Histamine ELISA Kit

Epinastine is an antiallergic drug with high selectivity for histamine receptors. It has been reported that 9,13b-dehydroepinastine is present as a metabolitein vivoin humans, but there was little information about their pharmacokinetics (PKs) in humans. Although several analytical methods have been reported for epinastine analysis in different matrices, none are available for its metabolite. Therefore, the purpose of this study was to develop an analytical method to simultaneously measure epinastine and its metabolite, 9,13b-dehydroepinastine, in human plasma samples using an ultra-performance liquid chromatography-tandem mass spectrometer. Analytes were separated on a C(18)column. Quantification of this analysis was performed on a triple-quadrupole mass spectrometer. Chromatograms showed high sensitivity, selectivity, and resolution with no interference with plasma constituents. Calibration curves for both epinastine and 9,13b-dehydroepinastine in human plasma were 0.1-50 ng/ml and displayed excellent linearity with correlation coefficients (r(2)) >0.99. The developed analytical method satisfied the criteria of international guidance and was validated. The method could be successfully applied to pharmacokinetic studies of epinastine and, for the first time, the metabolite kinetics of epinastine to 9,13b-dehydroepinastine in humans after oral administration of 20 mg epinastine hydrochloride tablets. Our study is expected to be useful in future studies such as dosage settings and clinical pharmacotherapy.

A reduction in the synthesis of the neuromodulator histamine has been associated with Tourette's syndrome and obsessive-compulsive disorder. Symptoms of these disorders are thought to arise from a dysfunction or aberrant development of corticostriatal circuits. Here, we investigated how histamine affects developing corticostriatal circuits, both acutely and longer-term, during the first postnatal weeks, using patch-clamp and field recordings in mouse brain slices (C57Bl/6, male and female). Immunohistochemistry for histamine-containing axons reveals striatal histaminergic innervation by the second postnatal week, and qRT-PCR shows transcripts for H-1, H-2, and H-3 histamine receptors in striatum from the first postnatal week onwards, with pronounced developmental increases in H-3 receptor expression. Whole-cell patch-clamp recordings of striatal spiny projection neurons and histamine superfusion demonstrates expression of functional histamine receptors from the first postnatal week onwards, with histamine having diverse effects on their electrical properties, including depolarization of the membrane potential while simultaneously decreasing action potential output. Striatal field recordings and electrical stimulation of corticostriatal afferents revealed that histamine, acting at H-3 receptors, negatively modulates corticostriatal synaptic transmission from the first postnatal week onwards. Last, we investigated effects of histamine on longer-term changes at developing corticostriatal synapses and show that histamine facilitates NMDA receptor-dependent LTP via H-3 receptors during the second postnatal week, but inhibits synaptic plasticity at later developmental stages. Together, these results show that histamine acutely modulates developing striatal neurons and synapses and controls longer-term changes in developing corticostriatal circuits, thus providing insight into the possible etiology underlying neurodevelopmental disorders resulting from histamine dysregulation.