the histamine-synthesizing enzyme histidine decarboxylase (HDC-KO) or acutely depleted of histamine via interocerebroventricular infusion of the HDC blocker α-fluoromethylhistidine (α-FMH). α-FMH abolished OEA-induced early occurrence of satiety onset while increasing histamine release in the CNS with an H3 receptor antagonist-increased hypophagia. OEA augmented histamine release in the cortex of fasted mice within a time window compatible to its anorexic effects. OEA also increased c-Fos expression in the oxytocin neurons of the paraventricular nuclei of WT but not HDC-KO mice. The density of c-Fos immunoreactive neurons in other brain regions that receive histaminergic innervation and participate in the expression of feeding behavior was comparable in OEA-treated WT and HDC-KO mice. Our results demonstrate that OEA requires the integrity of the brain histamine system to fully exert its hypophagic effect and that the oxytocin neuron-rich nuclei are the likely hypothalamic area where brain histamine influences the central effects of OEA

Evaluation of Efficacy and Sedative Profiles of H1 Antihistamines by Large-Scale Surveillance Using the Visual Analogue Scale (VAS)

Background: H1 antihistamines are widely used as therapeutics for allergic diseases. Sedation is a well-known side effect of H1 antihistamines and sometimes it is life-threatening for patients. Thus it is important to evaluate the sedative properties of H1 antihistamines to avoid side effects. For this purpose, histamine H1 receptor (H1R) occupancy and proportional impairment ratios (PIR) are now being used. However, it is not easy to obtain these parameters. Here, we sought to evaluate the sedative properties of H1 antihistamines by means of a large-scale surveillance at health insurance pharmacies. Methods: The survey was conducted at 37 health insurance pharmacies. The therapeutic efficacy and the degree of sleepiness were quantified through a questionnaire using the visual analog scale (VAS) directly from 1742 patients who received H1 antihistamines. Results: The degree of sleepiness caused by the first-generation antihistamines was significantly higher than that of the second-generation antihistamines. The high VAS score in case of efficacy was found in d-chlorpheniramine, olopatadine, and ebastine. Among the mean values of efficacy, all second-generation antihistamines except for loratadine, bepotastine, and mequitazine were significantly higher than that of clemastine. Regarding the degree of sleepiness, clemastine scored the highest VAS score, and significantly lower scores were obtained in all second-generation antihistamines. Conclusions: The sedative properties of the H1 antihistamines obtained from VAS analysis were very similar to those of H1R occupancy from positron emission tomography (PET) studies and PIR from meta-analysis. Our results indicate that large-scale surveillance using VAS might be useful to evaluate the profiles of H1 antihistamines

Sho-seiryu-to Suppresses Histamine Signaling at the Transcriptional Level in TDI-Sensitized Nasal Allergy Model Rats

Background: The therapeutic use of Kampo medicine, Sho-seiryu-to (SST) in allergic disorders is well known. As histamine plays a central role in allergic diseases, it is possible that SST affects the allergy-related histamine signaling. In this study, we investigated the effect of SST on allergy-related histamine signaling in the nasal mucosa of toluene 2, 4-diisocyanate (TDI)-sensitized nasal allergy model rats. Methods: Six-week-old male, Brown Norway rats were sensitized for 2 weeks with 10 μl of 10% TDI, and after a 1 week interval, provocation was initiated with the same amount of TDI. SST (0.6 g/rat) was given orally 1 hour before TDI treatment began for a period of 3 weeks. Nasal symptoms were scored for 10 minutes immediately after TDI-provocation. The genes expression in nasal mucosa was determined using real-time quantitative RT-PCR. Results: SST significantly suppressed TDI-induced nasal allergy-like symptoms. TDI provocation showed a significant up-regulation of histamine H1 receptor (H1R) and histidine decarboxylase (HDC) gene expressions. Prolonged pre-treatment of SST significantly suppressed the mRNA levels of H1R and HDC that was up-regulated by TDI. SST also suppressed TDI-induced interleukin (IL)-4 and IL-5 mRNA elevation. However, SST showed no significant effect for TDI-induced mRNA elevation of IL-13. Conclusions: These results demonstrate that SST alleviates nasal symptoms by the inhibition of histamine signaling through suppression of TDI-induced H1R and HDC gene up-regulation. SST also suppresses cytokine signaling through suppression of IL-4 and IL-5 gene expression. Suppression of histamine signaling may be a novel mechanism of SST in preventing allergic diseases

Combined Pre-Supernova Alert System with Kamland and Super-Kamiokande

International audiencePreceding a core-collapse supernova, various processes produce an increasing amount of neutrinos of all flavors characterized by mounting energies from the interior of massive stars. Among them, the electron antineutrinos are potentially detectable by terrestrial neutrino experiments such as KamLAND and Super-Kamiokande via inverse beta decay interactions. Once these pre-supernova neutrinos are observed, an early warning of the upcoming core-collapse supernova can be provided. In light of this, KamLAND and Super-Kamiokande have been monitoring pre-supernova neutrinos since 2015 and 2021, respectively. Recently, we performed a joint study between KamLAND and Super-Kamiokande on pre-supernova neutrino detection. A pre-supernova alert system combining the KamLAND detector and the Super-Kamiokande detector is developed and put into operation, which can provide a supernova alert to the astrophysics community. Fully leveraging the complementary properties of these two detectors, the combined alert is expected to resolve a pre-supernova neutrino signal from a 15 M$_{\odot}$ star within 510 pc of the Earth, at a significance level corresponding to a false alarm rate of no more than 1 per century. For a Betelgeuse-like model with optimistic parameters, it can provide early warnings up to 12 hours in advance