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The hypothesis that histaminergic neurons are involved in brain arousal is supported by many studies. However, the effects of the selective long-term abolition of histaminergic neurons on the sleep-wake cycle, indispensable in determining their functions, remain unknown. We have compared brain histamine(HA)-immunoreactivity and the cortical-EEG and(More)
To determine the respective role played by orexin/hypocretin and histamine (HA) neurons in maintaining wakefulness (W), we characterized the behavioral and sleep-wake phenotypes of orexin (Ox) knock-out (-/-) mice and compared them with those of histidine-decarboxylase (HDC, HA-synthesizing enzyme)-/- mice. While both mouse strains displayed sleep(More)
Tourette syndrome (TS) is characterized by tics, sensorimotor gating deficiencies, and abnormalities of cortico-basal ganglia circuits. A mutation in histidine decarboxylase (Hdc), the key enzyme for the biosynthesis of histamine (HA), has been implicated as a rare genetic cause. Hdc knockout mice exhibited potentiated tic-like stereotypies, recapitulating(More)
The hypocretins (Hcrts) (also called orexins) are two neuropeptides expressed in the lateral hypothalamus that play a crucial role in the stability of wakefulness. Previously, our laboratory demonstrated that in vivo photostimulation of Hcrt neurons genetically targeted with ChR2, a light-activated cation channel, was sufficient to increase the probability(More)
Brain histaminergic neurons play a prominent role in arousal and maintenance of wakefulness (W). H(3)-receptors control the activity of histaminergic neurons through presynaptic autoinhibition. The role of H(3)-receptor antagonists/inverse agonists (H(3)R-antagonists) in the potential therapy of vigilance deficiency and sleep-wake disorders were studied by(More)
To clarify functional roles of histamine in the circadian clock system, circadian rhythms of behavior and clock gene expression in the brain were examined in the mouse lacking histidine decarboxylase (HDC-/- mouse). Wheel-running and spontaneous locomotion were recorded under light-dark cycle (LD) and constant darkness (DD). mPer1, mPer2 and mBMAL1 mRNA(More)
We have recently suggested that the brain histamine has an inhibitory role on the behavioral effects of methamphetamine by pharmacological studies. In this study, we used the histidine decarboxylase gene knockout mice and measured the spontaneous locomotor activity, the changes of locomotion by single and repeated administrations of methamphetamine, and the(More)
Tics, such as are seen in Tourette syndrome (TS), are common and can cause profound morbidity, but they are poorly understood. Tics are potentiated by psychostimulants, stress, and sleep deprivation. Mutations in the gene histidine decarboxylase (Hdc) have been implicated as a rare genetic cause of TS, and Hdc knockout mice have been validated as a genetic(More)
BACKGROUND Statins are widely used to treat hyperlipidaemia. Their immunosuppressive effect has recently been confirmed in various immune mediated disease models. However, relatively few studies have been conducted on allergic inflammation, so the precise mechanisms of their actions against allergies have not been fully clarified. On the other hand, the(More)
Some studies suggest that the histaminergic system plays an important role in learning and memory. However, the results seem to be controversial in many behavioral tasks. In the present study, we used HDC knockout (HDC-KO) mice to investigate the effects of long-term histamine deficiency on learning and memory in contextual fear conditioning. We found that(More)